MCWP 3-16.7

Marine Artillery

Survey Operations

U.S. Marine Corps 

PCN 143 000087 00 

DISTRIBUTION STATEMENT A: Approved for public; distribution is unlimited
To Our Readers

Changes: Readers of this publication are encouraged to submit suggestions and changes that

will improve it. Recommendations may be sent directly to Commanding General, Marine

Corps Combat Development Command, Doctrine Division (C 42), 3300 Russell Road, Suite

318A, Quantico, VA 22134-5021 or by fax to 703-784-2917 (DSN 278-2917) or by E-mail to

morgann@mccdc.usmc.mil. Recommendations should include the following information:

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Additional copies: A printed copy of this publication may be obtained from Marine Corps

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reference locator: http://www.doctrine.usmc.mil.

Unless otherwise stated, whenever the masculine gender is used, both 

men and women are included.
DEPARTMENT OF THE NAVY

Headquarters United States Marine Corps

Washington, D.C. 20380-1775

28 Jaunary 2002

FOREWORD

Marine Corps Warfighting Publication (MCWP) 3-16.7, Marine Artillery

Survey Operations, sets forth the doctrinal foundation and technical information

that Marines need to provide accurate and timely survey support. It covers a

broad spectrum of issues from general knowledge to Marine-specific equipment.

As one of the five requirements for accurate predicted fire, survey is critical to

the success of artillery (and ultimately maneuver) on the modern battlefield.

Marine artillery surveyors support firing units and target acquisition assets,

enabling indirect fires to mass effectively and deliver surprise observed fires

and effective unobserved fires. 

This publication applies to Marine air-ground task force (MAGTF) artillery

commanders, their staffs, and personnel in the 0844/48 military occupational

specialty (fire direction controlman), and field artillery operations chief billets,

from battery through regiment, including infantry mortarmen.

Reviewed and approved this date.

BY DIRECTION OF THE COMMANDANT OF THE MARINE CORPS

EDWARD HANLON, JR.

Lieutenant General, U.S. Marine Corps

Commanding General

Marine Corps Combat Development Command

DISTRIBUTION: 143 000087 00
Marine Artillery Survey Operations _________________________________________________________________________ iii

MARINE ARTILLERY SURVEY OPERATIONS

TABLE OF CONTENTS

Chapter 1. Fundamentals 

Section I. Mission and Duties

Survey Operation Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Coordination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Field Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Computations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Echelons of Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Regiment Survey Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Establishing Initial Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Recovering Existing Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Priorities of Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Survey Information Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Mapping, Charting, and Geodesy After Action Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Dissemination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Battalion Survey Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Areas of Concern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Categories of Starting Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Marking and Witnessing Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

Dissemination of Survey Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

Battery Survey Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

Collective Duties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

Survey Officer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

Survey Chief . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Conventional Team (Party) Chief. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Survey Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Instrument Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Recorder/Computer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

PADS Operator (PADS Team Chief) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Assistant PADS Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10

Section II. Survey Accuracy Levels and Requirements 

Geodetic Control Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10

Artillery Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10

Relative Position Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10

Probable Error Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12

Relative Azimuth Accuracy (Fourth Order). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12

Relative Azimuth Accuracy (Fifth Order) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12

Required Survey Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12
iv ________________________________________________________________________________________________ MCWP 3-16.7

Section III. Converting to Common Control

Comparisons: Why We Convert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13

Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13

Radial Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

Swinging the Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

Recomputing the Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

Computing Individual Legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15

Determining the Common Azimuth of a Critical Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15

Sliding the Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15

Swinging and Sliding the Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16

Leveling the Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17

Chapter 2. Planning

The Artillery Fire Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

The Survey Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Mission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Administration and Logistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Command and Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Mission, Enemy, Terrain and Weather, Troops and Support Available-Time Available . . . . . . . . . . . . . . 2-2

Mission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Enemy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Terrain and Weather. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Troops and Support Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Time Available. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Space and Logistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Position and Azimuth Determining System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Intersection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Astronomic Observations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

RTK/OTF GPS Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Static/Rapid Static GPS Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

The Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Arctic Areas and Cold Weather Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Desert Areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Jungle Areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Urban Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Mapping, Charting, and Geodesy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

BAMCIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Begin Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Arrange for Reconnaissance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Make Reconnaissance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Complete the Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Issue the Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

Supervise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

Survey Sketch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Marine Artillery Survey Operations __________________________________________________________________________ v

Chapter 3. Basic Geodesy 

Section I. The Geodetic System

The Geoid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Ellipsoid Defining Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Reference Ellipsoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Geoid Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Ellipsoid Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Datums. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Vertical Datums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Horizontal Datums (Geodetic Datums) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Multiple Datum Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Seven Parameter Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Five Parameter Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

WGS 72 to WGS 84. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

NAD 83 TO WGS 84. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Multiple Regression Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Lateral Shift Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Section II. Coordinate Systems

Three-Dimensional Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Cartesian Coordinates System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Geographic Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

Geodetic Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

Astronomic Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

The Prime Meridian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

Angular Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

Deflection of the Vertical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

Chapter 4. Map Projections and Grid Systems

Section I. Map Projections 

Prescribed Projections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Scale Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Map Scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Mercator Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Transverse Mercator Projection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Gauss-Kruger Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

Polar Stereographic Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

Lambert Conformal Conic Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

Oblique Mercator Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

New Zealand Map Grid Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

Cassini Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
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Section II. Grid Systems

Universal Transverse Mercator Grid System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

Military Grid Reference System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

100,000-Meter Square Identifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18

MGRS Grid Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18

Nonstandard Grids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19

World Geodetic Reference System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19

User-Defined Grid Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19

Chapter 5. Conventional Equipment 

Section I. T-2E Theodolite 

Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

Telescope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Setting Up the Tripod GST-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Mounting the T-2E on the Tripod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Plumb and Level the T-2E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

Eliminating Parallax and Adjusting Focus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

Pointings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

Reading the Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Upper Window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Central Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Bottom Window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Coincidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Circle Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Setting the Horizontal Circle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Initial Circle Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Orienting the Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Horizontal Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Position Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Multiple Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Circle Closure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Two-Position Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Vertical Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Vertical Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Determining Vertical Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10

Reciprocal Vertical Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10

March Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10

Tests and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Plate Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Circular Bubble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Optical Plumb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Horizontal Collimation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

Vertical Collimation (Index Error). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

Artificial Illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14
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Section II. DI 3000 Distomat

Range and Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14

Power Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15

Mounting the DI 3000 to a T-2E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15

Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

System Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

Prism Constant (Millimeters) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

Decimal Fix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17

Scale Correction (Parts Per Million) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18

Temperature and Barometric Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18

Relative Humity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18

Distance Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18

Parallelism: DI 3000 to Telescope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19

Checking Parallelism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19

Adjusting Parallelism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20

Section III. Target Set 

Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20

Tribrach (GDF22). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20

Target Carrier (GZR2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20

Target Plate (GZT1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21

Illumination Kit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21

Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21

Plumb and Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21

Mounting the Target Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22

Tests and Adjustments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22

Plate Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23

Circular Bubble. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23

Optical Plumb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23

Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23

Chapter 6. Traverse

Section I. Fundamentals

Open Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Closed Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Directional Traverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Sources of Control Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Field Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

Traverse Legs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
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Section II. Field Notes

Survey Recorder Duties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

General Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

Recording a One-Position Angle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

Heading and Column Titles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

STA and T Columns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

Recording Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9

Recording a Two-Position Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

Heading and Column Titles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

STA and T Columns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

Recording Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

Closing an Angle on the Horizon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

Heading and Column Titles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

STA and T Columns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

Recording Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

Recording Reciprocal Vertical Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12

Recording Angles from an M2A2 Aiming Circle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13

Heading and Column Titles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13

STA and R Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14

Recording Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14

Recording Intersection Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14

Correcting Errors and Voiding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16

Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16

Storing the Recorder’s Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-17

Section III. Trigonometry

Extending Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

Azimuth-Angle Relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

Azimuth to the Rear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

Solutions of Right Triangles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

Forming the Coordinate Triangle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

Forming the Elevation Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

Trigonometric Functions To Compute a Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

Determining Coordinate and Elevation Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

Determining the Coordinates and Elevation of the Forward Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21

Computing the Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22

Section IV. Closure

Radial Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22

Computing Radial Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23

Allowable Radial Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24

Excessive Radial Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24

Elevation Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24

Azimuth Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25

Fourth Order. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25

Fifth Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25

Accuracy Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
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Section V. Adjustment

Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27

Determining Azimuth Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27

Applying Azimuth Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27

Recomputing with Adjusted Angle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27

Coordinate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Determining Total Coordinate Corrections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Determining Station Corrections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Determining Adjusted Corrections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Offset Legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Determining Elevation Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28

Determining Adjusted Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29

Discretion Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29

Section VI. Locating Traverse Errors

Sources of Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29

Coordinate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29

Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29

Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-30

Field Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-30

Locating a Traverse Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Traverse Error Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Azimuth Good, Coordinates Good . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Azimuth Good, Coordinates Bust. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Azimuth Bust, Coordinates Good. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Azimuth Bust, Coordinates Bust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Elevation Busts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Isolation of Distance Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

Isolation of Angle Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32

Perpendicular Bisector Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33

Mil Relation Formula (WeRM Rule) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33

Analyzing Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34

Isolation of Multiple Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34

Isolation of Elevation Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34

Chapter 7. Astronomy

Section I. Basic Astronomy 

The Tilted Polar Axis and Movement of the Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Celestial Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Celestial Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Astronomic Triangle (PZS Triangle). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Polar Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Coaltitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Colatitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

Angles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

The Relationship between Solar Time and Sidereal Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

Apparent Solar Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8

Mean Solar Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
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________________________________________________________________________________________________ MCWP 3-16.7

Equation of Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9

Solar Year. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9

Concepts of Sidereal Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9

Time Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10

Daylight Saving Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11

Converting Local Mean Time to Greenwich Mean Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11

Converting Greenwich Apparent Time to Greenwich Mean Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-12

Determining the Local Hour Angle and Angle t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-12

Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-13

Section II. Artillery Astro Method 

Arty Astro Method (Sun) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-13

Position of the Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-13

Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-14

Solving the PZS Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-14

Computations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Arty Astro Method (Star) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Position of the Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Solving the PZS Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Azimuth Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Selecting Methods of Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Observation and Tracking Procedures for Sun and Stars (Arty Astro). . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-15

Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-16

The Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-16

Direct and Reverse Readings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-16

Section III. Star Selection—Polaris

Orbit of Polaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-16

Identifying Polaris. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17

Section IV. Recording Astronomic Observations 

Arty Astro Method Field Notes (Fifth Order). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18

Heading and Column Titles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18

Recording Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-19

Arty Astro Method Field Notes (Fourth Order) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-20

Heading and Column Titles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-20

Recording Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-21

Chapter 8. Position and Azimuth Determining System Operations

Capabilities and Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Vehicles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Accuracy: Zero-Velocity Corrections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Primary and Secondary Pallets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

Inertial Measurement Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

Control and Display Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
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Control and Display Unit Operator Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

Status Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

Operator Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5

DS Alerts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

Power Supply Operator Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

Computer Operator Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

IMU Operator Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

Recording PADS Field Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

PADS Mission Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8

30-Day Azimuth Gyro Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8

Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8

Updating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

Mark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

PAE Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

Chapter 9. Global Positioning System

Section I. Configuration, Signals, and Code

Satellite Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

Carrier Frequencies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

Data Sequences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

Ephemeris and Almanac Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4

Section II. System Safeguards, Error Sources, and Survivability

Selective Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Accuracy Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Antispoofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Cryptovariables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Operational Key Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5

Maintenance Key Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

Simulator Key Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

User Equipment Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

GPS Error Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

Ephemeris Errors and Orbit Perturbations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

Clock Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

Ionospheric Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7

Tropospheric Delays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7

Multipath. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7

Receiver Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7

User Equivalent Range Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8

Absolute GPS Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8

Root-Mean-Square Error Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9

Probable Error Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9

Dilution of Precision. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10

Space Segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10

Control Segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11

User Segment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11

Cryptographic Key Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11

Spoofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11
xii _______________________________________________________________________________________________ MCWP 3-16.7

Continuous Wave Jamming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12

Wide Band Jamming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12

Pulse and Amplitude Modulated Jamming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12

Jamming Effects on Code Acquisition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12

Antijam Capabilities of GPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-13

Section III. GPS Measurements

GPS Reference System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-13

Code Phase Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-13

Pseudo-random Noise Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14

Time Delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14

Satellite Ranging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15

Carrier Phase Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15

Integer Ambiguity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Carrier (Beat) Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Continuous Carrier Phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Cycle Slips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Differencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Single Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Double Differences between Satellites and Receivers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

Triple Differences between Satellites, Receivers, and Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

Baseline Solutions (Vectors). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-18

Float Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-18

Fixed Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-18

Section IV. GPS Survey Methods and Techniques

Absolute Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19

Differential (Relative) Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19

Code Phase Differential Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19

Carrier Phase Differential Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20

Static and Kinematic Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20

Chapter 10. Hasty Survey 

Hasty Position Determination Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

MSGR 4000 (AN/PSN-13) Absolute. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

PLGR (AN/PSN-11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Map Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Hasty Azimuth Determination Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Hasty Elevation Determination Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2

The M2A2 Aiming Circle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2

M2A2 Body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

Telescope Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

Body Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3

Worm Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

Base Plate Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

Associated Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

Setting Up the Tripod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5

Attach the Aiming Circle to the Tripod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5

Plumb and Level the Aiming Circle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-5

Taking Down (March Ordering) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6
Marine Artillery Survey Operations ________________________________________________________________________ xiii

Measuring Horizontal and Vertical Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6

Determining Vertical Angle Correction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6

Comparison Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6

Alternate Set up Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7

UTM Grid Declination Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7

When to Declinate an Aiming Circle (Required) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-8

Declination Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-8

Declinating the M2A2 Aiming Circle at a Declination Station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-9

Converting a Grid Magnetic Angle to a Declination Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-9

Hasty Declination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-10

Determining a Grid Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-10

Orienting the M2A2 Aiming Circle on a Known Azimuth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-10

Care of the Aiming Circle and its Associated Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-10

Maintenance Checks and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Level Vial Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Titled Reticle Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Azimuth and Elevation Micrometer Knob Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Level Line Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Magnetic Needle Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Appendices

A Star Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

B World Time Zone Offsets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

C Radio Transmitting Stations For Time Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

D Conversions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1

E Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1

F References and Related Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1

Figures

1-1 Initial Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1-2 Recovery of Existing Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1-3 MC&G AAR Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

1-4 Areas of Concern - Artillery Battalion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

1-5 Distance Accuracy and Accuracy Ratio Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11

1-6 Swinging the Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

1-7 Sliding the Grid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16

1-8 Swinging and Sliding the Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17

3-1 Undulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3-2 Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3-3 Ellipsoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3-4 Defining Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3-5 Local Reference Ellipsoid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

3-6 ECEF Ellipsoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

3-7 Geoid Separation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

3-8 Ellipsoid Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3-9 Relationship between h, H, and N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3-10 Surface-Fixed Datum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

3-11 Geocentric Datum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
xiv_______________________________________________________________________________________________ MCWP 3-16.7

Figures (Continued)

3-12 Origin Shift Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

3-13 Coordinate Planes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

3-14 Cartesian Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

3-15 Geographic Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

3-16 Parallels of Latitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3-17 Meridians of Longitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3-18 Graticule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3-19 Geodetic Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

3-20 Astronomic Coordinates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

3-21 Astronomic Longitudes of Prime Meridians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

3-22 Deflection of the Vertical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

4-1 Projection Types: Tangent and Secant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4-2 Mercator Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4-3 Mercator Projection Flattened onto a Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4-4 TM Projection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4-5 Distortion within the TM Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4-6 Secancy in a 6° Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4-7 Line Distortion and Scale Factor in the TM Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4-8 GK Projection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

4-9 Line Distortion and Scale Factor in the GK Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6

4-10 Secant Condition of Lambert Conformal Conic Projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

4-11 Cone Flattened onto a Plane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

4-12 Oklahoma Lambert Projection; North and South Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4-13 UTM/UPS Grid Zones and Grid Zone Designators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4-14 UTM Easting and Northing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

4-15 UTM Grid Convergence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

4-16 Sign of Grid Convergence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

4-17 Nonstandard UTM Grid Zones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

4-18 MGRS: 100,000-Meter Square Identification Lettering Convention for the UTM Grid, 

WGS 84/GRS 80 Ellipsoids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17

4-19 Specifications for Secondary Grids Listed in DMA TM 8358.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

4-20 Specifications for Secondary Grids not Listed in DMA TM 8358.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 4-21

5-1 T-2E Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5-2 T-2E Components (Continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5-3 GDF22 Tribrach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5-4 T-2E Focusing Sleeve and Eyepiece . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

5-5 T-2E Reticle Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

5-6 First and Third Leveling Position. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

5-7 Second and Fourth Leveling Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

5-8 Pointings on a Range Pole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

5-9 Pointings on a Target Plate (GZT1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

5-10 Pointings on a Target Reflector (GRZ3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

5-11 Pointings on an Eleven-Prism Holder (GPH11). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

5-12 View of the T-2E Scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

5-13 Sample Circle Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

5-14 Vertical Readings/Angles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
Marine Artillery Survey Operations ________________________________________________________________________ xv

Figures (Continued)

5-15 Optical Plumb Adjustment Screws. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

5-16 Computing the Corrected Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13

5-17 GEB-63 with Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13

5-18 GEB-70 NiCad Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15

5-19 GEB-70 Discharge Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15

5-20 DI 3000 Bottom View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15

5-21 T-2E Modification for DI 3000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16

5-22 DI 3000 Mounted on T-2E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16

5-23 DI 3000 Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16

5-24 Prism-Target Distance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19

5-25 Adjusting Parallelism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20

5-26 Target Set with Target Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21

5-27 Target Set with GRZ3 and GPH3Z. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21

6-1 Traverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6-2 Open Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6-3 Closed Traverse on a Second Known Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

6-4 Closed Traverse on the Starting Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

6-5 Starting and Closing Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

6-6 Rear, Occupied, and Forward Stations and Horizontal Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

6-7 Vertical Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

6-8 Reciprocal Vertical Angles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

6-9 Slope and Horizontal Distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

6-10 Reduction to Sea Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

6-11 Traverse Legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

6-12 Standard Symbols for Recording . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

6-13 Index Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

6-14 Heading and Column Titles (One-Position Angle). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

6-15 STA and T Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

6-16 Standard Order for Recording a One-Position Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9

6-17 Example of a Completed One-Position Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9

6-18 Example of a Completed Two-Position Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

6-19 Angle Closed on the Horizon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

6-20 Example of an Angle Closed on the Horizon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

6-21 Example of Recording with Reciprocal Vertical Angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12

6-22 Heading and Column Titles (M2A2 Angles) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13

6-23 Example of Recorded Data for a Hasty Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14

6-24 Heading and Column Titles (Intersection) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15

6-25 Example of Completed Intersection Method (M2A2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15

6-26 Example of a Partial Void. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16

6-27 Example of a Full-Page Void . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-17

6-28 Azimuth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18

6-29 Azimuth-Angle Relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-19

6-30 Coordinate Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-19

6-31 Elevation Triangle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

6-32 Value of Trigonometric Functions of Angles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20

6-33 Right Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21

6-34 Determining the Sign of dE and dN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
xvi_______________________________________________________________________________________________ MCWP 3-16.7

Figures (Continued)

6-35 Main Scheme Legs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22

6-36 Offset Legs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22

6-37 Traverse Closing Data Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23

6-38 Radial Error of Closure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23

6-39 Pythagorean Theorem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23

6-40 Elevation Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-24

6-41 Azimuth Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25

6-42 Azimuth Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27

6-43 Error Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-31

6-44 Plotting the Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32

6-45 Determining the Error Leg-Parallel Line Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-32

6-46 Plotting the Traverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33

6-47 Determining the Error Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33

6-48 Mil Relation Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33

7-1 Earth’s Rotational Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

7-2 Celestial Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

7-3 Zenith Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

7-4 Ecliptic and Vernal Equinox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

7-5 Right Ascension and Declination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

7-6 Vertices of the PZS Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

7-7 Polar Distance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

7-8 Coaltitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

7-9 Determining Coaltitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

7-10 Parallax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

7-11 Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

7-12 Colatitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

7-13 Parallactic Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

7-14 Hour Angle (Time Angle or Angle t). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

7-15 Azimuth Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

7-16 PZS Triangle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

7-17 Relationship between Solar Time and Sidereal Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

7-18 Concepts of Solar Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8

7-19 Concepts of Sidereal Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9

7-20 Time and Apparent Motion of the Sun. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10

7-21 Time Zone Boundaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10

7-22 Political Time Zones in the U.S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11

7-23 Time Zone Letter Designations and Corrections: Local to Greenwich Mean Time . . . . . . . . . . . . . . 7-12

7-24 Solving the Arty Astro Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-13

7-25 Orbit of Polaris. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17

7-26 Identifying Polaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17

7-27 Relationship between the Observer’s Latitude and the Vertical Angle 

to the Celestial North Pole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18

7-28 Heading and Column Titles (Fifth Order Arty Astro) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18

7-29 Remarks for Arty Astro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-19
Marine Artillery Survey Operations _______________________________________________________________________ xvii

Figures (Continued)

7-30 Field Data (Fifth Order Arty Astro) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-19

7-31 Heading and Column Titles (Fourth Order Arty Astro) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-20

7-32 Field Data (Fourth Order Arty Astro First Set). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-21

7-33 Field Data (Fourth Order Arty Astro). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-21

8-1 Inertial Measurement Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

8-2 Computer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

8-3 Control and Display Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

8-4 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

8-5 Secondary Pallet (Battery Box). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

8-6 Status Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

8-7 Porro Prism Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

8-8 The PADS Recording Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7

8-9 PADS Recording Procedures for Optical Azimuth Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8

8-10 PAE Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

8-11 Example of PAE Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10

9-1 NAVSTAR System Configuration: Space, Control, and User Segments. . . . . . . . . . . . . . . . . . . . . . . 9-1

9-2 L1 Carrier Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

9-3 L2 Carrier Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2

9-4 P Code and C/A Code Data Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3

9-5 GPS Signal Data Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3

9-6 User Equivalent Range Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8

9-7 Error Ellipse at 2-σ RMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9

9-8 Pseudo-range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14

9-9 Carrier Modulated by PRN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14

9-10 Time Delay of a GPS Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14

9-11 Ranging One Satellite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15

9-12 Ranging Two Satellites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15

9-13 Ranging Three Satellites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15

9-14 Single Differences between Receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

9-15 Single Differences between Satellites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

9-16 Double Differencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

9-17 Triple Differencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

10-1 Aiming Circle M2A2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2

10-2 M2A2 Accessory Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

10-3 Angular Value Representing UTM Grid Declination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-8

10-4 Relationship between a GM Angle and a Declination Constant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-9

Tables

4-1 TM Projection Scale Factor by UTM Easting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4-2 Projection Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

5-1 Typical Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14
CHAPTER 1. FUNDAMENTALS

SECTION I. MISSION AND DUTIES

The mission of the Marine artillery surveyor is to

provide a common grid. This means that all fire

support and targeting assets are oriented the same with

respect to azimuth, position, and elevation to a

prescribed accuracy. A common grid is based on the

sum of the components of relative survey (the geodetic

system, the coordinate system, and the map projection/

grid system) of the operational area. See chapters 3

and 4 for detailed descriptions of these components. 

Establishing a common grid is a command

responsibility. A common grid does not apply to

artillery only. It must be established throughout the

battlespace and constantly maintained for use by all

fire support assets. To provide a common grid is to

provide data to the required accuracy that permits—

l Massing of fires; i.e., bringing more than one firing

unit to bear against a common target at the same

time without prior adjustment or registration of

separate artillery units. 

l Delivery of surprised observed fires; i.e., accurate

and timely fires against enemy positions with no

adjustment. If fires must be adjusted, the element

of surprise is lost. 

l Delivery of effective unobserved fires; i.e.,

effective and timely fires against enemy positions

that are not observed (group and series targets or

prep fires). Without survey, unobserved fires can

only be effective if the target had been previously

fired on.

l Transmission of target data from one unit to

another; i.e., the ability of one firing unit to provide

locations of adjusted targets to another firing unit

for subsequent engagement by that unit or for

massing fires. 

l A firing unit to carry a registration forward to a new

position. This is necessary when moving a battery

from one primary position to another and when

moving to an alternate or supplementary position. A

common grid is also required between a firing

position and an offset registration point. 

All stations surveyed in the same network are relative

to specific points regardless of the survey methods

used (those points being the known control used to fix

and adjust those networks). Stations surveyed from

other points that have already been listed as common

are relative to those stations within that unit’s

specified level of accuracy. For example, if a battalion

survey section establishes a battery position (orienting

station [OS] and end of orienting line [EOL]) from

fourth order or higher common control, the battery

position is common to the higher order control but at a

fifth order accuracy. 

All stations surveyed from a point whose location was

obtained by hasty methods (map spot or hasty

resection) or from absolute methods (military survey

grade receiver [MSGR] 4000, precision, lightweight,

GPS, receiver [PLGR]) are common to that point.

However, they are not common to any local control.

Stations not already common to another network can

be made common by adjustment or by conversion to

common control calculations. 

For two stations to be considered common, they must

meet the requirements of the previous paragraphs.

They must be referenced to the same datum/ellipsoid

and developed from the same map projection. The grid

system or the coordinate system must be the same

between the points. They must be from the same

network or have been adjusted or converted to the

same network. 

Survey Operation Steps

Planning 

Survey planning begins with understanding the

maneuver commander’s intent and receiving the fire

support coordinator’s guidance. During planning, full

consideration is given to the commander’s concept of

operations, priorities, the tactical situation, etc.
1-2 ______________________________________________________________________________________________ MCWP 3-16.7

Aggressive survey planning that answers the questions

who, what, where, when, why, and how is essential to

mission success. See chapter 2.

Coordination

Coordination is conducted at or through the combat

operations center (COC). The survey information

center (SIC) is the liaison with the topographic

surveyors and non-artillery units requiring survey

control. The coordination and planning effort at the

COC is conducted by the highest echelon artillery

survey officer in the area of operations. The survey

plan is further coordinated with the next lower echelon

survey officer and any survey officers with higher or

adjacent commands as needed.

Field Work 

Survey field work is performed by the survey section

using the methods and equipment to extend common

survey throughout the command’s area of

responsibility as directed by the survey plan. Field

work must be started immediately upon receipt of the

survey order and be continuously and aggressively

pursued until the survey plan is completed.

Computations 

Survey computations and field work are performed

simultaneously. Computations are the use and

calculations of all data needed to convert the field

work to usable azimuths, positions, and elevations.

This includes computations of conventional surveys,

updating and adjusting position and azimuth data,

calibrating kinematic global positioning systems

(GPS) data, and adjusting static GPS data. 

Echelons of Survey 

Three echelons of artillery survey exist: regiment,

battalion, and battery as well as three accuracy

levels: fourth, fifth, and hasty. The survey section’s

mission at each echelon determines what level of

accuracy is required. 

Regiment Survey Section 

The primary mission of regiment surveyors is to

provide a common grid over the division area. This

includes establishing initial control, recovery of

existing control, and conversion to common control

over stations not in the division network. The artillery

regiment’s survey section is the division’s survey

asset. The regiment survey section—

l Normally performs fourth order surveys. In some

cases, they will be required to establish fifth order

survey control for units not already covered by a

battalion survey section or for units attached to the

regiment. 

l Establishes permanent survey control markers when

necessary. 

l Establishes and maintains an SIC to provide

required data to lower echelon survey sections to

conduct their survey missions.

Establishing Initial Control 

Usually, the tactical situation on initial entry of forces

into an area will make the recovery of existing control

impossible. However, survey operations must begin

immediately at all levels. Establishing an initial common

grid throughout the division area is of the utmost priority

for surveyors. See figure 1-1.

Initial control is the first station or network of stations

established in theater. Establishing initial control can

be done by hasty means such as absolute GPS survey

or by map spot. Initial control can also be established

as a network by static GPS methods, kinematic GPS

methods or position and azimuth determining system

(PADS). In each case, a single absolute or map spot

station is the controlling grid and usually only includes

the battalion’s position areas.

Recovering Existing Control 

The initial control will suffice to start an operation.

But continuing that operation will require recovering

existing control into the target and connection areas of

the battalions and conversion of recovered control to

the common grid throughout the entire division area.

See figure 1-2.
Marine Artillery Survey Operations ________________________________________________________________________ 1-3

This effort must continue throughout the operation

using the most accurate methods available. Static

GPS methods are preferred as their accuracy allows

for establishing accurate calibration stations for

kinematic GPS networks at regiment and battalion

levels. These stations can also be used to position new

base stations and update PADS for forward movement

of the common network. 

When necessary, survey teams can employ PADS

and conventional assets in the recovery effort.

Control that existed in the areas formally held by

enemy forces should be included in the recovery

effort as the battle progresses. Data from captured

enemy trigonometry (trig) lists can be converted to

common control for inclusion in the division

network. The recovery effort is coordinated by the

regiment survey section and will usually be

conducted by available surveyors from all echelons.

Priorities of Survey 

Priorities of survey will be established in the operation

order. Normally, priorities will be focused at the

establishment of common survey within the position

areas of the artillery battalions. Second priority will

generally be focused at the target areas of the

battalions. In some cases, target acquisition assets not

attached to a battalion will receive the highest priority

for survey. Ultimately the priority is situationdependent and cannot be standardized.

Figure 1-1. Initial Control.

Figure 1-2. Recovery of Existing Control.
1-4 ______________________________________________________________________________________________ MCWP 3-16.7

Survey Information Center 

The SIC collects, evaluates, maintains, and

disseminates survey information. It is the centralized

planning and coordination element for all survey

operations. It consists of the regiment survey officer,

the survey chief, and assigned personnel. Although the

SIC is not reflected in the table of organization (T/O),

its duties are important to establish and maintain the

common grid. The SIC is responsible for collecting the

most up-to-date information available from some of

the following agencies:

l National Imagery and Mapping Agency (NIMA). 

l National Oceanic and Atmospheric Administration

(NOAA). 

l National Ocean Survey (NOS). 

l National Geodetic Survey (NGS). 

l United States Geological Survey (USGS). 

l Bureau of Land Management (BLM). 

l U.S. Forestry Department. 

l U.S. Army Corps of Engineers (COE).

l Department of Transportation (DOT). 

l State Geodetic Survey. 

l Local: County/City surveyors. 

l Base/Post Public Works Department. 

l U.S. State Department/Embassies. 

l U.S. Naval Oceanographic Office. 

l U.S. Army Topographic/Survey Units. 

l U.S. Marine Corps Topographic Units.

l MAGTF operation and intelligence sections.

Collected information consists of more than just

survey data. It is important that the SIC maintains

information such as time zone charts, country

handbooks, training area information, and any other

information that may help accomplish the mission.

A limited number of mapping products should be

kept on hand for planning, briefing, and verifying

survey control.

Mapping, Charting, and Geodesy 

After Action Report

For SICs to provide the most current survey

information data available, a mapping, charting and

geodesy after action report (MC&G AAR) should be

expeditiously submitted by returning deployed units.

The SIC uses this report to identify areas of operation

used by MAGTFs and to provide information about

the area of operation, map products required, and

availability of survey control. Figure 1-3 shows the

outline to generate a thorough MC&G AAR about the

area of operation.

Evaluation

The regiment’s survey section also evaluates surveys

conducted by lower echelon survey sections. All

computations and values recorded in the recorders

notebook (see chap. 6) are checked for proper

procedures, specifications, and techniques to complete

survey field work to the required accuracy.

Computations performed by computers are compared to

see that both sets of computations agree. Check to ensure

that the survey has been properly closed to within the

specified accuracy. If the surveyed data passes the

procedure check, computation check, and closure check,

data is plotted on the largest scale map available to check

the validity of the survey and the accuracy of the map. If

the map plots verify the recorder’s field notebook

description, the survey is accepted.

SIC personnel are equipped and trained to also make

the following checks and computations:

l Swinging and sliding operation to convert survey

data from one grid to another.

l Transformation of coordinates and grid azimuths

between universal transverse mercator (UTM)

zones.

l Conversion of geographic coordinates to grid

coordinates and grid coordinates to geographic

coordinates.

l Datum-to-datum transformation.

Maintenance 

The SIC must maintain the information it has collected

in a usable form. A survey information map with

overlays and a survey information file allow

information to be used.
Marine Artillery Survey Operations ________________________________________________________________________ 1-5

l Unit

l Exercise/Operation Name

l Date of Operation

l Country

l Training Area

l Nearest City/Town

l Area of Operation Coverage

n By Geographic Coordinates

— Minimum Latitude

— Maximum Latitude

— Minimum Longitude

— Maximum Longitude

n By Military Grid Reference System

— NE Corner

— SE Corner

— SW Corner

— NW Corner

l Map Coverage

n Map Series

n Map Sheet Number(s)

n Ellipsoid on Map Product

n Datum on Map Product

n Grid on Map Product

n Grid Zone Used

n What Agency Produced the Map Product

l Grids to Firing Positions (six-place grid)

l Grids to Observation Posts (best available grid)

l Grids to Identify Impact Area or Safety Box

l Target Grids (six-place grid)

l Amphibious Landing Beach Grids (left and right limits or center and length)

l Route of March Used During the Operation (identify problems unique to artillery: bridge, culvert, tunnel fords, 

road restrictions or other problems)

l Restricted Areas

l Points of Contact for Range Information (include name, address, and telephone number)

l Points of Contact for Survey Information (include name, address, and telephone number)

l Trig List Information (if data was provided before deployment, list problems, lack of data, lost or destroyed control points, 

accessibility of control, any information on geodetic control)

l Survey Control Recovery/Survey Information (copies of recovery notes, new survey control point information, trig lists)

l Grid Convergence and/or Datum Transformation (if needed, what method was used?)

l General Comments (artillery-oriented or other)

l Point of Contact at Unit

Figure 1-3. MC&G AAR Outline.
1-6 ______________________________________________________________________________________________ MCWP 3-16.7

The map shows all survey control in the area of

operation. Map overlays show the locations of artillery

units, possible position areas, and other information

required by unit standard operating procedure (SOP).

Maps and overlays should also show—

l Survey control points.

l Completed surveys.

l Proposed surveys.

l The friendly situation and the enemy situation when

it might affect the planning or performance of

survey operations in the division area.

The information file should contain all information

available through all resources. A record is maintained

of field notes and computations on control points. 

The SIC must ensure that known control points are

entered into a computerized data base. All survey

control points (SCPs) in the division area of interest

and in the supported unit areas of influence should be

entered and updated. The SCP data base must be kept

current to decrease the possibility of duplicate surveys

and to rapidly exchange survey data automatically. 

The survey information sheet permits quick

identification of SCP data. This form must contain the

following information:

l Control point name and number.

l Map sheet and series number.

l UTM grid and geographic coordinates.

l Elevation.

l UTM grid zone.

l Marking method.

l Accuracy of the data.

l Description.

l Sketch.

l Methods used in determining control.

l Verification information (unit, preparer, and date).

Dissemination 

Timely dissemination of survey information is just as

important as maintaining a complete and accurate

survey information file. Survey information is

disseminated by command and control systems, radio,

telephone, personal visits, and field liaison among

survey sections.

Survey data can be stored and rapidly transmitted by

using digital command and control systems. Unit SOP

will dictate the procedures to access, store, update and

disseminate survey information between echelons. A

digital net and a voice net may be allocated to the SIC.

Security requirements outlined in the unit

communications electronic operation instructions

(CEOI) must be observed. Radio or telephone

communication is the least desirable method of

disseminating survey information. Possible errors in

transmitting and problems in orally describing the

survey station sketches may occur.

This exchange of survey information works from

higher to lower echelons and vice versa. Often the

battalion surveyor has not only conducted surveys

requiring him to provide data to regiment levels, but

he has a fresh insight as to the happenings in the

battlespace. This information must also be

disseminated to all concerned. Seemingly innocuous

information may have far reaching implications when

applied to a larger picture.

Battalion Survey Section 

The primary mission of battalion surveyors is to

provide a common grid over the artillery battalion’s

area of operations. This includes providing control to

all units, organic or attached to the battalion. The

battalion survey section may be tasked to provide

control to units requiring survey who are not attached

to the battalion but who are operating within the

battalion’s area. Due to their wide ranging and

independent operating nature, the battalion survey

section also acts as the artillery battalion’s

reconnaissance element. 

The battalion survey section will normally perform

fifth order surveys. When a battalion is operating

independently from the artillery regiment, as with a

Marine expeditionary brigade (MEB), they may be

required to establish some limited fourth order control.

Normally the battalion survey mission requires a more

timely response than is afforded with fourth order
Marine Artillery Survey Operations ________________________________________________________________________ 1-7

work. If a regiment’s survey section is included in a

follow-on force, all fourth order work performed by

the battalion must be provided to the regiment section

for inclusion in their network.

Areas of Concern 

The artillery battalion operational zone is divided into

three areas of concern: the position area, target area,

and connection area. This delineation is necessary to

plan survey operations and to aid in prioritizing

installations. See figure 1-4.

The position area is the rear most area of the artillery

battalion’s zone. Installations here are usually afforded

the highest priority. The position area includes the

artillery firing positions (alternate, supplementary, and

offset registration positions), declination stations, and

possible meteorological and radar sites. Other sites

may be included to complete the mission. 

The target area is the forward area of the artillery

battalion’s zone. Installations in this area are usually

prioritized behind position area installations. The

target area includes observation posts, targets, and

other target acquisition assets. 

The connection area is the portion of the artillery

battalion’s zone that lies between the position area and

the target area. It is called the connection area because

its main function is to connect the target and position

areas into a common network. Installations requiring

survey support that lie in this area are included in the

connection area surveys. These installations may

include radar and meteorological sites, electronic

warfare sites, mortar positions, and other sites to

complete the mission. 

The battalion survey section will not establish permanent

survey control unless it is essential to the mission. 

Categories of Starting Control 

A battalion survey section must begin survey

operations immediately. The availability of survey

control, which depends largely on the tactical

situation, terrain, and weather, may be scarce.

Although there are several ways of obtaining starting

control, the survey section uses the best available

control to begin a survey. Variations in starting control

can be grouped into four different categories:

l Known coordinates, elevation, and azimuth.

l Assumed coordinates and elevation, known azimuth.

l Known coordinates and elevation, assumed azimuth.

l Assumed coordinates, elevation, and azimuth.

Known coordinates and elevation will be obtained

from higher echelon survey sections; i.e., SIC

normally from a trig list. When known coordinates and

elevations are unavailable, they must be assumed

Figure 1-4. Areas of Concern - Artillery Battalion. through hasty survey methods. 
1-8 ______________________________________________________________________________________________ MCWP 3-16.7

Known azimuths can be obtained from several

different sources. Normally, a known azimuth will be

computed from higher echelon coordinates or

published in a trig list. When celestial bodies are

visible, an azimuth from astronomic observation is

preferred. When known azimuths are unavailable, they

must be assumed through hasty survey methods. 

Marking and Witnessing Stations

This important procedure allows for ease of site

location and identification. Mark positions with a

wooden hub and tag. Stations will be witnessed by a

wooden stake and tagged. 

The OS of any position is marked and witnessed by a

stake painted yellow, and set in the ground at an angle

pointing towards the EOL. 

The EOL of any position is marked and witnessed by a

stake painted red, and set in the ground at an angle

pointing towards the OS. 

Information written on a tag is usually subject to SOP.

The position number is the only information that must

be listed on the tag. Make sure that valuable

information is not left on a tag that the enemy may use

if discovered; e.g., grid coordinates or unit name.

Dissemination of Survey Data 

Once required surveys are completed, the accumulated

data is provided to the battalion S-3 for dissemination

to firing units and fire support assets. Data is also

forwarded to the regiment SIC. A current list of

positions is generated, and on arrival at a position, this

list is referred to for the pertinent data. Position

number blocks may be assigned by SOP to the

battalion survey sections to alleviate confusion and

expedite dissemination of data.

Battery Survey Section

The primary mission of battery surveyors is to provide

survey control inside the battery position when higher

echelon survey is not already available or to carry

control from one battery position to another. This

second position could be used as an alternate/

supplemental position or for split battery operations.

Battery surveyors will only perform hasty surveys.

Higher echelon surveyors must upgrade these surveys

when mission requirements permit.

Collective Duties 

Assigning positions within the survey section should

be administrative. Versatility and adaptability are the

keys. All section members must be familiar with and

able to perform all current survey methods regardless

of their billet. Marines must understand the advantages

and disadvantages of all current survey methods.

Thorough knowledge, individual initiative, and a

belief that some form of survey is always possible

must be the tenets of a successful survey section. The

following duties pertain to regiment and battalion

survey sections collectively. 

Survey Officer

The survey officer fights the future battle, continually

planning for the next phase of an operation. He must

maintain situational awareness of the battle through

close liaison with the intelligence officer (S-2) and the

operations officer (S-3) and by coordinating the current

survey effort with the survey chief. Duties follow:

l Advise the commander of the capabilities and

limitations of the survey section. 

l Provide input to the commander on datum and

ellipsoid selection and options. 

l Recommend SOPs to the commander. 

l Coordinate, supervise, and inspect the training of

survey personnel; preventive maintenance program

for survey equipment; communications assets, and

vehicles; and SIC if authorized at his echelon.

l Formulate the survey plan after receiving orders

from the S-3.

l Issue survey orders and brief the survey chief and

team chiefs. 

l Conduct reconnaissance.
Marine Artillery Survey Operations ________________________________________________________________________ 1-9

l Coordinate survey operations with survey officers

of higher, lower, and adjacent commands.

l Advise and assist firing units and target acquisition

sections in training for and conduct of hasty survey

operations. 

Survey Chief 

The survey chief fights the current battle by

implementing the survey officer’s plan. He acts as the

direct link between the survey officer and the teams in

the field. He keeps the survey officer apprised of the

current situation and handles any immediate problems.

Duties follow:

l Assist the survey officer. 

l Perform the duties of the survey officer in his

absence. 

l Train the survey section in the performance of

reconnaissance, communications, maintenance, and

survey operations. 

l Act as the section’s logistician. 

l Maintain liaison with the survey officer. 

l Perform other duties as directed.

Conventional Team (Party) Chief 

l Train his survey party. 

l Inform/brief his party on the survey plan.

l Execute his portion of the survey plan.

l Supervise and coordinate field operations of his

survey team. 

l Maintain liaison with the survey officer/chief.

l Supervise and inspect preventive maintenance of

section equipment, including vehicles, communications

equipment, weapons, and survey equipment. 

l Perform other duties as directed.

Survey Computer 

l Maintain the current forms for survey computations. 

l Perform independent computations during field

operations with the current survey computer

system.

l Maintain the section’s survey computer systems

including all accessories (printers, batteries, etc.). 

l Perform other duties as directed.

Instrument Operator 

l Perform preventive maintenance on the team’s

survey instruments to include operator’s

adjustments.

l Operate the instruments during field operations. 

l Read measured values to the recorder and verify the

recorded data when read back.

l Familiarize himself with the field work requirements

for all survey methods. 

l Perform other duties as directed.

Recorder/Computer 

l Perform the duties of the team chief in his absence. 

l Maintain the field recorder’s notebook for all

surveys performed by his team. 

l Neatly and legibly record measurements and survey

data in accordance with this text and local SOP. 

l Check and mean measurements determined by the

instrument operator.

l Provide required field data to the computers.

Familiarize himself with the field work

requirements for all survey methods. 

l Perform other duties as required.

PADS Operator (PADS Team Chief) 

l Execute his portion of the survey plan. 

l Maintain liaison with the survey officer/chief

during field operations. 

l Supervise and inspect preventive maintenance of

section equipment, to include vehicles, communications

equipment, weapons, and survey equipment. 

l Operate and maintains the PADS.

l Monitor the PADS control and display unit (CDU),

fault indicators, and status indicators during

operation.

l Set up and operate the T-2E theodolite during

autoreflection operations. 

l Brief the assistant PADS operator on the survey

mission and requirements. 

l Perform other duties as directed. 
1-10 _____________________________________________________________________________________________ MCWP 3-16.7

Assistant PADS Operator 

l Operate and maintain the PADS vehicle. 

l Install, operate, and maintain the communications

equipment. 

l Maneuver vehicle for autoreflection or plumb bob

positioning over an SCP or points to be established

under the direction of the PADS operator. 

l Record PADS data and maintain the field recorder’s

notebook.

l Set up range poles and establish survey stations as

directed by the PADS operator. 

l Perform the duties of the PADS operator in his

absence. 

l Perform other duties as directed. 

SECTION II. SURVEY ACCURACY LEVELS 

AND REQUIREMENTS 

Figure 1-5 shows survey accuracy levels as designated

by the NGS and the NIMA as well as the three

artillery levels.

Geodetic Control Surveys

Geodetic control surveys are high order surveys

established for the purposes of mapping, engineering,

and other projects requiring extreme accuracy.

Classifications and standards for this type of survey

are issued by the Federal Geodetic Control SubCommittee (FGCS). FGCS classification and

specifications for relative GPS surveys are listed in

FGCS manual Geometric Geodetic Accuracy

Standards and Specifications for Using GPS Relative

Positioning Techniques. FGCS classification and

specifications for conventional surveys are listed in

FGCS manual Standards and Specifications for

Geodetic Control Networks. 

Artillery Survey

Relative Position Accuracy

A relative accuracy value (accuracy ratio {AR}) can

be determined to show the position accuracy for a

survey network. AR is the ratio between the position

error and the total length of a survey. It shows the

survey length necessary to allow for 1 meter of

position error in a given survey and is expressed as a

fraction with 1 as the numerator, and the survey length

producing that error as the denominator. Required

ARs for artillery surveys are fourth order (considered

accurate to 1-meter error for every 3,000 meters

surveyed [1/3,000]) and fifth order (considered

accurate to 1-meter error for every 1,000 meters

surveyed [1/1,000]). Hasty survey is considered

accurate to 1-meter error for every 500 meters

surveyed. 
Marine Artillery Survey Operations ______________________________________________________________________ 1-11

Category Order PPM AR

GPS: Global-regional geodynamics; deformation 

measurements

AA 0.01 1:100,000,000

GPS: NGRS, “primary” networks; regional-local geodynamics; deformation measurementA 0.1 1:10,000,000

GPS: NGRS, “secondary” networks; connections to 

the “primary” network; local geodynamics; deformation measurements; high precision engineering 

surveys

B 1 1:1,000,000

GPS: NGRS (terrestrial-based), dependant surveys 

to mapping, land information, property, and engineering requirements

(C)

Class 1

Class 2-I

Class 2-II

Class 3

10

20

50

100

1:100,000

1:50,000

1:20,000

1:10,000

Conventional 1st 10 1:100,000

Conventional 2nd, Class I 20 1:50,000

Conventional 2nd, Class II 50 1:20,000

Conventional 3rd, Class I 100 1:10,000

Conventional 3rd, Class II 200 1:5,000

Conventional, Artillery 4th 333 1:3,000

Conventional, Artillery 5th 1,000 1:1,000

Conventional, Artillery HASTY 2,000 1:500

GPS accuracy standards represent at 95% confidence level.

1st, 2nd, and 3rd order conventional standards represent the ratio 1:A, when A (distance accuracy) equals the 

distance between survey points divided by the propagated standard deviation between points.

4th, 5th, and Hasty order conventional standards represent the ratio 1:A, when A (accuracy ratio) equals the total 

traverse length divided by the radial error of closure.

Figure 1-5. Distance Accuracy and Accuracy Ratio Standards.
1-12 _____________________________________________________________________________________________ MCWP 3-16.7

Probable Error Values 

For some systems or survey methods; e.g., the PADS

or GPS; probable error (PE) values describe the

accuracy. These values generally express absolute

accuracy. However, depending on the system and the

survey method, they can describe a relative accuracy.

These values may be given in terms of circular error

probable (CEP), PE or various standard deviation

values; e.g., 2 DRMS or 3 sigma. These values are

expressed in terms of a percentage of probability or

confidence that the position given is located within a

line, circle or sphere of a given size. 

PE is a value which is exceeded as often as it is not,

i.e., it has a 50% probability of occurrence. With

respect to fixation (position), the PE applies to both

East/West and North/South axes.

CEP is a radius of a circle, centered about the true

position such as that any measured or calculated

position has a 50% probability of lying within that

circle.

PE and CEP are derived from the positive standard

deviation of the measurement as (sigma σ):

PE = 0.6745.

CEP = 1.1774.

CEP = 1.7456 PE.

Relative Azimuth Accuracy (Fourth Order)

Fourth order astronomic azimuths are established by

astronomic observations, the PE of which does not exceed

0.060 mils. The considered accuracy is 0.150 mils. 

An azimuth of a line in a fourth order survey that, from

its point of origin at a fourth order astronomic azimuth

or higher order direction, has depreciated in accuracy by

a PE value of 0.030 mils per main scheme angle (using

a T-2E); or the azimuth of a line computed between two

fourth order or higher survey control points is

considered accurate to fourth order standards. The

computed azimuth is considered accurate to 0.300 mils. 

Relative Azimuth Accuracy (Fifth Order) 

Fifth order astronomic azimuths are established by

astronomic observations, the PE of which does not exceed

0.120 mils. The considered accuracy is 0.300 mils.

The azimuth of a line in a fifth order survey that, from

its point of origin at a fifth order astronomic azimuth

or higher order direction, has depreciated in accuracy

by a PE value of 0.030 mils per main scheme angle

(using a T-2E); or the azimuth of a line computed

between two fourth order or higher survey control

points is considered accurate to fifth order standards.

A fifth order azimuth cannot be obtained by

computations between a fifth order point and a point

of equal or higher order.

Required Survey Formats 

The format of the survey data provided depends on the

type of position being surveyed. 

An artillery firing position requires establishing an OS

and the EOL. The orienting line must be one of the

main scheme legs of the survey when conducting a

traverse. Both ends of the orienting line must be

occupied. The required survey data for an artillery

firing position is the operational datum and ellipsoid,

UTM easting and northing of the OS, elevation

(meters) of the OS, and the UTM grid azimuth (mils)

from the OS to the EOL. 

The survey requirement for the multiple launch rocket

system (MLRS) is the operational datum and ellipsoid,

UTM easting and northing of initialization and update

points, as well as the elevation (meters) of those points. 

An artillery radar position requires establishing an OS

and the EOL. The required survey data for an artillery

radar position is the operational datum and ellipsoid,

UTM easting and northing of the OS, elevation

(meters) of the OS, UTM grid azimuth (mils) from the

OS to the EOL, distance (meters) from OS to EOL,

and vertical angle (mils) from OS to EOL.

For radio directional finder (RDF) operations, a

meteorological measuring system (MMS) position

requires establishing an OS and the EOL. For Loran or
Marine Artillery Survey Operations ______________________________________________________________________ 1-13

very low frequency (VLF)/Omega operations, only the

OS is required. The required survey data for an MMS

position is the operational datum and ellipsoid, latitude

and longitude (decimal degrees expressed to 0.01°) of the

OS, elevation (meters) of the OS, true azimuth in decimal

degrees expressed to 0.1° from the OS to the EOL. 

A remotely piloted vehicle/unmanned aerial vehicle

(RPV/UAV) position requires establishing a tracking

control unit (TCU) and a beacon. The required survey

data for an RPV/UAV position is the operational

datum and ellipsoid, UTM easting and northing of the

TCU, elevation (meters) of the TCU, and the UTM

grid azimuth (mils) from the TCU to the beacon. 

The requirement for a declination station is the

operational datum and ellipsoid, UTM easting and

northing (accurate for map spot) and a UTM grid

azimuth (expressed to 0.1 mils) to at least two azimuth

marks in different quadrants. The true azimuth in

decimal degrees expressed to 0.01° should be provided

for declination of the met theodolite. 

The requirement for an observation post is the

operational datum and ellipsoid, UTM easting and

northing, the elevation (meters), and a UTM grid

azimuth (mils) to an azimuth mark, preferably an

intervisible observation post (OP). 

The requirement for a registration point (RP) is the

operational datum and ellipsoid, UTM easting and

northing expressed to the nearest meter, elevation

expressed to the nearest meter, and the UTM grid

azimuth expressed to the nearest mil. The azimuth

should be from the OP designated as O1 for the target

survey. However, the tactical situation may deem it

necessary to perform the registration from an OP other

than O1. Ideally, the RP should fall within the 800

mil-fan of the registering battery’s azimuth of fire. 

The survey requirement for targets other than

registration points is the operational datum and

ellipsoid, UTM easting and northing expressed to 10

meters and elevation expressed to 10 meters.

SECTION III. CONVERTING

TO COMMON CONTROL

The highest echelon survey unit in the area establishes

the common grid. Missions of lower echelon units

require they initiate survey operations immediately

without waiting for control to be established by higher

echelon units. A firing battery must use hasty methods

to establish survey so that it can provide support

immediately. It cannot wait on control from the

battalion survey section. Battalion surveyors must

provide control to the firing batteries and target

acquisition assets assigned to that battalion. They

cannot wait on regiment surveyors to provide control.

Regiment surveyors must establish control

immediately throughout the division area without

waiting for topographic surveyors or recovery of

existing control currently in enemy territory. These

initial surveys are not considered to be on a common

grid so conversion to a common grid will be required.

Comparisons: Why We Convert 

Conversion to common control is performed by

making a comparison between the higher and lower

echelon data and converting the lower echelon to the

higher echelon based on that comparison. Data is

converted to common control when higher and lower

echelon data differ by—

l 2 mils or more in azimuth.

l 10 meters or more in radial error.

l 2 meters or more in elevation. 

Azimuth 

When a comparison is made between the azimuths of a

line that is included in the higher and the lower

echelon network, the lower echelon network must be

converted to common control if the azimuths differ by

2 or more mils. For example, a firing battery uses the

hasty astro method and determines an azimuth from

the OS to the EOL of 2319.0 mils. The battalion real

time kinematic/on the fly (RTK/OTF) team arrives

and determines an azimuth of 2321.6 mils over the

same line. The difference between the higher and

lower data is 2.6 mils. The azimuth must be converted.
1-14 _____________________________________________________________________________________________ MCWP 3-16.7

Radial Error 

When a comparison is made between the coordinates

of a point that is included in the higher and lower

echelon networks, the lower echelon network must be

converted to common control when the radial error

(RE) between the stations is 10 meters or more. RE in

this case is not the RE computed for a traverse closure.

It is the straight-line distance between the higher and

lower echelon coordinates of the same station. 

Elevation 

When a comparison is made between the elevations of

a point that is included in the higher and lower echelon

networks, the lower echelon network must be

converted to common control when the difference

between the elevations is 2 meters or more. For

example, a firing battery uses hasty survey methods to

determine an OS elevation of 432 meters; the battalion

survey team uses RTK/OTF methods to determine an

OS elevation of 437.4 meters. The difference between

the two elevations is 5.4 meters. The lower echelon

data must be converted to common control.

Several methods of converting data to a common

network are available. The method used depends on

the type and amount of azimuth, coordinate, and/or

elevation error between the higher and lower echelon

data. The rest of this section discusses methods to

convert data. 

Swinging the Grid

Swinging the grid converts a lower echelon network to

the higher echelon network when the azimuth

difference is 2 mils or greater and the RE is less than

10 meters. This is usually necessary when an azimuth

is assumed in conventional survey methods. For

azimuth from PADS, differential GPS methods or by

astronomic methods, the azimuths between higher and

lower echelons will usually be within the 2-mil

specification. See figure 1-6.

Recomputing the Survey 

As long as a survey is maintained in the memory of a

survey computer program, the easiest way to convert a

Figure 1-6. Swinging the Grid.
Marine Artillery Survey Operations ______________________________________________________________________ 1-15

lower echelon network to the higher echelon grid is to

enter the higher echelon data in the survey computer

and recompute the survey.

Computing Individual Legs 

Sometimes it is not necessary to recompute the entire

traverse. For example, if a traverse has 20 legs and

only 4 of those legs are between critical stations, it

may be faster to compute individual legs. When

swinging the grid over individual legs, perform Steps

1 through 4.

Step 1. Determine the azimuth correction by subtracting

the lower echelon azimuth from the higher echelon

azimuth. For example, the azimuth assumed by a

battalion survey section is 4390 mils, the azimuth over

that leg as determined by the higher echelon section is

4387.217 mils. Determine the correction as—

Step 2. Compute the azimuth and distance between the

starting station and each critical station using the

coordinates determined in the lower echelon survey.

Step 3. Determine the adjusted azimuth to each critical

station by applying the azimuth correction determined

in Step 1 to each azimuth determined in Step 2. For

example, if the azimuth computed in Step 2 from the

starting station to the OS is 2745.354 mils, determine

the adjusted azimuth as—

Step 4. Using the adjusted azimuth from Step 3 and

the computed distance from Step 2, compute a dogleg

(offset) coordinate for each station. This step places

the critical station on common grid.

Determining the Common 

Azimuth of a Critical Line

Apply the azimuth correction from Step 1 to the

azimuth determined in the original computations. This

places the azimuth line on a common grid. For

example, if the azimuth from the OS to the EOL in the

original computations was 1537.876 mils, determine

the adjusted (common) azimuth as—

Sliding the Grid

This method converts a lower echelon network to the

higher echelon network when the azimuth difference

is less than 2 mils, and the RE is 10 meters or greater.

This is usually necessary when a position is assumed.

Sliding the grid converts to common control with the

PADS and differential GPS operations. See figure 1-7

on page 1-16.

When using differential GPS survey methods, the

conversion to common control is performed in the

software. Conversion to common control is performed

by calibrating the kinematic network for RTK/OTF

operations. Conversion to common control is

performed by changing the fixed position of the

assumed station in the TrimNet software for a static

GPS network.

For PADS operations, there is no way to convert

stored stations to common control internally to the

PADS. Converting individual stations is performed

as shown in Steps 1 and 2. 

Step 1. Determine the easting and northing correction

between the lower and higher echelon data by

subtracting the lower echelon easting and northing

from the higher echelon easting and northing. For

example, a battalion survey section updates its PADS

with a PLGR grid of E: 555267 N: 3835216. A

regiment survey team later provides common control

over that station using differential GPS methods and

determines a grid of E: 555278.32 N: 3835211.87.

Determine the correction as—

Higher 4387.217

Lower 4390.000

Correction −2.783 mils

Computed 2745.354

Correction −2.783

Adjusted Azimuth 2742.571 mils

Computed 1537.876

Correction −2.783

Common Adjusted Azimuth 1535.093 mils

Easting Northing

Higher 555278.32 3835211.87

− Lower 555267.00 3835216.00

Correction +11.32

meters

(+11.3 meters)

−4.13

meters

(−4.1 meters)
1-16 _____________________________________________________________________________________________ MCWP 3-16.7

Step 2. Apply the corrections determined in Step 1

to the easting and northing coordinates of each

critical station in the survey. For example, if the

coordinates for an OS as determined by the PADS

are E: 556782.9 N: 3836346.9, determine the

common grid coordinates as—

Swinging and Sliding the Grid

Swinging and sliding the grid converts a lower

echelon network to the higher echelon network when

the azimuth difference is 2 mils or greater and the RE

is 10 meters or greater. This is usually necessary when

position and azimuth is assumed in conventional

survey methods. If an azimuth is determined by the

PADS, differential GPS methods or astronomic

observations, the azimuths between higher and lower

echelons will usually be within the 2-mil specification.

See figure 1-8.

As long as a survey is maintained in the memory of a

survey computer program, the easiest way to convert a

lower echelon network to the higher echelon grid is to

enter the higher echelon data in the survey computer

and recompute the survey.

Swinging and sliding the grid are performed at the

same time. When swinging and sliding the grid over

individual legs, perform Steps 1 through 5.

Step 1. Determine the azimuth correction between the

higher and lower echelon networks. For example, the

azimuth assumed by a battalion survey section is 4390

mils, the azimuth over that leg as determined by the

higher echelon section is 4387.217 mils. Determine

the correction as— 

Step 2. Compute the azimuth and distance between the

starting station and each critical station using the

coordinates determined in the lower echelon survey.

Easting Northing

OS 56782.9 3836346.9

Correction +11.3 −4.1

Common OS 56794.2 3836342.8

Higher 4387.217

Lower −4390.000

Correction −2.783 mils

Figure 1-7. Sliding the Grid.
Marine Artillery Survey Operations ______________________________________________________________________ 1-17

Step 3. Determine the adjusted azimuth to each critical

station by applying the azimuth correction determined

in step 1 to each azimuth determined in Step 2. For

example, if the azimuth computed in Step 2 from the

starting station to the OS is 2745.354 mils, determine

the adjusted azimuth as—

Step 4. To place the critical station on common grid,

use the higher echelon coordinates, the adjusted

azimuth from Step 3, and the computed distance

from Step 2, compute a dogleg (offset) coordinate

for each station. 

Step 5. To determine the common azimuth of a critical

line; e.g. orienting line or target area base, apply the

azimuth correction from Step 1 to the azimuth

determined in the original computations. This places

the azimuth line on a common grid. For example, if

the azimuth from the OS to the EOL in the original

computations was 1537.876 mils, determine the

adjusted (common) azimuth as—

Leveling the Grid 

Leveling the grid converts a lower echelon network to

the higher echelon network when the elevation

difference is 2 meters or greater. This will usually

occur with a map spot and an absolute GPS elevation.

Leveling the grid is performed at the same time as the

other conversion to common methods. 

When conventional methods are used, it may be easier

to recompute the survey. 

Computed 2745.354

Correction −2.783

Adjusted Azimuth 2742.571 mils

Figure 1-8. Swinging and Sliding the Grid. 

Computed 1537.876

Correction −2.783

Common Azimuth 1535.093 mils
1-18 _____________________________________________________________________________________________ MCWP 3-16.7

When using differential GPS survey methods, the

conversion to common control is performed in the

software. For RTK/OTF operations, conversion to

common control is performed by calibrating the

kinematic network For a static GPS network,

conversion to common control is performed by

changing the fixed position of the assumed station in

the TrimNet software.

Leveling the grid by converting individual stations can

be performed as shown in Steps 1 through 3.

Step 1. When leveling or leveling and sliding the grid,

determine the elevation correction between the lower

and higher echelon data by subtracting the lower

echelon elevation from the higher echelon elevation.

For example, a battalion survey section updates its

PADS with a PLGR elevation of 356 meters. A

regiment survey team later provides common control

over that station using differential GPS methods and

determines an elevation of 352.8.

Step 2. Apply the corrections determined above to the

elevation of each critical station in the survey. For

example, if the elevation for an OS as determined by

PADS is 398.3, the common grid elevation is

determined as—

Step 3. When leveling the grid is performed with

swinging or swinging and sliding the grid, the higher

echelon elevation is used in place of the lower echelon

elevation in the computations of the doglegs to each

critical station. 

Higher 352.8

− Lower 356.0

Correction −3.2 mils

OS 398.3

Correction −3.2

Common OS 395.1 meters
CHAPTER 2. PLANNING

The commander initiates survey planning

requirements in the form of an operation order. He

states his intent, the scheme of maneuver, the rate of

movement, the anticipated enemy threat, and the

critical phases of battle.

The survey plan must be simple and adaptable to the

chaotic and rapidly changing environment of the

battlespace. It must provide required control, provide

checks, and be timely.

Ultimately, the survey plan will result in an order

issued to the survey section. Execution of the order

will ensure accurate and timely fires are delivered,

and help alleviate any lapse in fire support to the

maneuver commander.

Survey planning is conducted at all levels at the same

time. Coordination between higher, lower, and

adjacent survey sections during planning will ensure

even distribution of the work load, eliminate

duplication of work, and provide a focus of effort in

establishing a common grid.

The survey officer must have a thorough

understanding of the commander’s intent and

concept of operations and the artillery fire plan. This

understanding will allow him to prioritize the surveys

that should be conducted first and what time

constraints he has for completion. Coordination with

the commander’s staff in developing the survey plan

(primarily with the S-3 and S-2) is paramount.

The survey officer will generally receive the

commander’s guidance through the S-3. He can

provide the survey officer with operational

information that will affect the survey plan. The S-3

must be kept informed of all survey related problems

that will affect the firing units and fire support assets.

The S-2 can make available mapping, charting, and

geodesy products as well as friendly and enemy

situations for the area of operations. He may also

request information be obtained during the course of

survey operations on routes of march, road

conditions, terrain conditions, volume of refugees,

etc. He can then consider all the other factors that

will impact the survey plan.

The Artillery Fire Plan 

The artillery fire plan is part of the maneuver

commander’s operation order. It contains information

on how artillery will support the maneuver element. The

following are some essential elements:

l Allocating all artillery assets.

l Projected changes to allocating artillery assets based

on tactical contingencies in the operation order.

l The artillery commander’s concept of artillery

support.

l Priorities of survey.

l Locations of command posts. 

l Artillery targets. This may consist of a target list

worksheet and scheduling worksheet. A target list is

also included in the fire support plan that includes all

targets, not just artillery targets. This list may be needed

for planning target surveys for non-artillery targets.

l Initial positions and planned movement of units. An

overlay may be included. Unit boundaries and range

fans are shown on the overlay.

l Artillery target overlay. This overlay includes

artillery targets, fire support coordinating measures

(FSCMs), and unit boundaries.

l Observation and target acquisition plan. It outlines

mission statements for collecting specific

information, reporting requirements, positioning,

and sectors of coverage of the artillery's target

acquisition assets; e.g., forward observers (FOs),

OPs, and UAVs/RPVs.
2-2 ______________________________________________________________________________________________ MCWP 3-16.7

The Survey Plan

The survey plan is written in the five-paragraph order

format and is contained in enclosure 6 of the artillery

fire plan, Tab B to Appendix 19 (Fire Support) of

Annex C (Operations) of the Operation Order/Plan.

The five paragraphs in the survey plan will not

duplicate the higher level planning documents. Only

information necessary for the survey teams to

complete their mission is included. The five-paragraph

order as it pertains to a survey plan follows.

Situation

This paragraph describes the general situation.

Enemy covers intelligence information regarding

the enemy situation as it affects survey (routes,

weapons, etc.).

Friendly covers the friendly (higher, lower, and

adjacent units) situation.

Attachments and Detachments covers units who can

support the survey mission; e.g., security or

maintenance or units attached to the section.

Mission

This paragraph is a clear, concise statement of what

must be accomplished. 

Execution

This paragraph consists of several subparagraphs that

answer the questions who, what, where, when, and

commander’s intent. It further establishes general

methods to be used and the priority of work. 

Concept of Operations describes in detail the survey

methods to be used. 

Specific Instructions For Each Party contain specific

instructions each team needs to accomplish its

portion of the mission. Survey control to be used by

this team, general locations (6-place grids) for

required control, and information which deviates

from SOP are listed. 

Coordinating Instructions contains instructions/

information common to two or more parties (timelines,

rally points, etc.) 

Administration and Logistics

This paragraph covers information to ensure service

support is adequate for the mission; e.g., rations,

ammunition, aid stations or handling of prisoners.

Command and Signal

This paragraph covers information such as the location

of the survey officer, survey chief, chain of command,

frequencies, call signs, medical evacuation

(MEDEVAC) procedures, and communications

between survey teams.

Mission, Enemy, Terrain and Weather, 

Troops and Support Available-Time 

Available

In forming the survey plan, the survey officer must

make an estimate of the situation. Mission, enemy,

terrain and weather, troops and support availabletime available (METT-T) provides the framework for

that estimate. Considerations include but are not

limited to the following.

Mission

The tactical mission of the artillery unit and supported

unit(s) will determine the priority of survey work and

the accuracy required. It also gives an understanding

of the tactical situation surveyors will be operating in

(defensive, offensive, high intensity or low intensity).

Rules of engagement, FSCMs, and boundaries may

hinder survey operations by restricting survey

methods or access to survey control points.

Enemy

The enemy situation has a tremendous influence on

survey operations. Disposition of enemy troops may
Marine Artillery Survey Operations ________________________________________________________________________ 2-3

interfere with or limit the movement and capabilities

of survey personnel. Communications restrictions

(radio silence or jamming) can greatly reduce a survey

team’s effectiveness. 

The ability of the enemy to degrade survey operations

by denying terrain or route of march is a prime

consideration. Surveyors must be able to readily

identify enemy vehicles and positions they may

encounter, and be trained to call for and adjust fires on

those targets. The survey section must be equipped

and trained to take immediate action to respond to the

type of enemy force they may encounter (regular

troops, militia, guerrillas, etc.) Enemy air capabilities

are also of importance due to the vulnerability of

survey teams. Lengthy initialization times with PADS

or occupying traverse and GPS stations leave

surveyors exposed to air attack and observation.

Terrain and Weather

Terrain and weather encountered will be a primary

factor in determining the survey method, and, to some

extent, the priority of installations to be surveyed first.

The survey planner must be familiar with the influence

of terrain and weather on survey operations. Adverse

weather conditions greatly reduce the capability of the

survey teams. Fog, rain, snow, or dust can make

observation through optical instruments virtually

impossible. Extreme heat or cold decrease efficiency,

and increase the time needed to complete survey.

Reconnaissance to determine the suitability of terrain

for the installation to be surveyed is vital. Alternative

areas may be required once the proposed position has

been reconnoitered.

Troops and Support Available

Personnel and equipment available to perform the

survey mission greatly affects the plan. The level of

training determines the methods and time required to

complete the mission. Availability and condition of

surveying equipment may further dictate what

methods can be used and the time required.

Availability of fire support depends largely on the

tactical mission of the artillery unit; i.e., direct support

(DS), general support (GS), general support-reinforced

(GS-R) or reinforce (R). 

Time Available

The time available to complete the survey is critical in

planning. Providing the required data within the time

allotted may result in a loss of accuracy. The

commander must be advised of any possible loss in

accuracy due to time constraints and decide if this is

acceptable. Time limitations may often be implied or

ambiguous and require clarification.

METT-T elements are interrelated and must be

considered together. It is a dynamic framework, not a

checklist. Other factors may have an effect on a survey

plan but are not necessarily covered in METT-T; e.g.,

refugees or political/diplomatic agreements.

Space and Logistics

For the survey planner, space is restricted to his

operational area, within his unit’s boundaries.

Available survey control may only exist outside these

boundaries thus requiring additional coordination and

planning.

Availability of logistical support must be considered

in all planning. The survey section has a wide array

of equipment that may need servicing or repair.

Regardless of the survey method used, surveyors rely

heavily on their motor transport assets to complete

their mission. At the same time they are operating

over a broad area far from their logistics base. Chow,

ammunition, water, and petroleum, oil, and

lubricants (POL) are just some of the supply issues

that must be addressed. 

In addition to evaluating the factors of METT-T, the

survey officer must also understand the

characteristics of the different survey methods, their

advantages and disadvantages, and their impact on

mission accomplishment.
2-4 ______________________________________________________________________________________________ MCWP 3-16.7

Position and Azimuth Determining System

The PADS is a vital survey asset. Its primary

advantage is how fast it provides survey data.

Consider the following:

l Is existing control accessible with a military

vehicle? If not, is existing control within 16 meters

of a location that will allow autoreflection?

l Is the mission within the PADS operational limits?

l Speed limitations for PADS vehicle:

n Cross-country: 10 kilometers per hour.

n Unimproved roads: 25 kilometers per hour.

n Improved roads: 50 kilometers per hour.

l Time limitations for PADS vehicle:

n 30-day bias: 2-3 hours.

n Initialization: 30-45 minutes.

n Update/mark: 5 minutes.

n Autoreflection: 15 minutes.

n Mission time: unlimited.

l Is existing common control available within 55

kilometers of the planned update point that can be

used for future updates?

l Does PADS support the operational ellipsoid in the

operation order? If not, is user-defined data

available? 

l Does PADS meet the accuracy requirements for the

unit being supported? 

Traverse

Traverse is the preferred conventional survey method.

Consider the following: 

l Is existing control available of the proper accuracy?

Are azimuth marks available for computed

azimuths, or do azimuths have to be determined by

astronomic observations?

l Is the area of operations within the UTM north and

south limits? If not, can the section perform manual

computations?

l Planning considerations:

n Distances traversed: 1-20 kilometers per hour

(line of sight-dependent). 

n LOS clearing (jungle): 100 meters per hour.

n Forest: 1 kilometer per hour.

l How far is existing control from the area requiring

survey?

l How much line of sight cutting is required? Is

engineer equipment available to help cut line of

sight; e.g., chain saws, weed eaters or bulldozers?

l Is the control accessible by military vehicles or does

equipment have to be carried into the area?

l What are the accuracy requirements? 

l What means of communications between team

members is available? (Radio, panel marker, hand

and arm signals, etc.)

l Will traverse provide a timely enough response to

the need for survey data?

Intersection

This is the primary method of survey used to

determine target locations. Considerations for

intersection include visibility, the accessibility and

availability of control, azimuth marks, and

communications between teams. Intersection can also

provide update and initialization points for PADS or

locate other critical points other than targets.

Astronomic Observations

When weather conditions allow the observation of

celestial bodies, the arty astro method is the primary

means used to determine an azimuth. The firing

battery’s primary method of astronomic observation is

hasty astro. Consider the following:

l Do weather conditions allow observations of

celestial bodies?

l Are celestial bodies within allowable observation

windows relative to time and position?

l What is the required accuracy?

l Is accurate time available?

RTK/OTF GPS Survey

RTK/OTF is the newest method available to Marine

artillery surveyors. Accuracy achieved is well above

that required for most artillery survey missions. It is

the fastest method available to provide survey data.
Marine Artillery Survey Operations ________________________________________________________________________ 2-5

Consider the following:

l Is existing control available or will the base station

be operated in the absolute mode? If control is

available, is there enough control of adequate

accuracy available to be used as calibration points?

l Are enough communications assets available to

provide each GPS team with a voice radio and an

additional single channel ground and airborne radio

system (SINCGARS) radio for digital

communications between the receivers?

l Have communications lines of sight been verified in

the areas requiring control? If not, has a map

reconnaissance shown that communications lines of

sight are clear?

l Are alternate sites available for the base station

when communications are not available or the

tactical situation forces evacuation of the original

position?

l What is the required accuracy?

l Is electronic line of sight to the satellites available?

If not, is engineer equipment (chain saws, weed

eaters, bulldozers, etc.) available to help cut

electronic line of sight?

l Are planned base receiver sites within 10

kilometers of installations requiring survey? If not,

are supplemental positions available? 

l What are the enemy radio direction finding assets?

Static/Rapid Static GPS Survey

Static/rapid static survey is the most accurate method

available. Static GPS methods provide geodetic level

accuracy and establish high order survey networks.

Consider the following:

l Is time available for occupation of sites and post

processing?

l Is existing control of sufficient accuracy to allow

for adjustment of GPS measurements?

l If no control is available, can absolute stations be

established distant enough (at least 50

kilometers) from each other to allow for

adjustment of GPS measurements?

The Environment

Survey operations must continue regardless of

environmental factors such as climate and terrain. 

Arctic Areas and Cold Weather Conditions

Arctic areas and cold weather conditions provide the

surveyor with unique problems that must be overcome

if the surveyor is to provide adequate survey control to

supported units. For the most part, arctic regions

provide the same problems as cold weather conditions

anywhere else. When committing survey teams to

field operations in extreme cold, the effects of ice,

movement, snowfall, prevailing wind, light refraction,

and other peculiarities must be considered. 

Cold seasons can provide the advantages of reduced

transportation difficulties in river, lake, and tundra

regions. Survey control can be extended easily along

riverbanks, large bodies of water or over the relatively

level, treeless plains of the arctic tundra.

Equipment malfunctions increase in cold weather

conditions. 

PADS operates without performance degradation at

temperature extremes as low as -50°F (-45°C).

Initialization will take longer but the heat exchanger

exhaust can be covered by a blanket or field jacket to

help reduce heat loss. The vehicle heater should be

used along with windbreaks to maintain an operational

temperature for the PADS. 

Optical equipment must be acclimatized before use

in cold weather conditions. Temperature equilibrium

will affect both the scales and optics of equipment.

Optical equipment should be stored in an area with

conditions as close to possible as those conditions

where they will be used. 

Personnel must be trained in the use of cold weather

equipment and cold weather field expedients.

Existing survey control in arctic regions is sparse to

say the least. Locating existing control will take longer

than in warm weather conditions. This is due in part to
2-6 ______________________________________________________________________________________________ MCWP 3-16.7

a lack of reference points to help identify or witness

the stations as well as the need to dig through snow

and ice to find it. Surveyors must understand that a

pick and shovel can cause severe damage to a survey

control point and that care must be taken when digging

for control. 

Desert Areas

A very large percentage of the world is covered by

desert. Operations in desert regions are a common

occurrence. These regions provide for their own

unique obstacles for surveyors. While the open terrain

and normally clear skies allow for long lines of sight

and an abundance of celestial bodies for observation,

other problems do exist.

PADS operates without performance degradation at

temperature extremes as high as 125°F (50°C). Sand

and dust will clog the PADS air vents and cause the

PADS to quickly overheat. Covering the PADS to

protect it from sand will have the same effect as the

sand itself. Post operation maintenance including

blowing the air vents clean is more important in desert

regions than in any other environment.

Optical equipment must be shaded during leveling and

protected from sand when not in use. Leveling vials

increase about 2 graduations past true center in

temperatures above 100°F and at temperatures

reaching 120°F, leveling may be impossible. The most

obvious obstacle to survey operations with optical

equipment is heat waves. Eyestrain is more prevalent

and instrument operator changes are more frequent.

Observing long distances may not be possible. At

those temperature extremes, survey operations using

optical equipment should be avoided.

Personnel must be trained in desert operations. Noise

and light discipline are more important in desert

regions than other environments. Personnel should be

trained in desert survival techniques since the time

necessary to acclimatize is not normally available. 

Existing control in desert areas, like arctic regions, is

sparse and hard to locate. The lack of reference points

and blowing sand will increase the time needed to

locate these stations.

Jungle Areas

Jungle areas provide obstacles to surveyors such as

heat, humidity, and a lack of adequate mapping

products. Line of sight is a major concern, even for

GPS operations, depending on the type of canopy.

Jungle heat will effect the equipment much like desert

heat; however, humidity will increase the effects of

heat on personnel and create fogging problems for

optical equipment.

Maps for most jungle areas are inadequate except for

coastlines, rivers, and roads.

Existing control will usually be located on

mountaintops. This may preclude the use of PADS

with those stations. Optical line of sight is a major

problem for conventional teams, as is electronic line of

sight for GPS teams.

Urban Areas

Survey in built-up or urban areas is restricted by

line of sight, communications, the enemy situation,

and accuracy.

PADS operations in urban areas may be the preferred

method due to line of sight restrictions.

Communications are also restricted due to the limited

range of FM radios in built-up areas.

The tactical situation has a strong influence on

survey operations in urban areas. The enemy can be

well hidden in sewers, ladder wells, and windows or

on rooftops. Enemy obstacles; e.g., mines or

barricades, may deny the use of certain terrain or

routes needed for the extension of survey through or

around a built-up area.

Locations of installations are a concern in urban areas.

OPs may have to be placed on rooftops, firing

positions in airports, parks, or riverbeds.

Reconnaissance and planning are essential for proper

use of survey assets in urban areas. 
Marine Artillery Survey Operations ________________________________________________________________________ 2-7

Mapping, Charting, and Geodesy 

Often, mapping products and existing control will be

of a different ellipsoid and datum combination than

prescribed in the operation order. Surveyors may be

required to perform datum-to-datum transformations

from the local datum to the operational datum and

develop overlays and provide insight to datum

problems and transformation accuracy. Most fire

support assets and survey computational devices do

not provide for computations outside of the UTM

system or the nonstandard grid zones that exist in and

around Norway. See chapter 4. 

BAMCIS

The steps for generating the survey plan are found in

the acronym BAMCIS.

Begin Planning

Review the commander’s intent, scheme of

maneuver, and the artillery fire plan. This

information is used with trig lists and intelligence

information to develop maps and overlays that

include survey control, current and planned firing

positions, and fire support asset locations.

Priorities can also be determined at this time as to the

installations or control that will be surveyed first. 

A warning order should be issued to the survey chief

and party chiefs to allow for preparation of personnel

and equipment to conduct the reconnaissance.

Using the information above and knowledge of the

capabilities and limitations of the section’s personnel

and equipment, make a tentative plan. Also perform a

map recon and mentally walk through the tentative

plan to ensure it will meet all requirements.

Arrange for Reconnaissance

Once the tentative plan is formulated, a thorough

ground reconnaissance should be made (if time and

the tactical situation permit.)

The survey chief ensures the required personnel and

equipment are prepared to conduct the reconnaissance.

The route of march (with check points) and a brief

itinerary should be provided to the S-2 and S-3. This

will allow for coordination with higher, lower, and

adjacent units, ensuring safe passage of the teams

involved. Consideration should be given to challenges,

passwords, and communications during the recon.

Coordination of the logistics requirements of the

reconnaissance should be addressed to the S-4.

Supplies, fuel, repairs, etc., may be provided by units

located in or near the area to be reconnoitered.

Additional security requirements should also be

requested through the battalion.

Make Reconnaissance

Only those Marines essential to accomplish the recon

should accompany the survey officer. Limit the

amount of equipment taken. During the recon mission

the survey officer should—

l Verify map data.

l Determine validity of his plan.

l Assess trafficability of routes and the condition of

terrain.

l Note weather conditions.

l Note changes to any intelligence information

received from the S-2.

l Make any changes necessary.

Complete the Plan

Upon returning from the reconnaissance the survey

officer finalizes his plan. The survey order is

written and briefed to the S-3. If time permits, the

survey plan is added to the artillery fire support

plan. The S-2 is also briefed on any changes to the

intelligence fire support plan. The S-2 is also
2-8 ______________________________________________________________________________________________ MCWP 3-16.7

briefed on any changes to the intelligence

information he provided previously.

Issue the Order

The survey officer issues the survey order to the entire

section in the form of a five-paragraph order. The

order may be written or oral. If oral, certain

information should be provided to the survey teams

separately, i.e., strip maps or trig lists.

The order should be simple, direct, and thorough. All

the information required to complete the mission

should be given to the surveyors to allow for action

in the absence of further orders. The order should

describe what needs to be accomplished and when.

The priorities, accuracy, and the methods to be used

should be stated together. Once teams depart they

must be able to use their initiative and the

information from the order to deal with the friction

that is bound to occur.

Use of a terrain model and/or a map during the brief is

of great importance for Marines to visualize the

mission and what is expected of them.

Time should be provided at the end of the brief for any

questions that may arise. This ensures a thorough

understanding of the mission.

Any acceptable deviations from current SOP should

be specifically noted.

Supervise

Once the survey order has been issued and teams

begin their portions of the plan, the survey chief

supervises conduct of the mission while the survey

officer begins the planning process all over again, and

coordinates with the S-3 on future operations. 

As the current mission progresses and the situation

changes, subsequent orders will be issued as frag

orders. The survey chief must maintain close

liaison with the survey officer and add to his

situational awareness.

Survey Sketch 

A survey sketch must reflect the survey order. It is

prepared and provided to the survey teams before the

order is issued so that each portion of the survey

mission is understood. The sketch should be as

detailed as possible without hindering the flexibility of

the survey plan. 

Draw the sketch to scale. Use a large-scale map or

plotting chart for surveys covering large areas or to

enlarge small surveys.

Make the sketch self-explanatory.

Show all known and required control. General

locations (6-digit grids) can be used for required

installations.

Label all points.

Draw a north arrow for orientation purposes if a map

is not used.

Include routes that must be taken for security purposes

and restricted areas; e.g., hazards or obstacles. 

For PADS operations, a detailed sketch is not always

necessary. Often, a strip map or route overlay that

includes known and required control may suffice. 

Prepare a sketch for an RTK/OTF roving team much

the same way as that for a PADS team. 

For a static GPS survey, include all stations in the

network, not just the stations planned for that team.

Include prescribed routes and in some cases preplanned observation times. 

A conventional survey sketch must be more detailed

than a PADS team sketch. Along with the information

above, show—

l All traverse stations.

l All horizontal angles drawn from the rear station to

the forward station. 

l Starting and closing azimuths as a dashed line with

an arrow pointing towards the azimuth mark.

Since the survey sketch includes a large amount of

information that can be useful to the enemy, it must

not be compromised. Destroy it if a serious threat of

capture exists. 
 CHAPTER 3. BASIC GEODESY

SECTION I. THE GEODETIC SYSTEM

A geodetic system serves as a framework for

determining coordinates on the Earth’s surface with

respect to a reference ellipsoid and the geoid. It consists

of both a horizontal datum and a vertical datum. 

The Geoid

The geoid is the equipotential surface in the gravity

field of the Earth that coincides with the undisturbed

mean sea level (MSL) extended through the

continents. It is the zero reference for elevation, a

closed surface of equal gravitational force. It is

perpendicular to the direction of gravity and closely

approximates MSL and the extension of MSL through

the land masses of the Earth.

The geoid is affected by variances in the density, type,

and amount of land mass that push up through the

water or lie below it, causing dips and swells over its

surface, thus conforming to an equal force of gravity

over that surface. The dips and swells are called

undulations. See figure 3-1.

Gravity pulls perpendicular to the geoid. This means

that a plumb line lies perpendicular to the geoid and

establishes a vertical direction of measurement. An

adjusted level vial is centered when it lies parallel with

the geoid and establishes a horizontal reference at a

specific location. The geoid provides a common

reference for elevation wherever the surface of the

geoid intersects a land mass is generally referred to as

approximate MSL. 

Elevation is the distance between a point on the

Earth’s surface and the geoid, measured along a line

perpendicular to the geoid (plumb line). Points

lying outside (above) the geoid have a positive

elevation; points inside (below) the geoid have a

negative elevation. Elevation can be referred to as

orthometric height or MSL height. Elevation is

labeled “H”. See figure 3-2.

Ellipsoid Defining Parameters

An ellipsoid is a surface whose plane sections (cross

sections) are ellipses or circles, or the solid enclosed

by such a surface. It can be more easily identified as a

sphere that is flattened or squashed on the sides or the

Figure 3-1. Undulation. top and bottom. In geodesy, we use an ellipsoid that is

Figure 3-2. Elevation.
3-2 ______________________________________________________________________________________________ MCWP 3-16.7

flattened on the top and bottom; i.e., an oblate

ellipsoid. The terms ellipsoid and spheroid are

interchangeable. See figure 3-3.

An ellipsoid is generally defined by three parameters

(or dimensions) that provide the size and ellipticity of

the ellipsoid. See figure 3-4.

The semi-major axis is the distance along the

equatorial plane of an ellipsoid from the center of that

plane to its edge or the equatorial radius. It is referred

to as the long radius of an ellipsoid or one-half of the

largest diameter and is labeled “a”. 

The semi-minor axis is the distance in a meridional

plane from the center of the plane to its closest edge,

or the polar radius. It can also be referred to as the

short radius of the ellipsoid or one-half of the shortest

diameter. It is labeled “b”. 

The flattening is the ratio of the difference between

the equatorial and polar radii (semi-major and semiminor axes to the equatorial radius (semi-major axis).

It is labeled “f”. It is more commonly expressed as

the inverse of flattening (1/f). Flattening can also be

called ellipticity. 

Other defining parameters for ellipsoids are discussed

in NIMA TR 8350.2, Department of Defense World

Geodetic System 1984, and DMA TM 8358.1,

Datums, Ellipsoids, Grids, and Grid Reference

Systems. Parameters include Earth gravity

information, angular velocity, and eccentricity.

Surveyors do not need to understand these parameters;

they are not discussed in this publication.

The three defining parameters discussed above will

not always be available. A user can compute the third

parameter from two known parameters using the

following formulas:

For the semi-minor axis (b) use b = a(1-f) 

Example: Geodetic Reference System (GRS)-80

ellipsoid

First, determine f: 1/f = 298.257222101 

so f = 0.00335281068118

Second, determine b: b = a(1-f) 

a = 6378137 (1 - 0.00335281068118) 

b = 6356752.31414 

NIMA published value for b is 6356752.3141.

For flattening (1/f) use f = (a-b)/a 

Example: GRS-80 ellipsoid

First, determine f: f = (a-b)/a 

f = (6378137 - 6356752.3141)/6378137 

f = 0.00335281068751 

Second, determine 1/f: 

Flattening = 1/0.00335281068751 

1/f = 298.257221538 

NIMA published value for 1/f is 298.257222101. 

Figure 3-3. Ellipsoid.

Figure 3-4. Defining Parameters.
Marine Artillery Survey Operations ________________________________________________________________________ 3-3

These computations may provide a quantity that

differs slightly than the accepted NIMA parameters.

This is generally due to rounding and is considered

insignificant for many geodetic applications and for all

artillery survey applications.

Reference Ellipsoid

The oblate ellipsoid is used in geodesy because it is a

regularly shaped mathematical figure. Unlike the

geoid, there is no undulation. If the geoid were

regularly shaped, there would be no need for an

ellipsoid. We would simply compute surveys

referenced strictly to the geoid. Since that is not the

case, an ellipsoid is defined and then fixed to a

specific location (usually located on the surface of

the geoid) and orientation that makes it closely

resemble the surface of the geoid. This is

accomplished by establishing a horizontal datum.

Once an ellipsoid is fixed by a specific datum, it

becomes a reference ellipsoid. 

Reference ellipsoids can be local in extent or global. If

the ellipsoid resembles only a small region of the

geoid and is fixed to a point on the surface of the

Earth, it is local. If the ellipsoid is fixed to the center

of mass of the Earth and is designed to resemble the

geoid as a whole, then it is global and is called an

Earth-centered Earth-fixed (ECEF) ellipsoid. See

figures 3-5 and 3-6.

Geoid Separation

Geoid separation is the distance from the geoid to the

reference ellipsoid, measured along a line that is

perpendicular to the ellipsoid. It is positive when the

geoid lies outside the ellipsoid; negative when the

geoid lies inside the ellipsoid. Geoid separation is

labeled “N” and is also called geoidal height or

undulation of the geoid. See figure 3-7. 

Figure 3-7. Geoid Separation.

Figure 3-5. Local Reference Ellipsoid. Figure 3-6. ECEF Ellipsoid.
3-4 ______________________________________________________________________________________________ MCWP 3-16.7

Ellipsoid Height

Ellipsoid height is the distance from a point on the

Earth’s surface to the reference ellipsoid, measured

along a line that is perpendicular to the ellipsoid.

Ellipsoid height is labeled “h” and can be referred to

as geodetic height. See figure 3-8.

The relationship between ellipsoid height (h),

elevation (H), and geoid separation (N) is shown in the

formula h= H+N. See figure 3-9. 

Datums

A datum is any numerical or geometrical quantity or

set of such quantities which may serve as a reference

or base for other quantities. Two types of datums are

generally considered by surveyors: Vertical and

horizontal. When the term datum is used by itself, it is

usually referring to a horizontal datum. Vertical and

horizontal datums are generally defined separately

from each other. For example, horizontal positions in

the Korean peninsula may be defined by the Tokyo

Datum referenced to the Bessel ellipsoid; while

vertical positions are defined by the geoid referenced

to the MSL datum.

Vertical Datums

A vertical datum is a level surface or arbitrary level to

which elevations are referred. Usually, the geoid

(mean low level) is that surface. However, other

vertical datums may include MSL, the level at which

the atmospheric pressure is 29.92 inches of mercury

(1013.2 millibars of mercury {MBS}) or an arbitrary

starting elevation. Vertical datums are usually defined

as a surface of “0” elevation and are also called

altitude datums.

Since it is impossible to determine exactly where the

geoid intersects a land mass, it is impossible to use the

geoid as the actual vertical datum. Historically, tide

gauge measurements were averaged over 19 years to

establish a local MSL. (These MSL datums are very

close to the geoid but not exactly.) For this reason

level lines run from tide gauge marks in different

regions do not connect exactly at the same elevation.

In the United States, the National Geodetic Vertical

Datum (NGVD) of 1929 replaced the MSL 1929 and

has since been updated to the North American Vertical

Datum (NAVD) 1988. This new vertical datum, based

on tide gauge measurements and precise geodetic

leveling, has extended a common vertical network to

most of the continental United States. The NAVD is

considered to be within a few meters of the geoid.

There is greater uncertainty in the relationship

between other local vertical datums and the geoid

throughout the world.

Because of the uncertainty between local MSL datums

and the geoid and unknown exact relationships

between those datums, all elevations should be

considered to be referenced to the MSL datum to shift

between vertical datums.

Figure 3-8. Ellipsoid Height.

Figure 3-9. Relationship between h, H, and N.
Marine Artillery Survey Operations ________________________________________________________________________ 3-5

Horizontal Datums (Geodetic Datums) 

A horizontal datum is a set of quantities that fix an

ellipsoid to a specific position and orientation. The

point where the ellipsoid is fixed is called the datum

point. There are two types of datums: surface-fixed

and geocentric.

A surface-fixed horizontal datum is a set of quantities

relating to a specific point on the surface of the Earth

that fixes an ellipsoid to a specific location and

orientation with respect to the geoid in that region.

The center of the ellipsoid and the center of mass of

the Earth do not coincide. Examples are North

American datum (NAD) 27, Tokyo, and ARC 1950.

See figure 3-10.

A surface-fixed datum is generally defined by

five quantities: latitude (φ), longitude (λ), and geoid

height (N) at the datum point; semi-major axis (a), and

either semi-minor axis (b) or flattening (f) of the

reference ellipsoid. A geodetic azimuth is sometimes

listed as a defining parameter for a horizontal datum. 

A surface-fixed datum can cover very small areas to

very large regions of the Earth. The geoid separation at

the datum point is generally zero. However, as you

move away from the datum point, the geoid separation

increases, creating the need for a new datum. Often,

the same ellipsoid fixed to a different location and

orientation is used.

A geocentric horizontal datum specifies that the center

of the reference ellipsoid is placed at the center of

mass of the Earth. This point at the center mass of the

Earth is also the datum point. Examples are the World

Geodetic Systems (WGSs). See figure 3-11.

At least eight constants are required to define a

geocentric datum. Three specify the location of the

origin of the coordinate system; three specify the

orientation of the coordinate system; and two specify

the reference ellipsoid dimensions.

Geocentric datums generally cover a large area of the

world and in some cases are global in extent. The

geoid separation remains relatively small for the

entire region covered by the datum. The WGS

developed by the DMA are global coverage datums;

WGS 84 is the newest and most accurate. A WGS

offers the basic geometric figure of the Earth

(ellipsoid) as well as an associated gravity model

(geoid). This is why the geoid separation remains

relatively small over the entire system (generally less

than 102 meters within WGS 84).

Multiple Datum Problems

Over 1,000 datums exist. Practically every island or

island group in the Pacific Ocean has its own datum.

Many areas are covered by multiple datums. This

causes the most concern for surveyors who must

decide which datum to use and how to convert data

between them. Mapping products established from

different datums will not match at the neatlines nor

will grid lines meet. Target acquisition assets will

provide inaccurate data to firing systems if the target

acquisition system is not on the same datum as the

firing system.

Figure 3-10. Surface-Fixed Datum.

Figure 3-11. Geocentric Datum.
3-6 ______________________________________________________________________________________________ MCWP 3-16.7

The WGS was developed to create a global system

that would alleviate many of these problems. NIMA

will eventually revise all mapping and charting

products to reference WGS 84 as the datum/ellipsoid

for the entire world except for the United States.

Mapping and charting products for the United States

will reference GRS 80 as the ellipsoid and NAD 83 as

the datum. 

All datums are defined relative to WGS 84. For this

reason, transformations between datums are

performed from and to WGS 84. When converting

from surface-fixed datum 1 to surface-fixed datum 2,

first transform datum 1 to WGS 84; then transform the

WGS 84 datum to datum 2.

To develop datum shift parameters, coordinates on

both datums at each of one or more physical locations

must be known. Typically, for shifts from a local

datum to WGS 84, the WGS 84 coordinates were

derived from Doppler satellite observations over

points with already existing surface-fixed datum

coordinates. Several methods of datum transformation

are available. The rest of this section discusses them.

Seven Parameter Model

This geometric transformation model assumes that the

origins of the two coordinate systems are offset from

each other, that the axes are not parallel, and that there

is a scale difference between the two datums. Data

from at least three well-spaced positions are needed to

derive a seven parameter geometric transformation.

The seven parameters come from differences in the

local and WGS 84 cartesian coordinate. There are

three axis rotation parameters, a scale change, and

three origin shift parameters (ΔΧ, ΔΥ, ΔΖ). The

origin shift parameters are the coordinates of the

origin of the local reference ellipsoid in the WGS 84

cartesian coordinate system. Use of the seven

parameter method is prescribed by standardization

agreement (STANAG) 2211, Geodetic Datums,

Ellipsoids, Grids, and Grid References, for some

applications in Europe and England. It is considered

more accurate than the five parameter model. See

figure 3-12. 

Five Parameter Model

This model considers only the relative sizes of the

ellipsoids and the offset differences in their origins.

The five parameters are the difference in the semimajor axes (Δα), the difference in flattening (Δfx104

),

and the three origin shift parameters (ΔΧ, ΔΥ, ΔΖ).

Origin shift parameters are the coordinates of the

origin of the local reference ellipsoid in the WGS 84

cartesian coordinate system. This model is used in

computing standard Molodensky equations and is

considered accurate to 5 to 10 meters. 

WGS 72 to WGS 84

Formulas transforming between these two geocentric

datums were created when WGS 84 was developed.

These formulas are discussed in detail in NIMA TR

8350.2. Care must be taken when using them to

determine the source of the WGS 72 coordinates. If

the WGS 72 coordinates were transformed from

original local datum coordinates, then a direct local

datum to WGS 84 transformation is more accurate.

NAD 83 to WGS 84

These two datums are considered the same. The GRS

80 is the reference ellipsoid for NAD 83. It was

Figure 3-12. Origin Shift Parameters.
Marine Artillery Survey Operations ________________________________________________________________________ 3-7

developed before WGS 84 and was a factor in

upgrading WGS 72. When developing WGS 84, three

of the system’s four defining parameters were made

identical to the parameters used for GRS 80. The only

difference was the gravity model. The two datums are

considered identical in all areas covered by NAD 83

except for the Aleutian Islands and Hawaii where a

datum transformation is necessary.

Multiple Regression Equations

Multiple regression equations (MRE) were developed

to deal with distortion on local datums. Datum shifts

were created to reflect regional variations within the

coverage area. This method is considered more

accurate than the seven and five parameter models,

usually 1 to 3 meters. 

Lateral Shift Method

When transforming between datums referenced to the

same ellipsoid, a constant shift (Δφ, Δλ) can be

determined that is adequate for artillery survey

applications over a small area. For example, both NAD

27 and Puerto Rico datums are referenced to the Clarke

1866 ellipsoid. A shift in latitude and longitude can be

computed over stations common to both datums, then

applied to stations that need to be transformed. The

lateral shift method produces accurate data for the

entire island of Vieques, Puerto Rico. 

SECTION II. COORDINATE SYSTEMS

Three-Dimensional Positioning 

The location of a point on the surface of the Earth is

generally represented by coordinates. A coordinate

system is a three-dimensional positioning system

represented by a set of three quantities, each

corresponding to angles or distances from a specified

origin. The origin is generally either the center or the

surface of a reference ellipsoid. Three-dimensional

coordinates should not be confused with plane

coordinates that are two-dimensional and are usually

related to a grid system.

Cartesian Coordinates System

Cartesian coordinates identify the location of a unique

three-dimensional (x,y,z) position in space. The

system consists of the origin and three coordinate

planes. See figure 3-13.

The origin is the intersection point of the three

coordinate planes and is located at the center of the

reference ellipsoid. When the origin is also located at

the center mass of the Earth, it is considered geocentric.

The three mutually perpendicular coordinate planes

intersect in three straight lines called coordinate axes.

The axes intersect at right angles at the origin.

The x-axis lies on the equatorial plane of the reference

ellipsoid at the intersection of the equatorial plane and

the plane containing the prime meridian. It is

Figure 3-13. Coordinate Planes.
3-8 ______________________________________________________________________________________________ MCWP 3-16.7

perpendicular to the plane containing the y- and z-axes.

The x-axis is positive from the origin to the

prime meridian.

The y-axis lies on the equatorial plane of the reference

ellipsoid, perpendicular to the x-axis. It is

perpendicular to the plane containing the x- and z-axes.

The y-axis is positive east of the prime meridian. 

The z-axis corresponds to the rotational axis of the

reference ellipsoid (semi-minor axis). It lies

perpendicular to the plane containing the x- and y-axes.

The z-axis is positive from the origin to the North Pole.

The position of a point on the Earth’s surface is

described in terms of x, y, and z coordinates. These

coordinates are distances, usually in meters, from the

plane formed by two axes to the point along a line that

is perpendicular to the plane and parallel to the third

axis. See figure 3-14.

An x coordinate is the length of a line in the x-y

plane that is parallel to the x-axis and measured from

the y-z plane.

A-y coordinate is the length of a line in the x-y plane

that is parallel to the y-axis and measured from the

x-z plane.

A-z coordinate is the length of a line that is parallel to

the z-axis and is measured from the intersection of the

x coordinate and the y coordinate to a point on the

surface of the Earth. The coordinates of the origin

are (0,0,0).

Geographic Coordinates

Geographic coordinates are any three-dimensional

coordinate system that specifies the position of a point

on the surface of the Earth in terms of latitude (φ),

longitude (λ), and ellipsoid height (h). It is an

inclusive term that describes geodetic and astronomic

positions. See figure 3-15. 

Latitude and longitude are generally represented in

degrees or degrees, minutes, and seconds along with a

cardinal direction corresponding to a hemisphere on

the Earth. A position will never have more than 60

minutes in a degree and never more than 60 seconds in

a minute.

Latitude lines are called parallels of latitude. Latitude

originates at the Equator at 0°. It increases toward the

North and South Poles to 90°. It is labeled N or + for

positions in the northern hemisphere; S or - for

positions in the southern hemisphere; i.e. 34°N, +34°,

34°S, -34°. See figure 3-16. 

Figure 3-14. Cartesian Coordinates.

Figure 3-15. Geographic Coordinates.
Marine Artillery Survey Operations ________________________________________________________________________ 3-9

Longitude lines are called meridians of longitude.

Longitude originates with 0° at the Greenwich

Meridian for most geographic systems; however, some

systems reference other meridians as the 0° origin or

prime meridian. Longitude increases east and west

toward the International Dateline at 180°. In the

eastern hemisphere, longitude is labeled E or +; in the

western hemisphere, it is labeled W or -. For example,

107°E, +107°, 107°W, -107°. In some cases, the

position of a point may include a longitude in excess

of 180° E. These are converted to the standard format

by subtracting the longitude from 360° e.g., 206°E =

154°W. The North and South Poles do not have a

longitude. See figure 3-17.

A network of lines on a map representing parallels of

latitude and meridians of longitude is called a

graticule. A graticule can represent the entire globe or

a small region of the Earth. See figure 3-18. 

The inclination of two meridians toward each other is

called convergence of the meridians, or more

commonly convergence. All meridians of longitude

are parallel at the Equator and intersect at the poles.

Convergence of the meridians at the Equator is 0°. At

the poles, the convergence equals the difference

between the longitude values of the meridians.

Between the Equator and the poles, the convergence

varies from 0° to the difference in the longitude

values. Because of this, a geodetic azimuth and its

back azimuth will differ by the convergence.

Figure 3-16. Parallels of Latitude.

Figure 3-17. Meridians of Longitude.

Figure 3-18. Graticule.
3-10 _____________________________________________________________________________________________ MCWP 3-16.7

Geodetic Coordinates

Geodetic coordinates are the quantities of latitude (φ),

longitude (λ), and ellipsoid height (H) that define the

position of a point on the Earth’s surface with respect

to the reference ellipsoid. This type of geographic

coordinate is the most commonly used by surveyors

and cartographers. If the reference ellipsoid is

geocentric; i.e., WGS 84, coordinates are termed

geocentric geodetic coordinates. 

The geodetic longitude of a point on the Earth’s

surface is the angle formed by the intersection of the

plane containing the prime meridian (x-z cartesian

plane) and the meridional plane containing the point.

The geodetic latitude of a point is the angle formed

by the intersection of the equatorial plane (x-y

cartesian plane) and a line that passes through the

point and is perpendicular to the reference ellipsoid.

See figure 3-19.

Geodetic coordinates are computed and adjusted as

part of a geodetic network. All the points in the

network are common to all the other points in that

network. They are also common to points extending

and adjusted from that network. Geodetic networks

can be adjusted together to complete a national

network such as the National Geodetic Reference

System (NGRS) in the United States. 

Astronomic Coordinates

Astronomic coordinates are those values that define

the position of a point on the surface of the Earth or

the geoid and reference the local direction of gravity.

Astronomic coordinates can also refer to the location

of a celestial body. Astronomic positions often

establish and define horizontal datums. An ellipsoid is

oriented so that a line through a point perpendicular to

the geoid (vertical) is also perpendicular to the

ellipsoid (normal). The geoid separation is generally

zero at that point. At that point, the geodetic and

astronomic coordinates are the same. 

Astronomic latitude is the angle formed by the

intersection of the plane of the celestial equator and

the plumb line (perpendicular to the geoid). It equals

the angle formed by the plane of the observer’s

horizon and the rotational axis of the Earth.

Astronomic latitude results directly from observations

of celestial bodies, uncorrected for the deflection of

the vertical. The term applies only to the position of

points on the Earth. Astronomic longitude is the time

that elapses from the moment the celestial body is over

the Greenwich Meridian until it crosses the observer’s

meridian. It results directly from observations of

celestial bodies, uncorrected for the deflection of the

vertical. See figure 3-20.

Astronomic coordinates are computed independent of

each other. They can be connected by geodetic

Figure 3-19. Geodetic Coordinates. methods and adjusted to a geodetic network.
Marine Artillery Survey Operations ______________________________________________________________________ 3-11

The Prime Meridian

The prime meridian is the meridian of longitude

referenced as 0° for a particular geographic system.

Usually, the term prime meridian is the Greenwich

Meridian. However, figure 3-21 lists several systems

using other meridians of longitude as the prime

meridian for that system. Whenever survey data is

provided in a system not referencing the Greenwich

Meridian as 0° longitude, a simple conversion can be

made by applying the longitude offset to the survey

data longitude. 

Angular Measurements

Care must be taken to ensure that if survey data is

Figure 3-20. Astronomic Coordinates. provided covering other nations, including mapping

Amsterdam, Netherlands Reformed Church, West Tower 4° 53’ 01” E

Athens, Greece Observatory, Geodetic Pillar 23° 42’ 59” E

Batavia (Djakarta), Indonesia Old Tidal Guage 106° 48’ 28” E

Bern, Switzerland Old Observatory 7° 26’ 22” E

Brussels, Belgium Observatory 4° 22’ 06” E

Copenhagen, Denmark New Observatory 12° 34’ 40” E

Ferro, Canary Islands (By definition 20° west of Paris) 17° 39’ 46” W

Helsinki, Finland Observatory 24° 57’ 17” E

Istanbul, Turkey Hagia Sophia 28° 58’ 50” E

Lisbon Portugal Castelo San Jorge, Observatory 9° 07’ 55” W

Madrid, Spain Observatory 3° 41’ 15” W

Oslo, Norway Observatory 10° 43’ 23” E

Paris, France Observatory 2° 20’ 14” E

Pulkovo, Russia (USSR) Observatory 30° 19’ 39” E

Rome, Italy Monte Mario 12° 27’ 08” E

Stockholm, Sweden Observatory 18° 03’ 30” E

Tirane, Albania First-Order Trig Point 19° 46’ 45” E

Figure 3-21. Astronomic Longitudes of Prime Meridians.
3-12 _____________________________________________________________________________________________ MCWP 3-16.7

products, that the data is shown or measured in the

correct angular system. Two angular systems show

coordinate systems on maps and to coordinate survey

points: centesimal and sexagesimal. 

The unit usually associated with a centesimal system

is the grad (used extensively in Europe and North

Africa). A grad is the hundredth part (1/100th) of a

right angle. One grad equals 100 minutes; 1 minute

equals 100 seconds. Grads are notated by g; centesimal

minutes by c; and centesimal seconds by cc. The entire

number is notated together like 12g8

c

27cc.

The unit usually associated with a sexagesimal system

is the degree. A degree is the ninetieth part (1/90th) of

a right angle. One degree equals 60 minutes; 1 minute

equals 60 seconds. Degrees are notated by the symbol

° e.g., 24°; sexagesimal minutes by a ’; e.g., 38’; and

sexagesimal seconds by a “; e.g., 02”. The entire

number is notated together like 24° 38’ 02”. 

Deflection of the Vertical 

Deflection of the vertical at a point is the angular

difference between the vertical (plumb line), which is

perpendicular to the geoid, and a line through the point

that is perpendicular to the reference ellipsoid. This

term can be more accurately referred to as the astrogeodetic deflection of the vertical. See figure 3-22.

Due to the deflection of the vertical in the plane of

the prime vertical (a circle in the east-west direction

of the observer’s horizon), there is a difference

between astronomic and geodetic longitude and

astronomic and geodetic azimuths. This is called the

laplace condition and is expressed by the laplace

equation. The laplace equation yields a correction,

which when subtracted from an astronomic azimuth,

will produce a geodetic azimuth.

Figure 3-22. Deflection of the Vertical.
CHAPTER 4. MAP PROJECTIONS AND GRID SYSTEMS

SECTION I. MAP PROJECTIONS

A map projection is a method of representing a portion

of the Earth’s round surface on a flat surface. Because

this procedure causes distortions of different types,

many different projections have been developed.

Each projection is dictated by the size of the area

being mapped, the map scale, and the intended use of

the maps. See table 4-2 at the end of this section. 

Each projection preserves certain properties and

distorts others. Most projections are cylindrical,

conical or azimuthal, and project an ellipsoid onto

cylinders, cones or plane surfaces. These surfaces may

be tangent to the ellipsoid or they may be secant. A

projection is tangent to the ellipsoid when only one

point or line of the projection surface touches the

ellipsoid. It is secant when two points or lines touch

the ellipsoid. See figure 4-1. 

One common characteristic applies to all United States

military maps: they are all based on a conformal

projection. A conformal map projection is one that at

any point, the scale is the same in any direction and the

angle between any two lines on the ellipsoid is the

same when projected onto a plane. 

Prescribed Projections

The Transverse Mercator (TM) Projection is the

preferred projection for all military mapping, though it

is not necessarily used on all military maps. The

following projections are prescribed for U.S. military

topographic maps and charts that display a military

grid on a standard scale. Military maps of non-U.S.

Figure 4-1. Projection Types: Tangent and Secant.
4-2 ______________________________________________________________________________________________ MCWP 3-16.7

areas produced by other nations may not always

conform to the following standards. U.S. maps of

foreign areas may be based on other projections due to

treaty agreements. 

Topographic maps at scales of 1: 500,000 or larger

that lie between 80°S latitude and 84°N latitude are

based on the TM Projection. 

Topographic maps at scales of 1: 1,000,000 that lie

between 80°S latitude and 84°N latitude are based on

the Lambert Conformal Conic Projection.

Maps at scales of 1: 1,000,000 or larger covering the

polar regions (south of 80°S latitude and north of 84°N

latitude) are based on the Polar Stereographic Projection.

Maps at scales smaller than 1: 1,000,000 are based on the

projection best suited for the intended use of the map.

Scale Factor

For most military applications, map distance and

ground distance are considered the same. However, for

some geodetic and artillery operations (especially when

long distances or high accuracies are involved), it is

necessary to correct between map and ground distances.

A scale factor is necessary to compensate for

distortions created when projecting an ellipsoidal

surface onto a cylinder, cone or plane depending on

the projection type. The scale factor of a projection is

the ratio of arc length along a differentially small line

in the plane of the projection to the arc length on the

ellipsoid. This number depends on both the location of

the point and on the direction of the line along which

arc length is being measured. For conformal

projections, the scale factor is independent of the

direction of the line and depends only on the location

of the point. The scale factor is labeled “k”.

The scale factor is considered exact (unity) when it has

a value of 1. Unity occurs at the points of tangency or

secancy between the ellipsoid and the projected

surface. In a projection where the projected surface is

tangent to an ellipsoid, the scale factor increases away

from the point of tangency. In a projection where the

projected surface is secant to an ellipsoid, the scale

factor decreases toward the central meridian or origin

and increases away from the points of secancy.

True ground distance can be converted to a map

distance by multiplying the ground distance by the

scale factor.

Map Scale

A map scale is a representative ratio of map distances

to ground distances. These ratios vary from map to

map. The scale of a map is customarily chosen to

correspond to the ratio at a given point or along a

given line (if constant along that line) multiplied by a

suitable scale factor (usually close to unity). It is

usually expressed as a common fraction having one as

a numerator and the integer closest to the actual ratio

as a denominator.

Maps used by the military vary from small-scale

planimetric maps showing all of the continents to

large-scale topographic maps suitable for tactical

operations of small units and fire control. Military

maps are classified according to their scale.

Map scales can sometimes be confusing in the sense

that the scale is smaller as the number increases. This

confusion can be cleared by viewing the map scale as

a fraction (1/100,000 is a smaller number than 1/

50,000). The following are standard scales for

military maps.

Small-scale: 1: 600,000 and smaller 

Medium Scale: larger than 1: 600,000;

smaller than 1: 75,000

Large Scale: 1: 75,000 and larger

1: 1,000,000 1: 500,000 

1: 250,000 1: 100,000 

1: 50,000 1: 25,000
Marine Artillery Survey Operations ________________________________________________________________________ 4-3

Mercator Projection 

The Mercator Projection is a cylindrical projection

where the rotational axis of the ellipsoid coincides

with the axis of the cylinder so that the Equator is

tangent to the cylinder. Points on the surface of the

ellipsoid are projected onto the cylinder from the

origin located on the equatorial plane and vary

around three-quarters of the way back from the

projected area. The cylinder is then opened and

flattened to produce a plane surface. The parallels

of latitude and meridians of longitude both appear

as sets of parallel lines that intersect at right

angles. The meridians are equally spaced, but the

distance between parallels increases as their

distance from the Equator increases. The poles

cannot be shown on this projection (the normal

limits are from 80°N latitude to 80°S latitude). See

figure 4-2 and figure 4-3.

As the distance from the Equator increases, so does the

amount of distortion; e.g., the map scale at 60°N or S

latitudes is nearly twice the map scale at the Equator.

Maps or charts with this projection will distort the size

of an area. This is why Alaska appears to be the same

size as the lower 48 states. This projection is not

commonly used for military purposes except when the

entire Earth must be displayed and relative positions of

land masses are more important than size and distance.

Figure 4-3. Mercator Projection Flattened 

onto a Plane.

Figure 4-2. Mercator Projection.
4-4 ______________________________________________________________________________________________ MCWP 3-16.7

Transverse Mercator Projection

The TM Projection is a cylindrical conformal

projection. It is based on a modified Mercator

Projection in that the cylinder is rotated (transverse)

90° so that the rotational axis of the ellipsoid is

perpendicular to the axis of the cylinder. Generally,

the TM Projection is considered as a cylinder that is

secant to an ellipsoid. Only a six-degree wide portion

of the ellipsoid is projected onto the cylinder. The

centerline of the projected area is called the central

meridian. The ellipsoid is then rotated six degrees

inside the cylinder and another six degree portion is

projected. See figure 4-4. 

When the TM Projection is used to project a portion

of the ellipsoid onto the cylinder, the Equator and

the central meridian will appear as perpendicular

straight lines. A hemisphere will be distorted

towards its outer edges. The shaded areas of figure

4-5 show the varying distortion of two equivalent

geographic areas on the same projection. Note that

both areas encompass a region 20° by 20° and are

both bounded by 20° and 40°N latitude. Therefore,

on the ellipsoid they are the same size. But on the

projected surface the area bounded by 60° and 80°

longitude is much larger than the area bounded by

0° and 20° longitude. To decrease the amount of

distortion, the ellipsoid is divided into 60 6°-wide

projection zones, each with a meridian of longitude

as its central meridian. Each zone is projected

between 84° 30’ N latitude and 80° 30’ S latitude.

The cylinder used as the projection surface for the TM

Projection is generally considered to be secant to the

ellipsoid as shown in figure 4-4. This means that the

cylinder intersects the ellipsoid in two places creating

lines of secancy that are parallel to the central meridian

of the projection. The lines of secancy are located

180,000 meters east and west of the central meridian of

each projected zone. See figure 4-6.

Figure 4-7 shows a cross section of an ellipsoid and a

cylinder of projection that is secant to the ellipsoid. The

cross section is made by passing a plane through the

ellipsoid at the Equator. Line A’M’D’ represents the

surface of the cylinder. Line AMD represents the

projected portion of the ellipsoid surface. M is the

central meridian; M’ is the projection of the central

meridian onto the cylinder. A and D are the meridians

located three degrees from the central meridian. A’ and

D’ are the projections of those meridians onto the

cylinder. B and C are the points where the cylinder

intersects the ellipsoid creating the secant condition.

Note that line BM’C is shorter than line BMC. This

shows that any line that lies between the lines of

secancy is shorter on its projected plane (map) than it is

on the ellipsoid surface. Note also that lines A’B and

CD’ are longer than lines AB and CD, respectively.

This shows that any line that lies between the lines of

secancy and the edges of the projection are longer on

the projected plane than they are on the ellipsoid

surface. 

For the TM Projection, the scale factor at the lines

of secancy is unity (1.000 or exact). The scale

factor decreases toward the central meridian to

0.9996. The scale factor increases toward the zone

limits to approximately 1.001 at the Equator. See

figure 4-7 and table 4-1.

Figure 4-5. Distortion within the TM Projection.

Figure 4-4. TM Projection.
Marine Artillery Survey Operations ________________________________________________________________________ 4-5

Figure 4-6. Secancy in a 6° Zone.

Table 4-1. TM Projection Scale Factor by UTM Easting.

Easting of Starting Station Scale Factor (Meters)

500,000 500,000 0.99960 

490,000 510,000 0.99961 

480,000 520,000 0.99961

470,000 530,000 0.99961 

460,000 540,000 0.99961 

450,000 550,000 0.99963

440,000 560,000 0.99963 

430,000 570,000 0.99966 

420,000 580,000 0.99966 

410,000 590,000 0.99970

400,000 600,000 0.99972 

390,000 610,000 0.99975 

380,000 620,000 0.99977 

370,000 630,000 0.99982 

360,000 640,000 0.99984 

350,000 650,000 0.99985 

340,000 660,000 0.99991 

330,000 670,000 0.99995

320,000 680,000 1.00000 

310,000 690,000 1.00005 

300,000 700,000 1.00009 

290,000 710,000 1.00014 

280,000 720,000 1.00021 

270,000 730,000 1.00025 

260,000 740,000 1.00030 

250,000 750,000 1.00037 

240,000 760,000 1.00044

230,000 770,000 1.00051 

220,000 780,000 1.00058 

210,000 790,000 1.00064 

200,000 800,000 1.00071 

190,000 810,000 1.00078 

180,000 820,000 1.00085 

170,000 830,000 1.00094

Figure 4-7. Line Distortion and Scale Factor in the TM Projection.
4-6 ______________________________________________________________________________________________ MCWP 3-16.7

Gauss-Kruger Projection 

The Gauss-Kruger (GK) Projection can be described as

the TM Projection derived by mapping directly from an

ellipsoid that is tangent to the cylinder. It is a conformal

projection with many similarities to the TM Projection.

The tangent point is the meridian of longitude chosen as

the central meridian for the projection. As with TM, the

GK Projection depicts 60 zones. Many geodesists

consider the GK and TM Projections to be the same

except for scale factor. See figure 4-8. 

When a meridian is tangent to a cylinder of projection,

there is no distortion along that line. Figure 4-9 shows all

lines not located on the central meridian are longer on the

projected surface than they are on the ellipsoid. For

example, line A’M is longer than line AM when A

represents the meridian located three degrees from the

central meridian. A’ is the projection of that meridian

onto a cylinder. M is the central meridian (tangent point).

For the GK Projection, the scale factor at the central meridian

is unity (1.000 or exact). The factor increases outward toward

the zone limits in excess of 1.004 at the Equator. 

Polar Stereographic Projection

The Polar Stereographic Projection is used for

mapping the Earth’s polar regions and identifies those

regions as north and south zones. The north zone

extends from the North Pole to 83° 30’ N latitude; the

south zone extends from the South Pole to 79° 30’ S

latitude. It is a conformal azimuthal projection that is

developed by projecting a polar region onto a plane

that is tangent to an ellipsoid at the pole or secant to

the ellipsoid at a specific latitude. The plane is

perpendicular to the polar axis. The origin of the

projection is the opposite pole. Meridians are straight

lines and parallels are concentric circles.

Lambert Conformal Conic Projections

Lambert Conformal Conic Projections are the most

widely used projections for civilian cartographers and

surveyors. Many nations use it for civil and military

purposes. This projection can be visualized as the

projection of an ellipsoid onto a cone that is either

tangent or secant to the ellipsoid. The apex of the cone

is centered in the extension of the polar axis of the

ellipsoid. A cone that is tangent to an ellipsoid is one

that touches the ellipsoid at one parallel of latitude. A

secant cone intersects the ellipsoid at two parallels

called standard parallels. This text discusses the secant

condition. See figure 4-10.

Figure 4-8. GK Projection.

Figure 4-9. Line Distortion and Scale Factor in the GK Projection.
Marine Artillery Survey Operations ________________________________________________________________________ 4-7

When the cone of projection is flattened into a plane,

meridians appear as straight lines radiating from a point

beyond the mapped areas. Parallels appear as arcs of

concentric circles centered at the point from where the

meridians radiate. None of the parallels appears in exactly

the projected positions. They are mathematically adjusted

to produce the property of conformality. This projection is

also called the Lambert Conformal Orthomorphic

Projection. See figure 4-11. 

The parallels of latitude on the ellipsoid that are to be

secant to the cone are chosen by the cartographer. The

distance between the secant lines is based on the purpose

and scale of the map. For example, a USGS map showing

the 48 contiguous states uses standard parallels located at

33°N and 45°N latitudes (12° between secant lines).

Aeronautic charts of Alaska use 55°N and 65°N (10°

between secant lines). For the National Atlas of Canada,

secant lines are 49°N and 77°N (28° between secants). The

standard parallels for USGS maps in the 7.5 and 15-minute

series vary from state to state. Several states are separated

into two or more zones with two or more sets of standard

parallels. See figure 4-12 on page 4-8.

Since this is a conformal projection, distortion is

comparable to that of the TM and Polar Stereographic

Projections. Distances are true along the standard parallels

and reasonably accurate elsewhere in limited regions.

Directions are fairly accurate over the entire projection.

Shapes usually remain relative to scale but the distortion

increases away from the standard parallels. Shapes on

large-scale maps of small areas are essentially true. Scale

factor is exact (unity or 1.000) at the standard parallels. It

decreases between and increases away from the standard

parallels. The exact number depends on the distance

between the standard parallels. 

Oblique Mercator Projection 

The Oblique Mercator Projection is actually many

different projections using variations of the TM. All are

cylindrical and conformal. But instead of the cylinder

being transverse 90° from the Mercator Projection, it is

transverse at an angle that places the long axis of the

cylinder 90° from the long axis of the area being mapped.

If the general direction of an area that is to be mapped lies

in a northeast/southwest attitude, the cylinder of projection

would be transverse 45° west of north. The cylinder is

usually secant to the ellipsoid to lessen the effects of

distortion. The location of the lines of secancy varies

between projections. Many Oblique Mercator Projections

exist. This publication discusses the Laborde Projection

and the West Malaysia Rectified Skew Orthomorphic

(RSO) Projection only.

The Laborde Projection is used to map the island of

Madagascar. It is an Oblique Mercator type projection

with the long axis of the cylinder oriented at 18° 54’ east

of north. Scale factor at the origin is 0.9995. This

projection is used with the International Ellipsoid.

The West Malaysia RSO Projection is used to map the

islands of Malaysia. It is an Oblique Mercator type

projection with the long axis of the cylinder oriented at 36°

58’ 27.1542" east of north. Scale factor at the origin is

0.99984. This projection is used with the Modified Everest

Ellipsoid to map the West Malaysia RSO Grid System.

Many other Oblique Mercator Projections are used to map

areas of the world. Most are designed to work with a

specific grid system like the West Malaysia system

described above. Examples of these systems include but

are not limited to—

l Alaska Zone 1 RSO. 

l Borneo RSO. 

l Great Lakes (4 Zones) RSO. 

Figure 4-10. Secant Condition of Lambert 

Conformal Conic Projection.

Figure 4-11. Cone Flattened onto a Plane.
4-8 ______________________________________________________________________________________________ MCWP 3-16.7

l Liberia RSO. 

l Malaya (chain) RSO. 

l Malaya (yard) RSO. 

l Switzerland Oblique Mercator.

New Zealand Map Grid Projection

The New Zealand Map Grid (NZMG) Projection is

used to map New Zealand. It is a sixth-order complexalgebra polynomial modification of the Mercator

Projection. A cylinder cannot necessarily be

considered in this projection. It is a mathematical

projection set secant to the International Ellipsoid. The

NZMG has no defined scale factor at the central

meridian. Scale factor ranges from 1.00023 to 0.00078

over the entire projection.

Cassini Projection

The Cassini Projection can be viewed outwardly as a GK

projection in that the cylinder is transverse 90° from the

Mercator Projection. It is also tangent to the ellipsoid at the

central meridian of a zone. The Cassini Projection predates

the GK and TM Projections. It is made by treating all

meridians as planes that extend from the ellipsoid out to the

cylinder. This projection causes the Equator and central

meridian to be perpendicular straight lines. All other

meridians appear as lines that intersect the Equator at right

angles and curve toward the central meridian except for

those meridians that are located 90° from the central

meridian. Those meridians appear as straight lines that are

parallel to the Equator. Scale factor at the central meridian

is unity (1.00 or exact). This projection is still used in some

areas for civil and local grid systems, but is considered

obsolete for most purposes. In many areas it has been

replaced by the TM Projection. This projection is

sometimes called the Cassini-Solder Projection.

Position differences between Cassini grid systems and

TM grid systems are slight. For example, northing is

the same in the Palestine Cassini Civil Grid as it is in

the Palestine TM Civil Grid. The easting difference

between the two is zero at 20 kilometers from the

central meridian and only 4.1 meters at 100 kilometers

from the central meridian.

Figure 4-12. Oklahoma Lambert Projection; North and South Zones.
Marine Artillery Survey Operations ________________________________________________________________________ 4-9

Table 4-2. Projection Features.
4-10 _____________________________________________________________________________________________ MCWP 3-16.7

Table 4-2. Projection Features (Continued).
Marine Artillery Survey Operations ______________________________________________________________________ 4-11

Table 4-2. Projection Features (Continued).
4-12 _____________________________________________________________________________________________ MCWP 3-16.7

SECTION II. GRID SYSTEMS

A grid system is a two-dimensional plane-rectangular

coordinate system that is usually based on and

mathematically adjusted to a map projection. This

allows for the transformation from geodetic positions

(latitude and longitude) to plane coordinates (easting

and northing) and for the computations relating to

those coordinates to be made by ordinary methods of

plane surveying.

Many grid systems are in use. Most of the local systems

will eventually be converted to one of the universal grid

systems. Some areas will continue to be mapped in a

local system such as the British National Grid (BNG),

the Irish Transverse Mercator Grid (ITMG), and the

Madagascar Grid (MG). There are two universal grids

used by the United States military and its allies: UTM

and Universal Polar Stereographic (UPS). 

Grids consist of a system of evenly spaced parallel

lines lying perpendicular to another system of evenly

spaced parallel lines forming squares. The ground

distance between the lines depends on the scale of the

map and the type of grid system. Most systems use

meters as a basis for grid line spacing. Others use

yards or feet. Standard scale military maps generally

adhere to grid lines on—

l Large-scale maps spaced at 1,000 meters. 

l Medium-scale maps at 1:250,000 spaced at 10,000

meters.

For scales smaller than 1:250,000, the grid lines may or

may not be depicted, depending on the map’s purpose.

North-south lines in a grid system are called eastings

and increase in value from west to east. East-west lines

in a grid system are called northings and increase in

values from south to north. (These rules do not apply

to grid systems that cover the polar regions such as the

UPS.) The numerical value of an easting and northing

are referenced to a specific origin. A false value is

applied to the easting or northing grid line that falls at

a particular reference line or point. Usually, that line

or point is a meridian of longitude; e.g., central

meridian of a zone or a parallel of latitude (like the

Equator, but it can have other references). The origin

for the false easting and false northing are normally

different lines or points.

Grid convergence is the angular difference between

true north and grid north. The direction and the value

of the angle are computed differently depending on the

grid system. In some systems, grid convergence can be

the same as convergence of the meridians. 

Universal Transverse Mercator Grid System

The Universe TM (UTM) Grid System is referenced to

the TM Projection. The ellipsoid is divided into 60

grid zones, each 6° wide, extending from 84° N

latitude to 80° S latitude. Zones are numbered from 1

to 60. Zone 1 starts at 180° − 174° west longitude,

zone 2 at 174° west − 168° west longitude, continuing

east to zone 60 at 174° E − 180° longitude. The prime

meridian (0° longitude) separates zones 30 and 31. See

figure 4-13. 

The location of any point in the UTM grid system can

be designated by coordinates by giving its distance eastwest (easting) and its distance north-south (northing)

from the origin of the grid zone. This origin (for each

UTM grid zone) is the intersection of the Equator and

the central meridian of the zone. Each UTM zone has a

central meridian corresponding to the central meridian

of each TM Projection zone. The grid is oriented by

placing the east-west axis of the grid in coincidence

with the Equator and the north-south axis of the grid in

coincidence with the central meridian of the zone.

Once the grid is oriented, the origin for easting and

northing are assigned false values. The central

meridian (origin for easting) of each zone is assigned

an easting value of 500,000 meters. The easting

increases east of the central meridian and decreases

west. The Equator (origin for northing) is assigned two

false values. If operating in the Northern Nemisphere,

the northing of the Equator is 0 meters and increases

north. If operating in the Southern Hemisphere, the

northing of the Equator is 10,000,000 meters and

decreases south. Grid lines that run north and south are

easting lines. They are parallel to the central meridian

of the grid zone. Grid lines that run east and west are

northing lines. They are parallel to the Equator. See

figure 4-14 on page 4-14. 
Marine Artillery Survey Operations ______________________________________________________________________ 4-13
4-14 _____________________________________________________________________________________________ MCWP 3-16.7

Grid convergence at a point in the UTM system is the

angle measured, east or west, from true north to grid

north. At any point along the central meridian of a

UTM grid zone, true north and grid north are the same.

At any point not located on the central meridian, grid

north departs from true north because of convergence

of the meridians. Grid convergence within the UTM

system is a function of both latitude and longitude. It

will rarely exceed 3° (53.333 mils) and is normally

listed in the declination diagram of a map. Grid

convergence should be computed for use in fifth order

or higher surveys because the information on the map

is generally computed for the center of the map sheet.

For example, the Lawton map sheet (6353III) lists the

grid convergence at 6 mils, the Cache map sheet

(6253II) lists it at 4 mils. There are two mils difference

between the centers of these two adjoining sheets. See

figure 4-15. 

Figure 4-14. UTM Easting and Northing.
Marine Artillery Survey Operations ______________________________________________________________________ 4-15

In the Northern Hemisphere, grid convergence is

negative east of the central meridian and positive

west. In the Southern Hemisphere, grid convergence

is positive east of the central meridian and negative

west. The direction (+, −) and the value of the grid

convergence are applied to a true azimuth to obtain

a grid azimuth. If a grid azimuth must be converted

to a true azimuth, the value of the grid convergence

is the same. However, the opposite sign (direction)

must be used. See figure 4-16.

The standard UTM grid zone is 6° wide. However,

portions of several grid zones have been modified to

accommodate southwest Norway and the islands of

Svalbard. These grid zone modifications are not

available in many survey or fire support systems.

User-defined options or work-around methods must be

used in these areas. Figure 4-17 on page 4-16 shows

the nonstandard portions of the respective grid zones. 

Easting and northing values of a point in the UTM

grid system are called grid coordinates. Easting

consists of six digits before the decimal point. The

only exception is positions that are actually located

in an adjacent grid zone. An easting can be written

with the first digit (100,000 meters) separated from

the next five with a space. Northing generally has

seven digits before the decimal point. The exception

to this is at locations north of the Equator by less than

1,000,000 meters. A northing can be written with the

first two digits (1,100,000 meters) separated from the

next five digits with a space. The number of digits

after the decimal point depends on the order of

survey and the accuracy needed. An example of a

UTM grid coordinate is 6 39127.84 − 38 25411.24.

If at any time you cross the Equator from north to

south (at which point you would have a negative

northing), you must algebraically add the northing to

ten million meters to obtain a northing for the

Southern Hemisphere. If you cross the Equator from

south to north (which would produce a northing

Figure 4-15. UTM Grid Convergence.

Figure 4-16. Sign of Grid Convergence.
4-16 _____________________________________________________________________________________________ MCWP 3-16.7

greater than ten million meters), you must subtract ten

million meters from your northing to obtain a northing

that can be used in the Northern Hemisphere.

Military Grid Reference System

UTM, GK, and UPS grid coordinates are not unique.

Any UTM grid coordinates can be plotted in each of the

60 grid zones. Many UTM and GK coordinates will plot

in both the Northern and Southern Hemispheres of the

same grid zone. All UPS grid coordinates between 84°

and 90° north and south latitudes will plot in each of the

two UPS grid zones. To make UTM and UPS grid

coordinates unique, the grid zone and grid zone

designator should accompany them. 

The MGRS is designed for use with the UTM and

UPS grid systems. It establishes a unique set of

coordinates for each specific location on the Earth. An

MGRS grid coordinate consists of a grid zone (UTM

only), a grid zone designator, a 100,000-meter square

identifier, and the easting/northing coordinate. 

A grid zone designator is a one-letter code specifying

a particular portion of a UTM/UPS grid zone. The grid

zone designator is usually listed in the marginal data

of a military map. See figure 4-18. 

Each of the 60 UTM grid zones is divided into 20 grid

zone designators. Each designator represents an 8°

portion of the grid zone except the northernmost

(represents 12°). Designators are identified

alphabetically by the letters C to X with the letters I

and O omitted. C is the southernmost designator, X is

the northernmost, and the Equator separates M and N.

Thus, a grid zone and grid zone designator together

specify a region of the Earth covering a 6° by 8° area

except in the northernmost designation X (specifies a

6° by 12° area).

Both UPS zones (north and south) are divided into two

grid zone designations separated by the 0° and 180°

meridians. In the north, the designator Y covers the

Western Hemisphere; Z covers the Eastern

Hemisphere. In the south, designator A covers the

Western Hemisphere; B the Eastern Hemisphere.

Since numbers are not used to identify UPS grid

zones, a UPS grid MGRS coordinate will begin with

the grid zone designator.

Figure 4-17. Nonstandard UTM Grid Zones.
Marine Artillery Survey Operations ______________________________________________________________________ 4-17

Figure 4-18. MGRS: 100,000-Meter Square Identification Lettering Convention 

for the UTM Grid, WGS 84/GRS 80 Ellipsoids.
4-18 _____________________________________________________________________________________________ MCWP 3-16.7

100,000-Meter Square Identifier 

Each UTM/UPS grid zone is divided into 100,000-

meter squares. Squares are identified by two letters

called a 100,000-meter square identifier. The first

letter is columnar. It is the same for all squares in a

north-south column. The second letter is linear. It is

the same for all squares in an east-west row in a grid

zone. This identifier is usually listed as part of the

marginal information on a military map. The lettering

convention used depends on the reference ellipsoid.

This text discusses the UTM lettering convention used

with the WGS 84 and GRS 80 ellipsoids and the UPS

lettering convention used with the International

ellipsoid. Other ellipsoid lettering conventions are

detailed in DMA TM 8358.1, Datums, Ellipsoids,

Grids, and Grid Reference Systems.

UTM

The first (columnar) letter of the 100,000 meter square

identification originates at the 180° meridian with the

letter A and increases alphabetically eastward along

the Equator for three grid zones to cover an area of

18°. The 100,000-meter columns, including partial

columns at grid zone junctions, are lettered from A to

Z but omit I and O. This alphabet is repeated every 18°

eastward around the Earth.

The second (linear) letter of the 100,000 meter square

identification is lettered from A to V but omit I and O,

from south to north covering an area of 2,000,000

meters and is then repeated northward. In oddnumbered grid zones, it originates at the Equator

increasing alphabetically north. In even-numbered

grid zones, the second letter originates 500,000 meters

south of the Equator increasing alphabetically north.

Thererefore, in odd-numbered grid zones the second

letter of the 100,000-meter square identification is A

along the Equator. In even-numbered grid zones the

second letter is F along the Equator.

Each 6° by 8° square is broken up into 100,000-meter

squares that occur only once. For example, there is

only one square identified by the letters WA inside of

the 6° x 8° square of grid zone designation 3N. The

only other square in this figure identified by the letters

WA is in grid zone designation 3Q. It can be seen in

figure 4-18 that unique coordinates can be established

for every position within the UTM grid using the

MGRS. 

UPS

The 100,000-meter square identifiers are the same for

both UPS grid zones. The difference between two UPS

grid MGRS coordinates with the same 100,000-meter

square identifiers is the grid zone designator. A/B in

the south, Y/Z in the north. Designators A and Y

(Western Hemisphere) are lettered the same, as are

designators B and Z (Eastern Hemisphere). The north

zone only includes that portion of the lettering

convention that falls inside of 84° latitude. 

In the Western Hemisphere the first letter of the

100,000-meter square identifier originates at the

intersection of the 80° latitude and 90° W longitude

lines. It is lettered alphabetically along the east-west

axis from J to Z. M, N, O, V, and W are omitted. 

In the Eastern Hemisphere, the first letter of the

100,000 meter square identifier originates at the 0° and

180° meridians. It is lettered alphabetically along the

east-west axis from A to R but D, E, I, M, N and O are

omitted.

The second letter of the 100,000-meter square

identifier originates at the intersection of the 80°

latitude/180° longitude lines. It is lettered

alphabetically from A to Z. I and O are omitted.

MGRS Grid Coordinates

Easting and northing coordinates used are the same as

the grid coordinates used with UTM/UPS with the

following modifications.

For UTM MGRS grid coordinates, delete the first digit

(100,000 meters) from the easting and the first two

digits (1,100,000 meters) from the northing of the

UTM grid coordinates. Add the grid zone number, the

zone designator, and the 100,000-meter square

identifier at the front of the coordinates.

For UPS MGRS grid coordinates delete the first two

digits (1,100,000 meters) from both the easting and

northing UPS grid coordinates. Add the zone

designator and the 100,000-meter square identifier at

the front of the coordinates. 
Marine Artillery Survey Operations ______________________________________________________________________ 4-19

The entire MGRS grid coordinate is written as one

entity without parentheses, dashes, or decimals.

Examples:

Nonstandard Grids

Many grid systems have been developed by individual

nations that cover only that nation or a region

surrounding that nation. Usually, no direct relationship

exists between local grid systems (the same as no

direct relationship exists between the state plane grid

systems of the U.S.). Nonstandard grids are generally

named for the nation or region they cover and contain

the term grid, zone or belt; i.e., Ceylon Belt, MG, and

India Zone I.

A grid covers a relatively small area. Its limits consist

of combinations of meridians, parallels, rhumb lines,

or grid lines. A zone is usually wide in longitude and

narrow in latitude. Its limits consist of meridians and

parallels. A belt is usually wide in latitude and narrow

in longitude.

World Geodetic Reference System

The World Geodetic Reference System (GEOREF) is

an alphanumeric system for reporting positions based

on geodetic coordinates. It is a worldwide position

reference system that can be used with any map or

chart graduated in latitude and longitude, regardless of

the map projection. The primary use of the GEOREF

is for inter-service and inter-allied positioning and

reporting of aircraft and air targets. 

User-Defined Grid Systems

When operating in an area that is mapped in a grid

system other than UTM and UPS, it may be necessary

to define the grid system. Defining the grid system is

basically orienting a fire support system or survey

system to measure or establish azimuths, distances,

and elevations from a different origin than it is

programmed for. Most current software versions do

not allow this option. If the option is available, the

following information is necessary:

l Operational ellipsoid. 

l Ellipsoid parameters (a, b, 1/f).

l Scale factor (at the origin) for the projection. 

l Latitude of the origin. 

l Longitude of the origin.

l Unit (meters, feet, yards, chains or rods).

l False easting of the origin. 

l False northing of the origin.

Figure 4-19 lists the needed information for several

common nonstandard grids published in DMA TM

8358.1, table 6. See page 4-20.

Figure 4-20 lists the needed information for several

common nonstandard grids not published in DMA TM

8358.1, table 6. See page 4-21.

3Q location within a 6° × 8° square

3QXV location to within 100,000 meter

3QXV41 location to within 10,000 meters 

3QXV4312 location to within 1,000 meters

3QXV432123 location to within 100 meters

3QXV43211234 location to within 10 meters

3QXY4321012345 location to within 1 meter
4-20 _____________________________________________________________________________________________ MCWP 3-16.7

O

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British West Indies Transverse Mercator Clarke 1880 00° 00’ 00.000” N 62° 00’ 00.000” W 400,000.000 m 0 m 0.9995Costa Rica

Norte Lambert Clarke 1866 10° 28’ 00.000” N 84° 20’ 00.000” W 500,000.000 m 271,820.522 m 0.99995696Sud Lambert Clarke 1866 09° 00’ 00.000” N 83° 40’ 00.000” W 500,000.000 m 327,987.436 m 0.99995696

Cuba

Norte Lambert Clarke 1866 22° 21’ 00.000” N 81° 00’ 00.000” W 500,000.000 m 280,296.016 m 0.99993602Sud Lambert Clarke 1866 20° 43’ 00.000” N 76° 50’ 00.000” W 500,000.000 m 229,126.939 m 0.99994848

Dominican Republic Lambert Clarke 1866 18° 49’ 00.000” N 71° 30’ 00.000” W 500,000.000 m 277,063.657 m 0.99991102Egypt Transverse Mercator International 00° 00’ 00.000” N 25° 30’ 00.000” E

28° 30’ 00.000” E31° 30’ 00.000” E34° 30’ 00.000” E37° 30’ 00.000” E

300,000.000 m 0 m 0.99985

El Salvador Lambert Clarke 1866 13° 47’ 00.000” N 89° 00’ 00.000” W 500,000.000 m 295,809.184 m 0.99996704Guatemala

Norte Lambert Clarke 1866 16° 49’ 00.000” N 90° 20’ 00.000” W 500,000.000 m 292,209.579 m 0.99992226Sud Lambert Clarke 1866 14° 54’ 00.000” N 90° 20’ 00.000” W 500,000.000 m 325,992.681 m 0.99989906

Haiti Lambert Clarke 1866 18° 49’ 00.000” N 71° 30’ 00.000” W 500,000.000 m 277,063.657 m 0.99991102Honduras

Norte Lambert Clarke 1866 15° 30’ 00.000” N 86° 10’ 00.000” W 500,000.000 m 296,917.439 m 0.99993273Sud Lambert Clarke 1866 13° 47’ 00.000” N 87° 10’ 00.000” W 500,000.000 m 296,215.903 m 0.99995140

Levant Lambert Clarke 1880 34° 39’ 00.000” N 37° 21’ 00.000” E 300,000.000 m 300,000.000 m 0.9996256Nicaragua

Norte Lambert Clarke 1866 13° 52’ 00.000” N 85° 30’ 00.000” W 500,000.000 m 359,891.816 m 0.99990314Sud Lambert Clarke 1866 11° 44’ 00.000” N 85° 30’ 00.000” W 500,000.000 m 288,876.327 m 0.99992228

Northwest Africa Lambert Clarke 1880 34° 00’ 00.000” N 00° 00’ 00.000” E 1,000,000.000 m 500,000.000 m 0.99908Palestine Transverse Mercator Clarke 1880

1 31° 44’ 02.749” N 35° 12’ 43.490” E 170,251.555 m

2 126,867.909 m 1.000

Panama Lambert Clarke 1866 08° 25’ 00.000” N 80° 00’ 00.000” W 500,000.000 m 294,865.303 m 0.999899091 Clarke 1880 Ellipsoid for Palestine, a = 6,378,300.790 and 1/f = 293.466307656.2 Add 1,000,000.000 m to coordinate when coordinate becomes negative.

Fig

ure

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Marine Artillery Survey Operations ______________________________________________________________________ 4-21

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Camp Fuji, Japan (Shizuoka and Yamanashi Prefectures)

Zone VIII Transverse Mercator Bessel 36° 00’ 00.000” N 138° 30’ 00.000” W 0 m 0 m 0.9999

Marianas Islands

Guam

Azimuthal Equidistant Clarke 1866 13° 28’ 20.879” N 144° 44’ 55.503” E 50,000.000 m 50,000.000 m

Rota Azimuthal Equidistant Clarke 1866 14° 07’ 58.861” N 145° 08’ 03.228” E 5,000.000 m 5,000.000 mSaipan Azimuthal Equidistant Clarke 1866 15° 11’ 05.683” N 145° 44’ 29.972” E 28,657.520 m 67,199.99 mTinian Azimuthal Equidistant Clarke 1866 14° 56’ 05.775” N 145° 38’ 07.198” E 20,000.000 m 20,000.000 m

M

C

AS Iwakuni, Japan Transverse Mercator Bessel 36° 00’ 00.000” N 132° 10’ 00.000” E 0 m 0 m 0.9999

Okinawa, Japan Transverse Mercator Bessel 26° 00’ 00.000” N 127° 10’ 00.000” E 0 m 0 m 0.9999St. Barbara Area, Republic of Korea

Central Zone Transverse Mercator Bessel 38° 00’ 00.000” N 127° 00’ 10.405” E 0 m 0 m 1.0 (Unity)

Subic Bay Area, Republic of the Philippines

Zone III Transverse Mercator Clarke 1866 00° 00’ 00.000” N 121° 00’ 00.000” E 500,000.000 m 0 m 0.99995

Tunisia

Nord Tunisie Grid Lambert Clarke 1880

1 36° 00’ 00.000” N 09° 54’ 00.000” E 500,000.000 m 300,000.000 m 0.999625544

1 Clarke 1880 (French) Ellipsoid, a = 6,378,249.2 and 1/f = 293.4660208.

Fig

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5

8.1.
CHAPTER 5. CONVENTIONAL EQUIPMENT

SECTION I. T-2E THEODOLITE

Components

The T2-E theodolite is a lightweight, compact, dust

proof optical reading instrument equipped with a fixed

reticle. This directional-type instrument measures

horizontal angles and vertical readings. 

Interior scales (circles) read by a built-in optical

system are graduated in mils. Scales can be read

directly to 0.001 mils. Circles are illuminated by

sunlight or a built-in wiring system that produces

artificial light. 

All parts of the instrument that can be damaged by

dust or moisture are enclosed.

The T-2E is divided into the tribrach, the lower part,

and the alidade. See figures 5-1 and 5-2. 

The most commonly used tribrach for the T-2E is

the GDF22. See figure 5-3. It is also used with the

target set. The GDF22 mounts on all tripods with a

standard 5/8-inch fixing screw. It has three leveling

knobs, a fish eye level, an optical plummet, and a

swivel-locking knob that attaches to the lower part

to the theodolite. 

Figure 5-1. T-2E Components.

Figure 5-2. T-2E Components (Continued).

Figure 5-3. GDF22 Tribrach.
5-2 ______________________________________________________________________________________________ MCWP 3-16.7

The lower part contains the centering flange that

attaches to the tribrach. It also contains the standing axis

system, the horizontal circle, the circle setting knob, the

horizontal mirror, and the cable plug-in for use with

artificial light. 

The lower part provides a fixed rotational axis around

the standing axis system for the alidade. The standing

axis system consists of the axis sleeve that is rigidly

connected to the centering flange and the axis stem that

is screwed fast to the alidade. 

The alidade contains the telescope, reading microscope,

and most of the T-2E operator controls.

The horizontal locking clamp fixes the alidade to

the lower part so that the alidade cannot be rotated

except by the horizontal drive screw. The horizontal

drive screw rotates the alidade for fine adjustments

in pointing.

The vertical locking clamp fixes the tilting axis of the

telescope so that it cannot be rotated except by the

vertical drive screw. The vertical drive screw rotates

the tilting axis of the telescope for fine adjustments

in pointing.

The circle selector knob allows the operator to change

his view from the horizontal circle to the vertical circle.

The micrometer knob brings the horizontal and

vertical scales into coincidence.

The automatic index button checks the functioning of

the automatic index. This ensures that any residual

error in leveling is eliminated.

Telescope 

The telescope provides an erect (upright) view of the

target. The reticle pattern is focused by rotating the

eyepiece. The target is focused by rotating the silverfocusing sleeve. The reticle pattern is a 1 to 100 scale

stadia pattern for optical distance measurements. See

figures 5-4 and 5-5. 

To remove the eyepiece, rotate the bayonet ring

counterclockwise so that another eyepiece can be

installed. The standard eyepiece has a 30X lens.

Optional eyepieces include the 40X FOK53 and the

18X FOK 117.

When using artificial illumination, the lever under the

optical sight can be pushed toward the objective lens

(front) to illuminate the reticle.

Figure 5-4. T-2E Focusing Sleeve and Eyepiece.

Figure 5-5. T-2E Reticle Pattern.
Marine Artillery Survey Operations ________________________________________________________________________ 5-3

Accessories

Accessories (one each) are carried and stored in the

plastic transportation case. Accessories are— 

l Users manual. 

l Eyepiece assembly with carrying case. 

l MZ2 elbow microscope and a GFZ1 elbow

telescope. 

l GOF4 black sun filter. 

l Jewelers screwdriver with two adjusting pins and

two standard screwdriver blades. 

l Plastic wet weather instrument cover. 

l GSP-1 Roelofs Prism with case. 

l Illumination Kit (two GEB-58 plug-in lamps, one

GEV-34 cable, and one GEB-63 battery box). 

Setting Up the Tripod GST-20

The GST-20 tripod is the primary tripod used with

conventional survey equipment in the Marine Corps. 

Upend the tripod, place the tripod head on the toe of

your boot, and unbuckle the restraining strap. Loosen

the leg clamp thumbscrews and extend the tripod legs

to the desired length. Tighten the leg clamp

thumbscrews sufficiently to maintain the weight of a

T-2E and DI 3000. Do not force the thumbscrews.

Spread the legs and place the tripod over the occupied

station with one leg bisecting the angle to be

measured. Set up the tripod head so that the telescope

will be at a convenient height for the operator. Rough

level the tripod.

Insert the bayonet of the plumb bob into the

instrument fixing screw. The plumb bob should hang

about 1 inch above the station. Center the tripod over

the station to within approximately 1inch of plumb. 

Firmly embed the tripod legs in the ground. The plumb

bob should now be within 0.5 inches laterally of center

of the station. The tripod head must approximate level

once the legs are embedded in the ground.

Remove the tripod head cover. Fix the cover to the

side of the tripod and lightly wipe your hand over the

tripod head to remove any sand or dirt.

Mounting the T-2E on the Tripod

Open the theodolite’s transportation case. Grasp the

theodolite by the right standard (this faces up in the

transportation case) and remove the theodolite. Place

the free hand underneath the tribrach. Maintain a hold

on the instrument with at least one hand until the T-2E

is securely tightened to the tripod.

Carefully place the theodolite on top of the tripod.

Keeping one hand on the instrument, attach the T-2E

to the tripod head by screwing the fixing screw snugly

into the base of the tribrach.

Replace the cover on the transportation case to

protect from dust and moisture. Move the case away

from the tripod to provide a working area for the

instrument operator.

Plumb and Level the T-2E

Step 1. Loosen the fixing screw slightly. Carefully

slide the instrument on the tripod head to center the

point of the plumb bob exactly over the station.

Step 2. With one hand on the theodolite, tighten the

fixing screw. Excessive tightening of the fixing screw

will bend the tripod’s slotted arm and damage the

tripod head. Be sure the point of the plumb bob

remains centered over the station. Remove the plumb

bob and return it to its case.

Step 3. Loosen the horizontal clamping screw.

Rotate the alidade until the axis of the plate level is

parallel to any two of the three leveling screw knobs.

Grasp the leveling screw knobs between the thumb

and forefinger of each hand. Turn the knobs at the

same time so the thumbs of both hands move either

toward each other or away from each other. This

movement tightens one screw as it loosens the other.

The bubble always moves in the same direction as

the left thumb. Center the bubble by using these two

leveling screw knobs. This is the first position. See

figure 5-6 on page 5-4.
5-4 ______________________________________________________________________________________________ MCWP 3-16.7

Step 4. Rotate the alidade clockwise 1600 mils. This

second position places the axis of the tubular level at a

right angle to the first position. Using the third

leveling screw knob only, center the bubble. See

figure 5-7.

Step 5. Rotate the alidade clockwise 1600 mils so that

it is 3200 mils from the first position. Level the

instrument using the same two leveling screws used in

the first position. This is the third position.

Step 6. Rotate the alidade clockwise 1600 mils so that

it is 3200 mils from the second position. Level the

instrument using the same single leveling screw used

in the second position. This is the fourth position. 

Step 7. Repeat Steps 5 and 6 above until the bubble

remains centered in both positions. 

Step 8. Rotate the alidade to the first position. If the

bubble remains centered in this position, rotate the

alidade to the second position. If the bubble remains

centered in this position, rotate the alidade throughout

6400 mils. If the bubble remains centered the

instrument is level.

Step 9. If the bubble does not remain centered during

the procedures in Step 8 but does remain within one

graduation, level the instrument by bringing the bubble

halfway back towards the centered position. If the

bubble continues to move more than one graduation, the

plate level adjustment should be performed. 

Step 10. After the instrument is level, check the optical

plumb to ensure that the instrument is centered exactly

over the station. If it is not, center the instrument over

the station by loosening the fixing screw on the tripod

and shifting the instrument on the tripod head. Check

the level of the instrument. Repeat the leveling process

if needed. Check the optical plumb again. Repeat this

process until the instrument is level and centered over

the station. The optical plumb must be in proper

adjustment. If not, the plumb bob may be a more

accurate method of plumbing the instrument. 

Eliminating Parallax and Adjusting Focus 

Before using the theodolite to measure angles, the

reticle parallax must be eliminated and the telescope

brought into focus. Parallax is eliminated by bringing

the focus of the eyepiece and the focus of the objective

lens to the plane of the reticle (crosslines). Point the

telescope toward the sky or a uniformly light surface.

Rotate the knurled ring of the eyepiece until the reticle

pattern is sharp, distinct lines. Focus your eyes on the

cross hairs and not on the sky. Point the telescope

Figure 5-6. First and Third Leveling Position. 

Figure 5-7. Second and Fourth Leveling Position.
Marine Artillery Survey Operations ________________________________________________________________________ 5-5

toward a well-defined distant point. While focusing on

the cross hairs, bring the distant point into a clear, sharp

image by rotating the focusing sleeve on the telescope.

To check for parallax, use the horizontal drive screw to

center the vertical cross hair on the point. Move your eye

horizontally back and forth across the eyepiece. If

parallax is eliminated, the cross hair will remain fixed on

the object as you move your eye. If parallax is not

eliminated, the cross hair will move back and forth across

the object. To eliminate any remaining parallax, change

the focus of the eyepiece slightly to bring the crosslines

into sharper focus and refocus the telescope accordingly

until there is no apparent motion.

Pointings 

Once the parallax has been eliminated and the

instrument is in focus, the instrument operator is ready

to make pointings on targets. These procedures are the

same for all pointings. However, placement of the

cross hairs depends on the type of target.

For pointings on a range pole, the standard rule is to

make the pointing centered on the lowest visible point.

When the range pole is too close to the theodolite to

judge the center, the operator can point to the left side

of the range pole with the telescope in the direct mode

and the right side in the reverse mode. The mean

between the direct and reverse will produce an angle

measured from the center of the range pole but will

usually not meet the 0.150 mil specification between

direct and reverse readings. See figure 5-8. 

When making pointings on the target plate (GZT1) of a

target set, the instrument operator should center the

cross hairs so that the vertical line is centered up and

down in the thin white extension of the small triangles.

The horizontal line should center left and right in the

thin extension of the large white triangle. See figure 5-9.

For pointings to a target reflector (GRZ3) with a single

or triple prism holder (GPH1Z or GPH3Z), the

instrument operator should center the cross hair below

the optical sight of the target reflector at the intersection

of the three yellow triangles. The target reflector must

be correctly oriented towards the theodolite for an

accurate sighting. See figure 5-10.

Figure 5-8. Pointings on a Range Pole.

Figure 5-9. Pointings on a Target Plate (GZT1).

Figure 5-10. Pointings on a Target 

Reflector (GRZ3). 
5-6 ______________________________________________________________________________________________ MCWP 3-16.7

When making pointings to an eleven-prism holder, the

instrument operator should center the cross hairs on

the center prism. Since this prism configuration is not

to be used for distances under 500 meters, parallelism

with the DI 3000 is not affected. If using the target

lamp (GEB72), place it in the center portal and use to

make pointings. See figure 5-11.

To make a pointing on a target, unlock the horizontal

and vertical clamp and point the telescope towards the

target. Roughly align the telescope on the target with

the optical sight. Lock the horizontal and vertical

clamps. Use the horizontal and vertical drive screws to

center the crosslines on the target as described above.

The last turn of the horizontal and vertical drive

screws should always be clockwise against the spring.

Reading The Scales

A system of lenses and prisms permits the instrument

operator to see small sections of either the horizontal

or vertical circles. The circles are viewed through the

circle-reading microscope eyepiece located beside the

telescope. The observer selects the circle to be viewed

by turning the circle-selector knob located on the right

standard. The field of view of the circle-reading

microscope contains three small windows. When the

red line on the circle-selector knob is horizontal, the

three windows will be yellow and horizontal readings

are taken. When the red line on the circle selector knob

is vertical, the three windows will be white and

vertical readings are taken. See figure 5-12.

Upper Window

This window is sometimes referred to as the

coincidence scale. When viewing this window, two

images of graduation lines of diametrically opposite

parts of the circle are seen. Both images move in

opposite directions and appear to be separated by a

fine line. The interval between gradations on each

circle is 2 mils but coincidence between the circles

occurs every 1 mil.

Central Window 

The central window has the main scale and the base

scale. The main scale in the upper portion of the

central window. It is made up of sets of three-digit

numbers representing tens of mils. In other words, 0

mils appears as 000; 10 mils as 001; 450 mils as 045;

Figure 5-11. Pointings on an Eleven-Prism 

Holder (GPH11).

Figure 5-12. View of the T-2E Scales.
Marine Artillery Survey Operations ________________________________________________________________________ 5-7

and 6390 mils as 639. Each three-digit number is

centered above a triangular index that reads the base

scale. The base scale is in the bottom portion of the

central window. It consists of a stationary scale

numbered 9 through 0, from left to right. Each number

represents its value in mils; e.g., 9 equals 9 mils and 1

equals 1 mil.

Bottom Window

This window is called the micrometer scale. It is

graduated clockwise from −0.006 mils to 1.006 mils in

0.001 mil increments. The scale is numbered every

0.010 mils. A stationary index line is set vertically

across the center of the window.

Coincidence 

Optical coincidence is obtained by aligning

diametrically opposite graduations of a circle by turning

the micrometer knob. Graduations of the circle (upper

window) are brought into coincidence by making the

graduations appear to form continuous lines across the

dividing line. See figure 5-13. 

To bring the scales into coincidence, rotate the

micrometer knob forward and then back through its

complete range of motion. Looking into the

microscope, view only the upper window. 

Rotate the micrometer knob until the graduations in

the top and bottom circles form single continuous

vertical lines across the thin horizontal line of the

upper window. 

Circle Readings 

Once the operator has sighted on the target and

brought the scales into coincidence, he is ready to

announce circle readings. This is done by reading the

central and lower windows from top to bottom.

Procedures for reading the scales are the same for

horizontal and vertical readings. 

Viewing the central window, only one triangular index

in the main scale will be over the base scale.

Announce the three digits above that index, and then

announce the digit in the base scale directly under the

index. Figure 5-13 shows 481 from the main scale and

2 from the base scale. 

Viewing the bottom window, read the two digits

directly to the left of the index line. Determine the

value of the graduation closest to the index line.

Announce the three digits together preceded by the

word “point” to designate the position of the decimal.

Figure 5-13 shows 156 in the bottom window. When

the index line appears to be centered between two

graduations, the instrument operator should read the

even number.

The circle reading should be announced in individual

digits for proper recording. Numbers are said as “four,

eight, one, two, point, one, five, six.” 

Setting the Horizontal Circle

The horizontal circle of the T-2E cannot be fixed.

Before setting the circle, a pointing at a target must be

made and the horizontal clamp locked. Generally,

there are two situations that require the instrument

operator to set the horizontal circle: establishing an

initial circle setting and orienting the telescope along a

line of known azimuth.

Figure 5-13. Sample Circle Reading.
5-8 ______________________________________________________________________________________________ MCWP 3-16.7

Initial Circle Setting 

An initial circle setting is used during the process of

measuring a horizontal angle. It provides a buffer for

both operator pointing errors and horizontal

collimation error. 

Make a pointing on the rear station. Ensure the circleselector knob is set for the horizontal circle. 

Use the micrometer knob to set 0.150 mils on the

micrometer scale (bottom window).

Rotate the circle setting knob so that the triangular

index located under the 000 number of the main scale

is directly over the 0 on the base scale.

Use the circle setting knob to bring the upper window

into coincidence. Make sure the reading in the central

window is still 0 mils. Close the cap over the circle

setting knob.

Rotate the micrometer knob forward then back

through its complete range of motion. Looking into the

microscope, view only the upper window. 

Use the micrometer knob to bring the upper window

into coincidence.

Read the horizontal circle. The reading should be

within ±0.100 mils of 0.150.

Orienting the Scale 

The horizontal circle of the T-2E can be set so that the

circle reading will correspond to a known azimuth to a

target or station. The azimuth to any point on which

the telescope is oriented can be read directly from the

horizontal circle. 

To orient the horizontal circle, make a pointing on the

station that lies along the known azimuth. Ensure the

circle-selector knob is set for the horizontal circle.

Use the micrometer knob to set the decimal mils value

of the known azimuth on the micrometer scale (bottom

window). For example, if the known azimuth is

2176.987 mils, the operator will set 0.987 on the

micrometer scale. 

Rotate the circle-setting knob so that the triangular

index located under the tens of mils value of the

known azimuth in the main scale is directly over the

1’s value on the base scale. Again, if the known

azimuth is 2176.987 mils, the operator places the

triangular index under 217 in the main scale over the 6

in the base scale.

Use the circle setting knob to bring the upper window

into coincidence. Make sure the reading in the central

and bottom windows still equals the known azimuth.

Close the cap over the circle setting knob.

Horizontal Angles

Position Angle 

The horizontal circle of the T-2E is a clockwise scale.

All horizontal readings from this instrument are said to

be clockwise horizontal angles. This should not be

confused with the rotational direction of the alidade.

The alidade is rotated clockwise in the direct mode

and counterclockwise in the reverse mode. Procedures

for measuring a horizontal angle follow.

Step 1. With the telescope in the direct mode, point to

the rear station. Set the circle selector knob for the

horizontal circle. Set the initial circle setting and

announce it to the recorder. Each time the recorder

reads back a set or measured angle the operator must be

looking into the micrometer scope to verify the reading.

Step 2. Rotate the alidade clockwise to the forward

station. Make a pointing at the forward station and

announce the circle reading to the recorder.

Step 3. Plunge the telescope to the reverse mode and

make a pointing at the forward station. Announce the

circle reading to the recorder. 

Step 4. With the telescope in the reverse mode, rotate

the alidade counterclockwise to the rear station. Make

a pointing at the rear station and announce the reading

to the recorder. 

Steps 1 through 4 above constitute one direct and one

reverse pointing on each station. This is called a oneposition angle.
Marine Artillery Survey Operations ________________________________________________________________________ 5-9

Multiple Angles 

When it is necessary to measure the angle to more than

one station, make a pointing on the rear station with

the telescope in the direct mode and then on each

station around the horizon in a clockwise direction.

After obtaining a circle reading on the last station,

plunge the telescope and make a pointing at each

station in a counterclockwise direction. Start with the

last forward station and end with the rear station. One

set of direct and reverse pointings on all of the

observed stations constitutes one position. This is

called measuring a multiple angle. 

Circle Closure 

The direct and reverse circle readings at each station

should differ by 3200 mils, ±0.150 mils. 

If the difference between direct and reverse readings is

constant over several pointings, it can be assumed that

the error is in the horizontal collimation of the

instrument. This error can be corrected through

horizontal collimation adjustment.

If the difference is not relatively constant, the error is a

mixture of collimation error and operator error. In this

case, the instrument should not be adjusted until

constant errors are measured. 

Two-Position Angle 

In artillery survey, one-position angles are normally

measured. However, it may be necessary to measure a

two-position angle. This method measures the same

angle twice and uses the mean of the two

measurements. The first position angle is measured as

described previously. The second position angle is

measured the same way except that the initial pointing

at the rear station is performed in the reverse mode.

The horizontal circle is set to 4800.150 mils (±0.100)

for an initial circle setting.

When two-position angles are observed, the two

measured angles cannot differ by more than 0.050 mils.

If they do, the angles must be rejected and remeasured.

Vertical Angles

The T-2E does not measure vertical angles directly.

The vertical circle places 0 mils at the zenith. So

vertical circle readings are zenith angles, or in

artillery, vertical readings. See figure 5-14.

To convert a vertical reading to a vertical angle, the

recorder determines the angular difference between the

horizon and the line of sight. The horizon is 1600 mils

in the direct mode and 4800 mils in the reverse mode;

the line of sight is the vertical reading (zenith angle). 

The vertical angle is positive if the line of sight is

above the horizon (vertical readings less than 1600

mils and greater than 4800 mils). It is negative when

the line of sight is below the horizon (vertical readings

greater than 1600 mils and less than 4800 mils).

Vertical Index

The T-2E has an automatic vertical index. Its

functioning is checked as part of each vertical reading.

To check, the operator presses and releases the black

index button located on the left standard. Holding it in

will eventually compress the spring and cause the

automatic index to malfunction. While pressing the

button, he must view the upper window in the

Figure 5-14. Vertical Readings/Angles.
5-10 _____________________________________________________________________________________________ MCWP 3-16.7

microscope. If the instrument is properly leveled, the

graduation lines on the vertical circle will swing away

from each other and then settle back smoothly to their

original position. This verifies that the index is

functioning properly. If the graduation lines do not

settle back smoothly to their original position but jerk

to a stop, the instrument must be leveled again or

turned in for maintenance.

Determining Vertical Readings 

Make a pointing on the target in the direct mode. Set

the circle selector knob for the vertical circle. While

viewing the upper window in the microscope, press

the index button to check the automatic index.

Viewing only the upper window, bring the scale into

coincidence using the micrometer knob.

Announce the circle reading to the recorder. When the

recorder reads this back the operator must be looking

into the microscope to verify the reading.

Plunge the telescope to the reverse mode and make a

pointing at the target. While viewing the upper

window in the microscope, press the index button to

check the automatic index. Viewing only the upper

window, bring the scale into coincidence using the

micrometer knob.

Announce the circle reading to the recorder. When the

recorder reads this back the operator must be looking

into the microscope to verify the reading.

The procedures described above are the same whether the

pointings are made to a forward station or to a rear station.

Once the recorder has determined the vertical angles

from the vertical readings, the direct and reverse vertical

angles at each station should be the same (±0.150 mils).

If the difference between direct and reverse readings is

constant over several pointings, assume that the error

is in the vertical collimation of the instrument. If the

difference is not relatively constant, the error is a

mixture of collimation error and operator error. In this

case, the instrument should not be adjusted until

constant errors are measured.

Reciprocal Vertical Angles

A reciprocal vertical angle is the mean of two vertical

angles measured in opposite directions along the same

leg. The sign of the reciprocal vertical angle is the

same as the sign of the vertical angle measured from

the occupied station to the forward station.

Measuring a reciprocal vertical angle diminishes the

effects of refraction and Earth curvature. Refraction is

the bending and slowing of light as it passes through

the Earth’s atmosphere. The angle of refraction is

affected by temperature and pressure. Reciprocal

vertical angles should be measured through similar

atmospheric conditions. The time span between

measuring reciprocal vertical angles should be as short

as possible.

The effects of curvature of the Earth are minimal at

distances under 1,000 meters. Corrections are not used

in manual computations. Reciprocal vertical angles

completely negate the effects of Earth curvature. This

is why reciprocal vertical angles for all legs of a

survey longer than 1,000 meters in both fourth and

fifth order surveys must be measured. 

Most computers and software for computing surveys

will prompt reciprocal vertical angles. If you tell the

computer that reciprocal vertical angles were not

measured, the computer will apply an Earth curvature

correction to the distance. If reciprocal vertical

angles were measured, the computer will not apply

those corrections.

March Ordering

Open the transportation case and place it near the

tripod. Place the black cap over the objective lens of

the telescope. Place the telescope in a vertical position

with the objective lens down. Lock the vertical clamp.

Replace any parts of the T-2E that were taken off

during operation. Close the mirrors and circle-setting

knob cover. Center the leveling screws on the tribrach. 

Rotate the alidade so that the red line on the right

standard is aligned with the red line on the lower part.
Marine Artillery Survey Operations ______________________________________________________________________ 5-11

Lock the horizontal clamp. Hold the theodolite by its

right standard and unscrew the tribrach from the fixing

screw. Lift the theodolite from the tripod and secure it

in the transportation case. Replace the tripod head

cover, collapse the tripod legs, and strap the legs

together. Make sure the legs are securely tightened.

Tests and Adjustments

Keep the theodolite in correct adjustment for accurate

results. There are five operator tests and adjustments

of the T-2E theodolite. When a test indicates that an

adjustment is needed, the operator adjusts and retests

for accuracy before making the next test in sequence.

Tests and adjustments are made with the instrument

mounted on its tripod. Setup the instrument in the

shade, on firm ground, with the head of the tripod as

level as possible. Protect it from the wind. Tests and

adjustments must be made in the following sequence: 

l Plate level.

l Circular bubble.

l Optical plumb.

l Horizontal collimation.

l Vertical collimation (index error).

Plate Level 

The plate level adjustment aligns the vertical axis of the

theodolite to a line that is perpendicular to the geoid

when the bubble of the plate level is centered in its vial. 

Unlock the horizontal clamp and rotate the alidade until

the axis of the plate level is parallel with any two

leveling screws. Center the bubble using those two

screws. Rotate the alidade clockwise through 1600 mils

and center the bubble with the third leveling screw.

Rotate the alidade through 3200 mils. Noting the

position of the bubble, use the third leveling screw to

bring the bubble halfway back to its centered position.

Use an adjusting pin from the jewelers screwdriver to

carefully turn the adjustment screw until the bubble

centers. The adjustment screw is located inside a small

aperture at the bottom of the left standard.

Repeat these steps until the bubble remains centered

within one graduation for all positions of the alidade.

Circular Bubble 

This adjustment makes sure the vertical axis of the

tribrach aligns with the vertical axis of the theodolite.

This is very important when taking the T-2E off the

tribrach and replacing it with a target carrier. 

This test ensures that when the plate level is level to

within one graduation of center, the circular bubble

must be centered or adjusted. 

On the GDF22 tribrach, two capstan screws are

accessible via the side slits under the circular bubble.

As either screw is loosened, the bubble runs towards

it; as it is tightened the bubble runs away. 

Use an adjusting pin in the jeweler’s screwdriver to

turn one of the two capstan screws until the bubble is

located on a line between the center of the circle and

the other screw. 

Turn the other screw until the bubble is centered in the

circle. Repeat if necessary. Do not turn the screws

anymore than is necessary. 

Optical Plumb

This adjustment makes the vertical axis of the GDF22

tribrach pass through the station mark when the

theodolite (or target carrier) is properly leveled and

plumbed. This test requires that a theodolite or a target

carrier be mounted in the tribrach. Leveling must be

precise to test the optical plummet. The plate level of

the theodolite or target carrier must have been already

adjusted to perform this test. 

Set up and fine level the theodolite on a level tripod.

Attach a plumb bob to the fixing screw. 

Place a piece of paper or tape on the ground under the

plumb bob. Use a fine tip pen to mark the plumb point

on the paper. Rotate the plumb bob’s bayonet plug and

mark several positions through 6400 mils. Determine

the center position of all the marks.

Remove the plumb bob. The tribrach should be

optically plumb over the center of the plumb bob

marks. If not, adjust the optical plumb. 
5-12 _____________________________________________________________________________________________ MCWP 3-16.7

The optical plumb has two adjusting screws located on

the optical plumb arm under the tribrach. To adjust the

optical plumb, look through the optical plumb. Use two

jewelers screwdrivers to turn the adjustment screws in

small increments in the direction shown in figure 5-15

at the same time until the optical plumb is centered over

the mark. 

Horizontal Collimation 

This adjustment makes the line of sight perpendicular

to the tilting axis of the telescope.

To test, select a well-defined point at least 100 meters

from and at about the same elevation as the

instrument. With the telescope in the direct position,

center the vertical cross hair on the target and read the

horizontal circle reading to the recorder. Plunge the

telescope to the reverse position and take a reverse

reading to the same point.

The difference between the direct and reverse readings

should be exactly 3200 mils. Assuming no operator

error is present, the discrepancy between the actual

difference in the two readings and 3200 mils is the

apparent horizontal collimation error or twice the

actual horizontal collimation error. If the apparent

horizontal collimation error exceeds the specified

standard (0000.150 mils for the T-2E), the operator

should perform the horizontal collimation adjustment.

The horizontal collimation is adjusted as small as

possible at the factory but cannot be completely

eliminated by adjustment. For this reason, adjustments

of the horizontal collimation should only be made when

absolutely necessary. Another reason is that if the

adjustment screws are not set correctly (too loose or

tight), the instrument will not maintain the adjustment. 

To adjust the horizontal collimation error, with the

telescope on the point in the reverse position, set the

mean value of the direct and reverse pointings on the

micrometer scale by using the coincidence knob.

Bring the main scale into coincidence by using the

horizontal tangent screw. This moves the vertical

crossline of the telescope off the point by the amount

of the actual horizontal collimation error.

Use the adjusting pins in the jewelers screwdriver to align

the vertical crossline back on the point by lateral

movement of the reticle within the telescope. The T-2E

has two pull-action capstan adjusting screws arranged

horizontally and on opposite sides of the telescope. To

align the vertical cross hair, loosen one screw and tighten

the opposite one an equal amount. The cross hair will

move laterally toward the screw that you tighten. Do not

try to make the entire adjustment in one step. Loosen and

tighten the opposite screws in small amounts. Proceed in

this manner until the cross hair is aligned on the station.

Make sure the capstan screws are rotated equally;

otherwise the reticle will be too loose or too tight and will

not remain in adjustment. 

Perform the horizontal collimation test again. Make

additional adjustments as needed until the

difference between the direct and reverse pointings

is less than 0.150 mils.

Vertical Collimation (Index Error) 

This adjustment makes the line of sight perpendicular

to the zenith when the vertical circle reads 1600 mils

with the telescope in the direct position or 4800 mils

with the telescope in the reverse position. The sum of

the direct and reverse readings should equal 6400 mils.

Any difference between the sum of the two readings

and 6400 mils is the apparent vertical collimation error

Figure 5-15. Optical Plumb Adjustment Screws.
Marine Artillery Survey Operations ______________________________________________________________________ 5-13

(or twice the actual error). If the difference exceeds

0.150 mils, adjust the vertical index.

The index error is adjusted as small as possible at the

factory but cannot be eliminated by adjustment. For

this reason, adjustments of the vertical collimation

should only be made when absolutely necessary.

To adjust, with the telescope in the reverse position

and accurately sighted on the selected point, use the

micrometer knob to set the fractional part of the

corrected reading on the micrometer scale. This will

bring the scale out of coincidence. See figure 5-16 to

compute the corrected reading. 

Use the wide tip in the jewelers screwdriver to open

the index cover located beside the vertical drive screw

to show the index adjustment screw. Turn the index

adjustment screw until coincidence is obtained in the

upper window of the scales. Close the index cover.

Repeat the test and adjust as needed until the sum of the

direct and reverse pointings is within 0.150 mils of 6400.

Artificial Illumination

The T-2E theodolite is equipped for artificial

illumination by way of a coaxial socket located on the

lower part of the theodolite and an illumination kit.

The horizontal and vertical circle can be illuminated as

well as the reticle.

All components of the illumination kit are stored in the

GEB-63 battery box. The battery box has three socket

holes along its bottom edge. The largest of these

socket holes is for a cable connected to an external

power source; i.e., GEB-70 battery. The other two

holes are for instrument illumination. The battery box

also has an ON/OFF switch located on its side. See

figure 5-17.

The illumination kit is powered primarily by a 9 volt

battery. Under normal conditions a new 9 volt battery

will last up to 20 hours. Place the ON/OFF switch in

the OFF position when power is not needed to prevent

undue discharge and increase battery life. Remove the

9 volt battery for storage. A cable is available to

provide external power from a GEB-70 NiCad battery.

Two GEB-58 plug-in lamps supply the illumination.

These lamps plug in to the mirror sockets when the

mirrors are removed. Each GEB-58 lamp has a rheostat

that rotates to adjust brightness. They also contain highperformance light emitting diodes (LED) for uniform

illumination of the circles and the field of view.

To attach the illumination kit before leveling the T-2E,

remove the mirrors and plug in the lamps. Place the

mirrors in the transportation case until replaced on the

theodolite. Hang the battery box on a tripod leg.

Plug in one end of the GEV-34 cable into the coaxial

socket on the lower part. Plug in the other end to one

of the two small socket holes at the bottom of the

battery box. Both ends of the cable are the same.

Attach external power if needed.

Place the ON/OFF switch in the ON position. Adjust

the illumination brightness with the rheostat knobs on

the plug-in lamps.

Direct Reading: 1609.812 1598.216

Reverse Reading: 4790.715 4801.208

SUM= 6400.527 5399.424

Apparent Error: +0.527 -0.576

Actual Error: +0.264 -0.288

Correction: -0.264 +0.288

Corrected Reading: 4790.451 4801.496

Figure 5-16. Computing the 

Corrected Reading.

Figure 5-17. GEB-63 with Accessories.
5-14 _____________________________________________________________________________________________ MCWP 3-16.7

Maintenance

Clean all lenses, mirrors, and bubbles with lens paper.

Do not touch the lenses with your fingers. Wipe all

paintwork with a dry, lint-free cloth. If needed,

moisten the cloth with ether or alcohol; never use oil,

benzene or water. 

Carefully wipe a wet instrument with a dry, lint-free

cloth. Let a wet instrument dry completely before

returning it to the case. Never store a wet instrument

in its case.

Keep the case clean inside and out. Remove the foam

rubber inserts to clean.

When a large temperature difference exists between

outside and storage temperatures, allow time for the

instrument to obtain temperature equilibrium. This is

necessary if full use of the instruments measuring

accuracy is to be obtained. As a general rule, the time

to obtain equilibrium corresponds to the temperature

difference in °C. In other words, if there is a 5°C

difference between storage and outside temperatures,

then allow 5 minutes.

The transportation case should not be used for storage

of the T-2E. Store the theodolite outside the case so

that air can flow around it. This helps to prevent

mildew and fungus in both the T-2E and the case.

Store the T-2E in an area as close to outside

temperatures as possible to decrease the effects of

steaming of the optics and condensation. Use a

dehumidifier in humid climates. 

Transport the T-2E in the foam rubber-padded

transportation cases. 

Test the T-2E on a quarterly basis. Adjust it only when

needed. Keep a test and adjustment log with

equipment records if possible.

Conduct calibration and repair through the survey

instrument calibration program (SICP). 

SECTION II. DI 3000 DISTOMAT

The DI 3000 is a timed-pulse electronic distancemeasuring device. The time needed for a pulse of

infrared light to travel to the reflector and back is

measured. Depending on the measuring mode, the

displayed result will be the mean of hundreds or

even thousands of such measurements. The laser is

listed as a Class 1 laser product meaning it is

completely harmless. 

Range and Accuracy

The maximum range depends on atmospheric

conditions and prism configuration. Poor atmospheric

conditions such as haze or bright sunlight will

decrease its maximum ranges. Table 5-1 shows the

typical ranges that can be expected with different

target configurations and different atmospheric

conditions using Wild (Leica) circular prisms. 

Accuracy of the displayed distances depends on the

operating mode. Standard deviation is listed at 3-5

millimeters +1 parts per million for all operating

modes except the tracking mode (10 mm + 1 ppm).

One parts per million equals 1 millimeter per

kilometer measured. This means that with a distance

of 10,000 meters in the normal mode, the standard

deviation equals 13-15 millimeters.

Table 5-1. Typical Ranges.

Number of ATMOSPHERIC CONDITIONS

Prisms Poor Average Excellent

about about about

1 2.0 km 6 km 9 km

3 2.3 km 7 km 11 km

11 2.7 km 9 km 14 km

Poor: Strong haze with visibility about 3 km or very bright sunlight with 

severe heat shimmer.

Average: Light haze with visibility about 15 km or moderate sunlight 

with light heat shimmer.

Excellent: Overcast, no haze, visibility about 30 km, no heat shimmer.
Marine Artillery Survey Operations ______________________________________________________________________ 5-15

Power Sources 

The DI 3000 requires a 12 volt DC power source.

Several sources of power are available. The GEB-70 is

a 2 amp hour, 12 volt DC, Nickel-cadmium

rechargeable battery. Fully charged it provides

sufficient power to measure about 2000 distances. The

GEB-70 has a clip on its side so it can hang on a tripod

leg. It has a 2.5A fuse on its bottom to prevent damage

to the battery and distomat. A 5-pin cable (GEV-52)

connects the GEB-70 to the DI 3000. See figure 5-18. 

The battery has a nonconstant discharge rate. The

battery discharges quickly between power indicators 9

to 7 and between indicators 3 to 1. It discharges slowly

between power indicators 7 to 3. The power indicators

are displayed on the DI 3000 Control Panel. When the

battery voltage drops below 11.0V (power indicator

1), the distomat will not measure a distance. Error

message 12 appears on the display. See figure 5-19.

The GEV-51 cable connects the DI 3000 to a 12 volt

vehicle battery. One end has alligator clips for the

battery terminals. The other end has a black box with a

2.5A fuse with two spares. The black box has a 5-pin

connection for the GEV-52 power cable.

The GKL-12 battery charger can recharge two GEB

70 NiCad batteries at a time. It generally takes 14

hours to recharge a completely discharged battery. The

charger plugs into a standard AC outlet and may be set

for either 115 or 220 volts. When the batteries are

connected, a red light illuminates on the charger. If no

light appears, then the cables are not connected

properly, no power is going to the charger or the fuse

in the batteries are blown.

The charger has a built-in overload protection timer. With

a battery connected, press the red button to start a 14-hour

charge. If there is a break in the AC main supply, the

timer restarts automatically. At the end of charging, it

automatically switches off the power supply.

Mounting the DI 3000 to a T-2E

Before the DI 3000 can be mounted on a T-2E, the

operator must ensure the theodolite has been properly

modified. Modification includes adding an adapter plate

to the reverse side of the telescope, adding a tension pin

on the standard of the theodolite, and changing the

spring in the vertical drive. See figure 5-20. 

Figure 5-18. GEB-70 NiCad Battery.

Figure 5-19. GEB-70 Discharge Rate. Figure 5-20. DI 3000 Bottom View.
5-16 _____________________________________________________________________________________________ MCWP 3-16.7

Setup and plumb the tripod. Mount the theodolite on the

tripod. Remove the carrying handle and lens cap from the

theodolite. Place the telescope in the reverse position.

Attach the GEB-70 battery to the tripod leg. Do not

disturb the plumb and level of the tripod. Holding the

DI 3000 by the carrying handle, press the two spring

levers at the keyboard end together with the other hand.

Place the DI 3000 over the telescope. Align the

tension pin on the standard between the balancing

springs on the distomat. Lower the distomat so that

the holes in the base plate are aligned to the posts on

the telescopes adapter plate. Release the two spring

levers. Check to ensure the DI 3000 is properly

seated. See figures 5-21 and 5-22.

Connect the large end of the GEV-52 cable to the GEB

70 battery or to the GEV-51 12v cable by aligning the

red dots on the connectors. Connect the small end of

the GEV-52 cable to the DI 3000 by aligning the red

dots on the connectors. 

Remove the lens covers from the front of the distomat

and place them in the instrument case. Close the

instrument case and place it out of the way. Plumb and

level the theodolite.

Control Panel

All DI 3000 operations are performed using the

control panel. It includes the signal strength indicator,

the LCD display, and the keyboard. See figure 5-23.

The signal strength indicator is located at the upper right

corner of the control panel. When a signal is received

from a prism set, the indicator illuminates in red. When

a weak signal is received, the indicator illuminates to

the left; when a strong signal is received, the indicator

illuminates to the right. If no return signal is received,

the indicator does not illuminate. 

Figure 5-21. T-2E Modification for DI 3000.

Figure 5-22. DI 3000 Mounted on T-2E.

Figure 5-23. DI 3000 Control Panel.
Marine Artillery Survey Operations ______________________________________________________________________ 5-17

The DI 3000 is equipped with a seven-digit LCD that

illuminates. The full distance is always displayed as well

as symbols indicating operating modes and functions.

The keyboard is the operator’s interface with the

distomat. The keys have several functions as indicated

by their colors. White keys are main commands, green

keys are display settings, and orange keys are set and

store parameters. The DI 3000 beeps with each

keystroke unless that keystroke is out of sequence,

illogical or is carrying out an operation. 

Operation 

Press the ON/OFF button to start. The LCD displays

the stored ppm and prism constant. To turn off, press

the ON/OFF button. By default, the DI 3000 switches

off automatically 10 minutes after the last keystroke

except when in the tracking mode. 

The display field is illuminated from the back. To

illuminate the display press the LAMP button. Press it

again to turn off.

To display the LCD test and the battery power

indicator, press and hold down the TEST button. The

display check appears while the TEST button is

pressed; when released the battery power indicator

displays the battery voltage in terms of a value from

1 to 9. The DI 3000 sends out a signal to the prism

set, the signal strength indicator illuminates, and a

tone sounds. The STOP button cancels the tone.

Press any command key to exit the test mode. 

The CE key (CE, RUN, +/-) allows the operator to exit

from a command while retaining the current setting.

While inputting data the CE button clears the entry

one figure at a time until RUN is touched. RUN

completes entries and commands. Once RUN is

touched, settings are made and their values stored. To

enter values that require a negative, press the +/− key.

Use the STOP key to halt—

l Tracking in the track mode.

l The repeat mode.

l A normal measurement. This is necessary if the

beam is interrupted by an object and the

measurement cannot be completed.

l The tone in the test mode.

System Settings

Prism Constant (Millimeters) 

The DI 3000 determines the distance to the center of

the reflective surface of the prism. The surface

position is offset differently depending on the type of

prism used. If the measured distance is to be correct,

the prism constant for the type of prism must be stored

in the DI 3000. The prism constant must be entered in

millimeters. Use the following settings:

l 0 millimeter for Wild circular prisms.

l −35 millimeter for Wild rectangular prisms.

l When using non-Wild prisms, determine the prism

constant by measuring on an accurately known base

line. To store the prism constant press SET, mm;

enter the millimeter value; and press RUN.

Units 

The DI 3000 can measure meters or feet. The unit of

measurement that has been stored will be used until it

is changed, even if turned off and then on again. An F

(for feet) will appear in front of the ppm value on the

display if feet are stored as the unit of measure. To set

units, press SET, MODE. Enter 41. Press RUN. Enter

0 for meters, 1 for feet. Press RUN.

Decimal Fix 

The number of digits displayed after the decimal point in

a measured distance can be set from 0 to 4. This setting

remains until changed. The displayed distances are as

follows (n = number of digits after the decimal point):

To set the number of digits after the decimal press

SET, FIX; enter n. 

n = 0 1m 1 ft 

n = 1 0.1m 0.1 ft

n = 2 0.01m 0.01 ft 

n = 3 0.001m 0.001 ft 

n = 4 0.0001m 0.0001 ft
5-18 _____________________________________________________________________________________________ MCWP 3-16.7

Scale Correction (Parts Per Million) 

The scale correction in parts per million applies

proportionate corrections to a measured distance. The

corrections negate the affects of atmospheric

conditions, sea level reduction, and projection scale

factor. The affects of atmospheric conditions are

discussed in this paragraph. The affects of sea level

reduction and projection scale factor are corrected in

most survey computer systems and should not be used

with the DI 3000. 

Atmospheric conditions affect the speed of the infrared

light that, in turn, affects the time for that light to travel

to the prism and back. So the time to compute the

distance is in error and a parts per million compensates

for this. The conditions used to determine parts per

million corrections are temperature, barometric

pressure, and humidity.

Temperature and Barometric Pressure 

Temperature and barometric pressure are generally

considered together to produce a scale correction. The

operators manual has a chart for figuring a parts per

million from temperature and pressure. The DI 3000

allows the operator to enter that parts per million or can

compute it from a user-entered pressure and

temperature. Let the distomat compute the parts per

million. Enter pressure in millibars, temperature in °Cs.

Both methods are explained below.

To store the scale correction (parts per million)—

l Press SET, ppm.

l Enter the ppm value.

l Press RUN.

To enter and store pressure and temperature—

l Press SET, p/t.

l Enter the pressure (550 mb to 1050 mb).

l Press RUN.

l Enter the temperature (-99 to +99°C).

l Press RUN.

Relative Humidity 

The influence of humidity on infrared light is very

small. It needs only to be considered in hot regions,

and if the most precise distance measurements are

needed. The humidity value defaults to 60 percent

when turned on. This default value is sufficient for all

artillery survey applications. The atmospheric

correction in ppm is calculated using the entered

temperature, pressure, and humidity values. If the

default value of 60 percent humidity is accepted, the

error in the calculated atmospheric correction will

never exceed 2 parts per million at 50°C. It will never

exceed 0.5 parts per million at 20°C. To enter the

relative humidity, press SET, MODE. Enter 45. Press

RUN. Enter the humidity value in percent. Press RUN.

The DI 3000 does not store the humidity value when

turned off. The default value of 60 percent is reset at

turn-on and the parts per million displayed is

recomputed using the default value.

Distance Measurement 

Once the DI 3000 has been mounted on the T-2E and

the theodolite is properly plumb and level, the operator

must sight on the target. To measure a distance press

ON. Enter the scale correction. Press TEST. If the

signal strength indicator displays a sufficient return

signal, the operator can measure the distance using one

of four operating modes shown below. If the return

signal strength is not sufficient to measure a distance,

correct the parallelism of the distomat.

The normal (DIST) mode takes 3.5 seconds and has a

standard deviation of 3 − 5 millimeters + 1 parts per

million. Press DIST. Distance is measured and

displayed. If the operator uses this mode, several

distances must be measured and meaned. At least three

distances must be measured. 

The rapid (DI) mode takes 0.8 seconds and has a

standard deviation of 5 millimeters + 1 parts per

million. Press DI. The DI 3000 measures the distance

and displays it. If the operator uses this mode, several

distances must be measured and meaned. At least three

distances must be measured. The primary difference

between this mode and the normal mode is the listed
Marine Artillery Survey Operations ______________________________________________________________________ 5-19

accuracy. This mode can also be used when heatshimmer conditions prevent the user from measuring

long distances with the normal and repeat modes. 

The tracking (TRK) mode takes 0.8 seconds for the initial

measurement followed by updates every 0.3 seconds. It

has a standard deviation of 10 mm + 1 ppm. Press TRK.

This mode sends a constant signal and continuously

displays a new distance. It will mostly be used with stake

out measurements but can be used during parallelism

adjustments. This mode can drain batteries if not

monitored because the automatic shut-off is disabled

while tracking. 

The repeat (DIL) mode takes 3.5 seconds for the initial

measurement and repeats automatically. The display

in the repeat mode alternates between the cumulative

mean of all measurements on one display and the

number of measurements taken (n) and the standard

deviation (s) in millimeters of a single measurement

on the next display. Press DIL. The instrument

operator monitors the standard deviation as it falls and

then levels out. Once the standard deviation levels out,

press STOP. The cumulative mean of all distances is

displayed. If the number of measurements and the

standard deviation needs to be viewed, press DSP.

Interruptions in the beam of infrared light will not

affect the result. If the beam is interrupted, the display

shows from 1 to 6 bars. The bars indicate how far the

measurement has progressed. One bar equals start of

measurement; six bars equals end of measurement.

Short interruptions can be caused by air turbulence.

Thus, long distance measurements may take slightly

longer in heat-shimmer conditions. In the normal, rapid,

and repeat modes, the measurement terminates

automatically if the beam is interrupted for 30 seconds.

In the tracking mode the tracking sequence starts again

with an initial 0.8 second-measurement if the beam is

interrupted for 0.5 seconds. 

Parallelism: DI 3000 to Telescope

The infrared beam of the DI 3000 and the line of sight

of the T-2E telescope should be parallel. The return

signal strength is strongest when a proper pointing is

made at a target. If parallelism is not correctly adjusted,

the return signal strength is weak or none at all. 

Parallelism is normally adjusted at the distomat but the

prism-target distance must be set for the type of

theodolite. Prism-target distance is the distance from

the center of the prism (GPR1) to the center of the

optical sight on the target reflector (GRZ3). This

distance must be set so that it equals the distance

between the center of the objective lenses of the DI

3000 and the center of the telescope’s objective lens.

See figure 5-24.

To set prism-target distance, use a jewelers

screwdriver to drive the grub screw in the stem of the

prism holder (GPH3Z) into the stem. 

Slide the two stems of the prism holder into the target

reflector so that the grub screw aligns with the 87 mm

hole labeled for the T-2 theodolite. 

Use the jewelers screwdriver to draw the grub screw

out of the stem enough to keep the prism holder fixed

in place in the target reflector.

Checking Parallelism

Check parallelism before starting a survey. The

adjustment can be made anytime. To check the

parallelism, set up the DI 3000. Set up a target at least

200 meters away with a clear line of sight. 

Figure 5-24. Prism-Target Distance.
5-20 _____________________________________________________________________________________________ MCWP 3-16.7

Make a pointing on the target reflector. Press ON,

TEST. If the signal strength indicator illuminates to

the right of center, do not adjust. If the indicator

illuminates to the left of center or not at all, adjust.

Adjusting Parallelism

If the procedures above indicate that a parallelism

adjustment is needed, ensure the telescope of the T-2E

is properly pointed on the target. Press TEST. View

the optical sight located on the bottom right side. 

Use the hex key to turn the horizontal and vertical

adjustment screws to bring the white cross onto the

prism. The signal strength indicator should illuminate

towards the right and an audible tone will be heard.

See figure 5-25. 

Viewing the signal strength indicator, adjust the

horizontal and vertical adjustment screws until the

strongest return signal is achieved. Press STOP, OFF,

ON, TEST. 

The signal strength indicator should illuminate to

the right and the audible tone should sound. Press

STOP, OFF. 

SECTION III. TARGET SET

The target set is a system that allows for forced

centering over a station being used as a target for

measuring angles and distances. It provides a rapid and

accurate method of switching between target and

theodolite and requires the tripod and tribrach to be

setup only once. Referred to as the target set, it has a

standard quick release mounting post. It holds the target

plate, prism holders, or the MSGR 4000 (GPS-S)

antenna with a quick release adapter. It has night

lighting capability and is virtually waterproof.

Components 

Tribrach (GDF22)

The tribrach for the target set is the GDF22 (the same

tribrach used with the T-2E). The GDF22 mounts on

all tripods with a standard 5/8-inch fixing screw. It

has three leveling knobs, a fish-eye level, and an

optical plummet. 

Target Carrier (GZR2) 

There are two types of target sets: simple and

precise. The difference is the target carrier. The

GZR2 is used with the precise target set. It has a

plate level for precise leveling-up. When properly

adjusted, leveled, and mounted in a tribrach with a

properly adjusted optical plummet, the target can be

centered over the ground point to within 0.5

millimeters. The GZR2 is designed for use with the

T-2E. It is placed in the tribrach and is locked in

place by turning the swivel-locking knob on the side

of the tribrach. See figure 5-26.

Figure 5-25. Adjusting Parallelism.
Marine Artillery Survey Operations ______________________________________________________________________ 5-21

Target Plate (GZT1) 

The target plate is fitted onto the target carrier by

pressing the release button on the bottom side of the

plate. It has a black and white target grid that creates

reference marks for horizontal and vertical pointings.

When fitted on the GZR2 carrier, the horizontal

pointing marks of the target plate are the same height

above the tribrach base as the T-2E tilting axis. The

vertical pointing mark is aligned with the plumb line

when the carrier and tribrach are properly adjusted and

leveled. The target is generally observable in daylight at

distances of over 1 kilometer. For longer distances, the

GZT2 large target plate can be fitted onto the GZT1

target. The large target plate is not a component of the

target set, but it is a component of the survey set. The

GZT2 target allows sightings as long as 8 kilometers in

good visibility conditions.

Illumination Kit

The illumination kit consists of a screw on reflector and

a battery box. The battery box has an ON/OFF switch on

the back of the case and is powered by two AA batteries.

The bulb is screwed into the front side of the case and an

extra bulb is inside. The reflector is screwed onto the

case over the bulb and slides over the backside of the

target plate (used with the GZT1 target only.) The target

set holds the target plate GRZ3 with the triple prism

holder GPH3Z. The prism holder has a release button

like the GZT1’s target plate for mounting on the target

carrier. When the prism holder is set for use with the

T-2E theodolite, the horizontal pointing markers on the

prism holder are the same height above the tribrach base

as the T-2E tilting axis. See figure 5-27. 

Mounting

Open the target set case. Carefully place the tribrach

on top of the tripod. Keep one hand on the tribrach and

attach the tribrach to the tripod head by screwing the

fixing screw snugly into the base of the tribrach. Make

sure the swivel-locking knob is open. Carefully place

the target carrier into the tribrach. Rotate the swivellocking knob clockwise one-half turn until the arrow

points down and the carrier is secure.

Plumb and Level 

Step 1. Loosen the fixing screw slightly and carefully

slide the target set on the tripod head to center the

point of the plumb bob exactly over the station.

Figure 5-26. Target Set with Target Plate.

Figure 5-27. Target Set with GRZ3 and GPH3Z.
5-22 _____________________________________________________________________________________________ MCWP 3-16.7

Step 2. With one hand on the target set, tighten the

fixing screw. Excessive tightening of the fixing screw

will bend the tripod’s slotted arm and damage the

tripod head. Be sure the point of the plumb bob

remains centered over the station. Remove the plumb

bob and return it to its case.

Step 3. Rotate the target carrier until the axis of the

plate level is parallel to any two of the three leveling

screw knobs. Grasp the leveling screw knobs between

the thumb and forefinger of each hand. Turn the knobs

at the same time so the thumbs of both hands move

either toward each other or away from each other. This

movement tightens one screw as it loosens the other.

The bubble always moves in the same direction as the

left thumb. Center the bubble by using these two

leveling screw knobs. This is the first position. 

Step 4. Rotate the target carrier clockwise 1600 mils.

This second position places the axis of the plate level

at a right angle to the first position. Using the third

leveling screw knob only, center the bubble. 

Step 5. Rotate the target carrier clockwise 1600 mils

so that it is 3200 mils from the first position. Level the

target set using the same two leveling screws as were

used in the first position. This is the third position.

Step 6. Rotate the target carrier clockwise 1600 mils

so that it is 3200 mils from the second position. Level

the target set using the same single leveling screw that

was used in the second position, this is the fourth

position.

Step 7. Repeat Steps 5 and 6 above until the bubble

remains centered in both positions.

Step 8. Rotate the target carrier to the first position. If

the bubble stays centered in this position, rotate the

target carrier to the second position. If the bubble stays

centered in this position, rotate the target carrier

throughout 6400 mils. If the bubble stays centered, the

instrument is level.

Step 9. If the bubble does not stay centered during the

procedures in Step 8 but is within one graduation,

level the instrument by bringing the bubble halfway

back towards the centered position. If the bubble

continues to move more than one graduation, adjust

the level vial. 

Step 10. After the instrument is level, check the

optical plumb to make sure the target set is

centered exactly over the station. If not, center the

instrument over the station by loosening the fixing

screw on the tripod and shifting the target set on

the tripod head. Check the level of the target set. If

necessary, repeat the leveling process and check

the optical plumb again. Repeat this process until

the target set is level and centered over the station.

The optical plumb must be in proper adjustment. If

not, the plumb bob may be a more accurate method

of plumbing the instrument. 

Mounting the Target Plate

Once the target set is plumbed and leveled, place the

target plate on the carrier. 

If using a GZT1 target plate, depress the release button

at the bottom-side of the target plate. Carefully place

the target plate over the target carrier mounting post.

Orient the target towards the station that will be

sighting on the target. Place the GZT2 large target

plate or the illumination kit over the GZT1 target plate

at this time.

If using the GRZ3 target plate with the GPH3Z triple

prism holder, depress the release button at the bottomside of the target plate. Carefully place the target plate

over the target carrier mounting post. Orient the target

towards the station that will be sighting on the target

using the optical sight on the target plate. If needed,

rotate the prisms vertically by loosening the screw

knobs on the sides of the target plate and rotating the

plate until the prisms are oriented towards the station.

Tighten the screw knobs. After placing the target

plate on the target carrier, verify the target set plumb

and level.

Tests and Adjustments 

The target set must be kept in correct adjustment to

get accurate results. Test and adjust with the set

mounted on its tripod. Set up the target set in the

shade on firm ground with the head of the tripod as
Marine Artillery Survey Operations ______________________________________________________________________ 5-23

level as possible. Protect the target set from the wind.

When a test shows that an adjustment is needed, the

operator adjusts and retests for accuracy before

making the next test in sequence. 

l Plate level.

l Circular bubble.

l Optical plumb.

Plate Level 

This adjustment aligns the vertical axis of the target

carrier to a line that is perpendicular to the geoid when

the bubble of the plate level is centered in its vial.

Rotate the target carrier until the axis of the plate level

is parallel with any two leveling screws. Center the

bubble using those two screws. Rotate the target

carrier clockwise through 1600 mils and center the

bubble with the third leveling screw. Rotate the target

carrier through 3200 mils. Noting the position of the

bubble, use the third leveling screw to bring the bubble

halfway back to it’s centered position.

Use an adjusting pin from the jewelers screwdriver

with the T-2E theodolite to carefully turn the

adjustment screw until the bubble is centered. The

adjustment screw is located inside a small aperture at

the base of the carrier.

Repeat these steps until the bubble remains centered

within one graduation for all positions of the alidade.

Circular Bubble

This adjustment ensures that the vertical axis of the

tribrach is aligned with the vertical axis of the target

carrier. This is very important when taking the

target carrier off the tribrach and replacing it with a

T2-E theodolite.

To test, simply level the target carrier plate level to

within one graduation of center. Then center or adjust

the circular bubble.

On the GDF22 tribrach, two capstan screws are

accessible via the side slits under the circular bubble.

As either screw is loosened, the bubble runs towards

it; as it is tightened the bubble runs away. 

To adjust, use an adjusting pin provided in the

jewelers screwdriver with the T-2E theodolite. Turn

one of the two capstan screws until the bubble is

located on a line between the center of the circle and

the other screw. 

Turn the other screw until the bubble is centered in the

circle. Repeat if necessary. Do not turn the screws any

more than is needed to adjust.

Optical Plumb 

This adjustment makes the vertical axis of the GDF22

tribrach pass through the station mark when the target

carrier is properly level and plumb. 

The test requires that a target carrier be mounted in

the tribrach. This is because leveling must be precise

to test the optical plummet. The plate level of the

target carrier must have been already adjusted to

perform this test. 

Set up and fine level the target set on a level tripod.

Attach a plumb bob to the fixing screw. 

Place a piece of paper or tape on the ground under the

plumb bob. Use a fine tip pen to mark the plumb point

on the paper. Rotate the plumb bob’s bayonet plug and

mark several positions through 6400 mils. Determine

the center position of all the marks.

Remove the plumb bob. The tribrach should be

optically plumb over the mark located in the center of

the plumb bob marks. If not, adjust the optical plumb. 

The optical plumb has two adjusting screws on the

optical plumb arm under the tribrach. Look through

the optical plumb. Use two jewelers screwdrivers to

turn the adjustment screws in the direction shown in

figure 5-15 on page 5-12 until the optical plumb is

centered over the mark. 

Maintenance

Clean the plate level and circular bubble with lens

paper. If needed, moisten a cotton ball or swab with

ether or pure alcohol. Never use liquids such as
5-24 _____________________________________________________________________________________________ MCWP 3-16.7

benzene, oil or water. Do not touch the objective

lenses with your fingers.

Wipe paintwork clean. If needed, use a cloth dampened

with water. Never use liquids such as benzene.

Wipe a wet instrument carefully with a dry, lint-free

cloth. Let the instrument dry completely before placing it

in the case. Never store a wet instrument in its case.

Wipe cables clean with a damp cloth. If a connection

or a cable plug is dirty, wash it in spirit and let it dry.

Keep the case clean inside and out. Keep the inside dry. If

water gets in the case, wipe and leave open to dry.

Do not store the target set inside the shipping case.

Remove the instrument from the case so that air can

flow around it. This helps prevent mildew and fungus

in the case and instrument. Store the instrument in a

low humidity, dust proof area.

Transport the target set in the foam rubber-padded

transportation cases.

Test the target set quarterly. Adjustments made to

a theodolite are useless if the target set is not

properly adjusted. 

Conduct calibration and repairs for the target set

through the SICP.

To change the AA batteries in the illumination kit,

unscrew the two screws on the backside of the

battery box. Be careful not to pull the back off too

far. A delicate cable inside the box only allows about

1-inch play. 
CHAPTER 6. TRAVERSE

SECTION I. FUNDAMENTALS 

Traverse is a conventional survey method that

determines the position and elevation of the stations

occupied by a survey team as well as the azimuth

between those stations. Traverse can be used for all

accuracy levels of artillery survey (fourth, fifth, and

hasty). But in the chaotic and rapidly changing

environment of the battlefield it may be too time

consuming to perform at battalion and battery levels

where accurate, timely direction is the most critical

data needed to begin firing. Establishing a fourth order

horizontal control by regiment surveyors is the most

likely traverse operation to be conducted when other

methods are not feasible. This chapter discusses fourth

and fifth order survey methods. Hasty survey is

discussed in chapter 10.

Traverse has several advantages over other

conventional survey methods. It is well-suited for any

terrain. Whether surveying in a forested area with 100-

meter legs or a desert region with 12-kilometer legs,

traverse is the preferred method. 

Traverse allows a great deal of flexibility. If

necessary, a survey plan can be easily modified while

traversing. Often, a traverse can be laid out ahead of

the instrument operator during the survey.

Traverse requires less planning and reconnaissance

than other conventional survey methods. A traverse

works similar to determining a polar plot grid from a

map sheet. But instead of plotting the azimuth and

distance, coordinates are plotted with plane

trigonometry. See figure 6-1.

Open Traverse

This traverse begins at a point of known control and

ends at a station whose relative position is known only

by computations. It is the least desirable type of

traverse because it does not check the accuracy of the

control, field work or computations. Use open traverse

only when time or the enemy situation does not permit

closure on a known point. See figure 6-2.

Closed Traverse

This traverse starts and ends at stations of known

control. Because it provides a basis for comparison of

computed data against known data, a closing accuracy

can be determined.

Closed traverse on a second known point begins from

a point of known control, moves through the various

required unknown points, and then ends (closes) at a

Figure 6-1. Traverse. second point of known control, fourth order or higher.

Figure 6-2. Open Traverse.
6-2 ______________________________________________________________________________________________ MCWP 3-16.7

This preferred type of traverse checks on field work,

computations, and control. See figure 6-3.

Closed traverse on the starting point begins at a point

of known control, moves through the various required

unknown points, and ends (closes) at the same starting

point. This type of traverse is more desirable than an

open traverse but less than closing on a second known

point. It checks field work and computations but does

not check starting data accuracy or detect any

systematic errors. See figure 6-4.

Directional Traverse

This traverse extends directional (azimuth) control

only. It can be open or closed. If open, close the

traverse at the earliest opportunity. Close on the

starting azimuth or another known azimuth. Since

direction is the most critical element of artillery survey

and time is an important consideration, sometimes

lower echelons must assume battery location and

extend direction only. 

Sources of Control Data

Three elements of survey control must be known to

start and close a traverse: the UTM grid coordinates

and the elevation of a point and an azimuth from that

point to a visible azimuth mark. See figure 6-5. 

Starting and closing data may be obtained from many

different sources, but the two basic types of control are

known and assumed. 

Position and elevation may be acquired from trig lists

of local or national survey agencies; e.g., NGS or

NIMA or from supporting survey elements of a higher

headquarters. An azimuth-to-an-azimuth mark may be

determined from astronomic observation, computation

from known coordinates or by reference to an existing

trig list. Use an azimuth determined by a PADS twoposition mark or PADS autoreflection as a starting and

closing azimuth for a fifth order traverse. An azimuth

cannot be determined from computations between

PADS points. PADS positions can be used for

extending fifth order traverse, but the survey must be

closed on the starting station.

If no known control is available, survey data may be

obtained by assuming control (map spotting control

through the best available resources). If any portion of

starting control (coordinates, elevation, and azimuth)

has to be assumed, the traverse must open and close on

the same station. 

Figure 6-3. Closed Traverse on a Second Known Point.

Figure 6-4. Closed Traverse on the Starting Point.

Figure 6-5. Starting and Closing Control.
Marine Artillery Survey Operations ________________________________________________________________________ 6-3

Field Work

Traverse field notes are recorded in the current version

of the field recorder’s notebook.

Stations 

In a traverse, three stations are of immediate

significance: the rear, occupied, and forward. See

figure 6-6.

The occupied station is where the theodolite is set up

or occupies.

The rear station is where an azimuth from the

occupied station is known or has been computed. It is

the initial azimuth mark in a traverse or the occupied

station during the previous angle.

The forward station is where the azimuth from the

occupied station needs to be determined; it will be the

next occupied station.

Measurements

At each occupied station (except the closing station)

horizontal angles, vertical angles, and distance are

measured. Only a horizontal angle is required at the

closing station.

Horizontal angles are measured at the occupied station

with a theodolite by sighting on the rear station and

measuring the angle to the forward station. Horizontal

angles determine the azimuth to the forward station.

See figure 6-6. 

Vertical angles are measured at the occupied station

with a theodolite to the height of instrument at the

forward station, usually a target set with a prism.

Vertical angles are used primarily to determine the

difference in height between the occupied and forward

station. See figure 6-7.

When the distance between two successive stations in

a traverse exceeds 1,000 meters, reciprocal vertical

angles must be measured from each end of that

particular traverse leg. This reciprocal measurement

procedure negates errors caused by the Earth’s

curvature and refraction. See figure 6-8.

Figure 6-6. Rear, Occupied, and Forward Stations 

and Horizontal Angles. 

Figure 6-7. Vertical Angles.

Figure 6-8. Reciprocal Vertical Angles.
6-4 ______________________________________________________________________________________________ MCWP 3-16.7

The Earth curvature correction increases with

distance. For example, at 1,200 meters, the correction

is 0.1 meters; at 2,700 meters, 0.5 meters; and at 9,800

meters, 6.5 meters. It is easy to see that these

corrections are substantial. If reciprocal vertical angles

are not measured, these corrections will accumulate

into very large errors. 

Refraction varies depending on the Sun’s altitude,

temperature, and distance. It cannot be modeled like

Earth curvature.

Some survey computer systems correct the vertical

angle for Earth curvature if nonreciprocal vertical

angles are measured, but not for refraction. A computer

cannot determine its value with the data provided. Since

this is only a partial correction, reciprocal vertical

angles should be measured over all lines when time is

available to negate the effects of refraction and Earth

curvature. This is especially important during

measurements in high heat shimmer conditions.

The distance between the occupied station and the

forward station is measured by using electronic distance

measuring equipment, horizontal taping or trig-traverse.

Distances

The distance that determines the coordinates of the

forward station is not necessarily the distance

measured. Slope, horizontal, and grid distances must

be considered. See figure 6-9.

A slope distance is a straight-line distance between two

stations that includes the effects of terrain. The straightline distance between two stations of different elevations

is longer than the distance between those same stations at

equal elevations. Any distance determined by using

electronic distance measuring equipment is a slope

distance.

A horizontal distance is a straight-line distance between

two stations, determined without the effects of terrain

(the distance between the stations if they were both at

the same elevation).

Any distance measured with a steel tape or

determined through trigonometric computations is a

horizontal distance.

A slope distance can be converted to a horizontal

distance using the formula horizontal distance =

cosine (cos) (vertical angle) × slope distance. 

The vertical angle should be the mean of the reciprocal

vertical angles if the slope distance exceeds 1,000 meters.

With most calculators, an angle must be in degrees to

determine the trigonometric function of that angle. 

A grid distance is the distance needed to compute the

traverse leg. This distance is the same as a map distance.

Determine a grid distance by reducing the horizontal

distance to sea level. Then correct the sea level distance

to grid by applying a scale factor correction. 

If the horizontal distance was determined by horizontal

taping, the correction for reduction to sea level is

usually not applied. This type of distance is not accurate

and is usually relatively short. Figure 6-10 shows that

the correction for reduction to sea level increases as the

elevation of the traverse lines increases.

Figure 6-9. Slope and Horizontal Distances.
Marine Artillery Survey Operations ________________________________________________________________________ 6-5

The reduction to sea level correction is negative when

elevation is positive. The scale factor correction can be

positive or negative depending on where the traverse

line is with respect to the secant lines of the projection.

Since most survey computer systems apply the reduction

to sea level correction to the horizontal distance

automatically, the scale corrections (parts per million) for

the DI 3000 must not include this correction. 

Traverse Legs

A traverse leg is the line between two traverse stations.

One end of the line is a point of known position

(easting, northing, and elevation). The other end is a

point requiring control. There are two types of traverse

legs in artillery survey: main scheme legs and offset

legs. See figure 6-11.

A main scheme leg is one where both ends of the leg

are an occupied station in the traverse. An offset leg is

one where only the first station of the leg is occupied.

The important difference is that an offset leg is left

open (the coordinates and elevation determined for the

offset station are not used in computations of other

stations). Offset leg computations are performed

before main scheme leg computations that originates

from the same station.

The field data for the offset leg is measured and

recorded during the same occupation as the main

scheme data. The horizontal angle measured is

called a multiple angle because it includes

determining two horizontal angles from one set of

observations. The vertical angle is determined the

same way as with a main scheme leg including

determining reciprocal vertical angles if the offset

leg is longer than 1,000 meters.

SECTION II. FIELD NOTES

Survey Recorder Duties

The recorder’s notebook is a legal document to

document field notes during the course of field

survey work. The recorder maintains the only

original record of field measurements and any

occurrences that may affect those measurements. He

must also be thoroughly trained in the requirements

for all survey methods. Data recorded includes but is

not limited to measurements, sketches, descriptions,

and remarks.

Figure 6-10. Reduction to Sea Level.

Figure 6-11. Traverse Legs.
6-6 ______________________________________________________________________________________________ MCWP 3-16.7

Duties include—

l Records survey data neatly and legibly.

l Checks and means angular data.

l Records and means distances.

l Provides required data to the survey computers.

Horizontal angles, vertical angles, and distances from

the instrument operator must be recorded. Sketches

must be oriented with a north arrow and should be as

close to scale as possible. In a long survey, the sketch

may be separated over several pages.

Descriptions of stations to supplement the sketch should

be written in the remarks section. Include distances

from objects used to locate a station, type of marker,

etc. Any changes to descriptions in a trig list should also

be noted for submission to controlling agencies. 

The remarks section should include any remarks that

clarify survey data. Include descriptions of extreme

weather phenomena and explanations of voided angles

and pages. Some survey methods have required entries

for the remarks section. These required entries are

listed in the sections describing that method of survey.

Temperature and pressure entries used as corrections

for the DI 3000, instrument heights, and target heights

should be included.

General Rules

Recording field notes is regulated by certain rules that

apply to all methods. For the most part, these rules are

designed for consistency between different recorders

and to aid in the legibility and neatness.

Record all information in pencil. Keep the pencil

sharpened to a fine point. Never erase in the notebook.

Use only upper case letters. Do not slant letters and

numbers nor strike over them. Use approved

abbreviations and symbols. Use a straight edge and

protractor for the sketch. Record directly into the

notebook. Never record into an extract or on paper and

then transcribe recorded data to the recorder’s

notebook. Do not use pages of the recorder’s book to

perform math; use scratch paper.

Abbreviations that can be used are— 

Sometimes symbols need to be used, especially in

the sketch. Generally, the symbols in the legend of a

map sheet from the area of operations should be

used. See figure 6-12.

AZMK Azimuth Mark 

COP Chief of Party 

D Direct 

DIST Distance

FWD Forward 

GN Grid North 

HI Height of Instrument

HORZ Horizontal 

HT Height of Target 

IO Instrument Operator 

MN Mean 

OCC Occupied 

R Reverse 

RCDR Recorder 

READ Reading 

SCP Survey Control Point 

STA Station 

VERT Vertical
Marine Artillery Survey Operations ________________________________________________________________________ 6-7

The first numbered page of the recorder’s book is the

index. Page 1 includes the left and right sides. Heading

and column blocks are set up as follows. See figure 6-13.

Fill in the designation block with the word “INDEX”.

Fill in the date block with the date the book was

officially opened, usually the day the first survey in

that book was performed.

Do not list any information in the heading blocks on

the right side.

Label the column titles under the heading from left to

right as—

1, PAGE. Identify the page number that includes a

particular set of survey data.

2, DATE. List the date written in the date block of that

page.

3, TITLE. List the designation written in the

designation block of that page. 

7, 8, and 9: Same as columns 1, 2, and 3. 

Recording procedures for—

l GPS-S surveys and RTK/OTF are discussed in the

4000 MSGR job aids.

l Astronomic observations are discussed in chapter 7.

l PADS operations are discussed in chapter 8.

Figure 6-12. Standard Symbols 

for Recording.

Figure 6-13. Index Page.
6-8 ______________________________________________________________________________________________ MCWP 3-16.7

Recording A One-Position Angle

This type of angle is used for fourth and fifth order

traverse and most fifth order conventional methods

and PADS autoreflection. See figure 6-14. 

Heading and Column Titles 

Fill in the designation block with the survey method

being conducted; e.g., traverse. Fill in the date block

with the date the field work was done.

Fill in column titles as—

1, STATION. Identify occupied, rear, and forward stations. 

2, T. Identify the telescope position, direct (D), or

reverse (R).

3, HORZ. Record horizontal readings measured at the

occupied station and the mean horizontal angle used

for computations.

4, MEAN. Record the mean of the direct and reverse

horizontal readings at the forward and rear stations.

5, VERT READ. Record vertical readings measured

by the IO.

6, VERT. Record direct and reverse vertical angles

calculated by the RCDR from the vertical readings and

records the mean vertical angle used for computations.

7, SLOPE DIST. Record slope distances from the DI

3000. If only horizontal distances are measured, then

title this column DIST. 

8-12, REMARKS. Record any information about

measurements and subsequent computations. 

On the right side of figure 6-14, list weather conditions

(left side of the top line). Use two words. The first word

describes visibility; e.g., clear, sunny, cloudy; the second

describes temperature.

List instrument types and serial numbers under

weather conditions. This helps identify the instruments

that may need adjustments due to errors.

List names of the COP, IO, and RCDR on the right

side above the top line. 

STA and T Columns 

See figure 6-15. Fill out the T (telescope) column as

shown. 

Record the rear station (AzMk) name in the direct

(D) mode row directly below the STA column. 

Skip one line and record the occupied station name.

Skip one line and record the forward station name.

)

Figure 6-14. Heading and Column Titles (One-Position Angle).

Figure 6-15. STA and T Columns.
Marine Artillery Survey Operations ________________________________________________________________________ 6-9

Recording Field Data 

Record field data in the columns and rows that

correspond to the pointings. For example, when the

instrument operator determines the initial circle

setting, the T-2E is in the direct mode, pointed at the

rear station. Determine the measurement from the

horizontal circle. Record the initial circle setting in the

horizontal angle column in the direct mode row for the

rear station. Figure 6-16 shows the standard order for

measuring and recording a one-position angle. Figure

6-17 shows data recorded with means computed. Note

that only data used by the computer is circled.

Figure 6-16. Standard Order for Recording a One-Position Angle.

Figure 6-17. Example of a Completed One-Position Angle.
6-10 _____________________________________________________________________________________________ MCWP 3-16.7

Recording A Two-Position Angle

This angle is required for certain fourth order methods

such as triangulation and trig traverse. Use of this method

for other survey methods is a matter of local SOP.

Heading and Column Titles

These are the same as for a one-position angle. See

figure 6-18.

STA and T Columns 

These are the same as for a one-position angle. The

second angle starts two spaces below the first angle. 

Recording Field Data 

The first of the two measured angles is determined the

same as a one-position angle. The second of the two

measured angles is the same as it is for a one-position

angle except that the initial circle setting for the

second angle will be 4800.000 mils (±0.100 mils).

Vertical angles and distances are determined during the

first-position angle. Determine the mean of the twoposition angles by adding the two angles together; then

divide that total.

When a two-position angle is observed, the two

measured angles must agree within +0.050 mils. If

they differ by more than 0.050 mils, reject and

remeasure both angles. 

Figure 6-18 shows data recorded with the means

computed. The mean horizontal angle of each position

angle is recorded in parentheses. The mean of the two

position angles is circled.

Figure 6-18. Example of a Completed Two-Position Angle.
Marine Artillery Survey Operations ______________________________________________________________________ 6-11

Closing an Angle on the Horizon

See figure 6-19. 

Use this angle when a two-position angle is required

or as local SOP directs. Closing on the horizon means

that the second angle measured closes a horizontal

circle at 6400 mils. The first angle is the station angle;

the second the explement angle.

Heading and Column Titles

These are the same as for a one-position angle. 

STA and T Columns

These are the same as for a one-position angle. The

explement angle starts two spaces below the position

angle.

Recording Field Data

Figure 6-20 shows an example of data recorded with

Figure 6-19. Angle Closed on the Horizon. the means computed. Note that the mean horizontal

Figure 6-20. Example of an Angle Closed on the Horizon.
6-12 _____________________________________________________________________________________________ MCWP 3-16.7

angle of each measured angle is recorded in

parentheses. The corrected station angle is circled. The

station angle is determined the same as a one-position

angle. The explement angle is the same as for a

position angle except the rear and forward stations are

reversed to measure the rest of the horizontal circle. 

Determine vertical angles and distances with the

station angle. Determine the mean horizontal angle by

applying half of the error (from 6400 mils) to the

station angle. When an angle closed on the horizon is

observed, the sum of the two measured angles must be

within ±0.050 mils of 6400 mils. If the sum differs

from 6400 by more than 0.050 mils, both angles must

be rejected and remeasured. 

Recording Reciprocal Vertical Angles

When conducting a fourth order traverse or surveying a

traverse leg of more than 1,000 meters, measuring

reciprocal vertical angles is required. Heading and

column titles (columns 1-6) are the same as for a oneposition angle. Columns 7-12 are discussed below. See

figure 6-21.

Figure 6-21. Example of Recording with Reciprocal Vertical Angles.
Marine Artillery Survey Operations ______________________________________________________________________ 6-13

Column 7, MN RECIP VERT. Record the mean of the

reciprocal vertical.

Column 8, SLOPE DIST. Record slope distances from

the DI 3000. If only horizontal distances are measured,

this column will be titled DIST.

Columns 9-12, REMARKS. Record any

information pertinent to the measurement and

subsequent computations.

STA and T Columns are labeled the same as for a oneposition angle. However, if the top angle on the page

includes a vertical angle to the rear station, the first

row below the column titles will be skipped.

Vertical angles are measured to the rear station the

same as they are to the forward station. Vertical

readings are measured and recorded when the

horizontal readings are made (the vertical reading to

the rear station in the direct mode is made directly

after the initial circle setting is recorded). 

Vertical angles determined by the recorder that will

be included in the mean of reciprocal vertical angles

will be recorded in parentheses. The mean of the

reciprocal vertical angles will be circled and

recorded in column 7 in the row corresponding to

the mean angle at the occupied station. 

Recording Angles From 

an M2A2 Aiming Circle

These angles are generally used for hasty survey

purposes. Hasty survey is discussed in chapter 10. As

with all field notes, the first page of the notebook is

the index. 

Heading and Column Titles 

Fill out as described below. See figure 6-22. 

Fill out the designation block with the survey method

being conducted; i.e., hasty traverse. Other entries

may be included after the method of survey.

Fill out the date block with the date the field work was

performed.

Fill out the heading of the right side of the page as

follows: 

List weather conditions at the left side of the top line.

Use two words; e.g., clear, warm.

List instrument types and serial numbers on the left

side of the second line of the header.

List the COP, IO, and RCDR at the right side of the

right page, above the top line. 

Fill in column titles as follows: 

1, STA. Identify the occupied, rear, and forward

stations.

2, R. Identify the reading.

Figure 6-22. Heading and Column Titles (M2A2 Angles).
6-14 _____________________________________________________________________________________________ MCWP 3-16.7

3, HORZ. Record the horizontal readings and the

mean horizontal angle.

4, VERT. Record the uncorrected vertical angle to the

forward station.

5, CORR. Record the vertical angle correction

determined during operator tests.

6, CORR VERT. Record the corrected vertical angles

and the mean corrected vertical angle.

7, SUBT DIST. Record the subtended distance as

extracted from the subtense tables in FM 6-50 and the

XO’s handbook. This column may also be labeled for

the subtended angle or horizontal distance if taped or

paced.

8-12: REMARKS. Record any information pertinent

to the measurements and subsequent computations.

STA and R Columns 

Fill out these columns as shown in figure 6-23.

Record the rear station name directly below the STA

column title. Record the occupied station name

directly below the rear station. Record the forward

station name directly below the occupied station.

Record a “1” in the row directly below the “R”, a “2”

below the “1”, and “MN” directly below the “2”.

Recording Field Data 

Record the horizontal, vertical, and subtended angles

to the nearest 0.5 mils. 

Record a subtended distance directly from FM 6-50 or

the XO’s handbook.

Record the mean horizontal angle to the nearest 0.1 mil.

If the second reading is greater than the first

reading, compute the mean horizontal angle by

dividing the second reading by 2. The mean

horizontal angle is circled.

If the second reading is less than the first reading,

compute the mean horizontal angle by adding 6400

mils to the second reading, then divide by 2. The mean

horizontal angle is circled. 

The mean horizontal angle must match the first reading

within + 0.5 mils. If not, void the angle and remeasure.

Recording Intersection Method 

The intersection method is the preferred way to

determine target location when the target cannot be

occupied. Follow the procedures below when

computation of the target location is performed with

azimuths measured to the target vice horizontal angles.

Figure 6-23. Example of Recorded Data for a Hasty Traverse.
Marine Artillery Survey Operations ______________________________________________________________________ 6-15

Fill out the heading and column titles as described

below. See figure 6-24. 

Fill out the designation block with the survey method.

Fill out the date block with the date the field work was

performed. Fill out the heading of the right side of the

page as follows:

List weather conditions at the left side of the top line.

Use two words. The first word describes visibility;

e.g., clear, sunny or cloudy. The second is a

description of temperature. 

List the instrument types and serial numbers on the left

side of the second line of the header.

List the COP, IO, and RCDR at the right side of the

right page, above the top line. 

Fill in column titles as follows. See figure 6-25. 

1, OCC STA. Identify the occupied stations.

2, AZ TO AZMK. Record the computed azimuth to

the rear station. This is the azimuth set on the

horizontal scale of the aiming circle.

3-5, TARGET DESCRIPTION. Identify the target and

fwd station.

6, AZ TO TGT. Record the measured azimuth to the

target.

7, VERT. Record the vertical angle to the target.

8-12, REMARKS. Record any information pertinent

to the measurements and subsequent computations.

Record the azimuth to the azimuth mark to the nearest

0.5 mils. Record the azimuths and vertical angles to

the targets to the nearest 0.5 mils. The target

description should be adequate for another observer to

identify that particular target. 

Figure 6-25. Example of Completed Intersection Method (M2A2).

Figure 6-24. Heading and Column Titles (Intersection).
6-16 _____________________________________________________________________________________________ MCWP 3-16.7

Correcting Errors and Voiding

The recorder must make entries small enough that if

an error is made in the data, there is enough room left

in the block to write the correct data. When a value is

recorded incorrectly, the value is lined out with a

single straight line and the correct value written above.

Do not erase errors in the notebook. 

A partial void voids an area of a recorder’s page. This

is usually done over a single angle. Include the reason

for the partial void in the remarks section. A partial

void is performed by sketching an “X” over the area to

be voided, using a straight edge, and writing “VOID”

over the “X”. See figure 6-26. 

A full-page void voids every entry made on a

recorder’s page. This is usually done when voiding

two-position angles, angles closed on the horizon, and

astronomic observations. These methods all require

the use of the entire page. Include the reason for the

void in the remarks section. A full-page void is

performed by sketching an “X” over each page, using

a straight edge, and writing “VOID” over the “X” on

each page. See figure 6-27.

Security 

The notebook could provide the enemy with a large

amount of valuable information should it fall into his

hands (firing positions, radar sites, met sites, OPs,

etc.). It could also provide names of personnel,

equipment types, locations of survey control points,

and other information that can be used for

intelligence purposes.

Figure 6-26. Example of a Partial Void.
Marine Artillery Survey Operations ______________________________________________________________________ 6-17

In a contingency situation, the notebook must be

safeguarded from the enemy. Some information

could be classified; e.g., OS or survey control point

coordinates. Therefore, the book becomes classified.

When the threat of capture becomes imminent, a

decision must be made as to the disposition of the

notebook. If the capture cannot be avoided, destroy

the notebook.

Storing the Recorder’s Book 

Use the notebook until filled. Then properly store it to

eliminate damage. The storage area must be dry and

safe from accidental damage such as spills. Maintain

the notebook for at least the minimum times as

discussed below.

Notebooks with information used in establishing

permanent control must be maintained for at least as

long as those control points are in tact or until they

are resurveyed.

Notebooks with information used in establishing

nonpermanent control must be maintained for at least the

same amount of time as position safety, per local SOP.

Notebooks may be maintained for archive purposes. If

a unit establishes survey control (permanent or

nonpermanent) in an area that is not used very often or

not used before, the notebook could include

information for planning future operations in that area.

Figure 6-27. Example of a Full-Page Void.
6-18 _____________________________________________________________________________________________ MCWP 3-16.7

SECTION III. TRIGONOMETRY

Extending Azimuth

An azimuth is the clockwise angle from a known

reference line to a second line. For artillery survey

purposes, the reference line is grid north and the

second line is the traverse line to the forward station.

Every line has a forward azimuth and a back azimuth.

In artillery survey, we consider the Earth to be a flat

surface. A forward azimuth and back azimuth differ

exactly 3200 mils. See figure 6-28.

Azimuth-Angle Relationship 

When traverse computations begin, the only known

azimuth is the azimuth from the occupied station to the

rear station. To determine the azimuth to the forward

station, add the horizontal angle measured at the

occupied station to the azimuth to the rear station. See

figure 6-29.

Sometimes the sum of the azimuth to rear and the

horizontal angle produces an azimuth larger than 6400

mils. Subtract 6400 mils from that sum to determine

the azimuth necessary for computations. 

Azimuth to the Rear 

Once the azimuth to the forward station is determined,

the computations necessary to determine the

coordinates of the forward station can be made. The

extension of the survey beyond that point requires that

the azimuth to the rear be determined from the

azimuth to the forward station, as determined above.

To do this, apply 3200 mils to the forward azimuth as

shown in the following example:

The azimuth to the forward station (Andy) from Carl

is 2520.254 mils. This azimuth is used to compute the

coordinates of Andy. To determine the coordinates of

the forward station when Andy is occupied, the

azimuth from Andy to the rear station (Carl) must be

known. In the example it is 5720.254 mils. 

Solutions of Right Triangles

Simple plane trigonometry can be used to compute a

survey. The solution of two right triangles is necessary

to determine differences in coordinates and elevation.

Forming the Coordinate Triangle 

The distance and azimuth between two points can be

used to form a right triangle. The grid distance between

the traverse stations is the hypotenuse of the right

triangle. The other two sides of the triangle are the

easting and northing coordinate differences between the

stations. The difference easting (dE) and difference

northing (dN) are the unknowns that are determined by

solving the right triangle. See figure 6-30.

Figure 6-28. Azimuth. 

 Az to Fwd Sta (Carl to Andy): 2520.254 mils

±3200 mils 3200.000 mils

Az to Rear (Andy to Carl) 5720.254 mils
Marine Artillery Survey Operations ______________________________________________________________________ 6-19

Figure 6-30. Coordinate Triangle.

Figure 6-29. Azimuth-Angle Relationship.
6-20 _____________________________________________________________________________________________ MCWP 3-16.7

Forming the Elevation Triangle 

The distance and vertical angle between two points

can be used to form a right triangle. The sides of the

triangle forming the right angle are the grid distance

and the elevation difference between the stations

(dH). The vertical angle is the angle formed by the

grid distance and the line of sight (the hypotenuse).

It is opposite the vertical interval. See figure 6-31.

Trigonometric Functions To Compute a Traverse 

Sine (sin) and cosine (cos) compute the differences in

easting and northing coordinates. Tangent (tan)

computes the difference in height. 

The values of sin and cos are the distances

corresponding to an angle formed at the center of a

circle whose radius is one. Figure 6-32 shows that in a

circle of radius 1, the length of side dE is the sin of 849

mils (47.75625°) and the length of side dN is the cos

of 849 mils. If you were to use a scientific calculator to

determine the sin of 47.75625°, the answer would be

0.74029 and the cos would be 0.67229. 

The value of tan equals the value of sin divided by the

value of cos.

Determining Coordinate and Elevation 

Differences

See figure 6-33. The formulas for solving a right

triangle are generally written as—

Figure 6-31. Elevation Triangle.

Figure 6-32. Value of Trigonometric Functions 

of Angles.

sin (angle) = O

 H

cos (angle) = A

 H

tan (angle) = O

 H

whereas: O is the side opposite the angle

A is the side adjacent the angle

H is the hypotenuse 

and: Angles are converted to degrees from 

mils using the formula degrees = 

mils × (0.05625).
Marine Artillery Survey Operations ______________________________________________________________________ 6-21

For computations of the coordinate and elevation

triangles, it is easier to understand if we substitute the

O, A, and H with the actual values used:

The formulas listed immediately above can also be

written as—

The previous example produced an azimuth forward

(Carl to Andy) of 2520.254 mils. If the grid distance

from Carl to Andy is 524.876 meters and the vertical

angle is +27.821 mils, the dE, dN, and dH can be

determined by substituting those values into the

formulas immediately above.

Determining the Coordinates and 

Elevation of the Forward Station

Determine the coordinates by algebraically adding the

dE and dN to the coordinates of the occupied station.

To algebraically add means to add or subtract

depending on the sign (+ or −) of the subject value. 

Determine the sign of the dE and dN by plotting the

azimuth to the forward station. See figure 6-34.

The dE and dN with the proper sign are then

algebraically added to the coordinates of the

occupied station.

Determine the elevation by algebraically adding the

dH to the elevation of the occupied station. The sign of

the dH is the same as the sign of the vertical angle.

The examples shown produced an azimuth forward

(Carl to Andy) of 2520.254 mils and produced a dE of

324.84 meters, a dN of 412.28 meters, and a dH of

14.34 meters.

The coordinates of Carl are E: 5 40666.21, N: 34 13666.78, El (m): 666.34

sin (AzFwd × 0.05625) = dE

Grid Dist

cos (AzFwd × 0.05625) = dN

Grid Dist

tan (AzFwd × 0.05625) = dH

Grid Dist

dE = sin (Az Fwd × 0.05625) × Grid Dist

dN = cos (Az Fwd × 0.05625) × Grid Dist

dH = tan (Vert Angle × Grid Dist

dE = sin (2520.254 × 0.05625) × 524.876 

dE = 324.84 meters

dN = cos (2520.254 x 0.05625) × 524.876 

dN = 412.28 meters

dH = tan (27.821 x 0.05625) × 524.876 

dH = 14.34 meters

Figure 6-33. Right Triangle.

Figure 6-34. Determining the Sign of dE and dN.
6-22 _____________________________________________________________________________________________ MCWP 3-16.7

The azimuth from Carl to Andy is 2520.254 mils

which plots in quadrant II in figure 6-34. So, the dE is

positive, the dN is negative. The coordinates of Andy

are determined as—

Computing the Traverse

After computation of a main scheme leg, the station

that was the forward station now becomes the

occupied station. The data determined for that station

determines the coordinates and elevation of the next

forward station. 

Figure 6-35 shows a traverse with only main

scheme legs. It can be seen that the coordinates and

elevation of Andy are used to compute the

coordinates of John.

A traverse cannot continue from an offset station

because the offset station is not occupied. Its

coordinates and elevation are not used to compute

another forward station. The next forward station is

computed from the same station as the offset.

Figure 6-36 shows a traverse with an offset leg from

Carl to Andy. The main scheme portion of the traverse

runs from Carl to John, then to Jim. The coordinates

and elevation of Andy will not be used to compute the

coordinates and elevation of John. The coordinates

and elevation of John must be computed using the data

from Carl.

SECTION IV. CLOSURE

Traverse closure is performed by comparing the

computed data for the closing station to the known

data for the closing station. These comparisons

produce errors that must meet certain specifications

for the order of traverse being performed.

Three comparisons must be made to determine if a

traverse meets closure specifications: coordinate

comparison, elevation comparison, and an azimuth

comparison. Closing data for a traverse consists of

radial error (RE) of closure, elevation error, azimuth

error, and accuracy ratio. See figure 6-37.

Radial Error 

A comparison between known and computed

coordinates of the closing station is performed to

produce an RE of closure. The RE is the distance from

Carl 5 40666.21 34 13666.78 666.34 

dE, N, H +324.84 −412.28 +14.34

Andy 5 40991.05 34 13254.50 680.68

Figure 6-36. Offset Legs.

Figure 6-35. Main Scheme Legs.
Marine Artillery Survey Operations ______________________________________________________________________ 6-23

the known coordinates to the computed coordinates.

See figure 6-38.

Computing Radial Error 

There are several ways to determine the RE. If the

traverse was computed on a survey computer

system, the RE is computed automatically. But it

should be computed using the azimuth and distance

programs in those systems or with the Pythagorean

Theorem manually.

RE can be determined by performing the azimuth and

distance computations available in survey computer

programs. Data should be entered from the known

coordinates to the computed coordinates. This is

because the azimuth provided by these computations

is the azimuth of the error that may be necessary to

determine the location of traverse errors should the

survey not meet specifications. 

The Pythagorean Theorem considers the RE as the

hypotenuse of a right triangle and as sides of the

triangle. See figure 6-39.

The Pythagorean Theorem states that in a right

triangle, the square of the hypotenuse is equal to the

sum of the squares of the sides. That formula can be

expressed as—

C = 

where C is the hypotenuse, and A and B are the sides

of the triangle.

The eE, eN, and RE can be substituted into the

formula as 

RE = 

The eE is the difference between the known and

computed easting. If the known easting value is a

larger number than the computed easting value, the eE

is negative. If the known easting value is a smaller

number than the computed, the eE is positive.

The eN is the difference between the known and

computed northing. If the known northing value is a

larger number than the computed, the eN is negative;

if the known northing value is a smaller number than

the computed, the eN is positive.

The following example uses the Pythagorean Theorem

to compute RE.

Figure 6-37. Traverse Closing Data Comparison. 

Figure 6-38. Radial Error of Closure.

Figure 6-39. Pythagorean Theorem. 

A2+B2

eE2 + eN2
6-24 _____________________________________________________________________________________________ MCWP 3-16.7

Determine eE and eN:

Determine RE:

RE = = 0.83 meters

Allowable Radial Error

The allowable position closure (RE) for a traverse

depends on the order of survey and the total traverse

length (TTL).

If a fourth order traverse length is less than 9 kilometers,

the allowable RE in closure is 1:3000 or 1 meter of RE

for each 3,000 meters of traverse. Determine the

allowable RE by dividing the total traverse length by

3,000. For example, if the traverse length of a fourth

order survey is 3,469.910 meters, the allowable RE is

1.16 meters (3,469.910/3,000 = 1.1566).

If a fourth order traverse length is greater than 9

kilometers, the accuracy achieved may be better than

1:3000, yet the RE may be excessive. Determine the

allowable RE by the following formula: square root of

K whereas K equals the TTL in kilometers. If the TTL

is 10,983.760 meters, then K equals 10.983760. In this

example, allowable RE equals 3.314175613935 or

3.31 meters. If the TTL were divided by 3,000, the

allowable RE would be 3.66 meters, 0.35 meters more

than with the square root of K. 

The allowable RE for a fifth order traverse is 1:1000

or 1 meter of RE for each 1,000 meters of traverse.

Determine the allowable RE by dividing the total

traverse length by 1,000. For example, if the traverse

length of a fifth order survey is 2,986.321 meters, the

allowable RE is 2.99 meters (2,986.321/1,000 =

2.986321). Allowable RE for a fifth order traverse

equals K (TTL in kilometers).

Excessive Radial Error

If the RE of a traverse exceeds the specifications listed

above for allowable RE, the traverse has “busted.” The

traverse error location must be determined and corrected. 

Elevation Error

A comparison between known and computed

elevations of the closing station is performed to

produce an elevation error (eH). The eH is the vertical

distance from the known elevation to the computed

elevation. See figure 6-40. 

If the known elevation is a larger number than the

computed, the eH is negative. If the known elevation

is a smaller number than the computed, the eH is

positive. Figure 6-40 shows station Jack with a known

elevation of 342.9 meters and a computed elevation of

343.5 meters. The difference between the two values

is 0.6 meters. Since the computed elevation is higher

than the known, the sign is positive. The eH is written

as +0.6 meters. 

The eH is computed automatically by survey computer

systems. Sometimes the value displayed by the

program is the elevation correction. Elevation

correction is the same value as eH with the opposite

sign and is used for traverse adjustments.

The allowable eH for a traverse depends on the order

of survey and the TTL. For fourth order, the allowable

eH equals the when K is the TTL in kilometers.

For example, if the total traverse length of a fourth

Known E: 5 17265.98 N: 38 27648.32

Computed E: 5 17265.54 N: 38 27649.02

Error (meters) dE−0.44 dN+0.70

0.442 + 0.702

Figure 6-40. Elevation Error.

K
Marine Artillery Survey Operations ______________________________________________________________________ 6-25

order survey equals 7643.765 meters, K is equal to

7.643765. Allowable eH in this example equals

2.764735972928 or 2.8 meters.

The allowable eH for a fifth order traverse whose TTL

is less than 4,000 meters is ±2 meters. As long as the

computed elevation is within 2 meters of the known,

the elevation closes.

The allowable eH for a fifth order traverse whose TTL

is equal to or greater than 4,000 meters is determined

from the formula—

1.2 ×

when K is the TTL in kilometers. For example, if the

TTL is 6843.874 meters, K is equal to 6.843874.

Allowable elevation error in this example is equal to

3.139 or 3.14 meters.

If the eH of a traverse exceeds the specifications listed

above for allowable eH, the traverse has “busted.”

Determine the eH location and correct. 

Azimuth Error

A comparison between known and computed azimuths

at the closing station is performed to produce an

azimuth error (eAz). The azimuth error is the angular

difference between the known azimuth and the

computed azimuth from the closing station to the

azimuth mark. See figure 6-41.

If the known azimuth is a larger value than the

computed, the eAz is negative. If the known

azimuth is a smaller number than the computed, the

eAz is positive. Figure 6-41 shows a known azimuth

of 0833.002 mils and a computed azimuth of

0832.876 mils. The difference between the two

values is 0.126 mils. Since the computed azimuth is

lower than the known, the sign is negative. The eAz

is written as −0.126 mils.

The eAz is computed automatically by survey computer

programs. Sometimes the value displayed by the

computer system is the azimuth correction. Azimuth

correction is the same value as azimuth error with the

opposite sign and is used for traverse adjustments. 

The allowable eAz for a traverse depends on the order

of survey and the number of main scheme angles,

including the closing angle, in the traverse.

Fourth Order 

The allowable eAz for a fourth order traverse with six

or fewer main scheme angles is determined from the

formula allowable eAz = 0.04 mils × N; when N

equals the number of main scheme angles, including

the closing angle. For example, if a fourth order

traverse contains 5 main scheme angles, the allowable

eAz = 0.04 mils × 5 = 0.200 mils.

The allowable eAz for a fourth order traverse with

seven or more main scheme angles is determined from

the formula when N equals the number of

main scheme angles, including the closing angle. For

example, if a fourth order traverse contains 8 main

scheme angles, the allowable eAz = 0.283 mils.

Fifth Order 

The allowable eAz for a fifth order traverse is

determined using the formula allowable eAz = 0.1

mils × N; when N equals the number of main scheme

angles, including the closing angle. For example, if a

fifth order traverse contains 12 main scheme angles,

the allowable eAz equals 1.2 mils. 

K

Figure 6-41. Azimuth Error.

0.1 X N
6-26 _____________________________________________________________________________________________ MCWP 3-16.7

If the eAz of a traverse exceeds the specifications

listed above for allowable eAz, the traverse has

“busted.” Location of the traverse error must be

determined and corrected. 

Accuracy Ratio

Certain minimum position accuracy requirements are

prescribed for survey field work and computations.

To determine whether this position requirement has

been met for a closed traverse, an accuracy ratio

(AR) is computed. 

An AR is the ratio of position error to TTL. TTL is

sum of the main scheme grid distances used to

compute the traverse. AR is computed by dividing the

TTL by the RE. For example, if the TTL of a traverse

is 9843.785 meters and the RE is 2.01 meters, then AR

= 9843.785/2.01 = 4897.405472637.

AR may be expressed as either a fraction with a

numerator of one (i.e., 1/3000) or as a ratio (i.e.,

1:3000). An AR ratio is read as one to the computed

value; e.g., one to three thousand.

After the AR has been computed, the denominator of

the fraction is always reduced to the next lower

hundred; e.g., 1/4897 is recorded as 1/4800.

The minimum accepted value for an AR depends on

the order of survey being performed. A traverse

performed to fifth order specifications must produce

an AR equal to or higher than 1/1000. A traverse

performed to fourth order specifications must

produce an AR ratio equal to or higher than 1/3000.

However, if the TTL exceeds 9 kilometers, the RE

must be within specifications.

If the computed accuracy ratio of a traverse does not

meet the specifications listed above for minimum AR,

the traverse has “busted.” The traverse error location

must be determined and corrected. 

Specifications

To verify that a traverse closes, compare computed

errors to the following specifications: 

REQUIREMENT FOURTH ORDER FIFTH ORDER

Adjusted Yes No

Position Closure 

If traverse length is—

less than 9,000 meters 1:3,000 1:1,000

more than 9,000 meters 1:1,000

Height Closure

If traverse length is—

less than 4,000 meters ± 2 meters 

more than 4,000 meters 1.2 *

Azimuth Closure 

Six or fewer stations 0.04 * N 0.1 * N 

Seven or more stations 0.1 *0.1 * N 

Azimuth carried to 0.001 mil 0.1 mil

Number of stations between

azimuth checks

20 25

Horizontal Angles

Measured as One-position One-position

Recorded to 0.001 mil 0.001 mil

Vertical Angles 

Measured as 1 D/R 1 D/R 

Recorded to 0.001 mil 0.001 mil 

Used in computations 0.001 mil 0.001 mil 

Reciprocals measured when Always Legs greater than 1,000 meters

Distance

Measured electronically 

(slope distance)

Mean of 3 measurements after

rejection limit of 0.01 from the mean

Mean of 3 measurements after rejection limit 

of 0.01 from the mean

K

K

K

K

N
Marine Artillery Survey Operations ______________________________________________________________________ 6-27

SECTION V. ADJUSTMENT

An adjusted traverse is one where errors have been

distributed systematically so that the computed

closing station coincides with the known closing

station. In artillery survey, only fourth order

traverses are adjusted. 

There is no way to determine the true magnitude of

errors in the angle and distance measurements that

occur throughout a traverse. A traverse adjustment is

based on the assumption that errors have

accumulated gradually and corrections are made

accordingly. A traverse adjustment is also based on

the assumption that all errors causing misclosure in

the traverse are from field measurements (no errors

are brought into the closure from previous

adjustments or a lack of commonality).

Three adjustments must be made when adjusting a

traverse: azimuth, coordinates, and elevation. These

adjustments eliminate the effects of systematic

(accumulative) errors assuming they have been

constant in magnitude and direction over each

traverse leg. Traverse adjustment cannot compensate

for blunders such as improperly recorded data or

misread angles. 

A traverse that does not meet the closure

specifications listed in section IV is not adjusted. It is

checked and corrected using the traverse error location

procedures in section VI.

Usually a traverse will close within specifications, but

because some error sources cannot always be

accounted for, closure will not be absolute. There will

always be some measure of position, elevation, and

azimuth error.

Most errors causing survey misclosure are cumulative.

A cumulative error will generally be of the same

magnitude, in the same direction, and occur in every

measurement of that type; e.g., errors introduced by

instruments that are not properly adjusted. 

Random errors are those errors that cannot be

accounted for. They vary in magnitude and direction

and do not occur in all measurements; e.g., plumbing,

leveling, and sighting errors. 

Survey computer systems automatically adjust the

main scheme portion of a traverse if so prompted. 

Azimuth

Determining Azimuth Correction 

The difference in easting and northing between two

stations is determined by multiplying the grid distance

by the sin and cos of the azimuth to the forward

station. When adjusting a traverse, the azimuths used

to compute those easting and northing differences are

adjusted first. The total amount of azimuth adjustment

is the azimuth correction. Determined by computing

the eAz. The azimuth correction is the eAz with the

proper sign affixed so that the computed azimuth with

the azimuth correction applied equals the known

azimuth. The azimuth correction is the same value as

the eAz with the opposite sign. 

Applying Azimuth Correction 

The azimuth correction is distributed equally among

the main scheme angles of the traverse with any

remainder distributed to the larger angles. For

example, assume a traverse has five main scheme

angles, including the closing angle and the eAz for

the traverse equals +0.966 mils. The azimuth

correction equals −0.966 mils and is divided by the

number of angles in the traverse. In this case, −0.966

mils/5 equals −0.193 mils per angle with a remainder

of 0.001 mil. Each of the five angles will be adjusted

by −0.193 mils and the largest angle will be adjusted

by an additional 0.001 mil each to compensate for the

remainder. See figure 6-42. 

Recomputing with Adjusted Angles 

After the main scheme angles have been adjusted, the

entire traverse is recomputed using the adjusted

Occupied

Station

Horizontal

Angle

Azimuth

Correction

Adjusted

Angle

Carl 2520.254 -0.193 2520.061

Andy 1895.364 -0.193 1895.171

John 3725.468 -0.194 3725.274

Jim 1564.258 -0.193 1564.065

Jack 2635.842 -0.193 2635.649

Figure 6-42. Azimuth Adjustment.
6-28 _____________________________________________________________________________________________ MCWP 3-16.7

angles. This produces new coordinates and closing

data for the traverse with an azimuth error of zero

mils. There will be no change in eH or TTL. It is now

assumed that all eAz has been eliminated. Any

remaining error is assumed to be a distance error.

Coordinate

Determining Total Coordinate Corrections 

The total easting and northing corrections (tcE, tcN)

for the traverse are determined by algebraically

subtracting the coordinates of the closing station

(after azimuth adjustment computations) from the

known coordinates of the closing station. Use the

following example to determine easting and

northing corrections:

Determining Station Corrections 

The easting and northing corrections determined

above are for the entire traverse. It is assumed that

errors causing coordinate misclosure are accumulated

proportionately throughout the traverse. The

corrections must be distributed proportionately

throughout the traverse. The amount of coordinate

correction to be applied to each main scheme station

(cE, cN) is determined by multiplying the total easting

or northing correction (tcE, tcN) by the partial traverse

length (PTL = sum of the traverse legs up to that

station), then dividing by the TTL. 

As an example, for a traverse with a TTL of 6734.973

meters and total coordinate corrections as determined

above, the cE and cN for station Jack whose PTL is

3974.652 meters is determined as— 

cE = +0.16 meters cN = −0.27 meters

Determining Adjusted Coordinates

Adjusted coordinates for a main scheme station in a

traverse are determined by algebraically adding the

easting and northing coordinate corrections (cE, cN) to

the coordinates of the stations that were determined by

the azimuth adjustment computations. 

The following example shows how to determine

adjusted coordinates using the coordinate corrections

determined above:

Offset Legs 

There is no requirement to adjust offset legs. Even so,

the computations performed for azimuth adjustment

produced a new set of coordinates for the occupied

station to determine the offset station coordinates. To

ensure relativity, adjust offset legs by recomputing a

single traverse leg using the adjusted coordinates of

the occupied station and the adjusted azimuth from the

occupied station to the rear station. 

Elevation

Because elevation is the least important of the three

elements of survey, it can be assumed that elevation

closure error is accumulated in equal amounts at each

traverse station. 

Determining Elevation Correction 

Compare the computed elevation of the closing station

with the known elevation of the closing station and

apply a sign (±) that causes the established height to

equal the known height. The elevation correction is the

same value as the elevation error with the opposite sign.

For example, if the known elevation for station Jack is

342.9 meters and the computed elevation is 343.5

meters, the elevation correction is −0.6 meters (342.9 −

343.5 = −0.6). For the elevation determined by traverse

to equal the correct elevation, subtract 0.6 meters from

the elevation of the computed closing station.

Easting Northing

Known 5 21874.98 34 87698.23

− Computed 5 21874.71 34 87698.68

Correction (tcE) +0.27 (tcN) −0.45

Easting Northing

Jack (Az Adj) 5 24987.56 34 85673.87

Correction +0.16 −0.27

Jack (Adjusted) 5 24987.72 34 85673.60
Marine Artillery Survey Operations ______________________________________________________________________ 6-29

Determining Adjusted Elevation 

The elevation correction is distributed equally among

the stations of the traverse with any remainder

distributed to those stations computed from the longest

legs. Assume that the traverse for the elevation

correction consists of five stations. To distribute the

elevation correction throughout the traverse, divide the

elevation correction by the total number of stations in

the traverse excluding the starting station (a known

height), in this case four, if the elevation correction is

−0.6 meters. The elevation correction is determined

from the formula −0.6/4 equals 0.1 with a remainder

of .2 meters. 

The adjustment is an accumulation of the correction

since the correction applies to the differences in

elevation between the stations and not directly applied

to their elevations. 

Discretion Adjustment

There will be times in the field when a surveyor will

rely on judgment alone. Error/correction may be

distributed arbitrarily in accordance with the

surveyor’s estimation of field conditions. It is

reasonable to assume that heat waves will introduce

larger errors over long lines than over short lines.

Larger angular errors would be expected when lines of

sight are steep and visibility is poor than when

observing conditions are relatively favorable.

Surveyors should not use this method of adjustment

unless experienced and have a keen knowledge of

where errors are most likely to occur and of their

effect on the overall survey. In any event, the field

notebook should contain a detailed account of any

unfavorable survey conditions so that is may be used

to substantiate any arbitrary adjustments.

SECTION VI. LOCATING TRAVERSE ERRORS

The artillery surveyor must isolate errors and

determine their causes. Often, a critical analysis of the

field work and the computations of a survey in error

will result in timely delivery of the surveyed data to

the firing unit.

Sources of Error

Many error sources exist that can cause a survey to

bust. When trying to locate a traverse error it is

assumed that only one error exists and that the error

exists in the field work or computations. Trig lists

from higher or adjacent echelon survey sections may

sometimes contain errors. These errors are usually a

misprint in the trig list and must be reported to the

publishing agency as soon as possible.

Coordinate 

When a trig list includes a misprint of a station’s

coordinates, it is usually a typographical error in either

easting or northing, but not both. Sometimes the error

may be due to several sets of coordinates being

established over the same point from different surveys

or different survey agencies and the wrong set of

coordinates being published. The SIC must determine

the most accurate with respect to commonality. 

A coordinate error will slide the entire traverse if

closed on the same known station. The survey will

appear to close but an unknown amount of position

error will exist at each station.

A coordinate will appear as if a distance error is

present in the survey if the traverse is closed on a

second known point.

Elevation 

When a trig list includes a misprint of a station’s

elevation, it is generally a typographical error.

Sometimes, as with coordinates, more than one elevation

may exist for the same station. The SIC must determine

the most accurate with respect to commonality. 

An elevation error will raise or lower an entire traverse

if closed on the same station. The survey will appear to
6-30 _____________________________________________________________________________________________ MCWP 3-16.7

close but an unknown amount of elevation error will

exist at each station.

Elevation error will appear as if a vertical angle error

exists in the traverse if the traverse is closed on a

second known station. The survey will close for

coordinates and azimuth but not for elevation. 

Azimuth

When a trig list includes a misprint of an azimuth

between two stations, it is usually a typographical

error of a computed or astronomic azimuth.

Sometimes the azimuth may have been computed

correctly but the stations were not common or as with

some coordinate errors, the wrong station coordinates

were used when more than one set of values were

available. Always perform your own computation of

an azimuth when using a computed azimuth from a

trig list.

An azimuth error will swing the traverse around the

starting point if closed on the same station. The

traverse will appear to close but it will contain an

unknown amount of coordinate and azimuth errors.

An azimuth error list will appear as if an angle error

exists in the traverse if the traverse is closed on a

second station.

Field Work 

Errors from field work will generally be of four types:

distance, horizontal angle, vertical angle, and

computational. The largest errors will be found in

computations and recording. For the most part, field

measurements made with the proper procedures will

not include errors large enough to cause a survey to

bust, especially with the precision available in current

instrumentation. Most errors can generally be

attributed to a lack of precise actions (attention to

detail) on the part of the surveyors. Proper training,

planning, organization, and field procedures will

eliminate most errors. If field work and computations

are done properly, the cause of position, azimuth, and

elevation errors will be primarily due to the level of

relativity of the survey control. In most cases, this will

not bust a survey. The following are examples of

errors caused by that lack of precise action.

All instrument readings must be clearly read to the

recorder, then read back to the instrument operator. The

IO must be viewing the scales when the values are read

back, not turning to the next station or measuring the

next distance. Improper instrument readings can result

in distance, horizontal angle, and vertical angle errors.

Recording errors are generally found in the meaning

of the recorded data. When possible and practical, the

IO or team chief should verify those means before

march ordering the equipment. The recorder must

record the entire reading from the IO then read back

what he has written, not what he heard. The recorder

must listen for the command “bubble level”, indicating

the use of the automatic index by the IO, before

recording vertical readings. Improper recording

procedures can result in distance, horizontal angle, and

vertical angle errors.

Computer errors are generally attributed to improper

computation and check computation procedures.

Computations and check computations must be

performed independently.

Pointing errors can be located by measuring a direct

and reverse reading over each station. Especially when

a station is hard to pinpoint due to long distance or

heat waves, a pointing error will result in horizontal or

vertical angle errors that create a measure of azimuth

and/or elevation error at closure. Very small distance

errors are introduced in a survey that includes vertical

angle errors and slope distances. This is because the

vertical angle converts the slope distance to a

horizontal distance.

Plumb and leveling errors can account for small

amounts of distance and horizontal angle errors. If a

target set and/or a theodolite is not properly plumb and

level over their respective control points, the azimuth

line being occupied is not the same azimuth line used

in computations. This creates an azimuth/angle error.

Forward stations must be properly plumb and level. The

forward station is the next occupied station. When the

theodolite is set up over that station in the same tribrach

as the target set, it must be already plumb and level,

except for minor adjustments. If large plumb and level

adjustments are made, the angle and distance
Marine Artillery Survey Operations ______________________________________________________________________ 6-31

measurements from that station will be made from a

different position than they were made to on the previous

angle. This introduces small angle and distance errors.

Locating A Traverse Error

Procedures for locating an error in a traverse will

isolate a suspect station (horizontal or vertical angle)

or leg (distance). These procedures assume that only

one error is present that is large enough to cause the

excessive misclosure. They also assume the error is

not in the control. Location of traverse error

procedures may designate a suspected station or leg

even when multiple errors are present.

Locating and correcting traverse errors can be

performed in five steps: 

Step 1. Close the traverse. 

Step 2. Determine the eAz, RE, and eH. 

Step 3. Determine the type of error indicated. 

Step 4. Isolate the suspect station or leg. 

Step 5. Check the field recorder’s notebook and

computations for math errors. If no error is found,

return to the field and remeasure the necessary

segments of the traverse. 

Traverse Error Indicators

Figure 6-43 shows the indicated traverse error based 

on the type of traverse and the status of the azimuth 

and coordinate misclosure. 

Azimuth Good, Coordinates Good 

Obviously, if both azimuth and coordinates close, the

traverse is good.

Azimuth Good, Coordinates Bust 

Whether closing on the starting point or on a second

point, if azimuth meets specifications but coordinates

do not, the indicated error is a distance error. If an

angle in the survey were bad, azimuth would bust also.

Azimuth Bust, Coordinates Good 

When closing on the starting point, if azimuth busts

and the coordinates are good, the error must be in the

starting (opening) or closing angle. If an angle other

than the opening or closing were in error or if a

distance error were present, coordinates would not

have closed. 

When closing on a second known point, if azimuth

busts and the coordinates are good, the error must be

in the closing angle. An angular or distance error

anywhere else in the traverse would create a

coordinate misclosure.

Azimuth Bust, Coordinates Bust 

When closing on the starting point, if azimuth and

coordinates bust, the error must be an angle other than

the opening or closing angle. A distance is not the

indicated error. If it were, the azimuth would be good.

When closing on a second known point, if azimuth and

coordinates bust, the error must be in the starting angle

or a station angle, not the closing angle. The closing

angle is not the indicated error, as the coordinates

would have closed.

Elevation Busts

If coordinates close and azimuth close but height

busts, see next paragraph.

Isolation of Distance Errors

A distance error is indicated when the azimuth for a

traverse closes within tolerance but coordinate closure

(RE) exceeds allowable specifications for that level of

Close On

Starting Station

Close On

Second Station

Azimuth Coordinates Error Indication

Good Good Good Traverse Good Traverse

Good Bust Distance Error Distance Error

Bust Good Opening or Closing 

Angle Closing Angle

Bust Bust Angle Error Opening or Station 

Angle

Figure 6-43. Error Indicators.
6-32 _____________________________________________________________________________________________ MCWP 3-16.7

accuracy. Two methods of isolating a distance error

can be used: the parallel line method and the

computation of azimuth of RE. Both methods work on

the assumption that the azimuth of the RE is the same

as the azimuth of the line with the distance error,

whether the error is short or long. 

Use the parallel line method to determine which line in

a traverse contains a distance error. It identifies the

indicated line by creating a line that lies along the

same azimuth or parallel to the error.

Plot the traverse on a 1/25,000 grid sheet using the

largest scale possible to make small errors easier to

see. Label the stations, including known and computed

closing stations. See figure 6-44.

Using a straight edge, trace a line between the known

and computed closing stations. Allow this line to

extend beyond the plotted points. See figure 6-45.

Identify the leg containing the error. The leg

containing the error lies roughly parallel to the line

traced above. Figure 6-45 shows the leg between TS-2

and TS-3 contains the distance error. 

Another way to locate a distance error in a traverse is to

compute the azimuth of the RE. Compute from the

known closing coordinates to the computed closing

coordinates with the handheld computer system (HCS). 

On the traverse form or the printout find an azimuth to

rear that roughly matches the azimuth of the RE. The

suspect leg is the leg with an azimuth or back azimuth

closest to the computed azimuth. 

In analyzing an error like this, some tolerance and

judgment must be used to determine the traverse leg in

error. In angular and distance measurements, minor

errors occur that have a large affect on the overall

accuracy but are small enough to make error analysis

difficult. In some traverses, several legs with azimuths

nearly parallel to the azimuth of the RE could be

indicated as the leg with the error. Check the recorded

data first, then the computations for each suspected

leg. If there is no error in recorded data or

computations, then each suspected leg must be

remeasured until the leg containing the error is found.

Isolation of Angle Errors

An angle error is indicated when the azimuth does not

meet allowable closure specifications for that level of

survey. Sometimes an angle error, depending on its

location, will result in coordinate error exceeding

allowable RE. Two ways of isolating an angle error

can be used: the perpendicular bisector method and the

mil relation formula (WeRM rule). 

Figure 6-44. Plotting the Traverse.

Figure 6-45. Determining the Error Leg - 

Parallel Line Method.
Marine Artillery Survey Operations ______________________________________________________________________ 6-33

Perpendicular Bisector Method 

To determine which station in a traverse contains an

angle error, use the perpendicular bisector by creating

a line that passes over or near the station.

Step 1. Plot the traverse on a 1/25,000 grid sheet using

the largest scale possible to make small errors easier to

see. Label the stations, including the known and

computed closing stations. See figure 6-46.

Step 2. Using a straight edge, trace a line between the

known and computed closing stations. Allow this line

to extend beyond the plotted points. Place a dot on the

line midway between the known and computed

station. If the RE is large enough, divide it by 2 and

measure the distance to ensure the dot is halfway

between the points.

Step 3. Using a protractor, trace a line perpendicular

to the RE line, extending into the survey. 

Step 4. Identify the station containing the error. The line

traced in step 3 will pass through or near the station with

the angle error. The example in figure 6-47 indicates

that station TS-3 contains the angle error.

Mil Relation Formula (WeRM Rule) 

Especially when closed on a second station or when

the traverse follows a linear path, more than one

suspect station could be identified by the

perpendicular bisector method. The WeRM rule is a

very good tool to isolate the error station.

The mil relation formula states that 1 mil of angle over

a 1 kilometer distance will cause a 1-meter shift at the

other end. See figure 6-48.

Figure 6-46. Plotting the Traverse.

Figure 6-47. Determining the Error Station.

Figure 6-48. Mil Relation Formula.
6-34 _____________________________________________________________________________________________ MCWP 3-16.7

The WeRM rule uses this relationship between angle

and distance to determine a distance to a station

containing an angle error that corresponds to the RE.

The distance in kilometers to the station containing the

angle error is computed by dividing the RE by the

azimuth error. Determine—

R = W/m when—

R is the range in kilometers

W is the radial error of closure 

m is the azimuth error

Once the distance in kilometers is computed, locate a

station that is that distance from the known station on

the grid sheet used to plot the perpendicular bisector.

The station in error should lie close to the distance.

Using a busted traverse that follows a linear path along

a highway, the team chief has determined that an angle

error exists. He isolates three possible stations that

may contain the error using the perpendicular bisector

method. The RE of closure is 66.32 meters, the

azimuth error is 10.178 mils. Using the WeRM rule,

the distance to the suspect station is determined as—

R = 66.32/10.178 

R = 6.516 kilometers (6,516 meters)

Analyzing Errors 

In analyzing an error of this nature, some tolerance

and judgment must be used to determine the traverse

station in error. In angular and distance measurements,

minor errors occur that have a large affect on the

overall accuracy but are small enough to make error

analysis difficult. In some traverses, several stations

could be indicated as the one containing the error.

Check the recorded data first, then the computations

for each suspected station. If there is no error in

recorded data or computations, then each suspected

angle must be remeasured until the station containing

the error is found.

Isolation of Multiple Errors

Multiple errors are errors in azimuth and distance or

more than one error in either azimuth or distance.

When multiple errors in a traverse indications are the

same as for an azimuth error. It is possible that using

the procedure for azimuth error determination definite

suspect stations will be located but an analysis will not

reveal the error. The entire traverse should be

performed again to locate the errors that were made.

 Isolation of Elevation Errors

Vertical angle errors cause elevation errors. When a

traverse does not meet allowable elevation error

specifications, the suspect station can usually be

isolated by comparing computed elevations and map

spot elevations. At some point in the comparison, the

elevation difference between computed and map spot

elevations will change indicating a vertical angle error

at the prior station. Check the recorded data and the

computations at that station to locate the error. If the

error cannot be located in the recorded data or the

computations, return to the field and remeasure. 
CHAPTER 7. ASTRONOMY

SECTION I. BASIC ASTRONOMY

The Tilted Polar Axis and 

Movement of the Earth 

The Earth can best be visualized as an ellipsoid. The

line connecting the flattened ends or the shorter axis is

the Earth’s rotating axis. The points on the Earth

where this axis intersects the surface are the north and

south poles; therefore, the rotating axis is also referred

to as the polar axis. If the Earth’s polar axis were

perpendicular to its orbit around the Sun, there would

be no change in seasons; the Sun’s rays would always

be directed at the Equator. Because the Earth’s axis is

tilted at an angle of approximately 23° 30’ (417.78

mils), the Sun’s rays are directed at different portions

of the Earth as it orbits the Sun. See figure 7-1. 

The Earth and its motions are of primary interest to the

artillery surveyor. These motions form a complex

pattern, all of which affect the Earth’s relationship to

the stars and other planets. 

The Earth’s axis has a cone-shaped motion (or

precession) making one turn in 25,800 solar years or

one platonic year (great year). This is caused by torque

imposed on the Earth mostly by the Moon and Sun.

Visualize it as a spinning top. As the spinning slows,

the top begins to wobble creating a cone-shaped

motion in its rotating axis.

The Earth makes one 360° rotation on its axis every 23

hours 56 minutes 04.09 seconds. Rotation is from west

to east. Because of revolution, the Earth must rotate

more than 360° for the same point to face directly at

the Sun on subsequent days. 

The Earth revolves around the Sun approximately once

every 365 days over a 600 million mile orbit at a rate of

18.5 miles per second. The counterclockwise orbit is

elliptical with an average distance to the Sun of about

93 million miles. Other types of motion affect the Earth.

The North and South poles are not stationary; they vary

through rough circles approximately 40 feet in

diameter. There is solar motion of 12 miles per second,

while the Earth’s portion of the galaxy is moving

through space at approximately 170 miles per second. 

Celestial Sphere 

For purposes of practical astronomy, we assume that

the Earth is at the center of the Universe and that

everything else (the Sun, stars, planets, etc.) falls on

the surface of a sphere of infinite radius referred to as

the celestial sphere. We also assume that the Earth is

stationary and that the celestial sphere rotates around

the Earth from east to west. This is because the Earth Figure 7-1. Earth’s Rotational Axis.
7-2 ______________________________________________________________________________________________ MCWP 3-16.7

rotates west to east (counterclockwise), so the

apparent motion of celestial bodies is the opposite

direction. See figure 7-2. 

The celestial sphere rotates around the stationary Earth

on an axis that coincides with the polar axis of the

Earth. Locations of the celestial poles are at the point

in the sphere where the Earth’s polar axis would

intersect the sphere if they were extended into space. If

the plane of the Earth’s Equator was extended into

space, the point where that plane intersects the

celestial sphere is the celestial Equator. 

Celestial Coordinates

Computations of astronomic observations are

performed in part using the celestial coordinates of

points on the celestial sphere. Since these coordinates

are located on the surface of a sphere, they are referred

to as spherical coordinates. Generally, there are two

systems of spherical coordinates: the horizon system

and the Equator system. For artillery survey methods,

the Equator system is used. 

Any circle on the surface of the celestial sphere whose

plane passes through the center of the celestial sphere is

called a great circle. For example, the celestial Equator is a

great circle. When that plane is set perpendicular to the

celestial Equator it is referred to as an hour circle and

includes both poles of the celestial sphere. 

The observer’s meridian is an hour circle that includes

the plane of the observer’s longitude. The upper transit

of the observer’s meridian is that part that includes the

observer’s longitude and the observer’s zenith (the

observer’s plumb line extended upward to the celestial

sphere). The lower transit of the observer’s meridian is

180° from the upper transit and includes the observer’s

nadir (the observer’s plumb line extended downward

to the celestial sphere). 

The position of the observer on the surface of the Earth is

located by latitude and longitude. When the observer’s

plumb line is extended upward to the celestial sphere, a

point referred to as the observer’s zenith or the zenith

position is established. The zenith position is also located

by latitude and longitude and provides a fixed position of

the observer’s instrument on the celestial sphere. The

zenith latitude is the arc distance from the celestial

Equator to the observer’s zenith. The zenith longitude is

the arc distance along the celestial Equator from the plane

of the prime meridian (Greenwich Meridian) to the plane

of the observer’s meridian extended to intersect the

celestial sphere. Zenith longitude is also the angle

between those two planes as measured at the celestial

poles. See figure 7-3. 

Figure 7-2. Celestial Sphere.

Figure 7-3. Zenith Position.
Marine Artillery Survey Operations ________________________________________________________________________ 7-3

The prime vertical for the position of an observer is a

great circle on the celestial sphere that is perpendicular

to the observer’s meridian at the zenith and intersects

the observer’s horizon at points due east and west of

the observer. 

The position of a star on the celestial sphere is defined

in terms of right ascension (RA) and declination (dec).

As the Sun moves across the celestial sphere it traces a

path referred to as the ecliptic. The ecliptic is tilted

approximately 23° 30’ (417.78 mils) from the celestial

Equator due to the tilt of the celestial sphere on its

axis. It crosses the celestial Equator at two points

along its path. The point where the ecliptic crosses the

celestial Equator from the southern hemisphere to the

Northern Hemisphere is the vernal equinox, the first

day of spring usually around March 21. See figure 7-4.

See figure 7-5. RA is the arc distance eastward along

the celestial Equator measured from the vernal

equinox to the hour circle of a celestial body. In most

cases, RA is expressed in terms of arc time; i.e., hours:

h, minutes: m, and seconds: s. It can vary from 0h to

24h east of the vernal equinox. Dec is the arc distance

measured from the celestial Equator to the body along

the hour circle of the star. It can be north (+) or south

(-) of the celestial Equator and is usually expressed in

terms of degrees (°), minutes (’), and seconds (“). It

can be expressed in terms of mils. Dec can vary from

0° to 90° north or south of the celestial Equator.

Astronomic Triangle (PZS Triangle)

Determining an astronomic azimuth requires on the

solution of a spherical triangle located on the surface

of the celestial sphere. This triangle is referred to as

the PZS triangle. The PZS triangle has vertices at the

celestial North Pole, at the observer’s zenith, and at

the star (or Sun). These vertices are the intersections of

great circles that include the triangle’s sides. See

figure 7-6 on page 7-4. The method of astronomic

observation determines the sides and vertices of the

triangle to be solved.

The sides of the PZS triangle are segments of great

circles passing through any two of the vertices. Sides

are arcs and as such are measured with angular values.

The three sides of the triangle are the polar distance,

the coaltitude, and the colatitude. 

Figure 7-4. Ecliptic and Vernal Equinox.

Figure 7-5. Right Ascension and Declination.
7-4 ______________________________________________________________________________________________ MCWP 3-16.7

Polar Distance 

Polar distance is a segment of the hour circle of the

celestial body. It is the arc length of the side of the

PZS triangle from the celestial North Pole to the

celestial body (the PS side). It is determined by

applying the celestial body’s declination to 90°. In

other words, if the declination is north (+), the polar

distance equals 90° minus the declination; if the

declination is south (−), the polar distance equals 90°

plus the declination. See figure 7-7.

Coaltitude 

Coaltitude is the arc length of the side of the PZS

triangle from the celestial body to the observer’s

zenith. The observer’s horizon is a plane that is

tangent to the surface of the Earth at the observer’s

position. It is also perpendicular to the observer’s

zenith. See figure 7-8.

Determine coaltitude by subtracting the vertical angle

(altitude) of the celestial body from 90° (1600 mils). This

vertical angle must be corrected for refraction and

parallax for sun observations and corrected for refraction

for star observations. The resultant angle is side ZS of the

PZS triangle and is referred to as the zenith angle of the

celestial body. See figure 7-9. 

Figure 7-6. Vertices of the PZS Triangle.

Figure 7-7. Polar Distance.

Figure 7-8. Coaltitude.

Figure 7-9. Determining Coaltitude.
Marine Artillery Survey Operations ________________________________________________________________________ 7-5

Parallax can be defined as the apparent displacement

of a body on the celestial sphere caused by a change in

position of the observer. In other words, the observed

altitude, or vertical angle, of a celestial body must be

corrected for the error introduced by the observer’s

location on the surface of the Earth vice the center of

the Earth. The nearest star is 26 x 1012 miles from

Earth; the Sun is only 93 x 106 miles from Earth;

because the stars are so distant, the apparent

displacement of the stars is nearly immeasurable. For

this reason, parallax corrections are used for

observations on the Sun only. Parallax on the Sun

varies from +9” when it is on the observer’s horizon

(vertical angle 0 mils) to 0" when it is on the

observer’s meridian. For artillery survey, a constant

value of +7” (0.04 mils) is used. See figure 7-10. 

Refraction can be defined as the apparent displacement of

a body on the celestial sphere caused by the deflection of

light rays as those rays pass through the Earth’s

atmosphere. A ray of light passing through the Earth’s

atmosphere at a large angle of incidence, (the angle formed

by the line of the light ray and a line which is perpendicular

to the atmosphere), will have a larger refraction correction

than a ray of light passing through an area close to the

observer’s zenith. Refraction of a body varies according to

the altitude (vertical angle) of the body above the horizon

and the temperature. For example, refraction of a celestial

body located on the observer’s horizon (0 mils) at a

temperature of 70° is 10.26 mils; refraction of a body

located on the observer’s zenith is 0 mils. Refraction

increases with an increase in barometric pressure and a

decrease in temperature. Refraction corrections are always

negative. See figure 7-11.

Colatitude 

Colatitude is a segment of an hour circle known as the

observer’s meridian. It is the arc length of the side of

the PZS triangle from the celestial North Pole to the

observer’s zenith (the PZ side). It is determined by

applying the observer’s latitude to 90°. If the

observer’s latitude is north (+), the colatitude equals

90° minus the observer’s latitude. If the observer’s

latitude is south (−), the colatitude equals 90° plus the

observer’s latitude. See figure 7-12.

Figure 7-10. Parallax.

Figure 7-11. Refraction.

Figure 7-12. Colatitude.
7-6 ______________________________________________________________________________________________ MCWP 3-16.7

Angles

The three angles formed by the intersection of the three

sides of the PZS triangle are the parallactic angle, the

hour angle (time angle), and the zenith angle. 

The interior angle at the celestial body formed by the

intersection of the polar distance side (PS side) and the

coaltitude side (ZS side) is the parallactic angle. It is

used in determining astronomic azimuths but is

canceled out during the computations. See figure 7-13.

The interior angle at the celestial North Pole formed

by the intersection of the polar distance side (PS side)

and the colatitude side (PZ side) is the hour angle. The

letter “t” designates the hour angle. The local hour

angle represents the elapsed time since the celestial

body crossed the observer’s meridian. See figure 7-14.

The interior angle at the zenith formed by the

intersection of the coaltitude side (ZS side) and the

colatitude side (PZ side) is the azimuth angle or zenith

angle. This angle is the product of computations and is

the angle used to compute the true azimuth from the

observer to the celestial body. When the celestial body

is east of the observer’s meridian, the true azimuth is

equal to the azimuth angle. When the celestial body is

west of the observer’s meridian, the true azimuth is

equal to 360° (6400 mils) minus the azimuth angle.

See figure 7-15.

If any three elements of the PZS triangle are known, the

other three elements of the PZS triangle can be

determined by spherical trigonometry. In the end, the

element that must be solved is the azimuth angle. This

angle is necessary to establish a true azimuth on the

ground. Figure 7-16 depicts the complete PZS triangle. 

Figure 7-13. Parallactic Angle.

Figure 7-15. Azimuth Angle.

Figure 7-14. Hour Angle (Time Angle or Angle t).
Marine Artillery Survey Operations ________________________________________________________________________ 7-7

The Relationship between

Solar Time and Sidereal Time

Since the celestial bodies are in constant motion with

the apparent rotation of the celestial sphere, the PZS

triangle for each body is constantly changing. In order

to compute an astronomic azimuth, the precise

moment of each observation must be fixed in time as

to fix the position of the observer with respect to the

position of the vertices of the PZS triangle. Because

the rotation of the Earth is extremely constant, it is an

excellent timekeeper. In the field of practical

astronomy two classes of time are used; solar time and

sidereal time. 

Both classes of time are based on one rotation of the

Earth with respect to a reference point. The reference

point is the difference between the two time classes.

Solar time is referenced to the Sun and a solar day is

the amount of time necessary for two successive

passes of the sun over a meridian of longitude.

Sidereal time is referenced to the stars and a sidereal

day is the amount of time necessary for two

successive passes of the vernal equinox over a

meridian of longitude.

See figure 7-17. Since there are approximately 365

days in a year, it can be said that the Earth moves

nearly 1° of its 360° orbit around the Sun in 1 day.

Note that the Earth must rotate nearly a full degree

more for a successive pass of a meridian in a solar day

than it has to in a sidereal day. This creates an apparent

motion of the Sun among the stars of nearly 1°. In

practical astronomy, with the Earth fixed and the

celestial sphere rotating about the Earth, intervals

Figure 7-16. PZS Triangle.

Figure 7-17. Relationship between Solar Time and Sidereal Time.
7-8 ______________________________________________________________________________________________ MCWP 3-16.7

between transits of the Sun over the observer’s

meridian are nearly 4 minutes longer than transits of

the vernal equinox over the observer’s meridian. In

other words, one 24-hour sidereal day equals 23 hours

56 minutes 04.091 seconds of a solar day.

One apparent rotation of the celestial sphere is

completed in a sidereal day. A star rises at nearly the

same sidereal time throughout the year. On solar time,

it rises about 4 minutes earlier from night to night or 2

hours earlier each month. At the same hour, day-byday, the star moves slowly westward across the sky as

the year lengthens. 

The solar day is considered the most natural unit of

time for ordinary purposes. The solar day begins at

solar midnight or the point when the Sun crosses the

observer’s lower transit. Solar noon is when the Sun

crosses the observer’s upper transit. 

Apparent Solar Time

Time indicated by the position of the actual Sun is

called apparent solar time. Apparent solar time for any

point is the amount of time that has elapsed since the

apparent Sun last crossed the meridian at that point.

Greenwich Apparent Time (GAT) is the amount of

time that has elapsed since the apparent sun last

crossed the lower transit of the Greenwich Meridian

(180° long.). Local apparent time (LAT) is the amount

of time that has elapsed since the apparent Sun last

crossed the lower transit of the observer’s meridian

(solar midnight). Since the calendar day begins at solar

midnight, the apparent solar time at any instant is

equal to the hour angle of the Sun plus or minus 12

hours. See figure 7-18.

Apparent solar time is not usually considered accurate

enough for most modern applications. For several

reasons the length of an apparent solar day varies from

season to season. Movement of the Sun is along the

ecliptic and not the celestial sphere. The rate of this

movement is not uniform. The Earth’s orbit is

elliptical and not circular. Thus, December 25 is 50

seconds longer than September 13 and days in January

average 15 seconds longer than days in July. 

Mean Solar Time 

Because a more consistent measure of time is needed,

a fictitious sun moving at a uniform rate along the

celestial Equator was computed from the average

Figure 7-18. Concepts of Solar Time.
Marine Artillery Survey Operations ________________________________________________________________________ 7-9

apparent solar time. Time measured by the position of

the mean sun is referred to as mean solar time. Mean

solar time is numbered from 0−24 uniform hours; each

hour consists of 15° of arc or longitude (360° × 24

hours = 15° per hour). Solar noon occurs when the

mean sun crosses the observer’s meridian.

Mean solar time for any point is the amount of time

that has elapsed since the mean sun last crossed the

meridian at that point. GMT is the amount of time that

has elapsed since the mean sun last crossed the lower

transit of the Greenwich Meridian (180° long.). Local

mean time (LMT) is the amount of time that has

elapsed since the mean sun last crossed the lower

transit of the observer’s meridian (solar midnight). 

Equation of Time

The difference between apparent solar time and mean

solar time is called the equation of time. This value

can vary from +16 minutes (mean sun slow) to −14

minutes (mean sun fast), depending on the season.

Solar Year

A year can be defined as one complete revolution of

the Earth around the Sun. A solar year is defined by

365.2422 mean solar days and can be referred to as a

tropical year.

Concepts of Sidereal Time 

The sidereal day begins when the vernal equinox

crosses the observer’s meridian at the upper transit

(sidereal Noon). Sidereal time for any point is the

amount of time that has elapsed since the vernal

equinox last passed the meridian at that point. Local

sidereal time (LST) is the amount of time that has

elapsed since the vernal equinox last passed the

observer’s meridian; Greenwich Sidereal Time (GST)

is the amount of time that has elapsed since the vernal

equinox last passed the Greenwich meridian. See

figure 7-19.

The annual apparent motion of the Sun along the

ecliptic is opposite in direction to its daily path.

Consequently, the relationship between solar time and

sidereal time is variable. For example, on September 21

at the instant the vernal equinox crosses the observer’s

meridian, the mean sun is crossing the lower transit of

the observer’s meridian. At this instant, the sidereal

clock of the observer will read 0h 0m 0s and a solar

(civil) clock will read 0h 0m 0s. Twenty-four sidereal

hours later, the vernal equinox will again cross the

observer’s meridian, but the mean sun will not yet have

crossed the lower transit of the meridian. From this, we

observe the solar clock reads 23h 56m 04.091s which

shows the sidereal clock gains on the solar clock about

4m per sidereal day. This interval is accumulated

throughout the tropical year so that while a solar year

contains 365.2422 mean solar days, a sidereal year

contains 366.2422 days. 

Figure 7-19. Concepts of Sidereal Time.
7-10 _____________________________________________________________________________________________ MCWP 3-16.7

Time Zones

The mean sun revolves around the Earth once every 24

mean solar hours (one mean solar day) and each hour

the mean sun travels along an arc that is 15° wide.

Each of these 15° arcs is referred to as a time zone. 

The prime meridian is used as a basis of reference for

time zones. Time at a point lying 15° west of the prime

meridian is 1 hour earlier than at the prime meridian

because the Sun has not yet crossed 15° W longitude.

The opposite is true for a point lying 15° east of the

prime meridian. Time is 1 hour later since the Sun has

already crossed 15° E longitude. The difference in

local time between two places equals the difference in

longitude between the two places. See figure 7-20.

Each 15° meridian east and west of the prime meridian

is referred to as a standard meridian. Each zone

extends 7.5° east and west of the standard meridian.

The time zone including the prime meridian extends

from 7.5° E longitude to 7.5° W longitude; the time

zone with a standard meridian at 90° W longitude

extends from 97.5° W to 82.5° W. Four of these

meridians (75°, 90°, 105°, and 120°) cross the United

States. See figure 7-21.

Standard time zone boundaries are often irregular,

especially over land areas. Time zones generally follow

the 7.5° boundary rule except when those boundaries

are shifted to conform to geographical or political

boundaries. For example, Ft. Sill, Oklahoma lies closer

to the 105° W standard meridian, but for political

boundary purposes, all of Oklahoma is located in the

time zone using the 90° W standard meridian. Artillery

surveyors use the term LMT in referring to standard

time or local time in a referenced locale. The time used

by the local inhabitants is local mean time unless a

nonstandard time is in use. See figure 7-22.

Each of the 24 time zones is designated by a letter A-Z

(J omitted). To preclude the problem of compiling and

publishing time data for each of the 24 time zones, data

was computed pertaining to one standard time zone.

Standard time zone Z, which uses the Greenwich

Meridian as a Standard Meridian, was chosen.

Greenwich standard time (Zulu time), also known as

Figure 7-20. Time and Apparent Motion of 

the Sun.

Figure 7-21. Time Zone Boundaries.
Marine Artillery Survey Operations ______________________________________________________________________ 7-11

GMT or Universal Time, is defined as the length of

time since the mean sun last crossed the 180th meridian

(lower transit of the Greenwich Meridian) or solar

midnight. This time can be expressed as the reading of

the standard 24-hour clock at the Greenwich

observatory at the moment an observation is made on a

celestial body. Hence, it is the same time throughout the

world. Since the observer’s clock is usually set to

standard (local) time, that time (LMT) must be

converted to GMT. See figure 7-23 on page 7-12.

Daylight Saving Time

Daylight saving time is clock time advanced by 1

hour from standard time. Effective 1987, federal

law required that daylight saving time be observed

from the first Sunday in April until the last Sunday

in October. However, individual states may exempt

themselves. During World War II, a double daylight

saving time (2-hour advance) was observed

nationwide and was called wartime. 

Converting Local Mean Time

to Greenwich Mean Time

LMT can easily be converted to GMT by applying a

time zone correction.

Figure 7-22. Political Time Zones in the U.S.
7-12 _____________________________________________________________________________________________ MCWP 3-16.7

For the Western Hemisphere, divide the value of the

standard meridian of the local time zone by 15°. The

result is the time zone correction in hours. Add this

correction to the LMT to determine GMT. If this result

is greater than 24 hours, subtract 24 hours and add 1

day to obtain the Greenwich time and date. 

For the Eastern Hemisphere, divide the value of the

standard meridian of the local time zone by 15°. The

result is the time zone correction in hours. Subtract

this correction from the LMT to determine the GMT. 

Converting Greenwich Apparent 

Time to Greenwich Mean Time

When the surveyor observes the Sun, he actually

observes the apparent sun on the celestial sphere and

not the mean sun on which his clock is based.

Consequently, the surveyor must convert his GAT to

GMT. This correction is contained within the arty

astro (hour angle) program and need not be

determined manually. 

Determining the Local 

Hour Angle and Angle t 

When the position of the apparent sun at the time of

observation has been determined and related to the

Greenwich meridian, the time is referred to as GAT.

By adding or subtracting 12 hours to or from the

GAT, the surveyor determines the value of the

Greenwich hour angle (GHA). GHA is the time that

has elapsed since the Sun last crossed the Greenwich

upper meridian (upper transit). To determine the

local hour angle (LHA) in mils of arc, the GHA and

the observer’s longitude must be converted to mils of

Standard

Meridian Letter Time ZoneCorrection

Standard

Meridian Letter Time ZoneCorrection

0° Z 0 0° Z 0

15° E A -1 15° W N +1

30° E B -2 30° W O +2

45° E C -3 45° W P +3

60° E D -4 60° W Q +4

75° E E -5 75° W R +5

90° E F -6 90° W S +6

105° E G -7 105° W T +7

120° E H -8 120° W U +8

135° E I -9 135° W V +9

150° E K -10 150° W W +10

165° E L -11 165° W X +11

180° E M -12 180° W Y +12

Figure 7-23. Time Zone Letter Designations and Corrections:

Local to Greenwich Mean Time.
Marine Artillery Survey Operations ______________________________________________________________________ 7-13

arc. In the Western Hemisphere, determine the LHA

by subtracting the observer’s longitude (mils of arc)

from the GHA in mils. In the Eastern Hemisphere,

determine the LHA by adding the observer’s

longitude (mils of arc) to the GHA in mils. 

Angle t is the angle in the PZS triangle at the polar

vertex. If the LHA is greater than 3200 mils, angle t

equals 6400 mils minus the LHA. If the local hour

angle is less than 3200 mils, angle t equals the LHA.

Appendices

Appendices A through C are critical tools for

conducting astronomic observations. Appendix D

gives conversions that may be required in unusual

circumstances. Appendix E is a detailed glossary of

acronyms, abbreviations, survey terms and definitions

surveyors must understand. Appendix F lists

references and related publications surveyors need to

do their job.

SECTION II. ARTILLERY ASTRO METHOD

The primary astronomic method Marine artillery

surveyors use is the artillery (arty) astro. Arty astro is

based on the hour angle method and can be used with

the Sun or stars. With the advent of the PLGR and

SINCGARS, accurate time is now readily available to

surveyors, making arty astro the preferred method. At

the battery level the hasty astro method of observation

will be used. See chapter 10. 

See figure 7-24. Using two sides and the included

angle solves the azimuth angle of the PZS triangle.

The sides are the polar distance and the colatitude; the

angle is the local hour angle (angle t). In addition to

the horizontal angle from an azimuth mark to the

observed body, three elements must be determined:

l Latitude of the observer to determine the side

colatitude.

l Declination of the observed body to determine the

side polar distance.

l Accurate time of the observation to determine the

LHA.

Arty Astro Method (Sun) 

The arty astro method may be used to determine

azimuths from Sun observations. The arty astro

method does not require measuring a vertical angle

or temperature and computations do not include a

refraction or parallax correction. This method was

once referred to as the hour angle method because

the solution of the PZS triangle depends on solving

the LHA.

Position of the Sun 

For the Sun to be suitable for use with the arty astro

method, it must not be within 1 hour of the observer’s

meridian. It must be between 175 mils and 1300 mils

(preferably between 175 and 800) above the

observer’s meridian. An experienced IO may observe

Figure 7-24. Solving the Arty Astro Method. the Sun above 800 mils with an elbow telescope. 
7-14 _____________________________________________________________________________________________ MCWP 3-16.7

Time 

In the arty astro method (Sun), time is critical to

accurately determine local hour angle. Time must be

accurate to 1 second. Accurate time is available

through radio time signals and GPS receivers; i.e.,

PLGR, MSGR, and SINCGARS. 

Solving the PZS Triangle 

The formula for solving the PZS triangle has been

arranged to require only determining the LHA. The

two sides are stated in the formula in terms of

declination of the Sun and latitude, thus

eliminating the need for the computations of polar

distance and colatitude.

For the hour angle solution, the element of the PZS

triangle that is necessary is the LHA. Determine this

angle by using the time of the observation. Generally,

the LHA is determined by converting the local mean

time (watch time) to Greenwich mean time (GMT), to

Greenwich apparent time (GAT), to GHA, and finally

to the LHA. 

Local Mean Time

+time zone correction

=Greenwich mean time

±equation of time for 0h 

±daily change for portion of day

=Greenwich apparent time

±12 hours

=Greenwich hour angle

±longitude

=local hour angle 

Greenwich Mean Time

The watch time of the observation is referred to as

local mean time. This watch time is standard time for

the area of operation. By applying a time zone

correction the GMT (Zulu time) is obtained. This step

can be skipped if the watch is set to Zulu time. 

Greenwich Apparent Time

GAT is the time that has elapsed since the last passage

of the apparent sun over the lower transit of the

Greenwich meridian. GAT is obtained by applying the

equation of time and the proportionate part of the daily

change in the equation of time to the GMT.

Greenwich Hour Angle

GHA is the amount of time that has elapsed since the

sun last crossed the Greenwich meridian. Therefore,

GAT is always ± 12 hours from the GHA. To

determine the GHA, add or subtract 12 hours to or

from the GAT. Remember: the result must be between

0 and 24 hours.

Local Hour Angle

The LHA of a celestial body is the time that has

elapsed since that celestial body last crossed the

observer’s meridian. The formula to determine the

LHA depends on the hemisphere (east or west) of the

observer. In the Western Hemisphere, longitude and

GHA are measured west from the Greenwich

meridian. The LHA equals the GHA minus longitude

(LHA = GHA − Long). In the Eastern Hemisphere,

longitude is measured to the east; the GHA is still

measured to the west. The LHA in the Eastern

Hemisphere equals the sum of the GHA and the

longitude minus 360° (LHA = (GHA + Long) −

360°).

Several formulas can be derived for the solution of the

spherical triangle when two sides and an included

angle are known. The following formula was selected

for use in artillery survey because of its simplicity:

cos 1⁄2(Lat − Dec) cot 1⁄2t

tan 1⁄2 (A + q) = sin 1⁄2 (Lat + Dec)

sin 1⁄2 (Lat − Dec) cot 1⁄2t

tan 1⁄2 (A − q) = cos 1⁄2(Lat + Dec)

Where: A is the astronomic azimuth

(true) of the Sun measured

east or west of the meridian. 

q is the parallactic angle

(cancels out in computations).

Lat is the latitude of the station. 

Dec is the apparent declination of the Sun. 

t is the local hour angle (less than 12 hours) of the Sun.
Marine Artillery Survey Operations ______________________________________________________________________ 7-15

Computations 

Survey computer systems contain the arty astro program

that easily computes an azimuth from the astronomic

observations performed. The required ephemeris data and

time calculations are completed within the program and do

not require any manual computation. 

Arty Astro Method (Star) 

The arty astro method may be used to determine azimuths

from observations on any of the 73 survey stars.

Observations of the stars are generally considered to be

preferred over those or the Sun due to more accurate

sighting. The preferred star for this method in the Northern

Hemisphere is Polaris. It displays the least apparent motion

being a circumpolar star. In the Southern Hemisphere the

preferred star is Alpha Acrux.

Position of the Stars 

Polaris may be observed any time it is visible, but best

results are obtained when it is 175 mils or higher above the

observer’s horizon. East-west stars can be selected by

using the star ID program. The 175-mil restriction

minimizes the effects of refraction. 

Time 

In the arty astro method (star), time is critical to the

accurate determination of the local hour angle. Time

must be accurate to 10 seconds for observations on

Polaris and 1 second for observations on east-west stars. 

Solving the PZS Triangle 

The formula for solving the PZS triangle with star

observations is the same as for the Sun. The only

difference in the computations is sidereal time determines

the LHA. See below: 

Local mean time

+time zone correction

=Greenwich mean time

±sidereal time for 0h GMT 

±correction for GMT 

=Greenwich sidereal time 

−right ascension of the star 

=Greenwich hour angle 

±longitude 

=local hour angle

Azimuth Specifications 

The arty astro method can determine fourth or fifth

order azimuth. For Marine artillery surveyors, a T2-E

theodolite is used in each echelon of survey. 

At least three sets of observations must be made on

the celestial body. For fifth order, mean the three sets

and reject any set that varies from the mean by more

than 0.3 mils. For fourth order, mean the three sets

and reject any set that varies from the mean by more

than 0.15 mils. At least two sets must remain to

determine the final azimuth for fourth and fifth order.

The considered accuracy for a fifth order astronomic

azimuth is ±0.3 mils and ±0.15 mils for a fourth

order azimuth.

Selecting Methods of Observation

Surveyors must consider— 

l Day or night, North or South latitude.

l Accuracy of the watch time.

l Positions of celestial bodies at specific times.

l Degree of accuracy required.

l Observer’s position accuracy. This is more important

for the computation of UTM grid convergence (true

azimuth to grid azimuth) than for the actual

observation computations.

l The experience of the instrument operator.

Observation and Tracking Procedures

for Sun and Stars (Arty Astro)

While tracking procedures are virtually the same for

the Sun and Star methods, observation is slightly

different. Tracking a star is much more accurate than

tracking the Sun due to the enormous distances

involved. Stars appear as pinpoints of light even

through the telescope, and offer a more defined target

than the large fiery mass of the Sun.
7-16 _____________________________________________________________________________________________ MCWP 3-16.7

Stars

When observing a star to determine astronomic

azimuth the most difficult part is locating the desired

celestial body. The instrument operator, with the

telescope in the direct position, sights in on the

azimuth mark to the desired direction. The initial

circle setting is placed on the scales and recorded in

the recorder’s book. The instrument operator turns to

the constellation containing the desired star and

locates the star in the telescope. It is important to

observe the movement of the star momentarily to

determine its path in the telescope.

Once the stars’ direction and rate of movement are

determined, tracking begins. The instrument operator

announces “tracking.” The recorder keeps time while

the instrument operator repeatedly announces

“tracking” until he has the star centered in the cross

hairs of the telescope. He announces “TIP” (meaning

target in position). Immediately at TIP, the recorder

notes and records the time of observation. The

instrument operator reads the horizontal circle reading

to the recorder who reads it back. Three direct

readings are taken this way. Only after the third direct

reading does the instrument operator plunge the scope

and take three reverse readings using the same

procedures, as required.

The Sun

When observing the Sun, the instrument operator, with

the telescope in the direct position, sights in on the

azimuth mark to which direction is desired. The initial

circle setting is placed on the scales, and recorded in the

recorder’s book. The instrument operator then places

the sun filter on the telescope and turns to the Sun. The

Sun must never be viewed through the telescope

without a sun filter. Inspect the filter before use to

ensure that the coated surface is free from any scratches

or other defects. Serious eye damage will result if

proper precautions are not taken. The Sun should also

be observed momentarily to determine its path and rate

of movement before tracking is announced.

The preferred position of the Sun in the telescope is

centered in the solar circle as opposed to using the

leading or trailing edge of the Sun. The instrument

operator announces “tracking” repeatedly until the Sun

appears in the center of the reticle. He then announces

“TIP.” The time is immediately noted and recorded in

the recorder’s book. The instrument operator reads the

horizontal circle reading to the recorder who reads it

back. Three direct readings are taken this way. Only

after the third direct reading does the instrument

operator plunge the scope and take three reverse

readings using the same procedures, if required.

Direct and Reverse Readings

Reverse readings are required for fourth order

azimuths only. Three direct readings may be taken

consecutively, and as stated above, the telescope is

plunged and the three reverse readings are taken.

SECTION III. STAR SELECTION—POLARIS

There are important advantages to using stars rather

than the Sun as a source for astronomic azimuths.

Stars appear as pinpoints of light in the telescope and

are easier to track. At least one of the 73 survey stars

can be found in a position that allows for astronomic

observation, regardless of the observer’s location or

the time of night. 

Polaris should always be used when it is visible. It is

the most desirable star to observe because it is

usually easy to locate and its slow apparent motion

makes it easy to track. Because of weather

conditions, ambient light, line of sight barriers, or the

observer’s latitude, Polaris may not always be

available. In this case, an east-west star must be used.

East-west stars must be selected based on their

position relative to the observer. 

Orbit of Polaris 

Polaris appears to move in a small, elliptical,

counterclockwise orbit about the celestial North Pole.
Marine Artillery Survey Operations ______________________________________________________________________ 7-17

The size of this apparent orbit varies slightly with the

observer’s latitude; at 35° N latitude, its minor

diameter is about 45 mils. Because Polaris stays so

close to the celestial North Pole, it is visible

throughout the night in most of the Northern

Hemisphere. When the Polaris LHA is 0 or 12 hours,

the star is said to be in its upper or lower culmination,

respectively. When the Polaris LHA is 6 or 18 hours, it

is said to be in its western or eastern elongation. The

small orbit of Polaris results in a very slow apparent

motion, so the star may be observed at any point in its

orbit. The least chance of error will occur when Polaris

is in elongation. See figure 7-25.

Identifying Polaris 

Polaris is the brightest star in the constellation Ursa

Minor (Little Dipper), which is near the constellations

Ursa Major (Big Dipper) and Cassiopeia (Lazy W).

Polaris is the anchor (end) star of the handle of the

Little Dipper.

Polaris can be identified by its relative position to Ursa

Major. The two stars forming the side of the bowl

farthest from the handle of the Big Dipper are called

the pointer stars. An imaginary line extended through

the pointer stars towards Cassiopeia nearly passes

through the celestial North Pole. Polaris is

approximately five times the distance between the

pointer stars along the imaginary line from the Big

Dipper. See figure 7-26.

Polaris can also be identified by its relative position to

Cassiopeia. Since Cassiopeia is on the same side of the

celestial North Pole as Polaris, its position relative to

the pole is approximately the same as Polaris’.

Therefore, Cassiopeia can be used to determine

whether Polaris is in elongation or culmination. A line

drawn from the star Ruchbah, bisecting the shallow

side of Cassiopeia, will pass closely by Polaris. 

The vertical angle to the celestial North Pole equals

the observer’s latitude. Therefore, the vertical angle to

Polaris is approximately equal to the observer’s

latitude. See figure 7-27 on page 7-18. Because the

celestial sphere (and therefore the celestial North Pole)

is an infinite distance from the Earth, the line to the

celestial North Pole from the observer can be

considered the same as the line of the rotational axis of

the Earth (and celestial sphere). Angle A represents

the observer’s latitude; angle B the vertical angle to

the celestial North Pole. The laws of geometry prove

that since the observer’s zenith is perpendicular to the

observer’s horizon and since the line to the celestial

Figure 7-25. Orbit of Polaris.

Figure 7-26. Identifying Polaris.
7-18 _____________________________________________________________________________________________ MCWP 3-16.7

north pole is perpendicular to the plane of the celestial

Equator, angles A and B must be equal. 

When the observer’s latitude in mils is subtracted

from 1600 mils, the result is the vertical reading

to the celestial north pole, angle C in figure 7-27.

When that vertical reading is set on the vertical

scale of the theodolite in the direct mode, Polaris

will appear in the field of view. If the star is at

elongation, its vertical angle is equal to the

observer’s latitude. When Polaris is moving from

eastern to western elongation, its vertical angle is

greater than the observer’s latitude; when Polaris

is moving from western to eastern elongation, its

vertical angle is less than the observer’s latitude.

When a pointing is made on Polaris, the observer

will see two other stars nearby which are not

visible to the naked eye. However, when the

reticle pattern in the telescope is illuminated,

Polaris will be the only visible star.

SECTION IV. RECORDING ASTRONOMIC 

OBSERVATIONS

Arty Astro Method Field Notes 

(Fifth Order)

Heading and Column Titles

See figure 7-28.

Fill in the designation block with ARTY ASTRO

(Sun) or (Star).

Fill in the date block with the date the field

work was performed. This will be the date used

in the computations.

Figure 7-27. Relationship between the Observer’s 

Latitude and the Vertical Angle to the Celestial 

North Pole.

Figure 7-28. Heading and Column Titles (Fifth Order Arty Astro).
Marine Artillery Survey Operations ______________________________________________________________________ 7-19

Fill out the heading of the right side of the page

the same as with traverse. Include the weather

description, instrument number, COP name, IO name,

and RCDR name.

Label column titles under the heading (from left to

right) as follows:

1, STA. Identify the occupied, rear, and forward

stations. The forward station star name will be listed.

2, T. Identify the telescope position (direct {D} or

reverse ({R}). 

3 and 4: TIME (h m s). This column designates the

exact time the IO announced TIP during the

observations. “TIME” is split between the columns in

the top half of the blocks. Hours (h) are listed in the

lower left corner of column 3, minutes (m) centered

between the columns, and seconds (s) in the lower

right corner of column 4.

5, HORZ. Record horizontal readings to the azimuth

mark and to the celestial body.

7-12, REMARKS. Use this side of the page to record

information pertinent to these observations. Include

required entries and some optional information that

may be needed by the computer or for future

reference. See figure 7-29. 

Required entries are—

Easting and northing of the occupied station. 

UTM grid zone. 

Horizontal datum/ellipsoid. 

Source of the position information. 

Center, leading or trailing edge if using the Sun. 

Time zone letter. If using local time, indicate daylight

saving or standard times. 

Sketch (as close to scale as possible).

Optional entries are—

Location of occupied and rear stations. 

Route to these locations from a known point. 

Changes to data in trig list on the stations. 

Weather phenomena not covered in header

information. 

RCDR, IO, COP initial blocks. 

Approximate azimuth to AzMk.

Recording Field Data

Record field data in the columns and rows

corresponding to the pointing. Record the initial circle

setting in the horizontal angle column in the rear

station/direct reading row. See figure 7-30.

Figure 7-29. Remarks for Arty Astro.

Figure 7-30. Field Data (Fifth Order Arty Astro).
7-20 _____________________________________________________________________________________________ MCWP 3-16.7

Fill out the “T” (telescope) column as shown in figure

7-30. The rear station (AzMk) name will be recorded

in the direct (D) mode row directly below the STA

column title. Skip one line to record the occupied

station name. Skip one line to record the forward

station (celestial body) name to the left of the first

direct pointing on the body. If the celestial body is a

star, record its name.

Record time (seconds, minutes, and then hours

{24-hour format}).

To record angles, record the entire number then read

the value back to the IO.

Record the closing angle and verify that the horizontal

collimation error is within specifications (±0.150 mils).

If the azimuth is being computed in the field using the

computer’s internal clock, the solution is part of the

field work. It must be included in the field notes.

Record the solution in column 6 in the row listing the

occupied station and circle it.

Arty Astro Method Field Notes

(Fourth Order)

Two sets of observations are made: one with the

telescope in the direct position, the second in the

reverse. This method minimizes the effects of small

pointing errors on the observed stations.

Heading and Column Titles

Titles will remain the same as fifth order recording

except for the addition of column 6, MEAN.

See figure 7-31.

Fill in the designation block with ARTY ASTRO

(Sun) or (Star).

Fill in the date block with the date the field work was

performed. This will be the date used in the

computations. 

Fill out the heading of the right side of the page the

same as with traverse. Include the weather description,

instrument serial number, COP name, IO name, and

RCDR name.

Label column titles under the heading from left to

right as follows:

1, STA. Identify the occupied, rear, and forward

stations. If the forward station is a star, list its name.

2, T. Identify the telescope position, direct (D) or

reverse (R). 

3 and 4, TIME (h m s). This column designates the

exact time the instrument operator announced TIP

during the observations. “TIME” is split between the

columns in the top half of the blocks. Hours (h) are

listed in the lower left corner of column 3, minutes (m)

centered between the columns, and seconds (s) in the

lower right corner of column 4.

Figure 7-31. Heading and Column Titles (Fourth Order Arty Astro).
Marine Artillery Survey Operations ______________________________________________________________________ 7-21

5, HORZ. Record horizontal readings to the azimuth

mark and to the celestial body.

6, MEAN. Record the solutions for the direct and

reverse sets and the mean solution of the sets. 

7-12, REMARKS. Use this side of the page to record

information pertinent to the observations. Include

required entries and some optional information that

may be needed by the computer or for future reference

as with fifth order observations. 

Recording Field Data 

Record the first set as the procedures listed for

fifth order except that the solution is not circled.

See figure 7-32. 

Fill out the “T” (telescope) column as shown in figure

7-33. Allow three spaces between the last direct

reading in the first set and the initial circle setting (“R”

reverse reading) in the second set. 

When recording the second set, record the rear station

(AzMk) name in the reverse (R) mode row. Skip one

line to record the occupied station name. Skip one line

to record the forward station (celestial body) name to

the left of the first reverse pointing on the body. If the

celestial body is a star, record its name.

When the field work is completed for the first set, the

IO has a pointing on the rear station in the reverse

position. This is the closing angle for the first set. The

recorder will enter that closing angle as the initial

circle setting for the second set. The IO needs only to

observe the celestial body in the reverse position and

close the angle in the direct mode to complete the

second set. 

Record seconds, minutes, and then hours (24-hour

format).

When recording angles, record the entire number

then read the value back to the instrument operator.

Record the closing angle and verify that the

horizontal collimation error is within specifications

(±0.150 mils).

Figure 7-32. Field Data (Fourth Order Arty Astro 

First Set).

Figure 7-33. Field Data (Fourth Order Arty Astro).
7-22 _____________________________________________________________________________________________ MCWP 3-16.7

If the azimuth is being computed in the field using

the computer’s internal clock, the solution is part

of the field work. Include it in the field notes.

Record the solution in column 6 (MEAN) in the

row listing the occupied station and place in

parentheses. The azimuth determined from the

direct readings must equal the azimuth from the

reverse readings, ±0.150 mils. After the second set

is computed, the solutions for the two sets are

meaned. The mean azimuth is recorded in column

6 (MEAN) in the center row of the three spaces

between the two sets. 
CHAPTER 8. POSITION AND AZIMUTH

DETERMINING SYSTEM OPERATIONS

Capabilities and Limitations

The Position and Azimuth Determining System

(PADS) is a self-contained inertial surveying system

that rapidly determines accurate position, elevation,

and azimuth. It can be used with or apart from other

assets available to the survey section, such as

conventional assets and GPS receivers. 

The PADS performs surveys faster than a

conventional survey party. It provides coordinates,

azimuth, and elevation to any point located where the

vehicle can be placed or within 16 meters of the

PADS. The PADS requires fewer personnel than a

conventional survey party and less time for

reconnaissance and planning. It provides data that

meets accuracy requirements of most artillery systems

and accurate azimuth when coordinates are assumed.

The PADS—

l Limitations are mostly software-driven. The current

PADS use a solid-state memory with Version 4

software. 

l Has a continuous mission time if the system is updated

at least every 7 hours or within a 55−kilometer radius,

whichever comes first.

l Is limited to surveying between the latitudes of 75°

N and 75° S.

l Is limited to operations between −150 meters to

4500 meters in elevation.

l Has ambient temperature operational limits of

−50°F to 125°F. 

l Requires the vehicle’s electrical system to include

at least a 100 amp alternator (200 amp preferable). 

l Requires an initialization/alignment time of 30 to

45 minutes.

l Is limited to 12 programmed ellipsoids and 2 user

defined options.

l Can only store 50 positions as update and mark

stations.

Vehicles

The PADS can be mounted in any military vehicle as

long as the correct lever arm information (plumb bob

position) is known. The current PADS software

(Version 4) is programmed with seven lever arms for

six vehicles. It also stores up to three nondefined

vehicles. Any vehicle used with the PADS must have

an available 24-volt system. The following ground and

air vehicles are programmed in the PADS with their

corresponding lever arm.

The high mobility multipurpose wheeled vehicle

(HMMWV) with the plumb bob mounted on the

driver’s door uses the PADS cue HUM for its lever arm. 

The first lever arm for the M151 1/4 ton utility vehicle

(Jeep) is located at the pintle hook with a PADS cue of

M151. The second lever arm is the PADS plumb bob

arm with a cue of PLMB. 

The plumb bob is mounted on the commercial utility

cargo vehicle’s (CUCV’s) pintle hook. The PADS cue

is CUCV. The plumb bob for the small unit support

vehicle (SUSV) is mounted on the driver’s side mount.

The PADS cue is SUSV.

When mounted on the UH-1 (Huey), the PADS plumb

bob arm is used with a PADS cue of UH-1. 

As with the Huey, the plumb bob arm for the OH-58

light observation helicopter is used. The PADS cue

is OH-58. 

The PADS can be transferred from a ground vehicle

to a Blackhawk (UH-60) equipped with an AC to

DC converter. 

Accuracy: Zero-Velocity Corrections

Accuracy obtained from the PADS depends on how

frequently Zero-Velocity Corrections (Z-Vels) are

used during the survey mission. Z-Vels are performed
8-2 ______________________________________________________________________________________________ MCWP 3-16.7

automatically by the PADS during all marks and

updates. They must be performed by the operator at

other times en route between stations. This operation

allows the PADS to correct itself based on the large

amount of data it has collected while moving from one

position to another. A 10-minute Z-Vel is sufficient

for most artillery survey operations. For some

missions, a 5-minute Z-Vel is required; e.g., Q-37

radar sites and declination stations. Z-Vels are

necessary for accurate computation of survey data.

The PADS automatically performs Z-Vels during a

30-day bias, initialization, and all marks and updates.

The operator must perform all Z-Vels during the

mission between stations.

The PADS cues the operator 30 seconds before the

scheduled Z-Vel by flashing the STOP and GO status

indicators and by sounding alarm DS3. The driver

stops the vehicle, places the transmission in neutral,

sets the parking brake, and releases the foot brake.

Once the vehicle stops, the operator presses the

STOP key to start the Z-Vel. The PADS flashes GO

when the Z-Vel is complete. Failure to perform the

scheduled Z-Vel will degrade the accuracy of the

survey data. 

The operator changes the scheduled Z-Vel by

performing the following keystrokes:

10 minutes: MON, ID, 4, 6, ENT, MON, 1, 0, 0, ENT.

5 minutes: MON, ID, 4, 6, ENT, MON, 5, 0, ENT. 

The PADS defaults to the last Z-Vel time that was

entered. Also see below.

Primary and Secondary Pallets

The PADS is contained in the primary and secondary

pallets. When unpacked for the first time, the system

will contain these pallets plus the mounting base

(subfloor). The primary pallet is named for the metalframed housing where the components are mounted. It

has four major components.

Inertial Measurement Unit 

The inertial measurement unit (IMU) contains three

accelerometer sensors, two gyroscopes, and the

associated electronics that maintain the survey

coordinate frame and measure distances traveled to

each coordinate axis. The accelerometers sense the

movement and the gyroscopes give the accelerometers

a reference point that detects actual movement. See

figure 8-1.

A gyroscope is a spinning wheel that maintains a fixed

orientation in space. It is also designed to act as a

gyrocompass that finds true north by sensing the

Earth’s rotation. One gyroscope is oriented to true

north while the other is aligned horizontal and

perpendicular to the spin axis of the other gyroscope.

This allows the PADS to provide a three-dimensional

reference point to the accelerometers. 

An accelerometer measures acceleration (the time rate

of velocity). (If a car is going 50 miles per hour and

10-Minute Z-Vel Accuracy

Latitude 0°−65° N/S 65°−75° N/S

Horizontal Position (CEP) 7.0 meters 10.0 meters 

Vertical Position (PE) 3.0 meters 3.0 meters

Azimuth (PE) 0.4 mils 0.6 mils

5-Minute Z-Vel Accuracy 

Latitude 0°−65° N/S 65°−75° N/S

Horizontal Position (CEP) 4.0 meters 7.0 meters

Vertical Position (PE) 2.0 meters 2.0 meters

Azimuth (PE) 0.4 mils 0.6 mils

Figure 8-1. Inertial Measurement Unit.
Marine Artillery Survey Operations ________________________________________________________________________ 8-3

accelerates to 70 miles per hour, the actual

acceleration time rate is 20 miles per hour.) The

PADS uses three accelerometers. One measures northsouth direction, one measures east-west direction, and

one measures vertical direction.

Computer 

The computer consists of a general-purpose digital

computer and interface circuitry. It processes IMU

data, computes survey data, and provides system

control functions. The computer receives three signals

from the accelerometers. These signals integrate with

time to produce velocity signals. Velocity signals once

again integrate with time to produce the distance

traveled in each cardinal and vertical direction. Error

signals are also produced for calculations for Earth

rotation rates and keeping gyroscopes level during

survey operations. See figure 8-2.

Control and Display Unit 

The control and display unit (CDU)is the operator’s

interface with the PADS. It is a keyboard and an

alphanumeric display for operator entry and display of

survey data and system commands. The CDU is the

input/output device for the PADS computer. It is the

only portion of the PADS that must be accessible

during a survey mission. See figure 8-3.

Power Supply 

The power supply receives unregulated power from the

vehicle or the PADS batteries and sends power out to

the other PADS components. It supplies, controls, and

regulates the amperage to the IMU, CDU, and

computer, and charges the PADS auxiliary batteries.

The computer also has a power supply. It receives the

input power from the PADS power supply and regulates

the amperage for the computer. See figure 8-4.

Figure 8-2. Computer.

Figure 8-3. Control and Display Unit.

Figure 8-4. Power Supply.
8-4 ______________________________________________________________________________________________ MCWP 3-16.7

The secondary pallet is the battery box. It contains two

12-volt DC batteries connected in series to provide 24

volts for back-up power. The battery box continues

survey operations while the PADS is transferred

between a ground vehicle and a helicopter. It provides

additional power for initialization and back-up power

if that vehicle power fails, and is a transport case that

houses cables, tools, small hardware, spare lamps,

modules, reference manuals, etc. See figure 8-5.

Control and Display Unit Operator Controls

Most of the operator controls are on the CDU. It has a

keyboard and display for status/fault indicators. Status

indicators usually appear as orange/yellow lights. The

DS2 fault indicator shows white. 

Status Indicators 

The status indicators below with their functions are

located on the top half of the CDU display. These

lights prompt the operator to perform a task or indicate

a possible malfunction. See figure 8-6.

COMP. Possible computer failure.

IMU. Possible IMU failure.

BATT. A steady BATT means the vehicle or PADS

battery is not connected, the PADS battery is being

discharged or one of the PS circuit breakers are off.

A flashing BATT means the input voltage is too low

and the PADS may turn itself off unless the problem

is corrected.

ATTN. Operator error.

STOP. A flashing STOP tells the operator to stop for Z-Vel.

A steady STOP tells the operator to remain stopped.

Figure 8-5. Secondary Pallet 

(Battery Box).

Figure 8-6. Status Indicators.
Marine Artillery Survey Operations ________________________________________________________________________ 8-5

GO. A flashing GO tells the operator the vehicle can

be moved. A steady GO means the vehicle has been

moved since the last Z-Vel.

CHRG. Batteries are charging.

ADZ. Entry and display of position data are in the

adjacent UTM grid zone.

MON. CDU displays user requested data in the

monitor table.

UPDT. The system is ready to accept update data.

CAL. Lights during initialization and 30-day bias.

Lighting during an update indicates the operator entered

incorrect data or the system is out of calibration.

MARK. The system is recording marked survey data.

Z-VEL. PADS is performing Z-Vel.

ENT. Computer is ready to accept data from the keyboard.

Operator Commands 

The CDU keyboard allows the operator to enter

system commands and data. 

STOP. Starts Z-Vel, lights STOP indicator, turns

off audible alarm (IF ALARM IS ON), and

illuminates the ATTN status indicator if pressed

while vehicle is moving.

MARK. Initiates position mark procedures. Lights

MARK indicator. Pressing MARK twice cancels a

position-mark procedure.

UPDT. Initiates position and/or elevation update

procedure. Lights UPDT indicator. Pressing UPDT

twice cancels an update procedure.

ON/OFF. If the system is off, pressing ON/OFF

applies power. If the system is on, pressing ON/

OFF causes the CDU to display commands for

shutdown procedures.

LAMP. Tests all CDU status indicators, alphanumeric

display lamps, and system fault indicators. When held

down varies lamp intensity and sounds DS3 ALARM.

MON. Selects the monitor mode. Lights MON

status indicator.

ADZ. Directs the system to enter or display the

adjacent UTM grid zone. Lights the ADZ indicator.

SPH. Allows the entry and display of spheroid

(ellipsoid) options. Allows the option for performing a

30-day bias or for entering geographic coordinates. 

TIME. During 30-day bias, initialization and Z-Vel,

displays elapsed time since turned on. When the

vehicle is moving, it displays time to the next Z-Vel.

Silences ALARM DS3 for 30 seconds.

ID. When pressed, followed by an ID number,

followed by ENT, cues PADS to provide mark data for

the ID number entered. ID, 0, ENT indicates current

data display. Pressing ID twice selects PAE display.

DIST. Allows entry and display of the distance

between the porro prism and a theodolite for an optical

position mark. Displays the distance between points

on a two-position azimuth mark.

<. > Allows entry and display of a horizontal angle

measured by a theodolite.

E. Allows entry and display of the UTM grid zone and

easting.

N. Allows entry and display of a northing coordinate;

when pressed twice, indicates Southern Hemisphere

by displaying “S”. Only during the initial entry of data

may the change in selection of hemisphere from

northern to southern be made.

EL. Allows entry and display of elevation.

GAZ/TAZ. Displays grid azimuth. When pressed

twice, displays true azimuth, clear or enter (TA C−E).

Operator may display true azimuth by pressing ENT.

If CLR is pressed, grid azimuth is displayed.

1,2,3,4,5,6,7,8,9,0. Enters numerical data as selected.
8-6 ______________________________________________________________________________________________ MCWP 3-16.7

When elevation has been selected for entry of data, the

first pressing of the 2 or 8 will enter a + or −,

respectively. Thereafter, the 2 and 8 revert to normal

number functions. Advances (+) and decreases (−)

through ID and monitor numbers.

ENT. Causes displayed data or function to be entered

into the computer or executed.

CLR. Clears display and mode selection.

DS Alerts

The CDU has two DS alerts that indicate a specific

task needs to be performed or that a malfunction has

occurred. ALARM DS3 warns the operator to stop for

a Z-Vel or may sound if there is excessive motion

during initialization. Fault indicator DS2 indicates the

CDU is functioning (black) or malfunctioning (white).

Power Supply Operator Controls

CB1 controls battery power from the PADS battery

box to the power supply. CB2 controls vehicle power

from the prime mover to the power supply.

The BATT FAIL fault indicator DS1 turns from

black to white when the PADS batteries lack

sufficient power to maintain standalone system

operations. The PS FAIL fault indicator DS2

indicates if the power supply is functioning (black) or

malfunctioning (white).

The M1 (elapsed time indicator) displays the total

power supply operating time.

Computer Operator Controls

The M1 (elapsed time indicator) displays the total

computer operating time. The fault indicator DS1

indicates whether the computer is functioning (black)

or malfunctioning (white).

IMU Operator Controls

The elapsed time indicator displays the total IMU

operating time.

The porro prism controls align the theodolite to the IMU

during optical measurements (offset). See figure 8-7.

The level adjustment knob levels the porro prism. The

level vial indicates the level of the porro prism.

Use the stadia scale with the theodolite stadia lines to

indicate the distance between the porro prism and the

theodolite to the nearest 0.1 meter. 

Use the plumb bob arm assembly for marks and

updates when mounted in a vehicle that uses the

standard plumb bob position (M151, OH-58).

Recording the PADS Field Notes

The PADS survey data is recorded in the current

version of the field recorder’s notebook. As with all

field notes, the first page of the recorder’s book is

Figure 8-7. Porro Prism Components.
Marine Artillery Survey Operations ________________________________________________________________________ 8-7

the index. Heading and column titles for normal

PADS missions will be filled out as described

below. See figure 8-8.

Fill out the designation block with PADS SURVEY. 

Fill in the date block with the date the field work

was performed.

In the heading of the following page, include the

PADS serial number (taken from the primary pallet),

ellipsoid, and datum. At the right side of that page, list

the names of the operator and assistant operator and

the interval that Z-Vels were made.

Label the column titles under the heading from left to

right as follows:

1, STA. Identify the update or marked stations.

2, ID #. Identify the storage position in the PADS

computer for update and marked positions. The PADS

Version 4 stores 50 positions; Core Memory systems

loaded with Version 3 stores 30. 

3, PAE. Identify the operation performed at each position. 

4, U/A. Identify unadjusted and adjusted data.

5 and 6, EASTING. Identify the UTM grid zone and

UTM easting of the position.

7 and 8, NORTHING. Identify the UTM northing of

the position.

9, EL. Identify the elevation of the position.

10, GRID AZ. Identify the UTM grid azimuth

between two marked points or to an optically sighted

azimuth mark. The PADS with Version 4 software

will adjust the azimuth;. Use only the unadjusted

azimuth. If the azimuth recorded is true, then record

TRUE in the block with the azimuth.

11, DIST. Identify the distance (in meters) between

two marked stations or to identify the distance

measured by an autoreflection.

12, REM. Identify any system malfunctions, magnetic

azimuth checks, etc. 

Recording the information obtained from the optical

azimuth method is performed in the same manner as

recording a one-position horizontal angle. Other

Figure 8-8. The PADS Recording Procedures.
8-8 ______________________________________________________________________________________________ MCWP 3-16.7

measurements such as distances to azimuth marks and

vertical angles may be obtained and an entry in the

remarks section made on those measurements. Record

the offset distance between the theodolite and the

PADS porro prism on the page of the recorders book

with the PADS mission. See figure 8-9. 

PADS Mission Procedures

The following PADS procedures are for PADS

Version 4 software. All PADS mission procedures

must begin with pre-operation checks and services as

outlined in Marine Corps TM 08837A-12/1A/Army

TM 5-6675-308-12, Operator’s and Organizational

Maintenance Manual for Position and Azimuth

Determining System AN/USQ-70. 

30-Day Azimuth Gyro Bias 

The 30-Day Azimuth Gyro Bias is a normal part of

scheduled maintenance on the PADS. Performed at

least every 30 days, but it may become necessary to

perform this procedure as part of regular operations.

This operation is performed to align the azimuth gyros

in the IMU. It should be done while plumb over a

fourth order or higher survey control point but may be

done using a GPS position if need be. This operation

cannot be performed with a theodolite. 

The PADS must be level to ±5°. Once the 30-Day

Azimuth Gyro Bias starts do not disturb the vehicle for

any reason. This procedure will last anywhere from

21⁄2 to 3 hours. The PADS will align its way through

18 modes. Once the PADS reaches mode 18, the GO

light flashes, informing the operator it can be moved.

A PADS that has just completed the 30-Day Azimuth

Gyro Bias does not have to go through the

initialization process.

Initialization

Perform initialization procedures every time the

PADS provides survey control except after a 30-Day

Azimuth Gyro Bias. This procedure aligns the gyros

for use during the mission. Initialization does not take

a space as an ID number in the PADS memory. 

Figure 8-9. PADS Recording Procedures for Optical Azimuth Method.
Marine Artillery Survey Operations ________________________________________________________________________ 8-9

The PADS must be within 100 meters of the

initialization site. Elevation should be within 10

meters. Initialization can be done using a GPS position

when no survey control is available. This procedure

cannot be performed with a theodolite.

The PADS should be level to ±5°. The PADS can be

initialized on slopes greater than 5° but with a possible

decrease in alignment accuracy. LEVEL will display

on the CDU. The operator should shut down the

PADS, wait 2 minutes, move to a more level position,

and reinitialize. If this is not possible, the PADS will

continue to initialize until it reaches mode 8. LEVEL

will go off and the GO light will flash.

Once the PADS is turned on it must not be moved for

at least 1 minute or damage may result. Face the

vehicle into the wind and allow it to set without

moving for about 30 to 45 minutes. Once the PADS

reaches mode 8, the GO indicator flashes informing

the operator it can be moved.

Updating

This procedure tells the PADS exactly where it is.

Perform it before marking a position. If adjusted data

is needed it must be performed after marking

positions. All updates are stored as ID numbers in the

PADS memory.

Updating the PADS should be done while plumb over

a fourth order or higher survey control point.

However, a GPS position can update if no survey

control is available. The PADS will not adjust stations

that were marked before or after a GPS update. If you

update over a survey control point, then mark stations

and update with a GPS position, the stations marked

between the two updates will not be updated. 

The PADS can be updated with the programmed

lever arm or with a theodolite (autoreflection). If

autoreflection is used, the PADS must be within

16 meters of the station. 

The position and elevation can be updated together or

separately depending on what survey data is available.

Azimuth cannot be updated. 

Mark 

This procedure obtains the position and elevation of a

point; e.g., OS, EOL or OP. It also obtains an azimuth

between two marked stations (two-position mark) or

between a marked station and an offset station (optical

azimuth method). All marked positions are stored as

ID numbers in the PADS memory.

When performing a two-position mark, the first

position mark is performed the same as a regular mark

with the PADS lever arm or the theodolite. The second

position must be marked with the PADS vehicle. The

PADS will not allow the second position to be marked

with a theodolite. The distance between the two

stations must be between 100 and 1,000 meters.

Otherwise an error (E) will appear in the PAE portion

of the mark. For more information on PADS

procedures, see Marine Corps TM 08837A-12/1A/

Army TM 5-6675-308-12.

PAE Codes

Each time a station is marked or the PADS is updated,

that station occupies one of 50 ID numbers stored in

the mark portion of the PADS memory. Part of that ID

number is the PAE, which tells the operator the

method used to mark or update and whether or not that

procedure was performed without error.

A separate code is assigned to each part of the PAE.

These codes are displayed on the CDU after the mark is

completed or after the update is accepted by the PADS.

The display appears on the CDU as “ID #PAE XYZ

where X represents the code assigned to Position, Y to

Azimuth, and Z to Elevation.” The three codes can be

the same, different or any combination. See figure 8-10.

PAE

CODE

MEANS

U Position and/or elevation updated using a plumb bob or

a theodolite over a control point. 

g Position and/or elevation updated using GPS only. 

d Position and/or elevation updated using Diff GPS.

1 Theodolite marked PAE.

2 Plumb bob marked PAE.

E Error may exist in position, azimuth, and/or elevation.

- PAE not updated or not marked.

Figure 8-10. PAE Codes.
8-10 _____________________________________________________________________________________________ MCWP 3-16.7

A g or d with a 1 or 2; e.g., g1, d2 may appear in one

of the PAE positions. This indicates that a mark has

been affected by using a GPS or Diff GPS method. A g

or d with a 1 indicates a GPS or Diff GPS association

with a theodolite mark. A g or d with a 2 indicates an

association with a plumb bob mark.

Figure 8-11 shows examples of PAE readings the

operator may see.

DISPLAY MEANS

PAE U-U Position and elevation updated.

PAE U-- Position only updated.

PAE --U Elevation only updated.

PAE g-g Position and elevation updated using GPS only.

PAE g-- Position only was updated by GPS.

PAE d-d Position and elevation updated with Diff GPS.

PAE d-- Position only updated with Diff GPS.

PAE --d Elevation only updated with Diff GPS. 

PAE 1-1 Position and elevation marked using a theodolite. 

PAE 111 PAE marked using a theodolite. Azimuth obtained by optical azimuth

method.

PAE 2-2 Position and elevation marked with a plumb bob.

PAE 222 PAE marked with a plumb bob. Azimuth obtained by a two-position

mark.

PAE 2E2 Position and elevation marked but the azimuth may be in error. This

normally occurs when the distance between two stations in a twoposition mark is less than 100 meters or too much time was used to

travel between stations.

PAE g1-g1 GPS-influenced position and elevation marked with a theodolite. This

will occur when the last update was performed with a GPS position. 

PAE g2-2 GPS-influenced position from a plumb bob marked with a standard

control elevation mark. This may occur if the last position update was

performed with GPS and the elevation was updated separately over a

survey control point.

Figure 8-11. Example of PAE Readings.
CHAPTER 9. GLOBAL POSITIONING SYSTEM

SECTION I. CONFIGURATION, 

SIGNALS, AND CODE

The Navigation Satellite Timing and Ranging

(NAVSTAR) GPS is configured into space, control,

and user segments. Each segment depends upon the

other. See figure 9-1.

Originally, the complete space segment was to consist of

24 Block II satellites. Block I satellites were considered

developmental. Block IIR (Replacement) satellites are

being developed to provide system operations through

the year 2025. More than 24 satellites are currently in

orbit. They are arranged into six orbital planes, each

inclined 55° from the Equator. Each orbital plane

contains at least four unevenly spaced satellites orbiting

the Earth twice a day at an altitude of 10,898 miles.

Satellites move continuously through their orbit in the

same direction as the Earth’s rotation. They orbit the

earth twice in 23 hours, 56 minutes, and 04.091 seconds

solar time or 1 24-hour sidereal day. 

Figure 9-1. NAVSTAR System Configuration: Space, Control, and User Segments.
9-2 ______________________________________________________________________________________________ MCWP 3-16.7

The control segment consists of five unmanned

monitor/tracking stations located in Hawaii,

Colorado, Ascension Island, Diego Garcia, and

Kwajalein. Tracking stations use special receivers to

track each satellite individually. The information

from tracking the satellites helps control the satellites

and predict their orbits. Three of the stations transmit

information back to the satellites. All data collected

at the tracking stations is transmitted to the master

control station, located at Colorado Springs,

Colorado where it is processed and analyzed.

Ephemerides, clock corrections, and other message

data are then transmitted back to the three stations for

subsequent transmittal back to the satellites. The

master control station is also responsible for the daily

management and control of the satellites and the

overall control segment.

The user segment consists of any one with a GPS

receiver. Military and civilian personnel (including the

enemy) use these receivers.

Satellite Signals

See figures 9-2 through 9-5. 

Carrier Frequencies

Each GPS satellite broadcasts signals on two spreadspectrum radio frequencies (RFs). These are termed

carrier frequencies because they are modulated with

signal codes “carried” on the radio wave. The

satellite’s onboard atomic clocks generate a

fundamental frequency of 10.23 megahertz

(10,230,000 cycles per second) multiplied by a factor

that produces the actual carrier frequency.

The Link 1 (L1) RF carrier frequency is generated by

multiplying the fundamental frequency by 154. It is

centered at 1575.42 megahertz and has a bandwidth of

20.46 megahertz. The majority of the intensity of the

signal lies at 1575.42 megahertz (±10.23 megahertz).

Signal wavelength is 19 centimeters. 

The Link 2 (L2) RF carrier frequency is generated by

multiplying the fundamental frequency by 120. It is

centered at 1227.60 megahertz and has a bandwidth of

20.46 megahertz. The majority of the intensity of the

signal lies at 1227.60 megahertz (±10.23 megahertz).

Signal wavelength is 24 centimeters.

Data Sequences

Each GPS satellite develops several binary data

sequences transmitted from the GPS control segment.

These sequences are the coarse/acquisition (C/A)

code, the precise (P) code, and the Navigation Data

Message (Nav Data).

The CA code is sometimes referred to as the standard

(S) code. It has also been called the clear access or

civilian access code. It is broadcast by all GPS

satellites on the L1 carrier wave. Transmission of the

data sequence is centered at 1575.42 megahertz (L1

frequency). It is modulated at ±1.023 megahertz

providing a bandwidth of 2.046 megahertz. The code

contains a sequence of 1,023 pseudo-random binary

biphase modulations on the GPS carrier at a chipping

rate of 1.023 megahertz, thus having a repetition

period of 1 microsecond. The C/A code is a 300-meter

Figure 9-2. L1 Carrier Frequency. measurement wave. 

Figure 9-3. L2 Carrier Frequency.
Marine Artillery Survey Operations ________________________________________________________________________ 9-3

Figure 9-4. P Code and C/A Code Data Sequence.

Figure 9-5. GPS Signal Data Flow.
9-4 ______________________________________________________________________________________________ MCWP 3-16.7

The P code is sometimes referred to as the protected

code. It is broadcast by all GPS satellites on both the L1

and L2 carrier. Transmission of the data sequence is

centered at 1575.42 megahertz on the L1 carrier and at

1227.60 megahertz on the L2 carrier. It modulates at

±10.23 megahertz on carrier frequencies providing a

bandwidth of 20.46 megahertz. The P code is a 30-meter

measurement wave and can be encrypted by the satellite

creating a Y code. 

The overall P code is a mathematically derived binary

sequence that is 267 days (approximately 37 weeks)

long. It is broken into 1-week segments for operational

use. Five of these 1-week segments are reserved for

the GPS control segment. The other 32 segments are

available for satellite vehicles (SVs). Each SV has a

unique 1-week segment code that is a subset of the

overall P code sequence. It is generally accepted that

the P code repeats every week.

The Nav Data is a 1,500 bit navigation message

broadcast on both L1 and L2 carriers at a rate of 50

bits per second or 50 hertz. The Nav Data contains

system time, clock correction parameters, ionospheric

delay model parameters, and the almanac (ephemeris

and health data) on the entire constellation. It is

broadcast once each hour by each GPS satellite and

can be referred to as the D code. 

The Nav Data is a separate binary data sequence in the

satellite. But it is modulated over the C/A and P codes

for transmission. Each satellite develops the binary

code sequence of the C/A code, the P code, and the

Nav Data. Since these sequences are all 1’s and 0’s,

the satellite combines the Nav Data with the C/A code

and P code to form two data streams: one a

combination of the C/A code and the Nav Data, the

other a combination of the P code and the Nav Data.

These codes are actually transmitted on the carrier

frequencies. The ground receiver then extracts the Nav

Data from the broadcast C/A or P code, whichever it

was receiving. 

Ephemeris and Almanac Data

Each GPS satellite transmits almanac data once an

hour. The almanac data is the position and health

status of all satellites in the constellation. The

ephemeris is the position data for each individual

satellite. There are two types of ephemeris data to be

considered: broadcast and precise.

The broadcast ephemerides are actually predicted

satellite positions transmitted as part of the Nav Data.

Ephemerides can be acquired in real time by any

receiver capable of acquiring the C/A or P codes.

Broadcast ephemerides are computed by the master

control station using past tracking data provided from

the five tracking stations. The new orbital parameters

are then transmitted back to the satellites once every 24

hours for subsequent transmission to the user segment. 

Precise ephemerides are computed from actual

tracking data post-processed to obtain more accurate

satellite positions. Precise ephemerides are available

later and are more accurate than broadcast

ephemerides because they are based on actual tracking

data and not predicted data.

SECTION II. SYSTEM SAFEGUARDS, ERROR 

SOURCES, AND SURVIVABILITY

Selective Availability

When the concept of GPS was initially developed, it

was planned that the P code would be reserved for

military use, while the less accurate C/A code would be

authorized for use by anyone. During initial system

testing, it was discovered that while P code

measurements provided the expected 10-20 meter

accuracy the C/A code provided accuracy as high as 20

meters (much better than the expected 100 meters). The

DOD, expecting much lower accuracy, determined that

a method of introducing errors into the satellite signals

was needed to ensure that enemy forces would not be
Marine Artillery Survey Operations ________________________________________________________________________ 9-5

able to obtain high position and timing accuracy from

GPS. Selective availability (SA) was the outcome.

Methods 

The DOD uses SA to deny precise position and timing

accuracy to unauthorized users. SA uses two methods

to intentionally introduce errors into the signals

transmitted to the user segment.

The dither method alters or manipulates the satellite

clocks. This method intentionally introduces timing

errors, which ultimately produces position errors at the

receiver because of the importance of accurate time to

the computation of the pseudo-range.

The epsilon method alters the orbital parameters

(satellite position) that are broadcast in the Almanac

portion of the Nav Data. Position error is then created

because the receiver is positioned based on the

satellite location.

Accuracy Levels

The level of accuracy achieved by a GPS receiver now

depends on if the receiver is equipped with an

encryption device that allows the receiver to accept and

store crypto variables referred to as a key. This key

allows the receiver to decrypt SA correction data that is

transmitted in the Nav Data message. This key also

allows the receiver to use the encrypted P code. The two

accuracy levels are the precise positioning service (PPS)

and the standard positioning service (SPS).

The PPS is a precise positioning and timing service

that is reserved for the US and allied military, as well

as, specific authorized civilian users as long as their

receiver accepts the crypto key discussed above. The

technical specification is listed at 16 meters spherical

error probable (SEP).

The SPS is the less accurate positioning and timing

service offered to all GPS users. The DOD has stated

that this service will be accurate to 100 meters in

horizontal position and 150 meters vertical, under

normal conditions, 95% of the time. The DOD does

have the ability to increase the errors created by SA

based upon national security needs.

Antispoofing

Antispoofing (S) is a method used by the DOD to

prevent possible hostile imitations of the GPS signal.

Encrypting the P code creates the Y code, which can

only be processed by GPS receivers with a valid crypto

key. This encrypted code is very difficult to imitate. It is

important to understand that the P code and the Y code

are not two separate codes; one is the encrypted version

of the other. A GPS receiver without a valid crypto key

cannot process the Y Code and will be limited to

measurements from the C/A code. 

Cryptovariables

As stated before, cryptovariables are necessary for a

GPS receiver to access the Precise Positioning

Service, allowing the receiver to correct for errors

caused by SA and AS. It is unauthorized to use a

military GPS receiver without a valid crypto fill.

There are three types of key materials available for use

with a GPS receiver: operational, maintenance, and

simulator. There are three formats for key loading: the

KOI-18 General Purpose Tape Reader, the KYK-13

Electronic Transfer Device (capable of loading

multiple keys), and the AN/CYZ-10 Data Transfer

Device (DTD).

Operational Key Material 

Two operational cryptographic keys (group unique

variable [GUV] key and cryptovariable weekly [CVW]

key) are available for issue to a GPS user. Both keys can

be used by a receiver to obtain a daily cryptovariable

key (CVd). All operational keys are classified

CONFIDENTIAL and are marked CRYPTO.

The GUV key is an annual key. It is a key encryption

key (KEK) that decrypts previously encrypted daily

keys. A GPS receiver loaded with a GUV key takes

longer to begin processing navigational data than the

weekly key because it must first acquire and decrypt

the CVd key being broadcast by any GPS satellite.

This process could take as long as 12.5 minutes after

initial GPS signal acquisition. The GUV key is not a
9-6 ______________________________________________________________________________________________ MCWP 3-16.7

years worth of daily keys. It is merely the data needed

by the receiver to decrypt the broadcast daily key. 

The cryptovariable weekly (CVW) key is sometimes

referred to as the crypto key weekly (CKW). It is a key

production key (KPK) that automatically generates

daily keys within the user equipment. Obtaining the

daily key from a satellite downlink is not necessary for

receivers loaded with a CVW key. A user with a CVW

key starts processing navigational data in less time

than those with a GUV key. Because of this special

capability, distribution of the CVW key is limited to

those users who demonstrate a valid need for initial

GPS acquisition in a minimal amount of time.

The GUV key and the CVW key will produce the

same CVd key. Once the receiver determines the

current working CVd, processing navigational data

may commence and the effects of SA and AS can be

removed from the GPS signal and full navigational

accuracy is restored. A CVd cannot be entered directly

into the receiver, only a CVW or a GUV key can be

entered. The same CVd is used for both SA and AS. 

Maintenance Key Material

A maintenance key is available to users for

troubleshooting GPS user equipment. It does not allow

a user to gain access to the daily encryption key.

Maintenance keys are unclassified and may be reused

until they are unusable.

Simulator Key Material

A simulator key is available to users for testing

receivers. The simulator and the equipment must be

keyed with the simulator key. The simulator key does

not allow a user to gain access to the daily encryption

key. Simulator keys are unclassified and may be

reused until they are physically unusable.

User Equipment Security

Because of the security classification of the CVW and

GUV keys, GPS receivers designed specifically for

military uses are equipped with a special certified

security module that prevents the extraction of

cryptographic information from the receiver. These

receivers can then remain unclassified even when

loaded with a cryptographic key. If classified

information other than crypto is stored in the receiver,

the receiver becomes classified at the level of the

stored information. 

GPS Error Sources

There are many sources of measurement error that

influence GPS performance. The sum of all systematic

errors or biases contributing to the measurement error

is referred to as range bias.

The observed GPS range (the range from the satellite

to the receiver) without the removal of biases is called

a pseudo-range. Principal contributors to the final

range error that also contribute to overall GPS error

are ephemeris error, satellite clock and electronic

inaccuracies, tropospheric and ionospheric refraction,

atmospheric absorption, receiver noise, and multipath

effects. Other errors include those induced by the

DOD (SA and AS). GPS also contains random

observation errors, such as unexplainable and

unpredictable time variation. Due to their random

nature, these errors cannot be modeled and corrected.

The following paragraphs discuss these errors as they

associate with GPS positioning and navigation. Most

are eliminated or their effects significantly reduced

when GPS is used in a differential mode. (The same

errors are common to both receivers during

simultaneously observed sessions.)

Ephemeris Errors and Orbit Perturbations

Satellite ephemeris errors are errors in the prediction

of the satellite position that are transmitted to the user

in the Nav Data. Ephemeris errors are satellitedependent and very difficult to predict and

compensate. The many forces acting on the predicted

orbit of a satellite are difficult to measure directly. 

Clock Error

GPS relies heavily on accurate time measurements.

GPS satellites carry rubidium and cesium time

standards that are usually accurate to 1 part in 1012 and

1 part in 1013, respectively. Most receiver clocks are

actuated by a quartz time standard accurate to 1 part in

108. The difference between the satellite time and the

receiver time is called the time offset. The product of
Marine Artillery Survey Operations ________________________________________________________________________ 9-7

the time offset and the speed of light equal the possible

error due to clock bias as—

RE = TOxc

For example, if the time offset is 1 microsecond 

(10−6) then the RE = 10−6 × 299,792,458 = 299.8 meters.

Ionospheric Delays

GPS signals are electromagnetic signals that are

dispersed nonlinearly and refracted when transmitted

through a highly charged environment, such as the

ionosphere. Dispersion and refraction of the GPS

signal is referred to as an ionospheric range effect.

(The dispersion and refraction of the signal results in

an error in the GPS range value.) Ionospheric range

effects are frequency dependent. L1 and L2

frequencies are affected differently even though they

follow the same path through the ionosphere.

The error effect of ionospheric refraction on the GPS

range value depends on sunspot activity, time of day,

and satellite geometry. Periods of high sunspot activity

produce greater range errors than periods of low

sunspot activity because of the effects of the Sun’s

gravity on the ionosphere. Daylight GPS operations

will produce greater range errors than night

operations. GPS operations with satellites near the

horizon will have larger range errors than those with

satellites near the zenith. (The signal must pass

through a larger portion of the ionosphere when the

satellite is near the horizon.)

Resolution of ionospheric refraction can be

accomplished with the use of a dual frequency

receiver (L1/L2). During a period of uninterrupted

observation of the L1 and L2 signals, the signals can

be continuously counted and differenced. The

resultant difference reflects the variable effects of the

ionosphere delay on the GPS signal. Single frequency

receivers in the absolute and differential positioning

modes normally rely on an ionospheric model that

model the typical ionosphere. Use of these models can

remove a significant amount of the ionospheric delay. 

Tropospheric Delays

GPS signals are not dispersed by the troposphere but

they are refracted. Tropospheric conditions causing

this refraction can be modeled by measuring the dry

and wet components.

The dry component can be modeled easily through

measuring the surface pressure using the equation—

Dc = (2.27 × 0.001) × Po

Example: if the surface pressure is 765 millibars 

then the dry term range error is (2.27 × 0.001) 

× 765 = 1.73655 or 1.7 meters. 

The wet component cannot be so easily modeled. The

wet component is approximated by not only surface

conditions, but by atmospheric conditions along the

entire path of the GPS signal (water vapor content,

temperature, altitude, and the angle of the signal path

above the horizon). 

Multipath

Multipath is a positioning error caused by the signal

arriving at the receiver from more than one path.

Generally, this is due to the receiver being located near

a reflective surface such as a metal building or

structure. Newer antenna designs have some filtering

capabilities to reduce the effects of multipath.

However, proper mission planning and site

reconnaissance is the best way to reduce this type of

error. Averaging of GPS signals over a period can also

reduce multipath effects.

Receiver Noise

This error source includes a variety of errors

associated with the receiver’s ability to measure a

finite time difference. Errors include signal processing

and filtering, clock/signal synchronization and

when RE is the range error due to clock bias.

TO is the time offset.

C is the speed of light (299,792,458 m/s).

when Dc is the dry term range contribution in zenith

direction in meters. 

Po is the surface pressure in millibars.
9-8 ______________________________________________________________________________________________ MCWP 3-16.7

correlation methods, receiver resolution, signal noise,

and electronic interference. Most errors cannot be

modeled or accounted. 

User Equivalent Range Error

User equivalent range error (UERE) can be referred to as

the total budgeted error caused by the error sources listed

above. Many of these error sources can be reduced

through planning or using L1 or L2 antennas. Differential

techniques can even eliminate some of these error

sources. Figure 9-6 lists these errors and biases by

associating them with their source segment. Error values

in this figure do not include the effects of SA.

Absolute GPS Accuracy

Absolute positions are those that are established with

no reference or tie to any other station. They are

sometimes referred to as autonomous. For GPS

purposes, this is generally accomplished by use of

code-phase measurements to determine a pseudorange. The accuracy of these ranges depends largely

on the code (C/A or P(Y)) being used to determine

the position. This range accuracy (UERE) when

coupled with the geometrical relationships of the

satellites results in a 3-dimensional confidence

ellipsoid that depicts uncertainties in all three

coordinates. Since satellites are constantly moving,

the geometry constantly changes. GPS accuracy is

time/position-dependent.

Segment

Source

Error

Source

Absolute, 

C/A code

Pseudo-range, m

Absolute,

P(Y) code

Pseudo-range, m

Differential

 Positioning, m

P(Y) code

Space Clock Stability 3.0 3.0 Negligible

Orbit Perturbations 1.0 1.0 Negligible

Other 0.5 0.5 Negligible

Control Ephemeris 

Predictions

4.2 4.2 Negligible

Other 0.9 0.9 Negligible

User Ionosphere 3.5 2.3 Negligible

Troposphere 2.0 2.0 Negligible

Receiver Noise 1.5 1.5 1.5

Multipath 1.2 1.2 1.2

Other 0.5 0.5 0.5

I-0 UERE ±12.1 ±6.5 ±2.0

Figure 9-6. User Equivalent Range Error.
Marine Artillery Survey Operations ________________________________________________________________________ 9-9

Root-Mean-Square Error Measures

The two-dimensional (2-D) (horizontal) GPS position

accuracy is normally estimated using a root mean

square (RMS) radial error statistic called standard

deviation or sigma (σ). A 1-RMS (one sigma) error

equates to the radius of a circle in which the position

has a 63 percent probability of falling. A circle twice

this radius represents an approximate probability of 97

percent. This is a 2-σRMS or 2DRMS (2-deviations

RMS) and is the most commonly used accuracy

statistic in GPS survey. In some instances, a 3-σRMS

(3DRMS) depicts a circle three times the radius of the

1-σcircle. This circle has a 99.7 percent probability.

An RMS error statistic represents the radius of a circle

and is not listed with a ±. 

Figure 9-7 depicts RMS on an error ellipse at 2-σ.

This ellipse represents a normal distribution of GPS

position errors and is centered at the indicated position

of the receiver. The radii of an error ellipse are

expressed in standard deviation (sigma (σ)) of the

position distribution and usually provide a direction

such as Sigma North, Sigma East, and Sigma Up. Each

sigma is a probability estimate of how close the actual

position is to the displayed position as discussed. 

Probable Error Measures 

In 2-D horizontal positioning, a circular error probable

(CEP) statistic is most commonly used, especially in

military targeting. CEP refers to the radius of a circle

with a 50 percent probability of position confidence. A

measured or calculated position will fall inside a circle

of some radius at least 50 percent of the time. 

Three-dimensional (3-D) GPS accuracy is most

commonly expressed as a spherical error probable

(SEP). This value represents the radius of a sphere

with a 50 percent confidence level or probability. It is

important to understand that this sphere only

approximates an actual 3-D-error ellipsoid that

represents the uncertainties in the geocentric

coordinate system. 

Figure 9-7. Error Ellipse at 2-σ RMS. 
9-10 _____________________________________________________________________________________________ MCWP 3-16.7

Dilution of Precision

Dilution of precision (DOP) is a scalar quantity

representing the contribution or effect of the satellite

geometry to the GPS accuracy. It is the ratio of the

standard deviation of one coordinate to the

measurement accuracy. It could be said that DOP is

the measure of the strength of the satellite geometry.

In general, the more satellites that are observed and

used in the final solution, the better the solution. Since

DOP can be a measure of geometric strength, it can

also determine the satellites a receiver uses to

determine the most accurate position.

Satellite geometry and DOP can best be visualized by

the following analogy. A rubber ball is suspended

from five strings. All five strings are attached at the

other end to the ceiling within a couple of meters of

each other. Because of poor geometry of the strings’

attachment to the ceiling, the ball can be moved easily.

A large portion of the possible error in the position of

the ball is due to poor geometry or high DOP. On the

other hand, if the ball was still attached to the same

strings but four of the strings were attached to the

ceiling at the four corners of the room and the fifth

string attached directly above the ball, the ball would

not move so easily. This would be due to strong

geometry. The DOP would be small.

The main form of DOP used in measuring absolute

accuracy is the geometric DOP (GDOP). GDOP is the

measure of accuracy of 3-D position and time. GDOP

is related to actual range error by stating that the actual

range error equals the GDOP multiplied by the UERE.

Position dilution of precision (PDOP) is the measure

of the accuracy in 3-D position only. PDOP values

are generally developed from satellite ephemerides

prior to the conduct of survey operations. The

surveyor can more adequately plan sessions and

occupations for his equipment. 

PDOP represents the position recovery at a particular

instance in time and is not representative of the entire

session. PDOP error is generally given in units of

meters of error per 1-meter error in pseudo-range

measurement; i.e., m/m. If the pseudo-range

measurement due to clock errors, atmospheric

conditions, etc., is in error by 2 meters and the PDOP is

5.5, the possible position error due to satellite geometry

is 11 meters. When using pseudo-ranging techniques for

absolute positioning (code phase), PDOP values lower

than 5 m/m are considered very good; values greater

than 10 m/m are very poor. For static-type surveys, it is

desirable to make observations during periods of

rapidly changing PDOP.

When the values of PDOP and GDOP are observed

over time, high values (> 10 m/m) can be associated

with poor geometry. The higher the PDOP the poorer

the solution for that instant in time. Poor geometry can

be the result of satellites being in the same plane,

orbiting near each other or at similar elevations. 

Horizontal dilution of precision (HDOP) is a

measurement of the accuracy in 2-D horizontal position.

It is significant in evaluating surveys intended for

horizontal control. Basically, HDOP is the RMS

position error divided by the standard error in the range

measurements. It roughly indicates the effects of

satellite range geometry on a resultant position. HDOP

values lower than 3 indicate the best geometry. 

Vertical dilution of precision (VDOP) is a

measurement of the accuracy in standard deviation

(σ) in vertical height. Mathematically, it is the σu

(Sigma Up) divided by UERE (around 6 meters with

P(Y) code and 12 meters with C/A code). A VDOP

value lower than 3 indicates a strong vertical

component in the geometry. 

Time dilution of precision (TDOP) is the measurement of

the accuracy of the time determined by the GPS receiver.

GPS vulnerabilities are generally grouped by the

segment they threaten.

Space Segment

The height of the GPS satellites (10,898 miles) is

outside the range of current antisatellite weapons.

Such space weapons would be deployed at lower

altitudes where they could possibly be used against

more attractive space-based systems. The constellation

generally keeps the satellites approximately 44,000

kilometers apart in each orbital plane. The control

segment manages the system so that no two satellites

will orbit within 8,100 kilometers of each other. This

spatial separation ensures that a single nuclear burst in
Marine Artillery Survey Operations ______________________________________________________________________ 9-11

space at half the closest distance will have little effect,

forcing a more direct assault against individual

satellites. A ground-launched attack by antisattelites

would be detected early enough in the 3-hour flight

time to allow for maneuvering of satellites.

It is unlikely that current or projected technology

would allow a nation to launch a direct attack or even

detonate a nuclear device in the GPS orbit. A nuclear

detonation in space would equally affect other spacebased systems with a blackout or scintillation effect

lasting 10 minutes or longer in the L-band. Detonation

would disturb the atmosphere and the ionosphere with

subsequent effects on propagation. Radiation effects

could incapacitate the functioning of the erasable read

only memories (EROMS) and random access

memories (RAMS) of these systems if the blast is

close enough. GPS satellites have built-in protection

against the electromagnetic pulse (EMP) caused by

nuclear detonations and can restore their erased

memories through the control segment.

Two other factors exist that add an unplanned edge of

survivability against antisatellites. The Russian Global

Navigation Satellite System (GLONASS) orbits at an

altitude close to the GPS orbit. A nuclear assault

against GPS would have the same effect on

GLONASS. The increased use of GPS by former

Eastern Bloc nations including the former Soviet

Union is also an unplanned edge. 

Since the introduction of the Strategic Defense Initiative

(SDI), lasers have become a planned vulnerability to

orbiting satellites. Survivability of GPS against laser

technology is enhanced by limited laser hardening of

the satellites. A space-based laser at low altitudes would

be an extremely heavy device to launch. Tracking and

targeting of a GPS satellite is extremely difficult due to

its relatively small size and its orbital rate (14,500

kilometers per hour). Technology is available for a

high-power ground-based laser-to-target and has a

limited effect on GPS satellites.

Should there be a loss of any GPS satellite,

replenishment from the ground can be accomplished

within 2 months. The system can operate fully even

with the loss of 9 or more satellites, still providing 3-D

coverage for 12 hours and 2-D coverage for more than

20 hours. 

Control Segment

This segment is considered by many to be the most

vulnerable GPS segment. The master control station

(Colorado Springs) is very well protected by being

collocated with several military bases. The tracking

stations do not have this protection. All stations are

susceptible to espionage and natural disasters, but

tracking stations are much more vulnerable to nuclear

and conventional assaults. These factors have been

considered, and although the ability exists to exert

complete control over the satellites from the master

control station, the uplink to each satellite will be less

frequent than the current 8 hours. Next-generation

satellites are planned to provide a cross-link ranging

capability that will allow satellites to communicate with

each other, making offshore tracking stations redundant.

Jamming the control segment between the tracking

stations and the master control station is a real possibility. 

User Segment

Only two major vulnerabilities exist with the user

segment: cryptographic key security and

jamming. Several types of jamming can be used

against GPS receivers. 

Cryptographic Key Security

Should the enemy capture a GPS receiver with a valid

crypto fill, the PPS-security module prevents reverse

engineering so that the enemy cannot gain access to

the cryptographic data stored inside the receiver. Also,

the regular change of crypto keys adds to the security

and survivability of the system.

Spoofing 

Spoofing is classified as the enemy’s attempts to

duplicate or imitate GPS signals. Spoofing requires

that the enemy have a knowledge of the received

satellite phase and frequency at the targeted receiver

antenna. The proper carrier frequency and timing code

phase plus a sufficiently higher power output will

allow a deceptive jammer to establish a false lock with

the receiver. The enemy must know which satellites
9-12 _____________________________________________________________________________________________ MCWP 3-16.7

are being tracked and the position and velocity of the

receiver to create a false signal with the correct

Doppler shift. Once false lock is established, the

spoofer can perturb the duplicated navigation signals

to cause navigation errors.

When GPS antispoofing protection is enabled, spoofers

cannot autonomously generate the signals needed to

deceive the receiver that is looking for the encrypted P

code. This technique transforms the P code by

cryptographic means. The resultant bit stream is a

cypher text called the Y code that replaces the P code in

its entirety. Receivers with a valid crypto key will

encrypt their own generated P code to produce a Y code

inside the receiver needed for correlation with the

satellites transmitted Y code. The C/A code is totally

unaffected by the P code encryption. This is why the C/

A code is very susceptible to deception jamming. 

Continuous Wave Jamming

A continuous wave (CW) jammer (or spot jammer)

concentrates its jamming power in a very narrow band

around the L1 or L2 carrier. In the GPS receiver the

jamming power spreads out according to the receiver

processing gain using the modulated C/A or P code.

After spreading, only a small portion of the jamming

power enters the tracking loops of the receiver.

Consequently, a CW (spot) jammer needs to be very

powerful to effectively jam a GPS receiver.

Wide Band Jamming

A wide band jammer needs a sufficiently wide spectrum

to cover the frequency band of the GPS signals.

Usually, wide band jamming is performed in either a

sweeping mode or a quasi-random noise (barrage)

mode. In a sweeping mode the jammer carrier moves

rapidly and possibly randomly through the band to be

jammed. In barrage jamming the spectral power density

is low compared to spot jamming. 

Pulse and Amplitude Modulated Jamming 

A pulse jammer switches its power on and off during

an operation cycle. The modulation rate can be chosen

as needed (pulse repetition frequency and pulse

duration). An amplitude modulated jammer varies its

power linearly; modulation depth and frequency can

be chosen as needed. Besides jamming effects already

described, this type of jamming could have a negative

impact on the GPS receiver by disturbing the internal

operating cycles of the receiver processor unit or the

electronics of the antenna.

Jamming Effects on Code Acquisition 

The GPS user is at a severe disadvantage when having

to use C/A code acquisition in a hostile region. Current

technology receivers have a limited tolerance to

jamming during C/A code acquisition (usually around

25 decibels). Although only 1,023 chips must be

searched in the C/A code, a large frequency window

must be searched to account for satellite and receiver

Doppler shift. The receiver must maintain a large

predetection bandwidth to acquire the C/A code at the

expense of reduced jamming tolerance (J/S). The C/A

code is widely disseminated. A smart jammer can

broadcast a false signal and lock up the receiver with

very low power. Tests indicate that a very modest 1-

watt noise jammer prevents a receiver from acquiring

the GPS signal using the C/A code out to 85

kilometers. If the jammer were to transmit a spoofing

signal, the receiver would not be able to discriminate

between the desired GPS signal and the spoofing

signal. The receiver’s jamming tolerance would be on

the order of 0 decibels, a 1-watt spoofer could deny C/

A code acquisition past 1,000 kilometers or to the

jammer’s horizon.

The P(Y) code is virtually impossible for an adversary

to spoof because of its long length and the encryption

of the P code into the Y code. Also, the P(Y) code has

10 decibel more antijam protection than the C/A code

because of its 10 times larger bandwidth. Some current

technology receivers using direct P(Y) code

acquisition (hot start) can tolerate a J/S level in excess

of 35 decibels. However, because the P(Y) code is so

long, (6 × 1012 chips) much time or more correlators

operating in parallel are needed for the twodimensional search over code timing and Doppler

frequency. Thus, up to date satellite ephemerides and

accurate code timing must be available to effectively

perform a hot start.

Reacquisition typically has very accurate initial code

timing. If this accuracy is available during direct P(Y)

code acquisition, the reacquisition problem is the same

as the acquisition problem with increased J/S tolerance

(in excess of 50 decibels depending on the receiver). 
Marine Artillery Survey Operations ______________________________________________________________________ 9-13

Antijam Capabilities of GPS 

GPS vulnerability to jamming can never be completely

eliminated. With constantly improving techniques and

technology, higher power outputs by the enemy

jammers is required to deny access to GPS signals. 

The GPS satellites broadcast in the ultra-high

frequency (UHF) domain. UHF signals cannot “go

around” obstacles such as buildings, hilltops, large

rocks, etc. the way low domain frequencies can. For

this reason, ground based jammers are restricted by

severe line-of-sight limitations. Air or space-borne

jammers, obviously, are not so restricted. A smart user

will position his GPS receiver to limit the effects of a

line-of-sight jammer. Defilade areas that still allow

open skies for satellite signals can be used. Handheld

receivers can be placed in a “cat hole” or the user can

simply turn his back to the suspected direction of the

jammer. Once the receiver has a lock on the P(Y)

code, the user should be able to operate normally in

most jamming environments.

The satellite signal is a continuous wave type signal. This

signal is spread by modulation and enters the receiver

with the jamming signal. The original signal is recovered

as the jammer energy is spread over the modulation and

most of the jammer power is filtered out.

To locate, track, and demodulate a satellite signal, the

receiver requires a certain minimum ratio between

received signal power and the noise power. This value

(or threshold) is referred to as the signal-to-noise ratio

(SNR). The noise power is dissipated over a wide

bandwidth, while the satellite signal power is

concentrated in a very narrow frequency band. Using

filters, the GPS receiver narrows its bandwidth to the

absolute minimum in order to receive the maximum

signal power and minimum noise. A receiver can

usually recognize the jammer power as noise;

therefore, much of its effects are filtered out.

Depending n the power output of the jammer, the SNR

may be too high for the receiver to filter out enough

noise to determine data.

Many other antijam capabilities exist for GPS. Among

them is the inertial navigation system (INS)

integration with GPS and high cost antennas. Both are

used in military applications but generally with

missile, rocket, and aircraft navigation technologies.

For the most part, antijam capabilities for Marine

ground units will be enhanced by proper planning and

positioning of GPS assets.

The surveyor must be aware of the ambient conditions

of the GPS satellites and their surrounding

environment. Solar flares, occurring in 11-year cycles,

send great fountains of electromagnetic energy and

radiation deep into space, causing interferences in

GPS signals. Meteor showers, such as the Lenoid

event, occur close to the Earth, and could potentially

damage satellites in the GPS constellation. GPS

satellites are hardened against such possibilities, but

are not invulnerable.

SECTION III. GPS MEASUREMENTS

GPS Reference System 

The GPS satellites reference their own position to the

WGS 84 coordinate system. This system is based on the

WGS 84 ellipsoid. To fix the Earth in time and space for

the development of the WGS 84 ellipsoid, the

Conventional Terrestrial Pole of 1984 (CTP 84) was

chosen. The position of the Earth’s polar axis at 1984.0

as defined by the Bureau International De l’Heure

(BIH) is used to define the z-axis of the WGS 84

cartesian coordinate system. The x- and y-axes are then

referenced to that z-axis. All positions determined by

GPS are originally in this format, WGS 84 cartesian.

Receivers and software applications for GPS have the

capability to provide positions in other coordinate

systems and other datum/ellipsoid references.

Code Phase Measurements

The primary purpose of code phase measurements is to

determine approximate ranges from satellites to the
9-14 _____________________________________________________________________________________________ MCWP 3-16.7

GPS receiver that allow the receiver to determine its

position. Since this position is not referenced or relative

to any other position or receiver, it is referred to as an

absolute position. Clock biases, atmospheric absorption

and refraction, and other inherent errors make

determination of a true range virtually impossible. The

actual range determined by the GPS receiver is referred

to as a pseudo-range. See figure 9-8.

Pseudo-random Noise Code 

The Pseudo-random noise (PRN) code is a binary data

string of digital ones and zeros that is unique to the

satellite broadcasting it. This code is used by the

receiver to identify the satellite it is tracking. This

code is repeated every millisecond (C/A) and every

week (P/Y). See figure 9-9. 

Time Delay 

Before the receiver can compute the pseudo-range to

the satellite, it must determine the time required for the

signal to travel from the satellite to the antenna. The

receiver stores a replica of each satellite’s PRN code.

When the receiver detects a satellite signal, it

identifies the satellite by its PRN that has been

replicated from memory. The code received from the

satellite is then compared to the replicated code. The

receiver slides the replicated code in time until it lines

up with the satellite’s transmitted code. The amount of

time that was needed to slide the code is the time delay

of the transmission or travel time. See figure 9-10.

Figure 9-8. Pseudo-range.

Figure 9-9. Carrier Modulated by PRN.

Figure 9-10. Time Delay of a GPS Signal.
Marine Artillery Survey Operations ______________________________________________________________________ 9-15

Satellite Ranging 

The only measurement made by a code-phase receiver

is the time delay or transmission time. Radio waves

travel at the speed of light. This constant value is

stored in the memory of the GPS receivers. A

receiver capable of making code-phase measurements

will compute the pseudo-range using the formula

pseudo-range = Δt × speed of light.

This procedure can be simultaneously performed on

many satellites. The number of satellites depends on

the receiver used, or more specifically, how many

channels are available in the receiver.

Once a satellite is tracked and the receiver determines

a pseudo-range, the receiver basically knows it is

located on a sphere whose radius equals the pseudorange with the satellite at the center of the sphere. See

figure 9-11. 

When the second satellite is acquired, the same

ranging technique is used creating a second sphere.

The intersection of the two spheres is a circle. The

receiver is located somewhere along the edge of that

circle. See figure 9-12. 

The third sphere determined by ranging a third

satellite would intersect the circle created above at two

points. The receiver knows that its position is

referenced to the WGS 84 ellipsoid/datum. Only one

of the two points of intersection will be located on this

geodetic system. The other point will be out in space,

deep inside of the ellipsoid or moving at an extreme

velocity. With three satellites, a receiver can provide a

2-D position. To achieve a 3-D position, at least four

satellites must be ranged. The fourth satellite provides

the timing data for the receiver to resolve timing errors

in the system. See figure 9-13. 

Carrier Phase Measurements

The primary purpose of carrier phase measurements is

to determine ranges from satellites to receivers that

will allow the receiver to position it. Usually these

Figure 9-11. Ranging One Satellite.

Figure 9-12. Ranging Two Satellites.

Figure 9-13. Ranging Three Satellites.
9-16 _____________________________________________________________________________________________ MCWP 3-16.7

positions are processed relative to another receiver

position and are referred to as differential positions.

Ranges to the satellites are pseudo-ranges, as in code

phase. However, this method of ranging requires the

solution of the integer ambiguity of the signal. The

determination of this distance requires that the number

of whole carrier wavelengths be known.

Integer Ambiguity 

The whole number of wavelengths between the

satellite and the receiver is known as integer

ambiguity or cycle ambiguity. Since we know the L1

carrier wavelength is 19 centimeters long and L2 is 24

centimeters long, and since most carrier phase

receivers can determine the partial wavelength to an

accuracy around 2 mm; the pseudo-range can be

accurately measured as long as we can determine the

number of complete wavelengths between the satellite

and receiver. This is done by comparing changes in the

received frequency (caused by the Doppler effect) to

the broadcast frequency over time.

Carrier (Beat) Phase 

Carrier phase GPS receivers contain an internal

oscillator that generates a carrier signal. This

generated carrier signal is compared to the received

signal from the satellite. The carrier phase

observations (also called carrier beat phase) are

determined from these measurements.

Continuous Carrier Phase 

When the receiver first locks on to a satellite signal, it

can only measure the fractional part of the wavelength.

It has no knowledge of the number of full wavelengths

at that specific point in time between it and the

satellite. After that first measurement, the receiver will

count the number of whole wavelengths it observes.

This is the continuous carrier phase.

If the satellite signal is interrupted (see next para), the

continuous carrier phase is reset. It is set to the next

fractional wave measurement (carrier phase

observable) immediately following the break.

Cycle Slips

A cycle slip is the interruption or break in the

continuous carrier wave. 

The wave fronts that are counted by the receiver

during continuous phase tracking are called cycles.

When the signal is interrupted, the continuous count of

those wave fronts or cycles is broken, or the count

slips. This cycle slip causes the continuous carrier

phase to be reset. The baseline processor in most GPSS systems can reestablish this count whether in a static

or a kinematic mode. 

Cycle slips can be caused by any number of barriers

between the satellite and the receiver. These barriers

can include terrain masks, trees, or even an operator

standing between the satellite and the antenna. Cycle

slips could cause burst jamming signals. Usually

reconnaissance, LOS clearing, and planning can

eliminate many sources of cycle slips. 

Differencing

Differencing is a method used by the processors to

solve for the first estimation of a baseline solution and

remove measurement errors.

Single Differences

A single difference can be formed by differencing the

measurements acquired by two receivers observing

the same satellite at a particular point in time or

epoch. Therefore, integer ambiguities associated with

each receiver are combined. Single differences

between receivers virtually remove all satellitedependent errors such as satellite clock error, and to a

large extent, orbit errors and atmospheric delays. See

figure 9-14.

A single difference can be formed by differencing the

measurements acquired by one receiver observing two

satellites at a particular point in time or epoch. Single

differences between satellites reduce most receiver

dependent errors. See figure 9-15.
Marine Artillery Survey Operations ______________________________________________________________________ 9-17

Double Differences between Satellites 

and Receivers

A double difference is formed by differencing two

single differences. This involves two receivers

observing the same two satellites at the same epoch.

Four separate measurements and four separate integer

ambiguities are combined to create a difference. The

double differencing mode removes most of the effects

of satellite and receiver clock drift. See figure 9-16.

Triple Differences between Satellites, 

Receivers, and Time

A triple difference is determined by combining two

double differences over time. The double difference

determined by a set of satellites and receivers at a

particular epoch is combined with the double

difference form the same satellites and receivers at a

different epoch. In this mode, integer ambiguities

cancel out of the computations because it does not

change over time. 

Triple differences are often used to find cycle slips. A

cycle slip, in the single differencing mode, causes the

receiver to recompute the combined integer; therefore

after a cycle slip, the integer ambiguity does change. A

large change in the triple difference is a good indicator

of a cycle slip at that epoch. See figure 9-17.

Figure 9-14. Single Differences

between Receivers.

Figure 9-15. Single Differences 

between Satellites.

Figure 9-16. Double Differencing.

Figure 9-17. Triple Differencing.
9-18 _____________________________________________________________________________________________ MCWP 3-16.7

Baseline Solutions (Vectors)

A baseline solution (vector) is a straight line defined

by its 3-D (ΔΧ, ΔΥ, ΔΖ) values when one end of the

vector is the origin and the other end is the point

containing those relative values. The processor uses

the differencing methods described above along with

code solutions to determine an initial estimate of the

baseline vector. This initial estimate is called the triple

difference solution. 

If the integer ambiguity is known, multiply that value

by the wavelength (19 centimeters − L1, 24 centimeters

− L2) and add the partial wavelength to obtain the

pseudo-range. At this point in the processing, the

integer ambiguity is still an unknown value. 

Float Solution 

Once an initial estimate of the baseline vector has been

determined, place that value in the formula—

ΔΧ, ΔΥ, ΔΖ = (N × λ) + Δφ

Often in processing, the value for N as determined in

the above formula is not an integer. The ambiguity

computes to a value such as 500.52. This value is not

close enough to a whole integer for the processor to

determine if the ambiguity is 500 or 501. It cannot set

the value to a whole integer. 

The value determined is compared against the

remaining observations to see how well it fits. If the

residuals (errors) are within a certain tolerance, the

processor generates a new baseline vector; i.e., the

float solution. 

Fixed Solution

A fixed solution is obtained when the processor

determines a set of integer values for the ambiguity

that is significantly better than the other values. 

The processor rounds the ambiguity value determined

above to whole numbers for each satellite, each time

testing different combinations of whole wavelength

values to compute a baseline.

Each time a new set of integers is used, an associated

variance (square of the standard deviation) is

generated. After all possible combinations of whole

wavelengths have been tried, the processor selects the

solution with the lowest variance (least error). This is

the fixed solution or fixed-integer solution.

The ratio of the errors between the integers used for

the last iteration (the last computation of whole integer

values) can be determined as—

With a single frequency receiver, this is the best

solution that can be determined. It is sometimes

referred to as a double-difference fixed solution. 

With a dual-frequency receiver, it is possible to

combine carrier phase observables to create other

fixed solutions. A wide lane carrier phase is generated

when the processor differences the carrier phase

observables (L1 − L2). The effective wavelength is

86.2 centimeters. This combination allows for easier

resolution of the integer ambiguities so it is often used

to solve long baselines. The narrowlane carrier phase

is generated when the processor combines the carrier

phase observables (L1 + L2). The effective

wavelength of the narrow lane carrier phase is 10.7

centimeters. This combination is very effective for

canceling out ionospheric errors. This baseline

solution uses a combination of the L1 and L2 carrier

phases to model and remove the effects of ionospheric

interference on the signals. This is the optimal

solution, used for high-order control networks and for

observing long baselines.

Whereas: ΔΧ, ΔΥ, ΔΖ is the baseline vector,

N is the integer ambiguity,

λ is the integer wavelength,

Δφ is the phase change observed in a

small portion of the data. 

Ratio = (integers giving next least) Errors

(integers giving least) Errors
Marine Artillery Survey Operations ______________________________________________________________________ 9-19

SECTION IV. GPS SURVEY METHODS 

AND TECHNIQUES

Absolute Positioning 

Absolute positioning is a GPS survey method that

involves using a single passive receiver; e.g., AN/

PSN-11 PLGR, AN/PSN-13 MSGR 4000. The term

absolute does not refer to a specific accuracy. It means

this method does not rely on any source of information

other than what is collected by the receiver at that

station. This position is not relative (common) to any

other station. The accuracy of this position depends on

many different error sources as well as the user’s level

of authorization (PPS or SPS). 

The receiver collects data from multiple satellites and

uses this data to determine position, velocity, and

timing information. The position is generally

determined from code phase measurements. Some

receivers can use carrier phase measurements to

determine absolute positions. 

Differential (Relative) Positioning

Differential positioning requires at least two receivers

collect data from at least four common satellites

simultaneously to compute a vector between them.

The vector is then fixed at one end to a point and the

other end is the relative position. 

Usually, one receiver is located at a known point.

Depending on the differential technique used, more

than four common satellites may be necessary.

Processing the collected data can be performed in the

office or by the receiver in the field, also depending on

the differential technique used.

Much of the accuracy achieved from this method is

due to the use of common satellites and common

epochs (a specific point of time selected for a GPS

measurement). Figure 9-16 shows that differential

techniques negate most sources of error. This is

because the same error exists at each station collecting

data from a specific satellite at a specific epoch. The

errors broadcast by satellite PRN23 and collected by

receiver A at epoch 1 are the same errors collected by

receiver B at epoch 1. The errors broadcast from the

satellites have no effect on the dimensions of the

vector because the errors are equal at each end.

This is actually only true for errors sources in the

Space and Control segments. User segment error

sources are not always equal at each end of the vector.

For distances under 25-30 kilometers, the tropospheric

and ionospheric errors are basically the same. Signals

from satellite PRN23 to receiver A travel through the

same sampling of the atmosphere as the signals from

PRN23 to receiver B. Larger distances may add some

small errors into these measurements. An L1/L2

antenna will decrease this error. 

Code Phase Differential Positioning

Determining differential positions from code phase

measurements is performed by applying a correction

to the pseudo-range determined from an individual

satellite to the receiver. 

This process begins with the pseudo-ranges from code

phase measurements used to determine the absolute

positions of the receivers. Since the errors collected at

each receiver are the same for each epoch, a pseudorange correction (PRC) can be computed. In other

words, assume we know the exact position of a

satellite at a specific epoch and the surveyed position

of a GPS receiver, we can determine a true range. If

the measured pseudo-range is 79 meters and the true

range is 81 meters, the PRC is +2 meters. A pseudorange correction can be generated for each satellite

being observed. Any receiver that is simultaneously

collecting data from at least four common satellites

can apply the PRC to its pseudo-range measurements

to obtain a relative (common) position; thus the

distance between the two points will be relatively

accurate (0.5-10 meters) even when the absolute

positions are not. 

Code phase differential positioning has its primary

applications in real-time navigation where relative

accuracy is as low as 10 meters are acceptable. Also,
9-20 _____________________________________________________________________________________________ MCWP 3-16.7

some engineering survey applications can tolerate this

accuracy. This would not be acceptable for geodetic

applications, and does not meet artillery specifications.

Carrier Phase Differential Positioning 

Determining differential positions from carrier

measurement is as simple as fixing an end of a

measured vector to determine the position of the other

end. Through processing, other vectors can then be

fixed to the end of the first vector to create a network.

Kinematic and static surveys are both usually

performed using carrier phase differential positioning.

Static and Kinematic Techniques 

When GPS receivers are used for surveying purposes,

it is generally accepted that the survey will be

performed using carrier phase differential (relative)

survey methods. Differential survey is usually divided

into two techniques: static and kinematic. 

Static surveys provide the most accurate results.

Receivers must remain stationary (static) for a period of

time depending on the type of static survey performed.

There are two types of static survey: static and fast

static. Both require extensive planning and postprocessing. Static survey allows for extremely accurate

networking of survey control. Due to planning, field

work, and post-processing requirements, this technique

should only be used by surveyors whose mission is to

provide fourth order control.

Kinematic surveys provide accuracy results sufficient

for most artillery survey missions (fourth and fifth

order) but does not provide the same networking

capabilities as static techniques. There are two types of

kinematic surveys: stop-and-go and continuous. Stopand-go surveys can be post-processed in the office

computers or in the field by the receivers using RTK

and RTK/OTF procedures. Kinematic survey

techniques require that one receiver remains static

while another acts as a rover, moving along a route or

from station to station collecting data. 
 CHAPTER 10. HASTY SURVEY

If no known control exists, control may be assumed

through the best available resources. Assuming control

allows all units to start their mission immediately

without waiting for survey teams to provide control.

Once higher echelon control is available, conversion

to common control procedures must be performed by

all lower echelon units. 

Hasty Position Determination Method

MSGR 4000 (AN/PSN-13) Absolute 

An absolute position from the GPS-S MSGR 4000 is

one source of assumed control. This will provide a

sufficient position (10 meter CEP) and elevation. An

azimuth must be determined by another means. Never

use an azimuth computed between two absolute

stations, even for assumed control. 

PLGR (AN/PSN-11)

If no MSGR 4000 absolute points are available, the

PLGR is the next best source of assumed control.

Using the PLGR in the averaging mode will provide a

sufficient absolute position (10 meter CEP) and

elevation. An azimuth must be determined by another

means. Never use an azimuth computed between two

PLGR stations, even for assumed control.

Accuracy of positions determined by GPS absolute

survey depends mostly on the amount of averaging

time allowed. When properly set up and operated, the

PLGR can provide data accurate to 10 meters CEP

(averaging mode, FOM 1, 1 day-old almanac, and 300

averages obtained). These values assume the presence

of a valid daily crypto key and correct datum selection.

Map Spot 

A careful map inspection may determine assumed

control. If possible, determine the azimuth from a

source other than a map. All positions determined by

these hasty methods must be verified by a map spot to

reduce the incidence of blunders

Map spot position accuracy depends on the scale of

the map sheet and the abilities of the surveyor. In

practice, a map spot position can be considered

accurate to approximately 100 meters on a 1:50,000

scale map. 

Hasty Azimuth Determination Method

Methods of assuming an azimuth are—

l Hasty astro. 

l Simultaneous observation.

l Declinated aiming circle. 

l Directional traverse. 

l Scaled from a map. 

l Compass; e.g., M2 or lensatic.

For any method above, the considered accuracy is ±2

mils when determined with an M2A2 aiming circle.

Azimuth accuracy of a directional traverse using an

aiming circle is determined by multiplying the number

of horizontal angles measured by 0.5 mils. 

An azimuth determined by a declinated aiming circle

(declination performed at a surveyed declination

station) is considered accurate to ±10 mils, not

counting the effects of local magnetic attraction. If the

declination was made from a map G-M angle, the

accuracy is diminished by the age of the map’s

declination diagram information.

Azimuth accuracy determined by a compass (M2 or

lensatic) depends on the accuracy of the type of grid to

magnetic conversion used and local magnetic

attraction (generally 10 to 20 mils).

Azimuth accuracy determined by scaling from a map

depends on the accuracy of the plotted positions, map

scale, and whether or not the map is generated from a

conformal projection (in practice, 10 to 100 mils). 
10-2 _____________________________________________________________________________________________ MCWP 3-16.7

All azimuths determined by these hasty methods must

be verified by a map spot to reduce the incidence of

blunders. The preferred hasty method of determining

azimuth is the one that provides the most accuracy for

that particular situation.

Hasty Elevation Determination Method

A hasty elevation can be determined by absolute GPS

methods, altimetric observations or by map spot.

Elevation is the weakest component of a GPS

absolute position. When a GPS elevation is

determined, that elevation must be verified by map

spot. A properly operated GPS can provide

elevations accurate to ±10 meters.

Altimetric elevation accuracy depends largely on the

quality of the barometer in the altimeter. All altimetric

elevations must be verified by map spot. Contour lines

on a NIMA topographic map (1:50,000 scale) are

considered accurate to 1/2 contour interval 90 percent of

the time. In other words, a map spot elevation should

never be considered more accurate than 1 contour

interval for that map sheet.

The M2A2 Aiming Circle

The M2A2 aiming circle is a small, lightweight

instrument used in firing battery and artillery survey

operations. In the firing battery, it is the instrument

used for orienting (laying) howitzers and for

performing hasty survey operations. In the artillery

survey section, it is used primarily for target area

surveys (intersection), checking surveyed azimuths,

and for hasty survey operations. See figure 10-1.

Figure 10-1. Aiming Circle M2A2.
Marine Artillery Survey Operations ______________________________________________________________________ 10-3

The M2A2 consists of a four-power, fixed-focus, 10°

field of view telescope mounted on a body that permits

unlimited (6400 mils) horizontal angle measurements

and vertical angle measurements from −400 mils to

+1100 mils. The M2A2 weighs approximately 9 pounds.

With its associated equipment, it weighs 21 pounds. 

The rest of this chapter discusses the M2A2.

M2A2 Body

Telescope Assembly 

The telescope assembly consists of the optical system,

the vertical level vial, the reflector, the eyeshield, and

the solar filter.

A four-power, fixed-focus telescope forms the optical

system of the aiming circle. The telescope reticle is

formed by a glass etched with a horizontal and vertical

crosshair intersecting at the center of the field of view.

Crosshairs are graduated every 5 mils from 0 to 85

from the center of the reticle. Graduations are

numbered every 10 mils. 

The Polaris 2 reticle is installed in most aiming circles.

This includes the reticle pattern described above as

well as three concentric circles used for aligning stars

for the Polaris 2 method of astronomic observations.

This method is no longer valid so the Polaris 2 portion

of the reticle is not used. The telescope body is

inclined 45° to allow the observer to stand erect and

look down into the telescope.

The telescope level vial is located on the left side of the

telescope. It establishes a horizontal plane along the

telescope’s line of sight. It is not used in artillery survey.

The reflector is a plastic signal post mounted on top of

the telescope at the vertical axis of the instrument. The

reflector is used as an aiming point for other

instruments sighting on the aiming circle. It can be

illuminated using the aiming circle’s illumination kit.

The eye shield is a rubber shield that blocks light from

entering your eyes from the side.

The solar filter mounts over the eyepiece end of the

telescope when used for observations on the Sun.

When not in use, store it on the filter post on the right

side of the telescope above the serial number plate.

Body Assembly 

The body assembly consists of the azimuth

(horizontal) and elevation (vertical) worm

mechanisms, the magnetic compass, the magnetic

compass locking lever, and two horizontal plate levels.

The azimuth mechanism is generally referred to as

recording motion or upper motion. Lateral movement

of the azimuth micrometer knob allows for fast motion

over the azimuth scale. Rotating the azimuth knob

allows for slow motion. Two scales read a horizontal

angle: the azimuth scale and the micrometer scale. The

azimuth scale reads hundreds of mils. It is graduated in

100 mil intervals and numbered every 200 mils from

0-6400. The micrometer scale reads tens, ones, and

half mils. It is graduated every whole mil and

numbered every 10 mils through a 100 mil circle. The

scale can be interpolated to 0.5 mils.

The elevation mechanism is generally referred to as

the vertical motion. Rotating the elevation

micrometer knob raises and lowers the telescope

through its 1500 mil arc. Stop rings in the mechanism

prevent the telescope from striking the body

assembly when the telescope is depressed. Two

scales are used to read a vertical angle: the elevation

scale and the micrometer scale. The elevation scale

reads hundreds of mils. It is graduated in 100 mil

intervals and numbered every 100 mils from −400 to

+1100 mils. Negative graduations are labeled in red,

positive in black. The micrometer scale reads tens,

ones, and half mils. It is graduated every whole mil

and numbered every 10 mils through a 100 mil circle.

Red numbers designate negative values, black

numbers designate positive values. The scale can be

interpolated to 0.5 mils. 

The magnetic compass is located in the oblong recess

in the top of the body assembly. The magnetic needle

is limited in movement to approximately 11° arc and is

provided with copper dampers to aid in settling the

needle quickly. Two viewing windows are available to

center the needle. The large window on the top of the

body assembly is used for rough centering of the
10-4 _____________________________________________________________________________________________ MCWP 3-16.7

needle. The second window is comprised of a small

glass magnifier and a reticle with three etched lines at

one end of the recess to aid in aligning the south end of

the needle.

On the opposite end of the recess is the magnetic

compass locking lever. When pointing down, the

needle is locked in place; when rotated left or right, the

needle is unlocked. The needle must always remain

locked except when it is being used to prevent damage

to the magnetic compass.

At the left side of the magnetic compass, are two

horizontal plate levels: a circular level for rough

leveling and a tube level fine leveling.

Worm Housing 

The worm housing is the portion of the aiming circle

between the horizontal azimuth scale and the base

plate. It contains the worm gearing for the orienting

motion and the leveling screws. 

The orienting motion is generally referred to as the

lower or nonrecording motion. Nonrecording motion

is similar to the recording motion in that lateral

movement of the orienting knob allows for fast

motion. Rotating the knobs allows for slow motion.

Nonrecording motion rotates the aiming circle around

a vertical axis without changing values on the

horizontal scales. Caps are provided to cover the

orienting knobs when they are not being used. Each of

the leveling screws are fitted into a threaded socket in

the worm housing and attached to the base plate by

means of a spring plate.

Base Plate Assembly 

This assembly is the base of the instrument when it is

mounted on a tripod. It also serves as the base of the

carrying case. The instrument is attached to the base

plate by means of the spring plate. The top of the

base plate contains a rectangular notation pad for

recording the declination constant and vertical angle

correction. The bottom of the base plate assembly

has a spring-loaded cap that covers a 5/8-inch

threaded hole. This hole allows the instrument to be

mounted on any tripod with a 5/8-inch fixing screw;

i.e., GST-20 or M24. The base plate is fitted with a

rubber gasket that creates a watertight seal when the

cover is properly attached.

Associated Equipment

Associated equipment includes the M24 tripod, the

carrying case cover, and the accessory kit. 

The M24 tripod has telescoping legs, an aluminum head

and cover, and a carrying strap. Legs are adjusted for

height and held in place by clamping screws. Hinges at

the tripod head are adjusted for friction by clamping

screws. The carrying strap holds the legs together in the

retracted position and carries the tripod. The head cover

is affixed to the tripod by a canvas strap.

The carrying case cover is a lightweight, domeshaped, aluminum cover that clamps to the base plate

assembly, creating a watertight seal.

The accessory kit consists of the backplate and cover,

the instrument light, the plumb bob, and two lamp

extractors. See figure 10-2. The backplate and canvas

cover serve as the carrying case for the instrument

light, plumb bob, and extractors. The backplate and

cover attach to two clamps on one of the tripod legs.

The instrument light provides artificial illumination to

the instrument and the operator. It consists of a battery

Figure 10-2. M2A2 Accessory Kit.
Marine Artillery Survey Operations ______________________________________________________________________ 10-5

tube (two D cell), a rheostat knob, and two flexible

cords. The rheostat knob adjusts light intensity. One of

the cords provides illumination to the instrument

through a lamp bracket that attaches to the machined

slot on the top of the telescope assembly. The other

cord is a penlight for the operator and recorder.

The plumb bob suspends from a hook attached to the

fixing screw. It is rolled and stored in a loop in the

canvas cover when not in use. The accessory kit

contains two lamp extractors. They store extra lamps

and remove bad bulbs from their sockets.

Setting Up The Tripod

The M24 tripod is the primary tripod used with M2A2

aiming circle. However, the instrument will mount on

any tripod with a 5/8-inch fixing screw.

Upend the tripod, place the tripod head on the toe of

your boot, and unbuckle the restraining strap. Loosen

the leg clamp thumbscrews and extend the tripod legs

to the desired length. Tighten the leg clamp

thumbscrews sufficiently to maintain the weight of an

instrument. Do not force the thumbscrews.

Spread the legs and place the tripod over the occupied

station with one leg bisecting the angle to be

measured. Set up the tripod head so that the telescope

will be at a convenient height for the operator. Rough

level the tripod.

Place the plumb bob loop over the hook at the fixing

screw. The plumb bob should hang about 1 inch above

the station. Center the tripod over the station to within

approximately 1 inch of plumb.

Firmly embed the tripod legs in the ground. The plumb

bob should now be within a 1/2 inch laterally of center

of the station. The tripod head must approximate level

once the legs are embedded in the ground.

Remove the tripod head cover. Leave the cover hang

on the side of the tripod and lightly wipe your hand

over the tripod head to remove any sand or dirt.

Attach the Aiming Circle to the Tripod 

With the cover still on the instrument, open the spring

loaded cover on the bottom of the base plate and

thread the fixing screw into the socket until the aiming

circle is firmly attached to the tripod. Unsnap the

cover latches and remove the cover. Hang the cover on

the leg clamp of the forward tripod leg. 

Plumb and Level the Aiming Circle 

Keeping one hand on the instrument, loosen the tripod

fixing screw. Carefully slide the instrument over the

tripod head until the plumb bob is centered exactly

over the point.

Tighten the tripod fixing screw. Do not overtighten the

fixing screw as this will bend the slotted arm and

damage the tripod head. 

Loosen the leveling screws to expose approximately

1/2 inch of threads. Rotate the instrument so that the

level vial aligns with any two leveling screws. Grasp

the leveling screw knobs between the thumb and

forefinger of each hand. Turn the knobs

simultaneously so the thumbs of both hands move

toward each other or away from each other. (This

movement tightens one screw as it loosens the other.)

The bubble always moves in the same direction as

the left thumb. Center the bubble by using these two

leveling screw knobs. This is the first position. 

Rotate the instrument clockwise 1600 mils. This

second position places the axis of the tubular level at a

right angle to the first position. Using the third

leveling screw knob only, center the bubble.

Rotate the instrument clockwise 1600 mils so that it is

3200 mils from the first position. Level the instrument

using the same two leveling screws as were used in the

first position. This is the third position.

Rotate the instrument clockwise 1600 mils so that it is

3200 mils from the second position. Level the instrument

using the same single leveling screw that was used in the

second position, this is the fourth position. 

Repeat the above steps until the bubble remains

centered in both positions.
10-6 _____________________________________________________________________________________________ MCWP 3-16.7

Rotate the instrument to the first position. If the bubble

remains centered in this position, rotate the alidade to

the second position. If the bubble remains centered in

this position, rotate the alidade throughout 6,400 mils.

If the bubble remains centered, the instrument is level.

If the bubble does not remain centered during the

procedures in the previous paragraph but remains

within one graduation, level the instrument by

bringing the bubble halfway back towards the

centered position. 

Taking Down (March Ordering)

Tighten the leveling screws to their lowest point, then

back them off 1/2 turn. Ensure the magnetic needle is

locked, the level vials are covered, and the orienting

knob covers are closed.

Place the azimuth knob over the notation pad. Set 0.0

mils on the vertical angle scale. Place the cover over

the instrument and latch the cover locks. Roll the

plumb bob and place it in the accessory case.

Keeping one hand on the instrument, unscrew the

tripod fixing screw and remove the aiming circle from

the tripod. Tighten the tripod cap onto the tripod head. 

Keeping one hand on the tripod head, loosen the

thumbscrews and collapse the tripod legs. Tighten the

thumbscrews. Strap the legs together.

Measuring Horizontal and Vertical Angles 

Horizontal angles are measured at the occupied station

from the rear station to the forward station. When

horizontal angles are made with the aiming circle, two

repetitions of the angle are measured and the

accumulative value is divided by 2 to determine the

mean angle. 

Step 1. Set up and level the aiming circle.

Step 2. Zero the azimuth and micrometer scales.

Step 3. Sight approximately on the rear station using

the lower (nonrecording) fast motion.

Step 4. Using the lower slow motion, sight on the

rear station with the vertical crossline. The last

motion should be from left to right to reduce

backlash due to play in the worm gear mechanism.

Check to make sure the scales are still set to zero.

Close the orienting knob covers.

Step 5. Using the upper (recording) fast motion, rotate

the instrument near the forward station, to the left of

the forward station. 

Step 6. Using the upper slow motion, bring the

crosshairs exactly on the station. Read the horizontal

angle to the nearest 0.5 mils to the recorder. 

Step 7. Sight the telescope to instrument height at the

target using the vertical angle knob if vertical angles are

required. Read the vertical angle to the nearest 0.5 mils

to the recorder.

Step 8. With the horizontal angle on the azimuth scale,

repeat steps 3 through 7. The horizontal angle

measured this time will be an accumulative measure of

two angles. 

Recording and meaning a horizontal angle measured

with an aiming circle is discussed on page 10-9.

Determining Vertical Angle Correction

To obtain correct measurements of vertical angles

with the aiming circle, the horizontal axis of the

telescope must lie in a true horizontal plane when the

elevation scale is at zero. If it does not, a vertical angle

correction must be determined and applied to each

vertical angle measured. Two methods may be used to

determine a vertical angle correction: the comparison

method and the alternate set up method.

Comparison Method 

The measured vertical angle is compared to a known

vertical angle. This is normally performed at a

declination station. 
Marine Artillery Survey Operations ______________________________________________________________________ 10-7

Step 1. After determining the declination constant,

verify the level of the instrument. Measure and record

the vertical angle to each azimuth mark to the nearest

0.5 mils, making sure that instrument height of the

aiming circle is the aiming point at the azimuth marks.

Step 2. Verify the level of the instrument. Measure

and record the vertical angles to each azimuth mark to

the nearest 0.5 mils a second time.

Step 3. Determine the mean of the measured vertical

angles to the nearest 0.1 mils. Determine the

differences (±) between the mean measured vertical

angles and the known vertical angles (Correction =

Known Vertical Angle − Mean Measured Vertical

Angle). If the differences agree within 1 mil of each

other, determine the mean difference to the nearest 0.1

mil and record this value with the declination constant

on the notation pad.

If the differences do not agree within 1 mil, repeat

Steps 1-3 above.

Example: Using a declination station with two

azimuth marks, determine the following values:

Alternate Set up Method 

Two stations are set up approximately 100 meters

apart and properly marked. It is not necessary to know

the coordinates and elevation of the stations or the

azimuth between the stations. 

The aiming circle is set up and leveled over one of the

stations (station A).

The instrument height is measured and marked on a

range pole. The range pole is set up over the other

station (station B).

Measure and record the vertical angle to the mark on

the range pole to the nearest 0.5 mils.

The aiming circle is then moved to station B, set up

and leveled.

The instrument height is measured and marked on the

range pole. The range pole is set up over station A.

Measure and record the vertical angle to the mark on

the range pole to the nearest 0.5 mils.

The vertical angles measured over the two lines are

compared; if they are numerically equal, no vertical

angle correction is necessary. If they are not equal, the

vertical angle correction is determined as follows:

The correction is numerically equal to one half of the

algebraic sum of the two vertical angles. In other

words, add the angles together and then divide by two.

Express the solution to the nearest 0.1 mils. 

The sign of the correction is opposite the sign of the

algebraic sum of the two vertical angles.

Example: If the first angle is +22.0 mils and the

second angle is −24.0, the algebraic sum is −2.0 mils.

The value of the correction is one half the sum or 1.0

mils. The sign of the correction is opposite the sign of

the sum so the vertical angle correction is +1.0 mils. 

UTM Grid Declination Constant

Three types of north are considered of importance to

artillery surveyors: true, magnetic, and UTM grid.

True north is the northerly direction of the meridian of

longitude that includes your position. Magnetic north

is the direction from your position to the North Pole of

the Earth’s magnetic field. UTM grid north is the

northerly direction of a line that includes your position

and is parallel to the central meridian of your UTM

grid zone.

AzMk 1: Kn Vert: +23.0 mils

Mn Meas Vert: +21.4 mils

Corr 1: +1.6 mils

AzMk 2: Kn Vert: −9.0 mils

Mn Meas Vert: −10.8 mils

Corr 2: +1.8 mils

Mn Corr = (Corr 1 + Corr 2)/2

= (1.6 + 1.8)/2

=+1.7
10-8 _____________________________________________________________________________________________ MCWP 3-16.7

To determine grid north with an instrument

equipped with a magnetic needle, the angular

difference between UTM grid north and magnetic

north must first be determined. The clockwise angle

from UTM grid north to magnetic north is the UTM

grid declination constant see figure 10-3. It may

also be referred to as the UTM grid azimuth of

magnetic north.

When To Declinate An Aiming Circle 

(Required) 

The following rules apply to the circumstances that

indicate that declination of an aiming circle is required:

The aiming circle must be declinated after an electrical

storm or after a severe shock such as falling from a

vehicle. The magnetic needle is a delicately balanced

mechanism and any shock can cause a significant

change in the declination constant of the instrument.

The aiming circle should be declinated when moved

more than 25 miles (40 kilometers from the area in

which it was last declinated). The change in the angle

between magnetic north and UTM grid north is

significant enough over 25 miles (40 kilometers to

change the declination constant). The effects of local

magnetic attraction may cause a change in the

declination constant over a few hundred meters.

The aiming circle should be declinated at least every

30 days to minimize the effects of accidents that have

occurred to the instrument and to factor in the changes

in the Earth’s magnetic field. The Earth’s magnetic

field has an annual change that can be calculated under

standard conditions. The field is also affected by other

forces such as sun spots and the Sun’s and the Moon’s

gravity field.

If a radical change (± 2 mils) in the declination

constant is observed after a monthly declination, the

instrument should be redeclinated after a few days.

This should ensure that the change was not caused by

the temporary effects of a magnetic storm or sun spots. 

When an aiming circle is returned from a maintenance

facility or upon initial issue of an aiming circle, it must

be declinated.

Batteries should check the declination of their aiming

circles at each firing position established by battalion

surveyors. This provides the battery with a valid

declination should they move to a new location

before the battalion surveyors have established

known control. 

Declination Stations

A declination station should be established at a

location that is convenient to the using units. It may be

established by any echelon of survey, regimental,

battalion, or battery, as required by the situation.

Declination stations within a battalion area of

operations are the responsibility of the battalion

survey section; however, for garrison training, most

declination stations on Marine Corps installations are

established by the regimental section.

Declination stations should have at least two (four if

possible) well-defined azimuth marks with known

azimuths in different quadrants, but one mark may suffice.

Azimuth marks should be more than 1,000 meters from the

declination station. This may not be possible in heavily

wooded areas. An azimuth mark must never be less than

300 meters from the declination station.

Figure 10-3. Angular Value Representing UTM

Grid Declination.
Marine Artillery Survey Operations ______________________________________________________________________ 10-9

Position and elevation of the declination station do not

have to be of any specific accuracy. The position must be

adequate to plot the station on a map and to locate the

station. The azimuths to the azimuth marks should be at

least fifth order. These azimuths can be determined by

astronomic observations, RTK/OTF survey, the PADS,

traverse, or by computations when coordinates of the

declination station and azimuth marks are of sufficient

accuracy to provide fifth order azimuths.

Establish the declination station in an area free of local

magnetic attraction. The following minimum distances

from common objects are prescribed:

Power lines, 150 meters. 

Electronic equipment, 150 meters. 

Railroad tracks, 75 meters. 

Artillery, tanks, etc., 75 meters. 

Vehicles, 50 meters. 

Wire fences, 30 meters. 

Personal weapons, 10 meters.

Declinating the M2A2 Aiming Circle at a 

Declination Station 

Set up and level the aiming circle over the station.

Using the recording motion, set the known azimuth to

the first azimuth mark on the azimuth scale. Using the

non-recording motion, sight on the azimuth mark.

Using the recording fast motion, rotate the instrument

towards north. Unlock the magnetic needle. Once the

magnetic needle stops bouncing, center the magnetic

needle with the recording motion while looking

through the magnetic needle magnifier.

Once the magnetic needle is centered, lock the

magnetic needle. Read and record the declination

constant to the nearest 0.5 mils. Check the level of the

aiming circle. Then repeat the above steps over the

remaining azimuth marks.

Compare the values determined in the procedures above. If

the spread between the largest and smallest reading is less

than 2 mils, determine the mean declination constant to the

nearest 0.5 mils by adding the individual readings together,

then dividing by the number of readings. If the values do

not agree within 2 mils, repeat the entire process. Record

the declination constant on the notation pad.

Converting a Grid Magnetic Angle to a 

Declination Constant 

If a declination station is not available, the grid

magnetic (GM) angle can be used to determine a

declination constant. The GM angle is the angle, east

or west, between UTM grid north and magnetic north.

This method must be used only in the absence of a

known azimuth and must be updated as soon as a

known azimuth is available, even if that known

azimuth is from hasty methods. Also, if the map

declination diagram is more than 10 years old, the GM

angle may be questionable due to annual change in the

Earth’s magnetic field.

A declination constant can easily be determined by

simple math. If magnetic north is east of grid north,

the declination constant is equal to the GM angle. If

magnetic north is west of grid north, the declination

constant is equal to 6400 mils minus the GM angle.

See figure 10-4.

Figure 10-4. Relationship between a GM Angle and 

a Declination Constant.
10-10 ____________________________________________________________________________________________ MCWP 3-16.7

Hasty Declination 

When a declination station is not available and the

map declination is questionable, select a point on the

map that is easily identifiable on the ground. Set up

and level the aiming circle over that point. Select two

distant points that can be identified on the map and the

ground. Scale the azimuth to the two points from the

occupied station. Use the azimuths scaled from the

map as if they were known azimuths. 

Declinate the aiming circle as described on page 10-9.

Compare the two values determined for the

declination constant; they must agree within 10 mils.

If they do, mean the values to determine the

declination constant. If they do not, repeat the entire

process. A declination constant determined in this

manner must be verified at the first opportunity.

 Determining A Grid Azimuth

A declinated aiming circle can be used to determine a

grid azimuth. This is used in artillery survey mostly

for verifying azimuths determined by other methods,

but can also be used for determining azimuths to

targets from an observation post without a surveyed

azimuth mark.

Set up and level the aiming circle. Using the recording

motion, set the declination constant on the azimuth scales.

With the non-recording fast motion, rotate the

instrument towards north. Unlock the magnetic

needle. Once the magnetic needle stops bouncing,

center the needle using the non-recording slow motion

while looking into the magnetic needle magnifier.

Lock the magnetic needle. Using the recording

motion, sight on the forward station or target. Read

and record the grid azimuth to the nearest 0.5 mils.

Orienting the M2A2 Aiming Circle on a 

Known Azimuth 

An aiming circle can be oriented to a known azimuth

and then used to determine a grid azimuth. This is used

in artillery survey mostly for determining azimuths to

targets from an observation post with a surveyed

azimuth mark. 

Set up and level the aiming circle over the station.

Using the recording motion set the known azimuth on

the azimuth scales. With the non-recording motion,

sight on the azimuth mark. Using the recording

motion, sight on the forward station or target. Read

and record the grid azimuth to the nearest 0.5 mils.

Care of the Aiming Circle and its 

Associated Equipment

Proper care of an instrument will prolong its life and

ensure its usability when needed. Care and

maintenance of the aiming circle is discussed in detail

in TM 9-1290-262-10.

The lenses should be cleaned with a camel hairbrush

and lens paper. If a smudge will not come clean with the

lens paper, moisten the paper with clean water, then

wipe the lens with a lint free cloth. Care should be taken

not to scratch the lens or to remove the bluish coating.

The bluish coating reduces glare for the observer.

The tripod head should be wiped clean of dirt and

moisture and should be examined for nicks or burrs

before mounting the aiming circle. The screws and

bolts must be kept snug. Loose screws can allow the

tripod to twist slightly, causing measurement errors.

Do not overtighten the bolts and screws to prevent

stripping the threads.

Always ensure the magnetic needle is locked when

not in use.
Marine Artillery Survey Operations _____________________________________________________________________ 10-11

The instrument and its accessories must be kept clean

and dry. Metal parts should be cleaned of grease and

oil with mineral spirits and wiped dry. Care must be

taken to insure that the threads of the leveling screws

are clean and turn easily. Polished surfaces can be

given a thin coat of light grade aircraft instrument

lubricating oil to prevent rust. Electrical equipment

can be cleaned with trichlorethylene. Canvas parts can

be cleaned with soap, water, and a scrub brush, as can

wood and metal parts not on the aiming circle itself.

The aiming circle should be stored in a dry ventilated

area. Never store the aiming circle or its equipment

while wet or damp. Allow the aiming circle to air dry

with its cover off before storing. 

Maintenance Checks and Adjustments

Five maintenance checks should be made. If any of

these checks other than the micrometer knob check

indicates an adjustment is necessary, turn the

instrument into a maintenance facility.

Level Vial Check 

After the aiming circle is set up and leveled, rotate the

instrument through 6400 mils. If either the fisheye

level or the vial level does not stay centered, turn the

instrument in to a maintenance facility.

Tilted Reticle Check 

After the aiming circle has been set up and leveled,

place the vertical crosshair on a distant well defined

point. Elevate and depress the telescope. If the vertical

crosshair moves off the point as the telescope is

elevated and depressed, return the instrument to a

maintenance facility.

Azimuth and Elevation Micrometer Knob 

Adjustment 

The only adjustment that may be made by the operator

is the micrometer knob adjustment. 

Set the zero of the scale opposite the index mark.

If the zero of the micrometer knob is opposite the

index mark, no adjustment is necessary. If the zero is

not opposite the index, loosen the screws on the end of

the micrometer knob and slip the micrometer scale to

align the zero and the index.

Hold the knob and the micrometer scale in position

and tighten the micrometer screws. These screws strip

easily, do not overtighten the screws.

Check to ensure both the zero on the scale and the

zero on the micrometer are opposite their respective

index marks.

Level Line Check

The level line check is the same procedure as the steps

for determining the vertical angle correction. This

check determines if the correct values are obtained

when vertical angles are measured with the aiming

circle. If correct vertical angles are not obtained and

there is not enough time to turn the instrument in for

repair, determine a vertical angle correction. This

check must be made after the micrometer knob

adjustment described above. 

Magnetic Needle Check 

Check the magnetic needle to ensure it does not stick

and that it settles smoothly when centered in the

needle magnifier. Once the instrument is set up and

leveled, orient the telescope towards north. Release

the magnetic needle and center it in the needlemagnifying window. Slowly move a piece of iron or

steel back and forth in front of the instrument to move

the needle to its pivot. Allow it to settle. If it does not

settle centered in the window, turn it in to a

maintenance facility. This test must be performed each

time the instrument is declinated and should be

performed each time the instrument is used to

determine any values with the magnetic needle. 
A

PPENDIX A. STAR CARDS

Constellation Star Name and Number Magnitude Card

Andromeda

Aquila

Aries

Auriga

Bootes

Canis Major

Canis Minor

Carina

Cassiopeia

Centaurus

Cetus

Corona Borealis

Corvus

Crux (Southern Cross)

Cygnus

Draco

Eridanus

Gemini

Grus

Hydra

Hydrus

Leo

Libra

Lyra

Octans

Ophiuchus

Orion

Pavo

Pegasus

Perseus

Phoenix

Piscis Austrinus

Sagittarius

Scorpius

Alpheratz 1

Altair 66

Hamal 11

Capella 17

Arcturus 51

Sirius 25

Adhara 26

Wezen 27

Procyon 29

Canopus 23

Avior 32

Miaplacidus 34

Schedar 5

Caph 2

Ruchbah 8

Gamma Cassiopeia 7

Rigel Kentaurus 52

Hadar 49

Menkent 50

Diphda 6

Menkar 13

Alphecca 55

Gienah 41

Acrux 42

Mimosa 44

Gacrux 43

Deneb 68

Eltanin 62

Achernar 9

Acamar 12

Pollux 30

Castor 28

Alhena 24

Al Nair 71

Alphard 35

Beta Hydri 3

Regulus 36

Denebola 39

Zebenelgenubi 53

Vega 64

Nu 69

Rasalhague 61

Sabik 59

Rigel 16

Betelgeuse 22

Bellatrix 18

Alnilam 20

Alnitak 21

Peacock 67

Enif 70

Markab 73

Mirfak 14

Ankaa 4

Fomalhaut 72

Kaus Ausralis 63

Nunki 65

Antares 57

Scaula 60

Dschubba 56

2.1

0.9

2.2

0.2

0.2

-1.6

1.6

2.0

0.5

0.9

1.7

1.8

2.3

2.4

2.8

1.6-2.8

0.1

0.9

2.3

2.2

2.8

2.3

2.8

1.0

1.5

1.6

1.3

2.4

0.6

3.4

1.2

1.6

1.9

2.2

2.2

2.9

1.3

2.2

2.9

0.1

3.7

2.1

2.6

0.3

0.1

1.7

1.7

2.0

2.1

2.5

2.6

1.9

2.4

1.3

1.9

2.1

1.2

1.7

2.5

967425555

18

18

18

17

17

17

17

19

19

191128

19

19

196

17

12

12444

108

13

14

14

156

13

15

1555555

11997

10,12

1033

3,15 3

3,15
A-2 ______________________________________________________________________________________________ MCWP 3-16.7

Taurus

Triangulum Australe

Ursa Major

Ursa Minor

Vela

Virgo

Aldebaran 15

El Nath 19

Atria 58

Alioth 45

Alkaid 48

Dubhe 38

Mizar 46

Merak 37

Phecda 40

Polaris 10

Kochab 54

Gamma Velorum 31

Suhail 33

Spica 47

1.1

1.8

1.9

1.7

1.9

1.9 

2.4

2.4

2.5

2.1

2.2

1.9

2.2

1.2

4,7

4

13

16

16

16

16

16

16

16,17

16,17

18

18

14

Constellation Star Name and Number Magnitude Card
Marine Artillery Survey Operations ______________________________________________________________________ A-3
A-4 ______________________________________________________________________________________________ MCWP 3-16.7
Marine Artillery Survey Operations ______________________________________________________________________ A-5
A-6 ______________________________________________________________________________________________ MCWP 3-16.7
Marine Artillery Survey Operations ______________________________________________________________________ A-7
APPENDIX B. WORLD TIME ZONE OFFSETS

For selected countries listed alphabetically, the local standard time offset from Greenwich (UTC) is given with

daylight savings time where observed. These offsets can be used to convert a UTC time to a local time; i.e.,

PLGR needs the offset to display local time. To determine Greenwich Mean Time from local time, a time zone

correction is needed. Determine time zone corrections by changing the sign of the offset. 

Country Local Standard Time Offset

Afganistan

Albania

Algeria

American Samoa

Andorra

Angola

Anguilla

Antarctica

Antigua

Argentina

Argentina Western Providence

Armenia

Aruba

Ascension Island

Australia NorthernTerritory

Australia Lord Howe Island

Australia New South Wales

Australia Queensland

Australia Victoria

Australia Australian Captial Territory

Austrialia South

Australia Tasmania

Australia Western

Austria

Azerbaijan

Azores

Bahamas

Bahrain

Balearic Islands

Bangladesh

Barbados

Belarus

Belgium

Belize

Benin

Bermuda

Bhutan

Bolivia

Bonaire

Bosnia Herzegovian

Botswana

Brazil Acre

Brazil Atlantic Islands

Brazil East

Brazil West

British Virgin Islands

Brunei

Bulgaria

Burkina Faso

Burundi

Cambodia

Cameroon

Canada Central

Canada Eastern

Canada Mountain

Canada Yukon and Pacific

Canada Atlantic

Canada Newfoundland

+4.5 hours

1 hour (Local summer +2 hours)

+1 hour (Local summer+2 hours)

-11 hour

+1 hour (Local summer+2 hours)

+1 hour

-4 hours

-2 hours (Local summer) -3 hours

-4 hours

-3 hours

-4 hours

+4 hours (Local summer +5 hours)

-4 hours

0 hours

+9.5 hours

+10.5 hours (Local summer +11 hours)

+10 hours (Local summer +11 hours)

+10 hours 

+10 hours (Local summer +11 hours)

+10 hours (Local summer +11 hours)

+9.5 hours (Local summer +10.5 hours)

+10 hours (Local summer +11 hours

+8 hours

+1 hour (Local summer +2 hours)

+3 hours

-1 hour (Local summer 0 hours)

-5 hours (Local summer -4 hours)

+3 hours

+1 hour (Local summer +2 hours)

+6 hours

-4 hours

+2 hours (Local summer +3 hours)

+1hour (Local summer+2 hours)

-6 hours

+1 hour

-4 hours (Local summer -3 hours)

+6 hours

4 hours (Local summer -3 hours)

-4 hours

+1 hour (Local summer +2 hours)

+2 hours

-4 hours (Local summer -5 hours)

-1 hour (Local summer -2 hours)

-3 hours (Local summer -1 hour)

-4 hours (Local summer-3 hours)

-4 hours

+8 hours

+2 hours (Local summer +3 hours)

0 hours

+2 hours

+7 hours

+1 hours

-6 hours (Local summer -5 hours)

-5 hours (Local summer -4 hours)

-7 hours (Local summer -6 hours)

-8 hours (Local summer-7 hours)

-4 hours (Local summer-3 hours)

-3.5 hours (Local summer -2.5 hours)
B-2 ______________________________________________________________________________________________ MCWP 3-16.7

Canary Islands

Canton Enderbury Islands

Cape Verde

Caroline Island

Cayman Islands

Central African Republic

Chad

Channel Islands

Chatham Islands

Chile

China People's Republic

Christmas Islands

Colombia

Congo

Cook Islands

Costa Rica

Cote d'Ivoire

Croatia

Cuba

Curacao

Cyprus

Czech Republic

Dahomey

Denmark

Djibouti

Dominica

Dominican Republic

Easter Island

Ecuador

Egypt

El Salvador

England

Equitorial Guinea

Eritrea

Estonia

Ethiopia

Falkland Islands

Faroe Islands

Fiji

Finland

France

French Guiana

French Polynesia

Gabon

Galapagos Islands

Gambia

Gambier Island

Georgia

Germany

Ghana

Gibraltar

Greece

Greenland

Greenland Thule

Greenland Scoresbysund

Grenada

Grenadines

Guadeloupe

Guam

Guatemala

Guinea

Guinea Bissau

Guyana

Haiti

Hondurast

Hong Kong

Hungary

0 hours (Local summer +1 hour)

-11 hours

-1 hour

+11 hours

-5 hours

+1 hour

+1 hour

0 hours (Local summer +1 hour)

+12.75 hours (Local summer +13.75 hours)

-4 hours (Local summer -3 hours)

+8 hours

-10 hours

-5 hours

+1 hour

-10 hours

-6 hours 

0 hours 

+1 hour (Local summer +2 hours)

-5 hours (Local summer-4 hours)

-4 hours

+2 hours (Local summer +3 hours)

+1 hour (Local summer +2 hours)

+1 hour

+1 hour (Local summer +2 hours)

+3 hours

-4 hours

-4 hours

-6 hours (Local summer -5 hours)

-5 hours

+2 hours (Local summer +3 hours)

-6 hours

0 hours (Local summer +1 hour)

+1 hour 

+3 hours

+2 hours (Local summer +3 hours)

+3 hours

-4 hours (Local summer -3 hours)

0 hours (Local summer +1 hour) +1 hour

+12 hours

+2 hours (Local summer +3 hours)

+1 hour (Local summer +2 hours)

-3 hours

-10 hours

+1 hour

-5 hours

0 hours

-9 hours

+4 hours

+1 hour (Local summer +2 hours)

0 hours

+1 hour (Local summer +2 hours)

+2 hours (Local summer +3 hours)

-3 hours (Local summer -2 hours)

-4 hours (Local summer -3 hours)

-1 hour (Local summer 0 hours)

-4 hours

-4 hours

-4 hours

+10 hours

-6 hours

0 hours

-1 hour(Local summer 0 hours)

-3 hours

-5 hours (Local summer -4 hours)

-6 hours

+8 hours

+1 hour (Local summer +2 hours)

Country Local Standard Time Offset
Marine Artillery Survey Operations _______________________________________________________________________ B-3

Iceland

India

Indonesia Central

Indonesia East

Indonesia West 

Iran

Iraq

Ireland, Republic of 

Israel

Italy

Jamaica

Japan

Johnston Island

Jordan

Kazakhstan

Kenya

Kiribati

Korea, Dem Republic of

Korea, Republic of

Kusaie

Kuwait

Kwajalein

Kyrgyzstan

Laos

Latvia

Lebanon

Leeward Islands

Lesotho

Liberia

Libya

Lithuania

Luxembourg

Macedonia

Madagascar

Madeira

Malawi

Malaysia

Maldives

Mali

Mallorcia Islands

Malta

Mariana Islands

Marquesas Islands

Marshall Islands

Martinique

Mauritania

Mauritius

Mayotte

Melilla

Mexico

Mexico Baja California Norte

Mexico Nayarit

Mexico Sinaloa

Mexico Sonora

Midway Islands

Moldova

Moldovian Rep Pridnestrovye

Monaco

Mongolia

Morocco

Mozambique

Myanmarr

Namibia

Nauru, Republic of

Nepal

Netherlands

Netherlands Antilles

Nevis Montserrat

0 hours

+5.5 hours

+8 hours

+9 hours

+7 hours

+3.5 hours

+3 hours (Local summer +4 hours)

0 hours (Local summer +1 hour)

+2 hours (Local summer +3 hours)

+1 hour (Local summer +2 hours)

-5 hours

+9 hours

-10 hours

+2 hours (Local summer +3 hours)

+6 hours (Local summer +7 hours)

+3 hours

+12 hours

+9 hours

+9 hours

+12 hours

+3 hours

-12 hours

+5 hours (Local summer +6 hours)

+7 hours

+2 hours (Local summer +3 hours)

+2 hours (Local summer +3 hours

-4 hours

+2 hours

0 hours

+2 hours

+2 hours (Local summer +3 hours)

+1 hours (Local summer +2 hours)

+1 hour (Local summer +2 hours)

+3 hours

0 hours (Local summer +1 hour)

+2 hours

+8 hours

+5 hours

0 hours

+1 hour (Local summer +2 hours)

+1 hour (Local summer +2 hours)

+10 hours

-9.5 hours

+12 hours

-4 hours

0 hours

+4 hours

+3 hours

+1 hour (Local summer +2 hours)

-6 hours

-8 hours (Local summer -7 hours)

-7 hours

-7 hours

-7 hours

-11 hours

+2 hours (Local summer +3 hours)

+2 hours (Local summer +3 hours)

+1 hour (Local summer +2 hours)

+8 hours

0 hours

+2 hours

+6.5 hours

+1 hour (Local summer +2 hours)

+12 hours

+5.75 hours

+1 hour (Local summer +2 hours

-4 hours

-4 hours

Country Local Standard Time Offset
B-4 ______________________________________________________________________________________________ MCWP 3-16.7

New Caledonia

New Hebrides

New Zealand

Nicaragua

Niger

Nigeria

Niue Island

Norfolk Island

Northern Ireland

Northern Mariana Islands

Norway

Oman

Pakistan

Palau

Panama

Papua New Guinea

Paraguay

Peru

Phillippines

Pingelap

Poland

Ponape Island

Portugal

Principe Island

Puerto Rico

Qatar

Reunion

Romania

Russian Federation zone one 

Russian Federation zone two

Russian Federation zone three

Russian Federation zone four

Russian Federation zone five

Russian Federation zone six

Russian Federation zone seven

Russian Federation zone eight

Russian Federation zone nine

Russian Federation zone ten

Russian Federation zone eleven

Rwanda

Saba

Samoa

San Marino

Sao Tome and Principe

Saudi Arabia

Scotland

Senegal

Seychelles

Sierra Leone

Singapore

Slovakia

Slovenia

Society Islands

Solomon Islands

Somalia

South Africa

Spain

Sri Lanka

St.Christopher

St. Croix

St. Helena

St. John

St Kitts Nevis

St. Lucia

St Maarten

St. Pierre and Miquelon

St. Thomas

St. Vincent

+11 hours

+11hours

+12 hours (Local summer +13 hours)

-6 hours (Local summer -5 hours)

+1 hour

+1 hour

-11 hours

+11.5 hours

0 hours (Local summer +1 hour)

+10 hours

+1 hour (Local summer +2 hours)

+4 hours

+5 hours

+9 hours

-5 hours 

+10 hours

-4 hours (Local summer -3 hours)

-5 hours

+8 hours

+12 hours

+1 hour (Local summer +2 hours)

+11 hours

+1 hour (Local summer +2 hours)

0 hours

-4 hours

+3 hours

+4 hours

+2 hours (Local summer +3 hours)

+2 hours (Local summer +3 hours)

+4 hours (Local summer +5 hours)

+4 hours (Local summer +5 hours)

+5 hours (Local summer +6 hours)

+6 hours (Local summer +7 hours)

+7 hours (Local summer +8 hours)

+8 hours (Local summer +9 hours) 

+9 hours (Local summer +10 hours)

+10 hours (Local summer +11 hours)

+11 hours (Local summer +12 hours

+12 hours (Local summer +13 hours)

+2 hours

-4 hours

-11 hours

+1 hour (Local summer +2 hours)

0 hours

+3 hours

0 hours (Local summer +1 hour)

0 hour

+4 hours

0 hours

+8 hours

+1 hour (Local summer +2 hours)

+1 hour (Local summer +2 hours)

-10 hours

+11 hours

+3 hours

+2 hours

+1 hour (Local summer +2 hours)

+5.5 hours

-4 hours

-4 hours

0 hours

-4 hours

-4 hours

-4 hours

-4 hours

-3 hours (Local summer -2 hours)

-4 hours

-4 hours

-4 hours

Country Local Standard Time Offset
Marine Artillery Survey Operations _______________________________________________________________________ B-5

Sudan

Suriname

Swaziland

Sweden

Switzerland

Syria

Tahiti

Taiwan

Tajikistan

Tanzania

Thailand

Togo

Tonga

Trinidad and Tobago

Tuamotu Island

Tubuai Islands

Tunisia

Turkey

Turkmenistan

Turks and Caicos Islands

Tuvalu

Uganda

Ukraine

United Arab Emirates

United Kingdom

USA Central

USA Eastern

USA Mountain

USA Arizona

USA Indiana East

USA Pacific

USA Alaska

USA Aleutian

USA Hawaii

Uruguay

Uzbekistan

Vanuatu

Vatican City

Venezuela

Vietnam

Virgin Islands

Wake Island

Wales

Wallis and Futuna Islands

Windward Islands

Yemen

Yugoslavia

Zaire Kasai

Zaire Kinshasa Mbandaka

Zaire Haut Zaire

Zaire Kivu

Zaire Shaba

Zambia

Zimbabwe

+2 hours

-3 hours

+2 hours

+1 hour (Local summer +2 hours

+1 hour (Local summer +2 hours)

+2 hours (Local summer +3 hours)

-10 hours 

+8 hours

+6 hours

+3 hours

+7 hours

0 hours

+13 hours

-4 hours

-10 hours

-10 hours

1 hour

+2 hours (Local summer +3 hours)

+5 hours

-5 hours (Local summer -4 hours)

+12 hours

+3 hours

+2 hours (Local summer +3 hours)

+4 hours

0 hours (Local summer +1 hour)

-6 hours (Local summer -5 hours)

-5 hours (Local summer -4 hours)

-7 hours (Local summer -6 hours

-7 hours

-5 hours

-8 hours (Local summer -7 hours)

-9 hours (Local summer -8 hours)

-10 hours

-10 hours

-3 hours

+5 hours

-+11 hours (Local summer +12 hours)

+1 hour (Local summer +2 hours)

-4 hours

+7 hours

-4 hours

+12 hours

0 hours (Local summer +1 hour)

+12 hours

-4 hours

+3 hours

+1 hour (Local summer +2 hours)

+2 hours

+1 hour 

+2 hours

+2 hour

+2 hours

+2 hours

+2 hours

Country Local Standard Time Offset
Marine Artillery Survey Operations _______________________________________________________________________ B-1

APPENDIX C. RADIO TRANSMITTING STATIONS

FOR TIME SIGNALS

Call Sign Location and Position Frequency (MHz)

BPV Shanghai, China

N 31° 12

E 121° 26'

5.0

10.0

15.0

CHU Ottawa, Canada

N 45° 18'

W 75° 45'

3.330

7.335

14.670

HBG Prangins, Switzerland

N 46° 24'

E 06° 15'

0.075

JJY Koganie,Tokyo, Japan

N 35° 42'

E 139° 31'

2.5

5.0

10.0

15.0

LOL1 Buenos Aires, Argentina

S 34° 27'

W 58° 21'

5.0

10.0

15.0

MSF Rugby, United Kingdom

N 52° 22' 

W 01° 11'

2.5

5.0

10.0

VNG Lyndhurst, Australia

S 38° 00'

E 145° 02'

4.5

7.5

12.0

WWV Fort Collins, Colorado, USA

N 40° 41'

W 105° 02'

2.5

5.0

10.0

15.0

20.0

WWVH Maui, Hawaii, USA

N 20° 46'

W 156° 28'

2.5

5.0

10.0

15.0

ZUO Olifantsfontein, South Africa

S 25° 58'

E 28° 04'

5.0

ZUO Johannesburg, South Africa

S 26° 11'

E 28° 04'

10.0
APPENDIX D. CONVERSIONS

Angular Measurement

Full Circle 3/4 Circle Half Circle 1/4 Circle

Mils 6400 4800 3200 1600

Degrees 360 270 180 90

Grads 400 300 200 100

Radians 2π 3π

2

π π

2

Decimal Degrees to Mils Mils = Degrees/0.05625

Decimal Degrees to Grads Grads = Degrees/0.9

Decimal Degrees to Radians Radians = Degrees x (exact) π (Pi)

180

Rads = Degrees x 0.174532777

Mils to Decimal Degrees Degrees = Mils x 0.05625

Mils to Grads Grads + Mils/16

Grads to Mils Mils = Grads x 16

Grads to Decimal Degrees Degrees = Grads x 0.9

Radians to Decimal Degrees Degrees = Rads x 180

π (Pi)

Mils to Degrees, Minutes, Seconds Degrees, Minutes, Seconds to Mils

Step 1: Mils x 0.05625 = Decimal Degrees Step 1: (Minutes x 60) + Seconds = Number of Seconds

Step 2: 60 x Number to Right of Decimal = Decimal Minutes Step 2: (Number of Seconds/3600) + Degrees = Decimal Degrees

Step 3: 60 x Number to Right of Decimal = Seconds Step 3: Decimal Degrees/0.05625 = Mils

Example: Convert 2198.876 Mils Example: Convert 123° 41' 12.39"

Step 1: 2198.876 x 0.05625 = 123.686775° Step 1: (41' x 60) + 12.39" = 2472.39"

Step 2: 60 x 0.686775 = 41.2065' Step 2:(2472.39"/3600) + 123° = 123.686775°

Step 3: 60 x 0.2065 = 12.39" Step 3: 123.686775/0.05625 = 2198.876 Mils

2198.876 Mils = 123° 41' 12.39" 123° 41' 12.39" = 2198.876 Mils

Vertical Angle (Mils)

VA = Vertical Interval/Range in Km x 1.0186
D-2 ______________________________________________________________________________________________ MCWP 3-16.7

Linear Measurement

From To Equation

Meters Feet (International) FT = M/0.3048 exact

Feet (U.S. Survey) FT = M/0.30480060960

Feet (British Ordnance) FT = M/0.304800756

Feet (Indian old) FT = M/0/30479842

Feet (Survey of India) FT = M/0.3047996

Yards (International) YDS = M x 1.093613

Statute Miles SM i = M/1609.344 exact

Nautical Miles NM i = M/1852 exact

Feet (International) Meters M = FT x 0.348 exact

Nautical Miles NM i = FT/6076.1033333

Feet (U.S. Survey) Meters M = FT x 0.30480060960

Meters M = FT x 1200/3937 exact

Statute Miles SM i = FT/5280 exact

Nautical Miles NM i = FT/6076.1033333

Feet (Great Britain in Ordnance Survey) Meters M = FT x 0.304800756

*Feet (Indian Old) Meters M = FT x 0.30479842

Feet (Survey of India) Meters M = FT x 0.3047996

Statute Miles Kilometers KM = M i /0.6213712

Statute Miles M i = KM x 0.6213712

Celsius/Fahrenheit Measurement

°F = 9 / 5 °C + 32 °C = 5 (°F - 32)

9

*Used by U.S. and Great Britain for surveys in India and border nations.
APPENDIX E. GLOSSARY

SECTION I. ACRONYMS AND ABBREVIATIONS

AR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . accuracy ratio

AS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .antispoofing

AZMK. . . . . . . . . . . . . . . . . . . . . . . . . . .azimuth mark

BAMCIS . . . . . . . . . . . . . . . . . . . . . . . begin planning;

arrange for reconnaissance;

make reconnaissance;

complete the plan;

issue the order; supervise

BIH . . . . . . . . . . . . . .Bureau International De l’Heure

BLM . . . . . . . . . . . . . . . Bureau of Land Management

BNG . . . . . . . . . . . . . . . . . . . . . .British National Grid

bps. . . . . . . . . . . . . . . . . . . . . . . . . . . . .bits per second

BUCS . . . . . . . . . . . . . . . . . .backup computer system

CA . . . . . . . . . . . . . . . . . . . . . . . comparative accuracy

C/A . . . . . . . . . . . . . . . . . . . . . . . . . coarse/acquisition

CDU . . . . . . . . . . . . . . . . . . . .control and display unit

CE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . circular error

CEOI . . . . . . . . . . . . . . . . communications-electronics

operating instructions

CEP . . . . . . . . . . . . . . . . . . . . . .circular error probable

COC . . . . . . . . . . . . . . . . . . .combat operations center

COE. . . . . . . . . . . . . . . . US Army Corps of Engineers

CONUS . . . . . . . . . . . . . . . . .continental United States

COP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . chief of party

COS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .cosine

CUCV . . . . . . . . . . . .commercial utility cargo vehicle

CVd . . . . . . . . . . . . . . . . . . . . . . . . .cryptovariable key

CVW . . . . . . . . . . . . . . . . . . . . . cryptovariable weekly

CW . . . . . . . . . . . . . . . . . . . . . . . . . . continuous wave

D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . direct

2-D . . . . . . . . . . . . . . . . . . . . . . . . . . two-dimensional

3-D . . . . . . . . . . . . . . . . . . . . . . . . . three-dimensional

DA. . . . . . . . . . . . . . . . . . . . . Department of the Army

dE . . . . . . . . . . . . . . . . . . . . . . . . . . difference easting

dH . . . . . . . . . . . . . . . . . . . . . . .difference in elevation

DI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .rapid mode

DIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .repeat mode

DIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . distance

DMA . . . . . . . . . . . . . . . . . .Defense Mapping Agency

dN . . . . . . . . . . . . . . . . . . . . . . . . . difference northing

DOD . . . . . . . . . . . . . . . . . . . . Department of Defense

DOP. . . . . . . . . . . . . . . . . . . . . . . dilution of precision

DOT . . . . . . . . . . . . . . .Department of Transportation

DS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .direct support

DSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . display

DTD . . . . . . . . . . . . . . . . . . . . . . . data transfer device

ECEF. . . . . . . . . . . . . . . . .Earth-centered, Earth-fixed

eH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . elevation error

EMP . . . . . . . . . . . . . . . . . . . . . electromagnetic pulse

EOL. . . . . . . . . . . . . . . . . . . . end of the orienting line

EROMS. . . . . . . . . . . . . . erasable read only memories

FGCS. . . . .Federal Geodetric Control Sub-Committee

FLOT. . . . . . . . . . . . . . . . . . . . . forward line of troops

FO . . . . . . . . . . . . . . . . . . . . . . . . . . . forward observer

FOM . . . . . . . . . . . . . . . . . . . . . . . . . . . figure of merit

FSCM . . . . . . . . . . .fire support coordinating measure

FWD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . forward

GDOP . . . . . . . . . . . . . geometric dilution of precision

GEOREF. . . . . . . . . . . . World Geographic Reference

System

GHA . . . . . . . . . . . . . . . . . . . . . Greenwich hour angle

GK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gauss-Kruger

GLONASS . . . . . Global Navigation Satellite System

GM . . . . . . . . . . . . . . . . . . . . . . . . . . . . .grid magnetic

GMT . . . . . . . . . . . . . . . . . . . . Greenwich Mean Time

GN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .grid north

GS . . . . . . . . . . . . . . . . . . . . . . . . . . . . general support

GS-R . . . . . . . . . . . . . . . . .general support-reinforcing

GPS . . . . . . . . . . . . . . . . . . . global positioning system

GPS-S . . . . . . . . . . . global positioning system-survey

GRS. . . . . . . . . . . . . . . . . Geodetic Reference System

GUV . . . . . . . . . . . . . . . . . . . . . group unique variable

GZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . grid zone

HCS. . . . . . . . . . . . . . . . . . handheld computer system

HDOP . . . . . . . . . . . . . horizontal dilution of precision

HI . . . . . . . . . . . . . . . . . . . . . . . . height of instrument

HMMWV . . . . . . . . . . . . .high-mobility multipurpose

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .wheeled vehicle

HORZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .horizontal

HT . . . . . . . . . . . . . . . . . . . . . . . . . . . . height of target

IMU. . . . . . . . . . . . . . . . . . . inertial measurement unit

INS . . . . . . . . . . . . . . . . . . . inertial navigation system

IO . . . . . . . . . . . . . . . . . . . . . . . . . instrument operator

ITMG . . . . . . . . . . . . .Irish Transverse Mercator Grid
E-2 ______________________________________________________________________________________________ MCWP 3-16.7

KEK. . . . . . . . . . . . . . . . . . . . . . . . key encryption key

KPK. . . . . . . . . . . . . . . . . . . . . . . . key production key

L1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . link 1

L2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . link 2

L1/L2 . . . . . . . . . . . . . . . . . . . .dual frequency receiver

LAT . . . . . . . . . . . . . . . . . . . . . . . . local apparent time

LED . . . . . . . . . . . . . . . . . . . . . . . light emitting diodes

LMT. . . . . . . . . . . . . . . . . . . . . . . . . . .local mean time

LST . . . . . . . . . . . . . . . . . . . . . . . . .local sidereal time

MAGTF. . . . . . . . . . . . . Marine air-ground task force

MBS. . . . . . . . . . . . . . . . . . . . . . . .milibars of mercury

MC&G AAR . . . . . . . mapping, charting, and geodesy

after action report

MEDEVAC . . . . . . . . . . . . . . . . . . medical evacuation

MEF-FWD. . . . . .Marine expeditionary force forward

METT-T . . . . . . mission, enemy, terrain and weather,

troops and support available-time available

MG. . . . . . . . . . . . . . . . . . . . . . . . . . . Madgascar Grid

MGRS . . . . . . . . . . . .Military Grid Reference System

MLRS . . . . . . . . . . . . . multiple launch rocket system

MMS . . . . . . . . . . . .metereological measuring system

MN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mean

MPF. . . . . . . . . . . . . . . .maritime prepositioning force

MRE . . . . . . . . . . . . . . . .multiple regression equation

ms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . microsecond

MSL. . . . . . . . . . . . . . . . . . . . . . . . . . . .mean sea level

MSGR . . . . . . . . . military survey grade receiver 4000

NAD . . . . . . . . . . . . . . . . . . . . North American datum

NAVD . . . . . . . . . . . . North American vertical datum

NAV Data . . . . . . . . . . . . . . . . . . . . . . navigation data

NAVSTAR . . . . . . . . navigation, satellite, timing and

ranging

NGRS . . . . . . . . National Geodetic Reference System

NGS. . . . . . . . . . . . . . . . . . National Geodetric Survey

NGVD . . . . . . . . . . . National Geodetic vertical datum

NIMA . . . . . .National Imagery and Mapping Agency

NOAA . . . . . . . . . National Oceanic and Atmospheric

Administration

NOS. . . . . . . . . . . . . . . . . . . . . National Ocean Survey

NZMG . . . . . . . . . . . . . . . . . . New Zealand Map Grid

OCC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . occupied

OP . . . . . . . . . . . . . . . . . . . . . . . . . . . observation post

OS . . . . . . . . . . . . . . . . . . . . . . . . . . . orienting station

OTF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . on the fly

P. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . precise

PADS. . . . . . . . . . Position and Azimuth Determining

System

PDOP. . . . . . . . . . . . . . . position dilution of precision

PE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . probable error

PLGR. . . . . . . . . precision, lightweight, GPS, receiver

PMCS . . . . . . . . . . . . preventive maintenance checks

and services

POL . . . . . . . . . . . . . . . . petroleum, oil, and lubricants

PPM. . . . . . . . . . . . . . . . . . . . . . . . . . parts per million

PPS . . . . . . . . . . . . . . . . . . precise positioning service

PPS . . . . . . . . . . . . . . . . . . . . . . . . . . pulse per second

PRC . . . . . . . . . . . . . . . . . . . . pseudo-range correction

PRN . . . . . . . . . . . . . . . . . . . . . . pseudo-random noise

QSTAG . . . . . . . . . . . . . . . . . . . quadripartite standing

agreement

R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .reverse

RA . . . . . . . . . . . . . . . . . . . . . . . . . . . . right ascension

RAMS . . . . . . . . . . . . . . . . . random access memories

RCDR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .recorder

RDF . . . . . . . . . . . . . . . . . . . . . radio directional finder

RDOP . . . . . . . . . . . . . . .relative dilution of precision

RE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .radial error

READ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . reading

RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . radio frequency

RMS . . . . . . . . . . . . . . . . . . . . . . . . root-mean-square 

RP . . . . . . . . . . . . . . . . . . . . . . . . . . .registration point

RPV . . . . . . . . . . . . . . . . . . . . remotely piloted vehicle

RSO . . . . . . . . . . . . . . . Rectified Skew Orthomorphic

RTK. . . . . . . . . . . . . . . . . . . . . . . . real time kinematic

S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .standard

S-2 . . . . . . . . . . . . . . . . . . . . . . . . . intelligence officer

S-3 . . . . . . . . . . . . . . . . . . . . . . . . . . operations officer

SA . . . . . . . . . . . . . . . . . . . . . . . . selective availability

SCP . . . . . . . . . . . . . . . . . . . . . . . survey control point

SDI . . . . . . . . . . . . . . . . . .Strategic Defense Initiative

SEP . . . . . . . . . . . . . . . . . . . . spherical error probable

SIC. . . . . . . . . . . . . . . . . . . Survey Information Center

SICP . . . . . . . .survey instrument calibration program

SINCGARS . . . . . single channel ground and airborne

radio system

SNR. . . . . . . . . . . . . . . . . . . . . . . signal-to-noise ratio

SOP . . . . . . . . . . . . . . . . standing operating procedure

SPS . . . . . . . . . . . . . . . . . standard positioning service

STA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . station

STANAG. . . . . . . . . . . . . . standardization agreement

SV . . . . . . . . . . . . . . . . . . . . . . . . . . . . satellite vehicle

T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . telescope

TCU. . . . . . . . . . . . . . . . . . . . . . . tracking control unit

TDOP . . . . . . . . . . . . . . . . . time dilution of precision

TFOM . . . . . . . . . . . . . . . . . . . . . .time figure of merit

TM. . . . . . . . . . . . . . . . . . . . . . . . .transverse mercator

T/O . . . . . . . . . . . . . . . . . . . . . . . table of organization

TTL . . . . . . . . . . . . . . . . . . . . . . . .total traverse length

TZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .time zone

UAV . . . . . . . . . . . . . . . . . . . unmanned aerial vehicle
Marine Artillery Survey Operations _______________________________________________________________________ E-3

UERE . . . . . . . . . . . . . . . . user equivalent range error

UHF. . . . . . . . . . . . . . . . . . . . . . . ultra-high frequency

UPS . . . . . . . . . . . . . . . . universal polar stereographic

USGS . . . . . . . . . . . United States Geological Survey

UT . . . . . . . . . . . . . . . Universal Time (same as GMT)

UTC. . . . . . . . . . . . . . . . .Universal Time Coordinated

UTM . . . . . . . . . . . . . . . universal transverse mercator

VERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vertical

VDOP . . . . . . . . . . . . . . vertical dilution of precision

VLF. . . . . . . . . . . . . . . . . . . . . . . . very low frequency

WGS . . . . . . . . . . . . . . . . . . . World Geodetic System

Z-Vels . . . . . . . . . . . . . . . . .Zero-Velocity Corrections

SECTION II. DEFINITIONS

absolute positioning—The unique ability of a GPS

receiver to produce positional values without the

reference of another receiver.

accelerometer—A device which measures

acceleration. The output is double integrated to

determine a change in distance. 

accumulative error—An error that occurs with the

same sign, and often with similar magnitude, in a

number of consecutive or otherwise related

observations. An example is measuring a distance with

an uncalibrated distomat (EDME); each distance

measured will be consistently long or short. The total

accumulated error will be equal to the error in one

measurement multiplied by the total number of

measurements. Repetition cannot reduce this error.

Also called constant error or systematic error. 

accuracy—(1) How close a measurement or a group of

measurements are in relation to a standard or true value.

(2) The degree of conformity with a standard, or the

degree of perfection attained in a measurement.

Accuracy relates to the quality of a result and is

distinguished from precision which relates to the

quality of the operation by which the result is obtained.

accuracy ratio—In artillery survey, it is the ratio

between the radial error in closure and the total

traverse length of a survey. It is usually expressed as a

fraction with a numerator of 1.

adjusted value—A value of a quantity derived from

observed data by some orderly process which

eliminates discrepancies arising from errors in those

observed data.

adjustment—The determination and application of

corrections to observations for the purpose of reducing

errors or removing internal inconsistencies in derived

results. The term may refer to mathematical

procedures or to corrections applied to instruments

used in making observations.

alidade—The part of a surveying instrument which

consists of a sighting device with index and reading

and recording accessories.

altitude—(1)The altitude of a celestial body is the arc

of its vertical circle measured from the observer’s

horizon to the body, or it is the vertical angle at the

observer’s position between the horizon and the body.

(2) The vertical distance between a point and a

reference surface; usually the topography.

ambiguity—The unknown number of whole carrier

wavelengths between a satellite and a receiver. Also

called cycle ambiguity. 

angle—The arc of a circle formed by the intersection 

of two lines at the center of the circle.

anti-spoofing—An encryption technique developed

by the US Department of Defense (DOD) that denies

access to the P-code to any unauthorized users.

anywhere fix—A receiver with the unique ability to

calculate a position without being given an

approximate location and/or time.

apogee—The point in the orbit of a satellite about the

Earth that is the greatest distance from the center of

the Earth.

arbitrary grid—Any reference system developed for

use where no grid is available or practical, or where

military security for the reference is desired.

astronomic position—A point on the Earth whose

coordinates were determined as a result of

observations of celestial bodies.
E-4 ______________________________________________________________________________________________ MCWP 3-16.7

autoreflection—A method of creating a line which is

perpendicular to a reflective porro prism by projecting

the image of a theodolite telescope onto the porro

prism, then back to the telescope. 

azimuth—The horizontal angle measured clockwise

between a reference direction and the line to an

observed or designated point.

azimuth, astronomic—The angle between the plane

of the observer’s meridian and the plane of the hour

circle containing the observed body, measured in the

plane of the horizon, preferably clockwise from north.

An astronomic azimuth is not by definition a

true azimuth.

azimuth, geodetic—The angle between the geodetic

meridian and the tangent to the geodetic line at the

observer, measured in the plane perpendicular to the

ellipsoidal, normal of the observer, preferably

clockwise from north. A geodetic azimuth can be

referred to as a true azimuth.

azimuth, grid—The horizontal direction of any line

measured clockwise from grid north.

azimuth magnetic—The horizontal direction of any

line measured clockwise from magnetic north.

azimuth, plane—The angle measured in a clockwise

direction between grid north and a line on a grid.

azimuth, true—The horizontal direction of any line

measured clockwise from true north.

back azimuth— (1) In a plane rectangular coordinate

system, like UTM grid, the back azimuth differs from

an azimuth by 180° (3200 mils). The azimuth and back

azimuth form a straight line. (2) In geodetic survey,

the azimuth and back azimuth do not differ by 180°

because of convergence of the meridians. If the

azimuth of point B from point A is given on a

reference ellipsoid, then the back azimuth is the

azimuth of point A from point B.

bandwidth—A measure of the width of the frequency

spectrum of a signal expressed in hertz.

baseline—The resultant three dimensional vector, V,

between any two stations from which simultaneous

GPS data have been collected and processed.

Generally given in Earth-centered cartesian

coordinates where: V=Δx, Δy, Δz.

bearing—The direction of a line as measured from the

north-south axis (X-axis) of a two dimensional system.

bearing angle—The acute angle formed between the

north-south axis (X-axis) of a two dimensional system

and a line connecting the origin with a point. In

artillery survey, it is the angle between the grid northsouth line and the azimuth line to the forward station.

bleeding edge—The edge of a map or chart on which

cartographic detail is extended to the edge of the sheet.

The bleeding edge usually includes overlap of a

portion of an adjoining sheet.

binary biphase modulation—Phase changes on a

constant carrier frequency of either 0 or 180 degrees.

The phase changes represent the binary digits 0 and 1

respectively. In other words, a phase change from the

carrier of 0° is the binary digit 0; a phase change from

the carrier of 180° is the binary digit 1.

binary code—A system used in communications

where selected strings of 0’s and 1’s are assigned

definite meanings.

built-in test—Usually an internal check for proper

functioning. Also called BIT.

built-in test equipment—Internal components of

equipment designed to conduct built-in tests on the

equipment. Also called BITE.

broadcast ephemeris—The ephemeris broadcast by

the GPS satellites.

calibration—The act of determining certain specific

measurements in an instrument or device by

comparison with a standard, for use in correction or

compensating for non-standard errors.

carrier—A high frequency radio wave having at least

one characteristic (frequency, amplitude, or phase)

which may be varied by modulation from an accepted

value. In general, the carrier wavelength is much

shorter than the wavelengths of the codes.

carrier frequency—The frequency of the

unmodulated fundamental output of a radio transmitter.

carrier phase—The phase measurement of the carrier

wave, converted from a percentage to millimeters.

cartesian coordinates—A coordinate system in

which locations of points in space are expressed by
Marine Artillery Survey Operations _______________________________________________________________________ E-5

reference to three mutually perpendicular planes,

called coordinate planes. The three planes intersect in

three straight lines called coordinate axes. The system

is referred to as geocentric Cartesian coordinates when

it defines the position of a point with respect to the

center of mass of the Earth. See X-axis, Y-axis,

and Z-axis. 

celestial coordinates—The coordinates used to

locate a celestial body by various systems. The

coordinates considered in artillery are declination and

right ascension.

celestial equator—The great circle on the celestial

sphere whose plane is perpendicular to the axis of

rotation of the Earth.

celestial geodesy—The branch of geodesy which

utilizes observations of near celestial bodies, including

man-made satellites, to determine the size and shape

of the Earth.

celestial horizon—That circle on the celestial sphere

formed by the intersection of the celestial sphere and a

plane through the center of the Earth and

perpendicular to the zenith-nadir line.

celestial north and south poles—The points at which

the prolonged polar axis of the Earth intersects the

celestial sphere. The celestial North Pole is the “P” in

the PZS triangle. 

celestial sphere—An imaginary sphere of infinite

radius concentric with the Earth, on which all celestial

bodies except the Earth are imagined to be projected.

Astronomic surveying establishes that the celestial

sphere and all bodies on the sphere rotate around the

Earth form east to west.

central meridian—(1) The line of longitude at the

center of a map projection. Generally, the basis for

constructing the projection. (2) The longitude of origin

at the center of each six-degree zone of the UTM grid

system. (3) The longitude of the center of a time zone.

channel—GPS receiver hardware and software which

allows the receiver to track the signal from one

satellite at one of the two carrier frequencies. An

eight-channel dual frequency receiver actually tracks

sixteen channels.

chip—The minimum transition time interval for

individual bits of either a 0 or a 1 in a binary pulse code,

usually transmitted in a pseudo-random sequence.

circular error—An accuracy figure representing the

stated percentage of probability that any point

expressed as a function of two linear components (e.g.,

horizontal position) will be within the given figure.

Commonly used figures are CEP (50%), CE 1

(39.35%), CE (90%). 

circumpolar—Revolving about the elevated pole

without setting. A celestial body is circumpolar when

its polar distance is approximately equal to, or less

than, the latitude of the observer.

clock bias—The difference between a clock’s

indicated time and true Universal Time.

clockwise angle—The horizontal angle measured on a

clockwise rotation scale. The alidade does not

necessarily have to turn clockwise to measure a

clockwise angle. For example, the horizontal scale of a

T2-E will measure the same angle between two

stations no matter what direction the alidade is turned.

coaltitude—The compliment of altitude, or 90° minus

the altitude. The term has significance only when used

in connection with altitude measured from the celestial

horizon, when it is synonymous with zenith distance.

codeless receiver—An instrument that does not

require knowledge of the P or C/A codes to perform

measurements. This type of receiver does not record

ephemeris data; consequently, before a baseline

solution is computed, an ephemeris file must be

obtained from another source.

code receiver—An instrument that does require

knowledge of the P or C/A codes to complete its

measurements. This type of receiver will record the

broadcast ephemeris.

coincidence—(1) In the measurement of angles with a

theodolite, the instant at which two diametrically

opposed index marks on the circle are in perfect

optical alignment and appear to form a continuous line

across the dividing line of the circle. (2) A prismatic

arrangement common to leveling instruments and

older theodolites wherein one-half of opposite ends of

the leveling bubble are brought into view in a single

image. Coincidence is achieved when two halves of

the bubble ends match.

colatitude—The side of the PZS triangle from the

zenith to the pole. The complement of latitude, or 90°

minus the latitude. 
E-6 ______________________________________________________________________________________________ MCWP 3-16.7

comparative accuracy—The ratio between the

difference in two measurements and the mean of those

measurements. It is used to describe the accuracy of

distances and is usually expressed as a fraction with 1

as a numerator. Also called CA.

conformal map projection—A map projection on

which the shape of any small area of the surface

mapped is preserved unchanged, and all angles around

any point are correctly represented. Also called an

orthomorphic map projection.

conic map projection, secant—A map projection

produced by projecting the geographic meridians and

parallels of a reference ellipsoid onto a cone which is

secant to the surface of the ellipsoid. The points of

secancy are usually two parallels of latitude. Also called

a conic map projection with two standard parallels. (An

example is the Lambert Conformal Projection.) 

conic map projection, tangent—A map projection

produced by projecting the geographic meridians and

parallels of a reference ellipsoid onto a cone that is

tangent to the surface of the ellipsoid. The point of

tangency is usually a parallel of latitude. Also called a

conic map projection with one standard parallel.

contour—Imaginary lines in which all points on each

line have the same elevation. Used to depict the terrain

of the ground onto the flat surface of a map.

contour interval—The difference in elevation

between two adjacent contour lines. This interval is

usually listed below the bar graph in the marginal data

of a map.

contour line—A line on a map in which all points on

the line have the same elevation.

contour line, index—An index contour line is a line

of equal elevation that is depicted on a map in a bold

print to distinguish it from intermediate contour lines.

These lines are normally depicted as every fifth line;

therefore, the elevation difference between these lines

is normally five times the contour interval. 

contour line, intermediate—The contour lines drawn

between index contour lines. The elevation difference

between these lines is equal to the contour interval.

contour line, supplementary—A contour line drawn

between two intermediate contour lines. These lines

are usually a dashed line and indicate an elevation

difference of one-half the contour interval.

control segment—One of three GPS segments. The

control segment is made up of monitoring and control

stations that ensure the accuracy of the GPS satellite

orbits and operation of their atomic clocks. There are

currently five stations in the control segment.

convergence—The angular difference between two

meridians at the intersection of two lines that are

tangent to the meridians at the same parallel of

latitude. Usually called convergence of the meridians.

coordinates—Linear or angular quantities that

designate the position of a point in a given frame of

reference. This term is usually referenced to three

dimensional positioning systems such as Cartesian

coordinates or Geodetic coordinates. The term has also

been used to describe the position of a point located on

a two dimensional grid system such as UTM or UPS.

counterclockwise angle—A horizontal angle

measured in a counterclockwise direction. Used for

the measurement of deflection angles.

course/acquisition code—The standard GPS code, it

is broadcast on the L-1 frequency and is not encrypted.

This code is subject to selective availability, and is

sometimes called the civilian access code or, the clear

access code. Also called C/A.

curvature of earth— (1) The offset from the tangent

to the curve as a result of the curvature of the Earth

and refraction combined. (2) The divergence of a

plane surface from the surface of the Earth.

cycle ambiguity—See Ambiguity.

cycle slip—A discontinuity in measured carrier beat

phase resulting in a temporary loss of lock in the

carrier tracking loop of a GPS receiver.

cylindrical map projection—A map projection

produced by projecting the geographic meridians and

parallels of a reference ellipsoid onto a cylinder, and

then developing the cylinder into a plane. This

projection can be either tangent to the ellipsoid, or

secant to the ellipsoid depending on the purpose of

the product. 

datum—(1) Any numerical or geometrical quantity,

or set of such quantities which may serve as a

reference or base for other quantities. (2) A point, line,
Marine Artillery Survey Operations _______________________________________________________________________ E-7

or surface used as a reference, as in surveying,

mapping, or geology. 

datum, horizontal—Also called a geodetic datum. A

horizontal datum is generally defined by at least five

quantities relating to position, azimuth, gravity

models, and a reference ellipsoid. It fixes a reference

ellipsoid to a specific orientation with respect to the

surface of the geoid.

datum point—Any reference point of known or

assumed coordinates from which calculations or

measurements may be taken.

datum transformation—The systematic elimination

of discrepancies between adjoining or overlapping

triangulation networks from different datums by

moving the origins, rotating, and stretching the

networks to fit together.

datum, vertical—A level surface to which elevations

are referred, usually mean sea level. Sometimes

referred to as an altitude datum.

D-code—See NAV data.

declination—(1)The angular distance from the

celestial equator to a celestial body measured along

the hour circle of the celestial body. Declination is

positive when the body is north of the celestial equator

and negative when south. Declination roughly

corresponds to astronomic latitude on the Earth.

(2) Often used as a shortened term for magnetic

declination, although this use is technically incorrect. 

declination, grid—The angular difference between

magnetic north and grid north.

declination magnetic—The angular difference

between magnetic and true north.

deflection of the vertical—The angular difference

between the upward direction of the plumb line (the

vertical), and the perpendicular (normal) to the

reference ellipsoid. This difference seldom exceeds

30” except in mountainous areas.

differencing—A technique used in baseline

processing to resolve the integer cycle ambiguity, and

to reduce a number of error sources including

oscillator variations and atmospheric and orbital

modeling errors. This technique “differences” the

measurement of the carrier beat phase across time,

frequency, receivers, satellites, or any combination of

these. The three most utilized differencing techniques

are described below: 

Single difference between receivers is the

instantaneous difference in the complete carrier beat

phase measurements made at two receivers

simultaneously tracking the same signal. 

Double difference between receivers and satellites is

found by differencing the single difference for one

satellite with the single difference for another satellite

where both single differences are from the

same epoch. 

Triple difference between receivers, between

satellites, and between epochs (time) is the difference

between a double difference at one epoch and the

same double difference at the following epoch.

differential positioning—The determination of the

position of a station relative to a reference station

when GPS receivers at each station are simultaneously

tracking the same signals.

dilution of precision—A measure of the geometric

contribution to the uncertainty of a position fix. The

more specific terms are given below. Also called DOP.

(1) GDOP—Geometric dilution of precision is the

measurement accuracy in 3D position and time. 

(2) PDOP—Position dilution of precision is the

measurement accuracy in 3D position. 

(3) HDOP—Horizontal dilution of precision is the

measurement accuracy 2D horizontal position. 

(4) VDOP—Vertical dilution of precision is the

measurement accuracy as standard deviation of

vertical height. 

(5) RDOP—Relative dilution of precision is a

measurement of the quality of baseline reductions.

distance—The spatial separation of two points,

measured by the length of a line joining them.

distance angle—An angle in a triangle opposite a side

used as a base in the solution of the triangle, or a side

whose length is to be computed.

distance, horizontal—The distance measured on a

horizontal plane. Horizontal distance refers primarily
E-8 ______________________________________________________________________________________________ MCWP 3-16.7

to taped distances or to distances reduced to horizontal

through computations.

distance, slope—A straight-line distance between two

points of unequal elevation. A slope distance is usually

derived by electronic means and must be reduced to

horizontal distance for use in artillery survey

computations.

doppler-aiding—A signal processing strategy that

uses a measured Doppler shift to help the receiver

smoothly track the GPS signal, allowing more precise

velocity and position measurement.

doppler shift—The apparent change in frequency of a

received signal due to the rate of change of the

distance between the transmitter and receiver.

double difference—See differencing.

dynamic positioning—See kinematic positioning.

earth-centered ellipsoid—A reference ellipsoid

whose geometric center coincides with the Earth’s

center of gravity and whose semi-minor axis coincides

with the Earth’s rotational axis.

earth-fixed coordinate system—Any coordinate

system in which the axes are stationary with respect to

the Earth.

easting—The eastward (left to right) reading of grid

values. This term is used with two dimensional

coordinate systems.

eccentricity—The ratio of the distance from the

center of an ellipse to its focus on the semi-major axis.

ecliptic—The great circle formed by the intersection

of the plane of the Earth’s orbit around the sun and the

celestial sphere.

elevation—Vertical distance from a datum, usually

mean sea level, to a point on the Earth’s surface. More

exactly, it is the distance between a point on the

Earth’s surface and the geoid, measured on a line

perpendicular to the geoid. Elevation should not be

confused with altitude which refers to points above the

Earth’s surface. Elevation is sometimes referred to as

orthometric height.

ellipsoid—A surface whose plane sections (cross

sections) are all ellipses or circles, or the solid enclosed

by such a surface. The terms ellipsoid and spheroid are

used interchangeably. See also reference ellipsoid.

ellipsoid height—The distance between a point on the

Earth’s surface and the reference ellipsoid, measured

along a line which is perpendicular to the ellipsoid.

The ellipsoid height is positive if the point is outside

of the reference ellipsoid. Also called geodetic height.

ellipsoid of revolution—The surface generated by an

ellipse rotating on one of its axes. Also called an

ellipsoid of rotation.

epoch—A period of time or a date selected as a

reference for a measurement.

equator—The great circle on the Earth midway

between the poles and in a plane perpendicular to the

Earth’s axis of rotation. It is the line of zero latitude.

equatorial axis—The diameter of the Earth described

between two points on the equator. Twice the semimajor axis of a reference ellipsoid.

equatorial plane—A plane which includes all the

points located at the equator.

equipotential surface—A surface having the same

potential of gravity at every point.

error—The difference between an observed or

computed value of a quantity and the ideal or true

value of that quantity. An error is generally classified

as one of three types: a blunder which can be

identified and corrected, a systematic error which must

be compensated for, and a random error which cannot

be identified or compensated for.

error of closure—(1)The amount by which a quantity

obtained by a series of related measurements differs

from the true or fixed value of the same quantity.

(2) (azimuth) The amount by which two values of the

same azimuth line, derived by different surveys or

other means, fail to be equal. This is usually termed

azimuth error. (3) (traverse) The amount by which the

value of the position of a traverse station, as obtained

by computation through a traverse, fails to agree with

another value of the same station as determined by a

different set of observations or procedures. Usually

called radial error, it is also called traverse error,

position error, or horizontal error. (4) (triangulation)

The amount by which the sum of the three interior

angles of a triangle differ from 180° (3200 mils).

(5) (horizon) The amount by which the sum of two or
Marine Artillery Survey Operations _______________________________________________________________________ E-9

more adjacently measured horizontal angles around

one point fails to equal 360° (6400 mils).

Measurement of the last horizontal angle completes a

circle and is called closing the horizon.

fast switching channel—A switching channel with a

time sequence short enough to recover the integer part

of the carrier beat phase. The switching time is

generally between 2 to 5 ms.

fault indicator—On the PADS, an indicator that

allows an equipment operator to see that the equipment

is either functioning properly or malfunctioning. 

flattening—The ratio of the difference between the

equatorial and polar radii of the earth to its equatorial

radius. Also called ellipticity.

frequency band—A range of frequencies in a region

of the electromagnetic spectrum.

fundamental frequency—The GPS fundamental

frequency, F, is 10.23 MHz. The carrier frequencies

are:

L1 = 154 * F = 1575.42 MHz

L2 = 120 * F = 1227.60 MHz 

gauss-kruger projection—The same as the transverse

mercator projection with the cylinder of projection

placed tangent to the reference ellipsoid.

GDOP— See DOP.

geocentric—Relative to the Earth or geoid as a center,

measured from the center of the Earth.

geocentric coordinates—Coordinates that define the

position of a point with respect to the center of the

Earth or geoid. Geocentric coordinates can be either

Cartesian (x, y, z) or spherical (geocentric latitude and

longitude, and radial distance). Astronomic

coordinates are geocentric. 

geocentric geodetic coordinates—Geodetic

coordinates referred to a geocentric reference ellipsoid.

geocentric latitude—The angle at the center of the

Earth or geoid between the plane of the celestial

equator and a line to a point on the surface of the

Earth. An astronomic latitude is geocentric. 

geocentric longitude—Same as geodetic longitude.

geodesy—The science which deals with the

determination of the size and figure of the Earth. It

also deals with determining the external gravitational

field of the Earth, the internal structure of the Earth,

and derives three dimensional positions for points

above, at, and below the surface of the Earth.

geodetic control—A system of horizontal and/or

vertical control stations that have been established and

adjusted by geodetic methods and in which the size

and shape of the Earth have been considered in

position computations.

geodetic coordinates—The quantities of latitude,

longitude, and ellipsoid height, which define the

position of a point on the Earth’s surface with respect

to a reference ellipsoid. 

geodetic height—See ellipsoid height.

geodetic latitude—The angle between the plane of

the equator and the normal to the ellipsoid through the

computation point.

geodetic longitude—The angle between the plane of

the geodetic meridian and the plane of the prime

meridian. A geodetic longitude can be measured by

the angle at the pole of rotation of the reference

ellipsoid between the local and initial meridians, or by

the arc of the geodetic equator intercepted by

those meridians.

geodetic meridian—A line on a reference ellipsoid

which has the same geodetic longitude at every point.

geographic coordinates—Any coordinate system that

relates positions on the Earth in terms of latitude and

longitude. Both geodetic and astronomic coordinates

are geographic coordinates.

geoid—The equipotential surface in the gravity field

of the Earth which coincides with the undisturbed

mean sea level extended continuously through the

continents. The direction of gravity is perpendicular to

the geoid at every point. The geoid is the surface of

reference for astronomic observations and for

geodetic leveling.

geoid separation—The distance between the geoid

and the reference ellipsoid measured along a line that

is perpendicular to the ellipsoid. The distance is

positive if the geoid is outside (above) the ellipsoid.

Also called geoid height or undulation of the geoid.
E-10 _____________________________________________________________________________________________ MCWP 3-16.7

global positioning system time—The broadcast GPS

time signals are synchronized with atomic clocks at

the GPS Master Control Station. These clocks are in

turn periodically synchronized with Coordinated

Universal Time “leap seconds” to correct for the

slowing of the Earth’s rotation with respect to the sun;

GPS time is not. As of Oct 1995, GPS time equals

UTC + 10 sec. The fundamental time scale for all

Earth time keeping is the International Atomic Time

(TAI). It is a continuous time scale not corrected by

“leap seconds.” There is a constant offset of 10

seconds between GPS time and TAI such that GPS

time = TAI + 10 seconds.

graticule—A network of lines representing the Earth’s

parallels of latitude and meridians of longitude.

great circle—A great circle is a circle, the plane of

which passes through the center of a sphere or ellipsoid.

Greenwich Mean Time—Mean solar time at the

meridian of Greenwich, England, used as a basis for

standard time throughout the world. Also called GMT.

Greenwich meridian—The meridian of longitude

through Greenwich, England; serving as the reference

for Greenwich time, in contrast with local meridians.

It is accepted, almost universally, as the prime

meridian or the origin of measuring longitude.

Greenwich Time—Time based upon the Greenwich

meridian as reference, as contrasted with that based

upon a local or zone meridian. Greenwich Time is

referred to as Zulu Time.

grid—Two sets of parallel lines intersecting at right

angles and forming squares. When oriented with a

map projection, the grid is used to determine

grid coordinates.

grid convergence—The angular difference between

the meridian of a point located within a plane grid

system (such as UTM grid) and a line which is parallel

to the central meridian of that grid and passing through

the point.

grid coordinates—Numbers and letters of a two

dimensional coordinate system which designate a

point on a gridded map, photograph, or chart.

grid coordinate system—A plane-rectangular

coordinate system usually based on, and

mathematically adjusted to, a map projection. Also

called a grid reference system.

grid north—The northerly or zero direction of a grid

oriented with a projection. Grid north in one grid

system may not be the same direction as in another

grid system.

grid zone—An arbitrary division of the Earth’s

surface designated for identification without reference

to latitude or longitude.

gyroscope—A spinning wheel which tends to keep a

fixed orientation in space. Used to sense rotation. 

gyrocompassing—A method used to find true north

by sensing the Earth’s rotation.

handover word—The word in the GPS message that

contains time synchronization information for the

transfer from the C/A-code to the P-code.

HDOP—See DOP.

height—The vertical distance of an object or point

above a reference plane. 

height of instrument—The height of the center of the

telescopic alidade above the ground or station mark.

horizon—The horizon for any place on the surface of

the Earth is the great circle formed on the celestial

sphere by the extension of the plane of the observer's

horizon. In general, the apparent or visible junction of

Earth and sky as seen from any position.

horizontal angle—In artillery survey, the angle

formed by the intersection of the line between the

occupied station and rear station and the line between

the occupied station and the forward. This angle is

measured from the rear station to the forward station.

horizontal control—A network of stations of known

geographic or grid positions referred to a common

horizontal datum. 

hour angle—The time elapsed since the upper transit

of a celestial body. It is the angle between the

observer’s meridian and the hour circle of the celestial

body, measured positive westward from the meridian.

hour circle—Any great circle on the celestial sphere

whose plane is perpendicular to the plane of the

celestial equator. 

instrument parallax—A change in the apparent

position of an object with respect to the reference
Marine Artillery Survey Operations ______________________________________________________________________ E-11

marks of an instrument which is caused by imperfect

adjustment of the instrument.

integer-cycle ambiguity—The unknown integer

number of whole carrier cycles between the satellite

and the receiver.

inter range operational number—A random number

assigned to various Earth orbiting objects assigned by

the joint US/Canadian North American Aerospace

Defense Command (NORAD). Each GPS satellite has

an individual IRON. Also called IRON.

intersection—The procedure of determining the

horizontal position of an unoccupied point by direction

observations from two or more known positions.

intersection station—A station whose horizontal

position is determined by observations made from

other stations. No observations are made from this

station to determine its position.

ionosphere—The region of the Earth’s atmosphere

between the stratosphere and the exosphere

approximately 50 to 250 miles above the surface of

the earth.

ionospheric refraction delay—A delay in the

propagation of the GPS signal caused by the signal

traveling through the ionosphere.

joint operations graphic—The standard 1:250,000

scale DoD cartographic product which may be

produced in three versions: JOG/G (Series 1501) is

designed to meet ground requirements, JOG/A (Series

1501 Air) is designed to meet air requirements, JOG/R

(Series 1501 Radar) is the air target material version

in support of radar/intelligence planning and

operations requirements.

kinematic positioning—A GPS differential surveying

technique, whereby one GPS unit, the fixed receiver,

stays on a known control point, while another unit, the

rover, collects data on a constantly moving vehicle,

while continually tracking four or more satellites

during the observation period. This method of GPS

survey is used to determine the position of the rover

receiver. Also called dynamic positioning.

L1—See L-band.

L2—See L-band.

lambert conformal conic map projection—A

conformal map projection of the conical type. This

projection presents all meridians as straight lines

which intersect at a common point outside the

boundaries of the map sheet. All parallels are

represented as arcs of circles with a common center

located at the intersection of the meridians. The cone

can be projected either tangent or secant to the

reference ellipsoid.

lambert grid—An informal designation for a

coordinate system based on a Lambert conformal

map projection.

latitude—The angular distance, for a specific spot on

the surface of the Earth, from 0° to 90° north or south

of the equator.

L-band—The radio frequency band from 390 MHz to

1550 MHz. The primary L-band signal radiated by

each NAVSTAR satellite is L1 at 1575.42 MHz. The

L1 beacon is modulated with the C/A and P-codes, and

with the NAV message. The L2 signal is centered at

1227.50 MHz and is modulated with the P-code and

NAV message.

leap second—The step adjustment made to UTC to

compensate for approximately 1 second of additional

time that is transmitted by UTC signals each year.

Normally, UTC is decreased by exactly 1 second (i.e.

the leap second) at 24 hours on the last day of

December, and/or June.

least squares—A method of adjusting observations in

which the sum of the squares of all of the deviations or

residuals derived in fitting the observations to a

mathematical model is made a minimum. Such an

adjustment is based on the assumption that blunders

and systematic errors have been removed from the

data, and only random errors remain.

lensatic compass—A type of magnetic compass

equipped with a lens which permits the observer to

read the far side of the moveable dial. The scale is

usually incremented in both mils and degrees.

leveling—The operations of measuring vertical

distances to determine elevations. 
E-12 _____________________________________________________________________________________________ MCWP 3-16.7

local coordinate system—A right handed rectangular

coordinate system of which the z-axis coincides with

the plumb line through the origin.

local datum—The point of reference for geodetic

control used exclusively in a small area. Usually

identified by a proper name.

local time—Time based on the local meridian as

reference, as contrasted with time based upon a time

zone meridian or the meridian of Greenwich.

lock—The state of noninteruption in the reception of a

radio signal.

loop traverse—A closed traverse which starts and

ends at the same station. This traverse provides no

check on starting position and azimuth, nor does it

provide validation against systematic distance error.

loran—A long-range radio navigation position fixing

system using the time difference of reception of pulse

type transmissions from two or more fixed positions.

loran C—A loran position fixing system using a

combination of time difference of reception and phase

difference of signals from two stations to provide a

line of position.

longitude—The angular distance, for a specific spot

on the Earth, from 0° to 180° east or west of the

Greenwich meridian, which is used by most nations as

the prime or initial meridian.

magnetic north—The direction indicated by the north

seeking pole of a freely suspended magnetic needle,

influenced only by the Earth’s magnetic field.

magnitude—Relative brightness of a celestial body. In

artillery survey, there are 73 (Sun not included) accepted

survey stars. Sirius (star #25) is the brightest of those

stars with a magnitude of -1.6; Octanis (star #69) is the

dimmest of those stars with a magnitude of +3.7.

map—A graphic representation of the Earth or a part

of the Earth at an established scale, projected on a

plane surface.

map projection—A systematic drawing of lines on a

plane surface to represent parallels of latitude and

meridians of longitude of the Earth or of a section of

the earth. The type of map projection used is

dependent upon the purpose of the map.

map scale—The ratio or fraction between the distance

on a map or chart and the corresponding ground

distance. Military maps are usually classified as one of

three types: Large scale maps have a scale of 1:75,000

or larger, medium scale maps have a scale that is

larger than 1:600,000 and smaller than 1:75,000, small

scale maps have a scale of 1:600,000 or smaller.

Standard scales for military maps are specified in

STANAG 3677.

map series—A collection of map sheets usually

having the same scale and cartographic specifications.

map sheet—An individual map or chart, usually part

of a series.

marginal data—All explanatory information given in

the margin of a map or chart which clarifies, defines,

illustrates, and/or supplements the graphic portion of

the map sheet. Marginal data requirements for military

maps and charts are specified in STANAG 3676.

mean sea level—The average height of the surface of

the sea for all stages of the tide; used as a reference

(datum) for elevations and closely resembles the

geoid. Also called MSL.

mercator map projection—A conformal map

projection of the cylindrical type. This projection

depicts the equator as a straight line true to scale. The

meridians of longitude are represented by evenly

spaced parallel lines set perpendicular to the equator.

The parallels of latitude are depictedas a set of lines

placed perpendicular to the meridians and therefore

parallel to the equator. Conformality is maintained by

increasing the space between the parallels of latitude

as they increase in distance from the equator.

meridian—A north-south reference line, particularly a

great circle, through the geographical poles of the Earth,

from which longitudes and azimuths are determined.

Military Grid Reference System—A system used to

accurately identify the unique position of a point on the

Earth’s surface. This system is designed for use with

the UTM and UPS grid systems. Also called MGRS.

monitor station—One of five worldwide stations

maintained by the DOD and used in the GPS control

segment to monitor and control satellite clock and

orbital parameters. Corrections are calculated and

uploaded to each satellite at least once per day.
Marine Artillery Survey Operations ______________________________________________________________________ E-13

multipath—A phenomenon similar to “ghosts” on a

television screen; whereby GPS signals from a

satellite arrive at an antenna after having traversed

different paths. The signal traversing the longer path

may have been reflected off one or more objects (i.e.,

the ground, water, building, etc.) and once received by

the antenna will result in a larger pseudo-range

estimate and increase the error. Multipath usually

results in multipath error.

multipath error—A position error resulting from

radio signals traveling from the transmitter to the

receiver by two paths of different electrical lengths.

nadir—That point where the extension of the plumb

line beneath the observer intersects the celestial sphere.

national geodetic reference system—A system of

common or relative survey control points throughout

the United States and Puerto Rico as adjusted by the

National Geodetic Survey (NGS). Also called NGRS.

NAV data—The 1500-bit navigation message

broadcast by each satellite at 50 bps on both the L1

and L2 beacons. This message contains system time,

clock correction parameters, ionospheric delay model

parameters, and the satellite vehicle’s ephemeris and

health. This information is used to process GPS

signals and obtain user position and velocity.

Sometimes referred to as the navigation message,

satellite message, or the D-code.

NAVSTAR—NAVigation satellite timing and ranging.

NAVSTAR is the name given to GPS satellites,

originally manufactured by Rockwell International.

neatlines—The lines that bound the body of a map;

usually parallels and meridians, they can sometimes be

conventional or arbitrary grid lines.

normal—A straight line that is perpendicular to a

surface or to another line.

northing—A northward (bottom to top) reading of

grid values on a map.

oblate ellipsoid—An ellipsoid whose shorter axis is the

axis of rotation. All current reference ellipsoids

are oblate.

observer’s meridian—The great circle on the

celestial sphere that passes through both celestial

poles, and the observer’s zenith. 

open traverse—A traverse which begins from a

station of known or assumed position, but does not end

on such a station. This procedure allows no

verification of fieldwork or starting control.

optical plummet—See vertical collimation.

orienting line—A line of known azimuth between

two points on the ground.

orthometric height—See elevation.

outage—The period of time when the dilution of

precision exceeds a specified maximum.

overlapping grid—The extension of a military grid

beyond its designated limits to map sheets in areas

bordering grid, grid zone, or ellipsoid/datum junctions.

Normally a large-scale map within 25 miles of a

junction will depict the overlapping grid as tick marks

located outside the neatlines of the map.

parallax—The difference in altitude of a body as seen

from the center of the Earth, and from a point on the

surface of the Earth. There is no apparent parallax of

the fixed stars, but that of the sun and planets is

measurable. Parallax makes the body appear lower

than it actually is; therefore, the correction is added.

parallel—A circle on the surface of the Earth or

ellipsoid, parallel to the equator, which connects all

points of equal latitude.

PDOP—See DOP.

perigee—The point in the orbit of a satellite about the

Earth that is the least distant from the center of

the Earth.

phase measurement—A measurement expressed as a

percentage of a portion of an entire wave (e.g., a sine

wave). For example, a complete wavelength is 100%,

one-half is 50%.

plane rectangular coordinates—A system of

coordinates in a horizontal plane used to describe the

positions of points with respect to an arbitrary origin.

The origin is established by a pair of axes which

intersect at right angles. The position of a point is

determined by its distance from these axes.
E-14 _____________________________________________________________________________________________ MCWP 3-16.7

plane survey—A survey in which the surface of the

Earth is considered a plane. Precise results may be

obtained with plane survey techniques in small areas;

however, the accuracy and precision of such results

will decrease as the survey increases in size.

polar distance—The side of the PZS triangle from the

celestial north pole to the celestial body. The polar

distance is determined by algebraically subtracting the

declination of the body from 90° (1600 mils). 

polar map projection—A map projection centered on

a pole.

polar stereographic map projection—A

stereographic projection centered on a pole of the

reference ellipsoid.

polaris—The second magnitude star, Alpha, in the

constellation Ursa Minor (Little Dipper). In artillery

survey, it is the recommended star for astronomic

observations. It is listed as star #10 and has a

magnitude of 2.1. Polaris is called the North Star.

porro prism—A prism which has two reflecting

surfaces at right angles to each other. It deviates the

axis 180° and inverts the image in the plane in which

the reflection takes place.

precise code (P-code)—A sequence of pseudorandom binary biphase modulations on the GPS

carriers L1 and L2 at a chipping rate of 10.23 MHz

which repeats every 267 days. It is divided into 37

one-week segments, five of which are used by the

ground segment and the other 32 are available for

satellite vehicles. Therefore, each SV has a unique

one-week segment code which is a subset of the

overall P(Y) code sequence.

precise ephemeris—The ephemeris computed after

the transmission of the satellite signal and based on

satellite tracking information. The broadcast

ephemeris tells where the satellite is expected to be,

and the precise ephemeris is where the satellite

actually was.

precise positioning service—Dynamic positioning of

a single receiver based on the P-code. Currently, PPS

is the most accurate dynamic positioning service

offered with GPS. In general, a receiver can only be

considered a PPS receiver if it can use the encrypted

Y-code, and negate S/A. Also called PPS.

precision—How close a group or sample of

measurements are to each other. A group of

measurements will have high precision and low

accuracy if the measurements are close together yet

not close to a standard or true measurement. High

precision is indicated by a low standard deviation. 

preferred datum—A geodetic datum selected as a

base for consolidation of local independent datums

within a geographical area.

prime meridian—The meridian of 0° longitude, used

as the origin for measurement of longitude. Also

called the Greenwich meridian.

prime vertical—The vertical circle that is

perpendicular to the plane of the observer’s meridian

and intersects the celestial horizon at the points

directly true east and west of the observer’s meridian.

projection—The extension of lines or planes to

intersect a given surface; the transfer of a point from

one surface to a corresponding position on another

surface by graphical or analytical methods.

pseudolite—A ground based GPS station that can be

used in a ranging solution. The station transmits a

signal with a structure similar to that of an actual

GPS satellite.

pseudo-random noise—When used as a description

of code, it indicates that the code has some random

noise-like properties. Each GPS satellite has a unique

PRN number assigned to it. Also called PRN.

pseudo-range—The time shift required to align a

replica of a GPS code generated in the receiver with

the code received from the satellite, scaled into

distance by the speed of light. The time shift is the

difference between the time of signal reception and the

time of signal transmission where the reception is

measured in the receiver time reference and the

transmission is measured in the satellite time

reference. Therefore, the pseudo-range contains

several errors including satellite/receiver time offset

and satellite ephemeris error.

pseudo-range observable—The difference between

the time of transmission and the time of arrival of a

particular signal transmitted by the satellite.

radial error—See error of closure, (3).
Marine Artillery Survey Operations ______________________________________________________________________ E-15

random error—Those errors not classified as

blunders, systematic errors, or periodic errors. They

are numerous, individually small, and each is as likely

to be positive as negative.

RDOP— See DOP.

reciprocal vertical angle—A vertical angle measured

over a line at both ends to eliminate (at least partly) the

effects of curvature and refraction. Reciprocal

observations must be made as simultaneously as

practical to reduce error caused by changing

refractive conditions.

reference ellipsoid—A mathematical figure used to

closely approach the dimensions of the geoid in the

section of the Earth's surface being considered.

refraction—The refraction of a celestial body is the

apparent displacement of the body caused by the

bending of light rays passing through the Earth's

gravitation, and layers of varying air density. The

celestial body will appear higher than it actually is;

therefore, the correction is subtracted.

rejection limit—Used in survey to refer to a maximum

allowable error or deviation from a standard, usually a

mean value, of two or more measurements.

relief—Inequalities of elevation and the configuration

of land features on the surface of the Earth which may

be represented on maps or charts by contours, shading,

or spot elevations.

resection—The determination of the horizontal

position of a station by observed directions from that

station to points with known positions.

residual—A general term denoting a quantity

remaining after some other quantity has been

subtracted. For example, if the true value of a

measurement is subtracted from the observed value,

the difference can be called a residual; it is often

referred to as an error.

residual error—The difference between any value of

a quantity in a series of observations, corrected for

known systematic errors, and the value of the quantity

obtained from the combination or adjustment of that

series. Frequently used as the difference between an

observed value and the mean of all observed values of

a set.

reticle—A system of wires, hairs, etched lines, or the

like, placed normal to the axis of a telescope at its

principle focus, by means of which the telescope is

sighted on a target, or by means of which readings are

made on some scale such as a leveling or stadia rod. 

revolution—The turning of a body about an exterior

point or object. The Earth revolves around the sun on a

600 million mile orbit at a speed of about 18.5 miles

per second.

right ascension—The right ascension (RA) of a

celestial body is the arc on the celestial equator

measured from the vernal equinox eastward to the

hour circle of the body. It is measured in units of time

from 0 to 24 hours. Right ascension roughly

corresponds to longitude on Earth.

root mean square— See Standard Deviation.

rotation—The turning of a body on its axis. The body

usually rotates around its north-south axis; the Earth

rotates from west to east.

satellite surveying—(1) (Doppler) The process of

positioning one or more points on the Earth’s surface by

collecting Doppler shift data from passes of Navy

navigation satellites. (2)(NAVSTAR GPS) The process

of positioning one or more points by resection with

signals received from Global Positioning Satellites.

scale factor—A multiplier for reducing a distance

from a map to the actual distance on the datum of the

map. Scale factor is dependent on the map projection.

S-code—Another name for C/A-code.

secant—A line that intersects a geometric curve or

surface at two or more points. For example, a cone that

is secant to an ellipsoid, intersects the ellipsoid at two

different parallels of latitude. 

secondary grid—An obsolete grid shown on maps in

conjunction with the primary grid. An example is a

map sheet with UTM as the primary grid and British

National as a secondary grid.

selective availability—The DOD policy of

intentionally degrading the accuracy of the C/A-code.

semi-major axis—One-half of the longest diameter of

an ellipse.
E-16 _____________________________________________________________________________________________ MCWP 3-16.7

semi-minor axis—One-half of the shortest diameter

of an ellipse.

sidereal time—Time determined by the stars. A

sidereal day is 3 minutes and 56 seconds shorter than a

24-hour day.

simultaneous measurements—A measurement or set

of measurements referred to the same epoch.

single differencing—See differencing.

slow switching channel—A channel that switches

with a period too long to recover the integer part of the

carrier phase.

solar time—Time determined by the sun. A solar day

is 24 hours in duration.

solstice—The solstice occurs at two points on the

ecliptic midway between each equinox. When the

ecliptic is north of the celestial equator, the midpoint is

called the summer solstice and occurs about 21 June.

When the ecliptic is south of the celestial equator, the

midpoint is called the winter solstice and occurs about

21 December. The solstice occurs when the Sun is at

its greatest distance north or south of the equator.

space segment—The portion of the GPS system with

the major components in space; consists mainly of

the satellites.

spherical coordinates—A coordinate system used to

locate points on the celestial sphere. The two systems

currently in use are the horizon and equator systems.

Artillery surveyors use the equator system. The origin

for this system is the vernal equinox and the celestial

equator. See celestial coordinates.

spheroid—See ellipsoid. 

spot elevation—A point on a map or chart whose

elevation is noted, usually not monumented.

squaring-type channel—A receiver channel that

multiplies the received signal by itself to obtain a

second harmonic of the carrier which does not contain

the code modulation.

standard deviation—(1) The range of how close the

measured values are from the arithmetic average. A

low standard deviation indicates that the

measurements or observations are close together.

(2) The square root of the quantity obtained by

dividing the sum of the squared errors by the number

of errors minus one. Also called standard error and

root mean square (RMS).

standard positioning service—Positioning of a

single receiver based on the C/A-code.

state plane coordinate system—The planerectangular coordinate systems established by the

National Geodetic Survey (NGS), one for each state in

the US, for use in defining positions of geodetic stations

in terms of plane-rectangular (X, Y) coordinates.

stereographic map projection—A perspective,

conformal, map projection on a tangent plane, with the

point of projection at the opposite end of the diameter

of the sphere from the tangent plane.

stop-and-go kinematics surveying—A GPS

differential survey technique whereby one GPS

receiver, the fixed receiver, remains on a station of

known position while the other receiver, the rover,

collects signals on an unknown station for a short

period of time, then moves to subsequent points to

collect signals for a another short period of time, all

the while, continually tracking four or more satellites

during the observation period. This technique is used

to determine the position of the rover receiver.

survey—The act or operation of making

measurements for determining the relative positions of

points on, above, or beneath the Earth’s surface.

survey, geodetic—Survey procedures that take into

effect the size and shape of the Earth. A reference

ellipsoid that mathematically represents the geoid and

the horizontal and vertical datums is used.

survey, plane—Those survey procedures in which the

curvature of the Earth is not usually considered and

computations of relative positions are made using the

principles of plane geometry and plane trigonometry.

switching channel—A channel that is sequenced

through a number of satellite signals at a rate that

is slower than and asynchronous with the message

data rate.

systematic error— See accumulative error.

tangent—A line, curve, plane or other geometric

figure that touches another geometric figure in only

one point.
Marine Artillery Survey Operations ______________________________________________________________________ E-17

theodolite—A precision surveying instrument

consisting of an alidade with a telescope. It is mounted

on an accurately graduated circle and is equipped with

necessary levels and reading devices. Sometimes the

alidade includes a graduated vertical circle.

time tag—The time appended to a GPS measurement.

time zone—An area in all parts of which the same time

is kept. In general, the world is divided into 24 time

zones, each 15° wide and centered on a meridian whose

longitude is evenly divisible by 15. In many areas of the

world, political time zones are observed which means

that the standard time zone has been expanded to cover

the entire political boundary of the area.

topographic map—A map which presents the vertical

position of features in measurable form as well as their

horizontal positions.

translocation—See differential positioning.

transverse mercator map projection—A conformal,

cylindrical map projection, being in principle

equivalent to the Mercator map projection turned

(transverse) 90° in azimuth. In this projection, the

central meridian of each 6° zone is represented by a

straight line. The cylinder can be tangent to the ellipsoid

but is usually considered to be secant to the ellipsoid.

traverse—A method of surveying in which distances

and azimuths between stations are determined for use

in the computations of the positions of the stations.

triangulation—A method of surveying in which

interior angles of single or adjacent triangles are

measured to determine the position of stations located

at the vertices of each triangle.

trig list—A list of essential information of accurately

located survey control points, both horizontal and

vertical. For military units, guidance for these listings

is provided in STANAG 2210.

trilateration—A method of surveying wherein the

lengths of the triangle sides are measured, usually by

electronic methods, and the angles are computed from

the measured lengths.

triple differencing— See differencing.

troposhere—The inner layer of the atmosphere,

located between 6 and 12 miles above the Earth’s

surface.

true north—The direction from an observer’s

position to the geographical North Pole. The north

direction of any geographic meridian.

undulation—The dips and swells that are the surface

of the geoid.

universal polar stereographic grid—A military grid

system based on the polar stereographic map

projection. Applied to maps of the Earth’s polar

regions north of 84° N latitude and south of 80° S

latitude. Also called UPS grid.

universal time—Standard universally accepted time

based on the Greenwich meridian.

universal time coordinated—A uniform time system

based on an atomic second maintained within 1 second

of true time (UT1 and UT2) by the addition or deletion

of leap seconds. Also called UTC.

universal transverse mercator grid—A military grid

system based on the transverse mercator map

projection. Applied to maps between the latitudes of

84° N and 80° S. Also called UTM grid.

user equivalent range error—A term for GPS

measurement accuracy which represents the combined

effects of ephemeris uncertainties, propagation errors,

clock and timing errors, and receiver noise. A high

UERE may indicate that S/A has been imposed on

the satellite. Also called UERE.

user segment—The portion of the GPS system that is

directly interfaced by the user; mainly GPS receivers.

vertical dilution of precision—See DOP.

vector—See baseline.

vernal equinox—The imaginary point on the celestial

sphere where the apparent annual path of the sun crosses

the celestial equator moving from south to north. The

point from which right ascension is measured.

vertical—The line perpendicular to the geoid at any

point. It is the direction of which the force of

gravity acts.

vertical angle—(1) An angle in a vertical plane. (2) A

vertical angle can be either the angle formed between

the zenith and a line to a point (zenith distance) or the

angle formed between the horizon and a line to a point

(altitude). The zenith distance and altitude are
E-18 _____________________________________________________________________________________________ MCWP 3-16.7

complimentary angles. In artillery survey the second is

used. Our instruments provide a zenith distance which

we have termed the vertical reading. This reading is

applied to 1600 mils (4800 mils in reverse mode) to

compute the vertical angle. 

vertical circle—Any great circle on the celestial

sphere that passes through the observer’s zenith-nadir.

vertical collimation—A telescope so mounted that its

collimation axis can be made to coincide with the

vertical (or direction of the plumb line). The vertical

collimator serves as an optical plumb; it is usually

designed for use in placing a mark on the ground

directly under an instrument or for placing an

instrument directly over a mark on the ground. Also

called optical plummet.

World Geodetic System—One of several Earthcentered Earth-fixed ellipsoid/datum systems which

positions its origin at the center of the Earth’s mass.

Designed by the DoD to replace local datums, WGS84 is the current system in use. Also called WGS.

X-axis—(1) In a system of plane rectangular

coordinates, the x-axis is the line on which distances to

the right or left (east or west) of the reference line are

marked and measured. (2) In a three dimensional

system (i.e. Cartesian coordinates) the x-axis is the

line that lies perpendicular to the y-z plane and

intersects that plane at its origin. An x-coordinate is

the length of a line in the x-y plane that is parallel to

the x-axis and measured from the y-z plane.

Y-axis—(1) In a system of plane rectangular

coordinates, the y-axis is the line on which distances

above or below (north or south) of a reference line are

marked and measured. (2) In a three dimensional

system (i.e. Cartesian coordinates) the y-axis is the

line that lies perpendicular to the x-z plane and

intersects that plane at its origin. A y-coordinate is the

length of a line in the x-y plane that is parallel to the yaxis and measured from the x-z plane.

Y-Code—Essentially the P-code after encryption.

Z-axis—In a three dimensional coordinate system (i.e.

Cartesian coordinates), the z-axis is the line that lies

perpendicular to the x-y plane and intersects that plane

at its origin. The z-axis coincides with the rotational

axis of a reference ellipsoid. A z-coordinate is the

length of a line that is parallel to the z-axis and is

measured from the intersection of the x-coordinate and

y-coordinate to a point on the surface of the Earth.

Z-count word—The GPS satellite clock time at the

leading edge of the data subframe of the transmitted

NAV data message.

Z-time— See Greenwich Mean Time.

zenith—The point where the extension of the plumb

line overhead intersects the celestial sphere.

zenith distance—A vertical angle measured from the

zenith to a point or object.

zenith-nadir—The zenith and nadir for any place on

the surface of the Earth are two points where an

extension of the observer’s plumb line intersects the

celestial sphere. The zenith is the point directly

overhead, the nadir is the point directly below. 

zero-velocity correction—A term used with inertial

survey systems, particularly the Position and Azimuth

Determining System (PADS), which refers to a

method of minimizing navigation errors. Whenever

the vehicle is stopped, the system measures its velocity

errors and the computer applies corrections to the

accelerometer data. 
APPENDIX F. REFERENCES AND

RELATED PUBLICATIONS

Standardization Agreements (STANAGs)

2210 Trig Lists (Lists of Geodetic Data)

2211 Geodetic Datums, Ellipsoids, Grids, and Grid References

2934 Artillery Procedures

3676 Marginal Information on Land Maps, Aeronautic Charts, and Photomaps

3677 Standard Scales for Land Maps and Aeronautic Charts

National Imagery and Mapping Agency (NIMA)

DMA TR 80-003 

Edition 5

Geodesy for the Layman

DMA TM 8358.1 

Edition 1

Datums, Ellipsoids, Grids, and Grid Reference Systems

DMA TM 8358.2

Edition 1

The Universal Grids: Universal Tansverse Mercator (UTM) and Universal

Polar Stereographic (UPS)

NIMA TR 8350.2 

Edition 3

DOD World Geodetic System 1984: Its Definition and Relationships with

Local Geodetic Systems

MIL-HDBK-850 MILITARY HANDBOOK: Glossary of Mapping, Charting, and Geodetic

Terms

National Oceanographic and Atmospheric Agency (NOAA) 

Technical Memoranda

NOS NGS-16 Determination of North American Datum 1983 Coordinates of Map

Corners

NOS NGS-43 Performing Centimeter-Level Surveys in Seconds With GPS Carrier

Phase: Initial Results

NOS NGS -50 NADCON

NOAA Technical Reports

NOS 73 NGS 8 Control Leveling

NOS 88 NGS 19 Horizontal Control

NOS 110 NGS 32 Orthometric Height Determination Using GPS Observations and the

Integrated Geodesy Adjustment Model

NOS 121 NGS 39 National Geodetic Survey Gravity Network

NOAA Manuals

NOS NGS 1 Geodetic Bench Marks

NOS NGS 3 Geodetic Leveling

NOS NGS 5 State Plane Coordinate System of 1983
F-2 ______________________________________________________________________________________________ MCWP 3-16.7

NOAA Professional Paper

NOS 2 North American Datum of 1983

Federal Geodetic Control Subcommittee (FGCS) Publications

Geometric Geodetic Accuracy Standards And Specifications for Using GPS Relative Positioning

Techniques

NGS Charting & Geodetic Services Bull. Geod. 59 

Standards and Specifications For Geodetic Control Networks

Use and Value of a Geodetic Reference System

Input Formats and Specifications of the National Geodetic Survey Data Base:

Volumes 1, II, and III

U.S. Army Engineer Manuals (EMs)

1110-1-1002 Survey Markers and Monumentation

1110-1-1003 NAVSTAR Global Positioning System Surveying

U.S. Army Field Manuals (FMs)

5-36 Route Reconnaissance and Classification

5-232 Topographic Survey

5-233 Construction Surveying

5-553 General Drafting

6-2 Tactics, Techniques, and Procedures for Field Artillery Survey

6-20-10 Tactics, Techniques, and Procedures for the Targeting Process

6-30 Tactics, Techniques, and Procedures for Observed Fire

6-50 Tactics, Techniques, and Procedures for the Field Artillery Cannon Battery 

6-121 Tactics, Techniques, and Procedures for Field Artillery Target Acquisition 

21-26 Map Reading and Land Navigation

21-31 Topographic Symbols

101-5-1 Operational Terms and Graphics

Marine Corps Technical Manuals (TMs) 

08837A-12/1A Operators and Organizational Maintenance Manual for Position and

Azimuth Determining System, AN/USQ-70

9-1290-262-10 Aiming Circle, M2A2 

Miscellaneous

Distomat TM Wild DI3000 User Manual