TMTMTM

OnPOZ Precision Positioning is a division of VGI Solutions. EZTag CE and EZField are recognized trademark of VGI Solutions. EZSurv is a registered trademark of VGI Solutions.
All other trademarks are registered or recognized by their respective owners. Windows and the Windows logo are trademarks or registered trademarks of Microsoft Corporationin the United States and/or other countries. © 2008 VGI Solutions. All rights reserved.

Product Technical Notes // october 2008
TMEZSurv
GNSS Post-Processing Software

EZSurv

TM

GNSS Post-Processing Software

EZSurv Post-ProcessorTM

TO get the best out of your GNSS data

EZSurv software is a complete solution designed by OnPOZ
Precision Positioning to easily process raw GNSS data. It
is an open solution that processes GPS as well as GLONASS
signal. It provides all the flexibility you need by offering
fully graphical (PlanView) and Windows Explorer types(ProjectManager) of user interfaces to a
­ ccommodate
your preferred way of working.
TMThe software can also be adapted to the user’s profile byoffering a choice of manual post-processing steps or using
a single keystroke to do it all in one step. This technicaloverview presents some of the key features of EZSurv .
TMEZSurv facilitates the post-processing of GNSS files since
it is fully compatible with multiple GNSS receivers. EZSurv
uses GNSS manufacturer binary format allowing users toskip RINEX conversions.
TM

TMEZSurv is fully compatible with OnPOZ Precision Positioning’s
EZTagCE and EZField field data acquisition software.
TMTM

TMEZSurv key features
TM• Easy-to-use graphical user interface•	Rigorous Noise Reduction System (NRS) to smooth noisy data

• Project Manager for easy data handling• Support for all kinds of processing modes• Data archiving capability•	Single keystroke to automatically launch all processing steps•	Fully automated Base Station search
to post-process Rover data

• Advanced quality control tools• Multiple mapping system supports

EZSurv is powered by OnPOZ Precision Positioning //© 2008 VGI Solutions. All Rights reserved.
TM• Compatible with many GNSS receivers raw format

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EZSurv

TM

GNSS Post-Processing Software

Planning Tools

EZSurv ’s Planner helps schedule your GNSS data collection.
Different types of visibility plots: sky plots, number ofvisible satellites, DOPs plots, etc., can be g
­ enerated tohelp determine the most suitable times for your datacollection. Site obstructions (e.g. buildings and trees) canalso be input (using azimuth and elevation) at each of yoursurvey sites to help generate more realistic visibility plots.
TMExtend Your
Base Station Network
To post-process your data, EZSurv uses smart technology tosearch the Internet for the best GNSS base station that fits yourfield data. This search is performed on a number of existing
GNSS networks around the world. Using this feature, you donot have to worry about post-processing your data since it’shandled automatically with a single keystroke. All you needis an Internet connection. If you maintain your own GNSS
network, it could be easily incorporated into the search througha LAN connection. Other networks can easily be integrated.
TMEasy Data Import

Importing your GNSS datasets becomes a straightforwardtask since you can easily drag and drop your files into theobservations window to quickly see their descriptions andattributes. To avoid long conversion processes, EZSurv
directly supports raw binary formats from several
manufacturers as well as the receiver independentexchange format (RINEX).
TM

SUPPORTED GNSS DATA FORMATS
Rinex v2.10

Any GNSS receivers

Hemisphere GPSAll products

Magellan

DG14, ProMark 500

NavComAll products

NovatelAll products

Septentrio

All products

Ublox

TIM-LH, LEA-4T, LEA-5T

Coordinate Systems
EZSurv ’s Mapping Systems tool provides complete­coordinate-systems support. Over 62 standard datums
and 22 standard ellipsoids are predefined. Additionally,
you can create your own user-defined datums and­ellipsoids. There are also over 12 different map projection
templates, from which you can derive most mapping
systems used in the world. The US State-Plane Coordinate
System is fully supported, and local grids can be defined.
TMEZSurv is powered by OnPOZ Precision Positioning //© 2008 VGI Solutions. All Rights reserved.
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EZSurv

TM

GNSS Post-Processing Software

Powerful Processing Engine

EZSurv uses the latest GNSS processing techniques to get the mostout of your GNSS data. Depending on your fieldwork methodology,
the software will process any of the following modes:TM• Rapid static• Stop and go• Kinematic• Semi-kinematic• OTF (for single and dual frequency receivers).
The processing engine has the following key features:Precise Point-Positioning mode

Obtaining good accuracy for a site can be hard to achieve
if no established network is available to perform differential
GNSS. EZSurv ’s precise point-positioning mode gives you theability to build your own network to an absolute accuracy
better than 20 cm with a dual frequency receiver (50 cm withsingle frequency). To achieve such accuracy in ­point-positioningmode, precise orbits and clock files are used.
TM

Efficient outlier detection

One of the key steps in data processing is the detection of badobservations that can greatly affect the quality of your results.
EZSurv has efficient algorithms to detect and remove noisy
data and outliers so you always get optimized results.
TM

Automatic ambiguity fixing process

EZSurv relies on the well-known Lambda method to search and fix
phase ambiguities, giving you a powerful tool to achieve centimeter
accuracy surveys. It also has the advantage of automatically fixing
solutions on the fly when your observation window is appropriate,
without the need to use static sites (initialization).
TMEfficient data smoothing for noisy data

Urban canyon and dense forest canopy are tough­environments in which GNSS is often needed. To obtainacceptable results in those extreme areas, EZSurv uses
a Noise Reduction System (NRS) to optimize positioning
accuracy. The NRS uses Doppler and phase observations togreatly reduce the noise affecting pseudorange measurements.
TMFully adapted to process EZBar setup

Any tool that can help achieve a high level of accuracy isvery important for GNSS users. One of them is the EZBar
setup (bar with a known fixed length) which allows you tofix phase ambiguities within less than 2 minutes when using
a single frequency receiver. EZSurv automatically recognizes
EZBar’s file attributes during the import process so you don’t
have to worry about their location in your dataset.

Ambiguity smoothing

Some software allows you to use a backward process toget optimized solutions for your GNSS trajectories. EZSurv
makes this task obsolete since a rigorous forward ambiguity
smoothing process is used to do the same job with muchless data management.

TMTM

Data interpolation

You don’t have to worry about your base station’s data ratesince EZSurv can automatically perform a polynomialinterpolation (up to 60 sec.) to fit the rate you’ve used in
the field. Using EZSurv , you no longer have to interpolate
your RINEX base station data.
TMTMEZSurv is powered by OnPOZ Precision Positioning //© 2008 VGI Solutions. All Rights reserved.
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EZSurv

TMGNSS Post-Processing Software

Accuracy Table

EZSurv can process single or dual frequency data. The tablebelow illustrates the accuracies that can be achieved indifferent modes of operation depending on the GNSS data.
TMACCURACY
RECEIVERKINEMATICSTATICSEMI KINEMATIC

OTF

Singlefrequency

submeter1,
subfoot2

centimeter3

centimeter4,5

centimeter6

Dualfrequency

N/A

centimeter7

N/A

centimeter8

Advanced Quality
Control Tools

EZSurv offers a number of tools to help analyze your final survey
results. Graphical representations of phase or code residuals allow
you to assess your baseline and trajectory results, and graphicaltools help analyze cycle-slip occurrences in data. After processing,an analysis of common vectors is presented in a comprehensive
report, and baselines that did not achieve the specified accuracy
are flagged to isolate them for further analysis.
TM

1.	Horizontal accuracy (HRMS). Requires 5-10 minutes of continuous
tracking with at least 5 satellites and a PDOP better than 6. Multipath
and ionospheric effects can affect final accuracy. Base station
separation may affect accuracy by about 5 ppm (depending onthe quality of the base station data).
2.	Horizontal accuracy (HRMS). Requires 15-20 minutes of continuous
tracking with at least 5 satellites and a PDOP better than 6. Multipath
and ionospheric effects can affect final accuracy. Base station
separation may affect accuracy by about 5ppm (depending on
the quality of the base station data).
3.	Horizontal baseline accuracy (HRMS). Requires 15-30 minutes of gooddata on a minimum of 4 satellites and a PDOP better than 6. Multipath
and ionospheric effects can severely affect final accuracy. This
horizontal accuracy usually translates into 1cm +/- 2 ppm.
4.	Requires L1 frequency receiver that outputs quality code, Doppler
and carrier phase observations along with reliable real-timecycle-slip detection.
5.	EZField data collection software is designed to ease thesemi-kinematic process. It allows you to easily initialize
on an initialization bar or a known point.
TM

6.	Horizontal accuracy (HRMS). Requires 45 minutes of continuous
tracking with at least 5 satellites and a PDOP better than 6. Basestation must be within 10 km. Multipath and ionospheric effectscan affect this accuracy. This horizontal accuracy usually translates
into 2cm +/- 2 ppm.
7.	Static results require only 10-15 minutes of data to achieve
centimeter accuracy. This horizontal accuracy usually translates
into 1cm +/- 1 ppm (with good dual frequency data).
8.	OTF requires approximately 30 seconds of continuous tracking
with at least 5 satellites and a PDOP better than 6. Multipath
and ionospheric effects can affect final accuracy.

Data Editing
EZSurv ’s interface allows you to easily edit all site properties: name, coordinates, geoid undulation, height, time span, antennamodel, antenna height, multiple occupations, etc. Rover (moving receiver) file properties such as antenna model and height,time span, site within a rover file, etc., as well as baseline and trajectory properties, can also be easily edited.
TMEZSurv is powered by OnPOZ Precision Positioning //© 2008 VGI Solutions. All Rights reserved.
TM

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EZSurv

TM

GNSS Post-Processing Software

Loop Closure Tools

EZSurv allows you to analyze your baseline closure when you have redundant data. This helps you detect outliers in your dataset.
Loops can be directly created in the plan view by selecting the required baselines, or they can be created within Project Manager.
TMNetwork Adjustment
EZSurv ’s 3D network-adjustment tool allows you
to choose between a fixed or weighted station typeof adjustment that can be automatically or manually
made in your baseline results. During manual adjustment,
vectors can be included or excluded from your network witha simple mouse-click. After ­adjustment, a ­comprehensive
report is generated showing all the adjusted parameters
along with their statistical information. The plan view
displays both point and baseline (relative error)
ellipses and elevation error bars.
TMConclusion

All members of an engineering project team requirereliable survey results. EZSurv can help them without
numerous settings. Our main focus is “easy-to-use”
applications that provide optimum results.
TMEZSurv versionSTMEZSurv VersionFeatures

TMLITE•

Submeter/subfootL1 fixe
OTF L1L1•••

L1/L2 Fixe
OTF L1/L2

L1/L2•••••

Each version is available with full GNSS capability or GPS only.

EZSurv is powered by OnPOZ Precision Positioning //© 2008 VGI Solutions. All Rights reserved.
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