Position Location for Marine Science and Technology Applications Using a Satellite-Based Range and Range Rate Radio System
Authors: Inciardi Richard A. 
Published: October 2008

1. Abstract

The marine science and technology area is characterized by a continually increasing number of users who require position location with varying degrees of accuracy and frequency. These users include (but are not restricted to):commercial ships (for navigation aid, harbor traffic control, search and rescue, and offshore drilling);unmoored buoys (for correlation of collected data and position information in order to develop environmental profiles); andunmanned instrumentation at offshore locations (for survey purposes).

The required accuracies range from a few feet for survey applications to one and one-half miles or more for commerical ship navigation, and frequencies of position finding from almost continuously to once a day or more are needed.

This paper treats the design and position accuracy analysis of a promising satellite-based position location system which can satisfy, in an economical fashion, the performance requirements of the various marine science and technology users. Position location is carried out by means of a single satellite employing an original range and range rate measurement method. Active participation of satellite ground control station, satellite, and user is required. The system design was executed under the important practical constraint of simple measurement instrumentation at the user in order to minimize the per unit user investment.

The material in the paper is divided into four sections:description of position location system and the role of ground station, satellite, and user in the position determination procedure;probabilistic analysis of position location accuracy with emphasis of evolution of criteria for instrumentation measurement accuracy;design of measurement instrumentation with emphasis on user equipment; andapplications to marine science and technology users.

Two new analytical techniques, developed specifically for the study of the range and range rate problem but applicable to position location systems in general, will be emphasized. Briefly, these techniques deal with:the notion of "distribution-free" accuracy for evaluating position accuracy in situations where the error distribution is unknown; andthe inclusion and statistical treatment of bias errors in the probabilistic analysis of position accuracy.

II. Description of the Range and Range Rate Position Location System

All position location systems can be unified in terms of the geometry of quadric surfaces, i.e., three-dimensional surfaces. Measurements are made which determine -distance and/or angle variables. These measurements are relative to positions or orientations either known or determined by other measurements. Each variable generates a quadric surface on which the measurement-determined position is located. An example of a quadric surface is the sphere generated by the measurement determined range between a user-and a satellite. Solution of the equations of three quadric surfaces yields the position (in general the solution yields a number of positions and the ambiguities must be resolved). A spherical or ellipsoidal approximation to the Earth's figure is often used as one of the surfaces (suitably extended to take into account user altitude above mean sea level).

The position location concept considered in this paper is based on the measurement of the range and range rate between a single satellite and the user as well as a knowledge of user altitude and velocity and satellite position and