A position-location system utilizing geosynchronous communication satellites

Abstract

This dissertation describes a novel method of providing position-location from geosynchronous communication satellites. The Global Positioning System (GPS) has become the standard for position-location and navigation in the world. It provides extremely accurate coordinates to military users and slightly less accurate coordinates to "non-authorized" users. Disadvantages of GPS are complexity and high cost. The U.S. Department of Defense (DoD) has spent billions of dollars in developing and fielding the system. Maintenance and GPS satellite replenishment costs will continue to climb.

A simpler, lower cost alternative to the GPS system is explored. This study describes a position-location system using transponders on-board geosynchronous communication satellites. The system uses three geosynchronous communication satellites at a time to relay synchronized television signals. The signals provide a timing system to measure the ranges from the satellites to the receiver. The least squares method is used to calculate the location of the receiver.

A software model is developed to demonstrate the ability of the system to "track" three geosynchronous satellites and calculate receiver position. A test is conducted to demonstrate the use of television signals to provide timing for the system. The basic model is further refined by adding perturbation forces which act on the satellites. The Intelsat Eleven-Parameter algorithm is incorporated into the systenl model and provided the most precise location of the satellites. The accuracy of the proposed system in determining the position-location of the receiver is estimated based on the results of the simulation and the test. Further research is proposed to build on the concepts discussed in this dissertation.