Simulating the GPS Constellation for High Fidelity Operator Training

Lee Corrie, Rob Hazlehurst, Rick Walker, and Darlene Greenhut

Abstract:	The accuracy, integrity and availability of the Global Positioning System enjoyed by all users today is the result of well trained operators managing a robust satellite constellation with a reliable control system. To further improve operator training and control system reliability, the Air Force has contracted with Loral to develop a simulator where operators can become familiar with GPS operations in an off-line, realistic, penalty free environment, while developers can thoroughly test control system upgrades prior to delivery and without tying up operational resources. This paper describes the high fidelity GPS simulator Loral is developing. The simulator will build upon existing ground system simulator software, and will take advantage of actual GPS spacecraft software developed by the satellite and payload manufacturers. Using multi-processor computers, the system will simulate the entire satellite constellation to provide training in managing GPS worldwide navigation performance. At the same time, up to 4 complete satellite simulations can be run simultaneously to train in routine and anomalous operations of the satellites and satellite subsystems. Finally, all ground resources outside the walls of the MCS are simulated, such as the ground antennas, monitor stations and links to auxiliary users, to simulate communications with the satellite vehicles and external agencies. The simulator’s user interface will allow instructors to easily input all types of anomalies to test the reaction of the students. The simulator will allow GPS operators to train individually, or as a unit, in handling true “day-in- the-life” scenarios prior to becoming certified. In addition, this paper discusses how the simulator will allow high fidelity testing of control system upgrades, reducing the need for operational resources during test. This will allow a greater number of test scenarios to be run, and will allow testing and troubleshooting of ground system upgrades in a repeatable, controlled environment. The simulator will be especially vital during the next five years as the GPS control system is migrated from the current mainframe platform to an open systems, distributed architecture. This paper will overview approaches to interfacing and utilizing the simulator with other OCS resources including training facilities, development labs and off-line analysis systems. Finally, the paper will discuss how the simulator can be adapted to support other less traditional applications.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	115 - 123
Cite this article:	Corrie, Lee, Hazlehurst, Rob, Walker, Rick, Greenhut, Darlene, "Simulating the GPS Constellation for High Fidelity Operator Training," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 115-123.
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