GPS Block IIR Autonomous Navigation Emulator

Susan Bower, Dale Klein, Paul Slonaker, Lawrence Wiederholt, Gong Chen and Lawrence Doyle

Abstract:	As the NAVSTAR Global Positioning System (GPS) Replenishment Satellites (Block IIR) are launched, a testing and training environment is required. The Autonomous Navigation (AutoNav) Emulator described in this paper provides this environment. This paper discusses the purposes of the AutoNav Emulator which are: to aid in AutoNav certification; to isolate AutoNav related problems and test solutions; to verify AutoNav constellation operation with simulated and real data; and to assist in training operations personnel and generating AutoNav data loads for the Telecommunications Simulator. The GPS Control Segment will use this tool as the Block IIR satellites are launched into the GPS constellation. The 24 hour S-band data dump from the satellite can be compared to ground-generated data. Evaluations of partial constellations, where there are less than twenty-four (24) Block IIR satellites in orbit, are possible. AutoNav operational mode transitions can be demonstrated. The AutoNav Emulator environment consists of two interconnected processors: a Digital Equipment Corporation VAX and the mission processor, a MIL-STD-1750A which is identical to the flight hardware. The AutoNav Emulator can operate in four different modes. The Multiple Satellite Simulation mode operates using simulated input data or real on-orbit data which has been down-loaded in 24 hour dumps. Error plots, statistics, and reports are output. The Single Satellite Emulation mode uses real on-orbit data that is down-loaded and re-played through the mission processor. A comparison can be made between the ANE output and the on-orbit data . The On-Board Performance Analysis mode compares the on-board AutoNav data that is down-loaded and the Control Segment state estimates. The Telecom mode generates data for the Telecommunications Simulator. The software developed for the AutoNav Emulator is in Ada, and it complies with DOD-STD-2167A.
Published in:	Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991) September 11 - 13, 1991 Albuquerque, NM
Pages:	459 - 466
Cite this article:	Bower, Susan, Klein, Dale, Slonaker, Paul, Wiederholt, Lawrence, Chen, Gong, Doyle, Lawrence, "GPS Block IIR Autonomous Navigation Emulator," Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991), Albuquerque, NM, September 1991, pp. 459-466.
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