Global Positioning System Integrity and Automated L-Band State of Health

A. Gower, W. Mathon

Abstract:	Since its inception, the GPS design has been oriented towards achieving a high level of integrity in the navigation service. The Master Control Station (MCS) software monitors Space Vehicle (SV) pseudorange, transmitted data, and vehicle telemetry. The GPS operators are provided with updated SV accuracy information and will, if a failure is evident, either remove the SV from service or correct the problem. The Block II SVs protect the user from memory errors and frequency synthesizer errors by automatically going into non-standard code (which prevents users from tracking the affected SV) upon detection of an error. These existing GPS integrity mechanisms will be discussed before addressing future enhancement. The GPS Joint Program Office (JPO) has decided to enhance the integrity of the GPS by adding an Automated L-band State Of Health (ALSOH) function. The ALSOH will use Monitor Station (.MS) data to monitor navigation message content, SV range errors, signal strength and clock stability. The processing will be independent of the MCS computer and will provide a check on the quality of the navigation service. The emphasis for ALSOH will be on rapid detection of any anomalous situation, allowing the GPS operators to remove the SV(s) from navigation service until the anomaly is corrected.
Published in:	Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990) September 19 - 21, 1990 The Broadmoor Hotel Colorado Spring, CO
Pages:	421 - 423
Cite this article:	Gower, A., Mathon, W., "Global Positioning System Integrity and Automated L-Band State of Health," Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990), Colorado Spring, CO, September 1990, pp. 421-423.
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