Global Positioning System Operational Control System Accuracies

R. Bowen, P. L. Swanson, F. B. Winn, N. W. Rhodus, W. A. Feess

Abstract:	In early 1985, an improved ground Operational Control System (OCS} will maintain the navigation service. Primary among the OCS improvements over past GPS navigation systems is a global network of ground antennas (to upload satellite navigation data) and tracking/monitor stations. In addition, a refined Kalman filter will continuously estimate the Global Positioning System (GPS) satellite ephemerides and clock phases and frequencies. Although the user-GPS interface remains unaltered, the accuracy of the GPS navigation service is expected to improve by a factor of three. Using real and simulated GPS pseudo range radiometric tracking data, The Aerospace Corporation has completed a detailed error analysis which shows that the satellite clock noise contributes more than 90 percent of the total satellite-to??user pseudo range error. If the number of OCS uploads is increased to three per day (as planned), then the accuracy of the navigation service is also expected to improve by nearly a factor of three because the clock-noise contribution to the range error increases linearly with time. Also, this analysis shows the con??sequence of satellite ephemeris uncertainties in the GPS ??navigation application.
Published in:	Proceedings of the 1985 National Technical Meeting of The Institute of Navigation January 15 - 17, 1985 San Diego, CA
Pages:	60 - 66
Cite this article:	Bowen, R., Swanson, P. L., Winn, F. B., Rhodus, N. W., Feess, W. A., "Global Positioning System Operational Control System Accuracies," Proceedings of the 1985 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1985, pp. 60-66.
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