Obtaining the Short Term Stability of the GPS Satellite Clocks From Tracking Data

Paul S. Jorgensen

Abstract:	This paper shows how the short term stability of the GPS satellite clocks can be obtained from tracking data. As of November, 1983, there were five fully operating satellites on orbit (Navstar 3, 4, 5, 6 and 8) and four monitor stations tracking these satellites. The monitor stations are located at Vandenberg, Guam, Hawaii, and Alaska. Both code and carrier tracking is performed where, in particular, tracking the 1.575 GHz carrier frequency (19 em wavelength) is very precise. An analysis of the accumulated delta range (integrated Doppler) makes possible a detailed evaluation of satellite clock performance. Of course, this is the relative performance of a satellite clock and a monitor station clock. Because there was a total of 20 combinations of satellites and monitor stations, it was possible to perform some separation of satellite and monitor station clock effects. The criterion for evaluating clock performance is the Allan variance or sigma-tau plot. This paper discusses this valuable means for conveniently assessing clock behavior, how this technique is applied to the carrier tracking data, and presents several examples of the results of this analysis. Cases of both normal and substandard clock performance are given in this paper.
Published in:	Proceedings of the 1984 National Technical Meeting of The Institute of Navigation January 17 - 19, 1984 San Diego, CA
Pages:	235 - 239
Cite this article:	Jorgensen, Paul S., "Obtaining the Short Term Stability of the GPS Satellite Clocks From Tracking Data," Proceedings of the 1984 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1984, pp. 235-239.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In