Using Standalone GPS to Evaluate Precise Oscillator Stability in the Time Domain

M.G. Petovello and G. Lachapelle

Abstract:	The recent development of low-cost, high precision oscillators has allowed many applications in various fields to become financially feasible. The stability of an oscillator is ultimately what determines its usefulness for a certain application, and is therefore desirable to quantify. Current methods of evaluating stability require a direct comparison of the oscillator under test (OUT) with a more stable reference oscillator, the cost of which often offsets the initial benefit a low-cost device. However, a relatively inexpensive GPS receiver is capable of exploiting the highly stable GPS time scale, thus obviating the need for an expensive reference oscillator. By allowing the OUT to drive a GPS receiver and processing the data with precise GPS orbits and clock corrections to eliminate the effects of Selective Availability, the time series of computed clock offsets provides a measure of the oscillator’s stability relative to GPS time. The use of GPS for assessing clock stability in the time domain is evaluated herein via the computation of Allan variance values. Performance of one rubidium and three ovenized crystal oscillators are investigated. Initial results show the method is limited to time intervals of 300 seconds or longer where the effect of measurement noise is less pronounced.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1081 - 1090
Cite this article:	Petovello, M.G., Lachapelle, G., "Using Standalone GPS to Evaluate Precise Oscillator Stability in the Time Domain," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1081-1090.
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