Initial Demonstration of a Point Solution Algorithm for Orbit Determination Using the microGPS Receiver

A. Reichert, P. Axelrad, SC. Wu, W. Bertiger, and J. Srinivasan

Abstract:	This paper presents a preliminary demonstration of algorithms developed for orbit determination using the microGPS receiver. The receiver design, developed by JPL, and more properly described as a “bit-grabber” or receiver front end, was introduced at last year’s 1996 ION National Technical Meeting [l]. It is characterized by low mass (-0.5 kg), average power consumption of less than 0.125 W, and a peak power of < 1 W. This is accomplished by putting as little hardware in space as possible and powering on most receiver components only as needed. For low accuracy orbit determination requirements this will amount to only a few milliseconds several times per orbit. The initial space flight of the microGPS will be on the SNOE (Student Nitric Oxide Explorer) mission, with all data processing performed on the ground. Target orbit determination accuracy for this mission is about 200 meters. Two of the unique aspects of processing the microGPS data are the resolution of ambiguous C/A code pseudorange measurements and separate estimates of receiver time tag error and clock bias. Orbit determination algorithms for the microGPS data have been coded in C and tested on GPS flight data collected with a more conventional GPS receiver, the Trimble TANS Vector. This paper describes the algorithms in detail and provides performance analysis based on both the Trimble flight data and simulations. Position accuracy for the flight data is approximately 90 m and time tags are determined to 50 to 100 msec. These results are consistent with the simulated data which also gives insight into the contributions of both pseudorange and Doppler errors to orbit determination accuracy.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	377 - 386
Cite this article:	Reichert, A., Axelrad, P., Wu, SC., Bertiger, W., Srinivasan, J., "Initial Demonstration of a Point Solution Algorithm for Orbit Determination Using the microGPS Receiver," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 377-386.
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