Carrier Phase Model For Satellites and Pseudolites

Jonathan M. Stone, J. David Powell

Abstract:	Applications requiring carrier phase differential GPS (CDGPS) using satellite and pseudolite signals for real-time positioning and control are drawing much attention. In situations where less than four satellites may be visible (like open pit mining), a single master transmitter may be used as a timebase instead of solving for GPS time. This allows the common timebase to be used between the user and reference station such that a model of the reference carrier phase may be created. The model may be used to extrapolate the reference phase to correct for sampling time offset, transmission latency, and missed data-points. Additionally, the required data transmission rate may be significantly reduced even with a highly dynamic user vehicle. The phase stability of an existing pseudolite design has been improved by a factor of 2, improving the extrapolation of the carrier phase. The details of a reference model of satellite and pseudolite carrier phases is described that provides ranging errors within 3cm even with a 5 second latency. The model is used in a real-time positioning system to correct for sampling time offset, transmission latency, and missed data points in a CDGPS system, while decreasing the required transmission rate to 1200 Baud. The system has been demonstrated in a miniature open-pit mine with centimeter level accuracy using one satellite and three pseudolites .
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:	1509 - 1516
Cite this article:	Stone, Jonathan M., Powell, J. David, "Carrier Phase Model For Satellites and Pseudolites," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1509-1516.
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