Evaluation of Precise, Kinematic GPS Point Positioning

Oscar L. Colombo, Andrew W. Sutter, Alan G. Evans

Abstract:	We present the results of precise static and kinematic point-positioning solutions obtained in post-processing, with a recursive Kalman filter and smoother estimator (i.e., a state space approach). The observations are dual-frequency GPS carrier phase and pseudo-range, treated as two distinct data types, each with its own measurement equations. The receiver data is single-differenced between satellites, to eliminate the receiver clock, and processed using precise satellite ephemerides and clock corrections available from the Analysis Centers of the International GPS Service (IGS), while estimating: receiver coordinates, ionosphere-free carrier phase Lc biases, and tropospheric refraction model errors. Phase windup, relativity, satellite and receiver antenna corrections are all applied, as well as receiver position corrections for earth tides, ocean loading, and pole tide, in accordance with the IERS Conventions 2003. These features are part of a general upgrade to long-baseline differential software created by the first author, which now can be used also in point-positioning, and in mixed modes. Part of the motivation has been to gain experience that could be useful in developing a real-time system. The point-positioning accuracy has been evaluated using data from different test data sets, including fixed receivers at known locations and a moving receiver mounted on a van. The receiver positions so obtained have been verified using as “truth”, in some tests, the known coordinates of the fixed sites, and, in the case of the van, a precise trajectory, differentially determined relative to a nearby receiver, with correctly fixed carrier phase ambiguities. The results indicate a precision at the level of a few centimeters, for static solutions, and below one decimeter, in kinematic mode.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	1423 - 1430
Cite this article:	Colombo, Oscar L., Sutter, Andrew W., Evans, Alan G., "Evaluation of Precise, Kinematic GPS Point Positioning," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 1423-1430.
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