On Reducing the Impact of GDOP Discontinuities on Receiver Positioning Accuracy

Mark Zhodzishsky, Peter Zagnetov, Alexey Zinoviev, and Javad Ashjaee

Abstract:	This paper presents a simple yet robust GPS algorithm (patent pending) that allows the user to avoid large errors -- specifically, the errors caused by temporary loss of lock to some of the satellites being tracked (due to obstructions) or by receiver motion -- in the estimated receiver coordinates. When some of the satellites being locked are temporarily blocked by obstructions, this may result in short-term discontinuities in GDOP factors thus bringing about considerable “jumps” in the receiver position fixes. For Kalman filter techniques, the problem of “GDOP discontinuities” is somewhat less critical. However, such techniques may not be considered perfect either, since in high-dynamic applications a Kalman filter can introduce large dynamic errors caused by the filter time lag. Besides, computations based on Kalman filter are usually more involved and complicated. It is well-known that McBumey’s method (U.S. patent No. 5,590,043), which is based on employing the receiver velocity’s estimates, allows the reduction of the “GDOP discontinuity effect.” We would like to emphasize that, compared to McBumey’s method, the technique presented in our report provides a higher positioning accuracy.
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:	1629 - 1634
Cite this article:	Zhodzishsky, Mark, Zagnetov, Peter, Zinoviev, Alexey, Ashjaee, Javad, "On Reducing the Impact of GDOP Discontinuities on Receiver Positioning Accuracy," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1629-1634.
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