Ultra-Tight Coupling (UTC) Technique in GPS RAIM

Yu Ding and Jim Sennott

Abstract:	In this paper, we present a new solution to GPS RAIM, called Ultra-Tight Coupling (UTC) RAIM, for both GPS fault detection and isolation. It is capable of detecting the onset of very small ramp type range biases, typically at the 0.1 m/s level, within a very short period of time following fault onset, usually under 4 seconds. This yields a small range bias prior to detection, ensuring that position estimation errors caused by the bias are kept within a very small range. For maintaining continuity, a sub-filter method is used to isolate the satellite having bias. The “Coupling” in this scheme refers to the fact that the raw correlator I and Q data from all channels is used to update the carrier phase and frequency estimates on each channel. This can occur with or without IMU aiding and DGPS. A key point here is that since the channels are coupled, we can expect a range bias in one satellite channel can affect all the other satellite tracking channels. In this paper we take advantage of this property in structuring the filter, its nominal stochastic model, and our residual monitoring approach.
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:	1803 - 1812
Cite this article:	Ding, Yu, Sennott, Jim, "Ultra-Tight Coupling (UTC) Technique in GPS RAIM," 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. 1803-1812.
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