A New RAIM Algorithm for Triple-Frequency GNSS Receivers

J. Guo, M. Lu, X. Cui, Z. Feng

Abstract:	Future Global Navigation Satellite System (GNSS) will incorporate multiple civil navigation frequencies. By using measurements from multiple frequencies, users would be able to eliminate the ionosphere delay error, which is the largest error source for single frequency receivers and greatly increase the positioning accuracy. Besides, additional measurements from the new signals will improve system integrity and extend the use of GNSS to applications where strict integrity requirements are demanded. In order to make full use of the multi frequency signals and improve system integrity, this paper introduces a new RAIM algorithm for triple-frequency GNSS receivers, where the correlation of the triple frequency signals is considered in order to approach the real case. In this algorithm, we design two different triple frequency RAIM methods based on the parity space method to deal with two types of satellite failure scenarios respectively. One is all frequencies of one satellite are failed with the same bias, which means the satellite clock or ephemeris is failed and we name it Scenario-I. The other is one frequency of one satellite is failed, which means the circuit of one frequency in satellite is failed and we name it Scenario-II. A pre-detection is implemented to decide the scenario type and choose the appropriate method. Simulation results show that the triple-frequency RAIM algorithm can greatly improve the fault detection and isolation performance compared with the single frequency and dual-frequency algorithms for both failure scenarios. And for Scenario-II, it can further isolate the failed frequency after identifying the failed satellite. This advantage is very important when the failed satellite is the crucial one for positioning.
Published in:	Proceedings of the 2011 International Technical Meeting of The Institute of Navigation January 24 - 26, 2011 Catamaran Resort Hotel San Diego, CA
Pages:	271 - 278
Cite this article:	Guo, J., Lu, M., Cui, X., Feng, Z., "A New RAIM Algorithm for Triple-Frequency GNSS Receivers," Proceedings of the 2011 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2011, pp. 271-278.
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