Use of Multicorrelator Techniques for Interference Detection

Christophe Macabiau, Olivier Julien and Eric Chatre

Abstract: The interference is among the most feared events in civil aviation use of GNSS. A large number of techniques were designed to alleviate the sensitivity of modern receivers to this perturbation. Most of these techniques are either based on spatial discrimination like adaptive antennas, on spectral selectivity such as notch filters or on amplitude detection. The advent of multicorrelator receivers widens the range of methods that can be considered to tackle this problem. In particular, this enables the characterization of interference effects on the tracking loops through the analysis of the shape of the correlation peak. The aim of this paper is to present the observed effect of CW and FM interference on the correlation peak with a real receiver, to compare this result with theoretical expressions and characterize the resulting pseudorange and position errors. The paper starts with the theoretical derivation of the effect of CW interference on the code and phase tracking loops I and Q samples for a typical receiver. Based on these results, specification of a test equipment is derived allowing real data collection. Results of CW interference tests are described for different test configurations. Correlation peak and pseudorange error measurements are collected for different CW interferer frequencies and power levels. These observations were used to validate the theoretical derivations mentioned above, therefore demonstrating the feasibility of interference detection with multicorrelator techniques. These tests were further extended to FM type interference with different bandwidths and power levels and yielded similar results. End-to-end testing is finally carried out on a standard receiver to determine the impact of the interference on a multi-channel receiver, showing that the position output can be significantly disturbed if the interference is not detected.
Published in: Proceedings of the 2001 National Technical Meeting of The Institute of Navigation
January 22 - 24, 2001
Westin Long Beach Hotel
Long Beach, CA
Pages: 353 - 363
Cite this article: Macabiau, Christophe, Julien, Olivier, Chatre, Eric, "Use of Multicorrelator Techniques for Interference Detection," Proceedings of the 2001 National Technical Meeting of The Institute of Navigation, Long Beach, CA, January 2001, pp. 353-363.
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