Correlator Beamforming for Multipath Mitigation in High-Fidelity GNSS Monitoring Applications

Sanjeev Gunawardena, John Raquet and Mark Carroll

Peer Reviewed

Abstract: Safety and security critical GNSS applications ensure system integrity by performing long-term monitoring to quantify and characterize GNSS signal anomalies. Multipath represents a significant error source that hinders these high fidelity signal quality monitoring activities. Currently, multipath at monitoring stations is addressed by careful antenna siting and the use of azimuth and elevation-based masking. However, as urban development around airports and other monitoring installations continues to occur, these solutions may not suffice and more aggressive multipath mitigation technologies are needed. This paper explores the use of Correlator Beamforming as a potential solution. Correlator Beamforming multiplexes the received signals from a multi-element antenna into a single data stream and forms independent beams towards satellites as part of the GNSS receiver’s correlation processing. The resulting attenuation at off-beam directions has been shown to reject multipath almost as effectively as a traditional controlled reception pattern antenna (CRPA) digital beamformer, but at a fraction of the cost of the latter. This paper compares the relative multipath rejection performance of four antenna-receiver topologies: 1) a single element antenna and typical receiver processing, 2) a geodetic-grade antenna and typical receiver processing, 3) a multi-element antenna and traditional CRPA beamforming, 4) the same multi-element antenna and Correlator Beamforming. The effects of multipath are analyzed in terms of carrier-to-noise ratio fading, de-trended code-carrier divergence, and three-dimensional position solution errors. The results presented in this paper are relevant for all GNSS monitoring applications.
Published in: Proceedings of the 2017 International Technical Meeting of The Institute of Navigation
January 30 - 2, 2017
Hyatt Regency Monterey
Monterey, California
Pages: 1173 - 1188
Cite this article: Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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