Coasting Through Wideband Interference Events using Robust Carrier Phase Tracking

Stefan Stevanovic and Boris Pervan

Abstract:	This this paper introduces a technique for improving the positioning capability of GPS receivers that are vulnerable to wideband radio frequency interference (RFI). The method is directly applicable to ground-based reference receivers for differential GPS systems that require high continuity of service. Positioning availability is improved by using time-differenced carrier-phase measurements to coast through interference events. Due to the infrequent update of ephemeris parameters, it is possible to coast for up to four hours using the most recent successfully decoded navigation data, without accuracy penalties, as long as carrier phase is tracked continuously. A robust phase lock loop (PLL) design including a low phase-noise reference oscillator and extended averaging time (beyond the length of a navigation data bit) is used to provide significant broadband noise rejection. Clock aiding allows the PLL bandwidth to the tightened, maintaining carrier measurement quality through interference, while allowing the averaging time to be extended without encountering loop stability issues. In addition, the effect of extended averaging time on the discriminator output distribution and associated PLL performance metric is studied. It is shown that the method used to extend averaging time beyond 20 ms affects the distribution of the phase discriminator output. And, it is not obvious that the variance of the discriminator output is the ideal metric to use in PLL design.
Published in:	Proceedings of the 30th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2017) September 25 - 29, 2017 Oregon Convention Center Portland, Oregon
Pages:	4184 - 4196
Cite this article:	Stevanovic, Stefan, Pervan, Boris, "Coasting Through Wideband Interference Events using Robust Carrier Phase Tracking," Proceedings of the 30th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2017), Portland, Oregon, September 2017, pp. 4184-4196. https://doi.org/10.33012/2017.15389
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