Receiver Phase-Noise Mitigation

Donald Leimer and Sanjai Kohli

Abstract:	Oscillator phase noise in the receiver is a basic limitation on narrowing the carrier tracking loop bandwidth and, therefore, on the achievable carrier-track C/No for a GPS receiver tracking a single satellite signal. However, when receiving several satellite signals, the receiver phase noise is common to all tracking loops and, in principle, can be removed by a common-mode rejection scheme. The phase noise contributed by the satellites is negligible in comparison with the phase noise contributed by the receiver's oscillator; hence, the common-mode rejection is improved by tracking multiple satellite signals. A software algorithm is proposed to estimate the common phase-noise component, which is then removed prior to coherent tracking. Removal of the phase-noise permits coherent operation with narrower loop bandwidths for higher J/S performance in inertial-aided receiver systems. Alternatively, receivers can use lower quality oscillators to lower cost, but provide equivalent measurement quality. Computer simulations are presented which show reduced phase-tracking errors, and thus lower tracking thresholds, when the proposed algorithm is used. The performance improve increases as the number of satellite signals are simultaneously tracked; tracking improvements up to 6 dB are shown for 8-satellite reception.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	627 - 632
Cite this article:	Leimer, Donald, Kohli, Sanjai, "Receiver Phase-Noise Mitigation," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 627-632.
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