Wengxiang Zhao and Boris Pervan, Illinois Institute of Technology

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In this paper, we develop a carrier phase estimation algorithm to allow GPS receivers to maintain continuous signal tracking through wideband radio frequency interference events. Due to the nature of the GPS signal, carrier phase estimation is a hybrid estimation problem, requiring simultaneous estimation of the discrete-time navigation data bits and the continuous carrier phase. We use an interacting multiple model algorithm with two measurement models corresponding to the two possible choices of navigation data bits (+1 and -1) over each 20 ms coherent integration interval. At the end of each interval, we extract the final state vector estimate by combining the two modes’ estimation results using their likelihood functions. We present experimental results to evaluate the performance of the IMM filter during wideband interference events.