A Self-Adaptive Maximum Likelihood Bit Synchronization Approach for a GPS Receiver

R. Zheng, M-H. Chen, X-H. Ba, J. Chen

Abstract:	A self-adaptive maximum likelihood bit synchronization approach dedicated for GPS receivers is proposed. The approach introduces the normalized gap between the maximal and the submaximal bit energies to the conventional maximum likelihood method with fixed noncoherent accumulation times as an indicator, to constrain the noncoherent accumulation times for different signal powers and bit transition rates selfadaptively. Numerical simulations show that the approach is able to significantly reduce the mean estimation time, especially for relative strong signals. In the meantime, the estimation error rates of both strong and weak signals are kept almost the same low as the conventional method. Simulations show the estimation error rate and the mean estimation time of the proposed approach is not sensitive to phase or frequency errors. It also shows that small bit transition rates affect little on the approach. In addition, a FPGA implementation tested by Spirent® GPS simulator validates the simulation results.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	219 - 226
Cite this article:	Zheng, R., Chen, M-H., Ba, X-H., Chen, J., "A Self-Adaptive Maximum Likelihood Bit Synchronization Approach for a GPS Receiver," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 219-226.
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