Optimum C/A Code Ranging Methods and Performance Evaluation

Norman F. Krasner

Abstract:	The optimum estimator for code phase is given by the conditional mean of the code phase given observations. This estimator may be derived for a number of cases of interest to a C/A code ranging system. It is shown that the estimator has a general form that is a weighted integral of the sample cross-correlator function. Simulations of the performance of this estimator relative to conventional maximum likelihood estimators shows significant performance improvement at low signal levels, such as those commonly observed in Assisted GPS applications. The performance of the optimum estimator is compared with various estimation lower bounds, where it is shown that the lower bounds are extremely optimistic at low signal levels. The approach of this paper may be extended to other parameter estimation problems present in GPS signal processing, such as the estimation of message data baud epoch, carrier frequency and carrier phase.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	501 - 509
Cite this article:	Krasner, Norman F., "Optimum C/A Code Ranging Methods and Performance Evaluation," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 501-509.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In