Achievable GPS Multipath Mitigation Performance Using Dual Civil Frequencies

摘要

Proposed changes in the civil GPS signal structure offer the possibility of greatly improved in-receiver multipath mitigation in high-performance differential positioning systems.rnAs an example, this paper shows that a properly chosen second civil GPS frequency, containing an identical C/A code, can offer an order of magnitude improvement in multipath mitigation performance compared to what is currently available to the civilian community. If the separation of the two carrier frequencies is properly chosen, ranging errors of several decimeters or less are shown to be possible, even with substantial close-in multipath and relatively short signal observation times. Phase estimation performance is also strikingly improved.rnThe author takes a fundamental approach to develop the best achievable performance for two-carrier multipath mitigation, both for ranging and for estimation of carrier phase, according to a useful optimality property possessed by the minimum-mean-square-error (MMSE) estimator of the multipath parameters. The results provide important information regarding the design of transmitted GPS signals and also of GPS receivers.