ION GNSS 2008 , Session C 2 , Savannah , GA ,

The Time Of Arrival (TOA) of a received signal is the most important parameter for position estimation. The accuracy of the estimated TOA is limited by multipath errors. Consequently, multipath mitigation techniques are essential for high accuracy positioning using TOA observations. Narrow Correlator and double delta correlator were introduced to reduce multipath errors in pseudoranges. These correlator-based multipath mitigation techniques have been used extensively in most high grade GNSS receivers. Besides early-late correlators, the super-resolution techniques such as Multiple Signal Classification (MUSIC) have been applied broadly in the TOA estimation of indoor propagation channels. In this paper, the MUSIC TOA estimation technique is adopted for estimating the propagation delay of GNSS signals. The main contribution of this paper is the comparison of the performance of the early-late correlator family with the MUSIC high-resolution TOA estimator under various multipath environments. Experimental results reveal that early-late correlators cannot correctly estimate the code phase in severe multipath environments or in specular multipath situations where the multipath component has more power than the direct signal (e.g. indoor environments and urban canyons). A hardwarein-the-loop system configuration is used to provide a controlled environment for these investigations. Experimental results reveal that the performance of the MUSIC algorithm is better than early-late estimators under the severe multipath scenarios tested. Empirical results confirm that the code phase estimation error using the Narrow Correlator and double delta correlator can reach up to one chip.