Effect of Multipath on Code-Tracking Error Jitter of a Delay Locked Loop

Kurzfassung

It is very well known that multipath propagation is a major source of error for code and carrier phase measurement performed by a GNSS receiver. The presence of multiple reflections confounds the receiver and the estimation of the time delay will carry a bias dependant on the propagation channel. While this issue has been addressed in a certain number of works, there is another aspect that does not seem to have been investigated: the tracking error jitter alteration. Indeed in assessing the performance of an estimator, the mean value of the estimation error is as important as the variance, which indicates how the error is statistically distributed around its mean value. The variance of the tracking error in the single path scenario has been determined in a single path scenario, but in a multipath environment these results are no more valid. The objective of this work is to investigate the effect of multipath on the tracking error variance, adding a useful tool in the evaluation of performance of GNSS receiver. Analytical results will be presented for a static multipath scenario, and multipath mitigation techniques, as the Narrow Correlator and the Double Delta Correlator, thought with the intention of reducing the multipath bias, will be analysed and compared from this new perspective.