Signal Estimation Technique for Enhanced Sensitivity Navigation Receivers

摘要

Individual satellite signals do not always reach a positioning receiver in line-of-sight (LOS) propagation. Various obstructions, particularly in urban areas, lead to a multipath signal propagation environment. Delayed signal components frequently cause errors in the pseudo-ranges, since cross correlation peaks are shifted. Finally, positioning errors are the consequence This paper defines means to distinguish between LOS and non-LOS scenarios in order to reduce positioning errors. Based on statistical signal processing, a metric is defined that allows an estimation on how strong the LOS component of each individual positioning signal is. The measure for the reliability of each pseudo-range allows optimal combination of all visible satellite signals when calculating the position solution and therefore leads to increased position accuracy. Multipath errors are reduced by giving higher weight to signals with stronger LOS proportion. The metric that estimates the strength of the LOS component is mathematically derived in detail in this paper. Based on this metric, an estimator implementation is presented and tested with simulations of different multipath propagation scenarios.