Multipath and satellite clock bias error minimization in DGPS based radiolocation

This paper offers a novel approach to improve the accuracy of position fixing in a GPS-based wireless caller system. While the DGPS based system offers accuracy of a few meters in open-sky conditions, the accuracy degrades considerably when signal from a satellite-in-view experiences obstructions like buildings, foliage, etc., known as multipath effect. Another source of error is a satellite clock drift. In this work, we estimate both types of errors. Then, a hypothesis testing is done to ensure the presence of the multipath error. Finally we filter out the multipath and clock drift error to improve the location fix. This methodology is tested on field trial data collected by SnapTrack Inc