Accuracy enhancements for robust TOA estimation on resource constrained mobile platforms

Abstract

This thesis develops techniques for accurately estimating the time-of-arrival (TOA) on resource constrained sensor units of a distributed radio geolocation system. Firstly, a multi-resolution approach for discriminating between signals of interest and spurious transmissions, which reduces computational costs involved in the discrimination operation by nearly two orders of magnitude, is presented. Secondly, Doppler frequency shifting is proposed as a solution for minimizing the effect of drifting sample rate clocks on different units. To avoid the computational costs associated with the Doppler frequency shifting solution, a related time-domain shifting technique is developed and analyzed. Finally, the problems of estimating a unit’s operating frequency and GPS jitter problem are posed together as a linear regression problem. It was shown that the proposed compensation techniques reduce the error contribution from sampling frequency disparity and GPS jitter from approximately 500 ns down to about 80 ns.