Adaptive realization of a maximum likelihood time delay estimator

This paper presents an adaptive maximum likelihood method for estimating the time difference of arrival of a source signal at two spatially separate sensors. It is well-known that the maximum likelihood technique achieves the Cramer-Rao lower bound for time delay estimation error for certain signal conditions. The /spl alpha/-/spl beta/ tracker is a heuristic mechanism that is heavily used in target tracking applications. In this work, we combine an adaptive realization of the maximum likelihood time delay estimator with the /spl alpha/-/spl beta/ tracker to obtain significant improvement in the performance of the tracker, Experimental results showing 2 to 8 dB improvement in the mean-square estimation error over the conventional /spl alpha/-/spl beta/ tracker for various signal-to-noise ratios are also included in the paper.