An improvement to the explicit time delay estimator

The explicit time delay estimator (ETDE) provides an efficient way to estimate the time difference of arrival between signals received at two separated sensors. However, the algorithm is biased for finite filter length and the delay bias increases when the signal-to-noise ratio (SNR) or the number of filter taps decreases. In this paper, we add an adaptive gain control to the ETDE to decouple the effect of changes in the SNR during adaptation. As a result, a smaller delay variance and an unbiased delay estimate for a wide range of filter lengths can be attained. Computer simulations are presented to validate the theoretical derivations of the proposed estimator for static and linearly time-varying delays under both stationary and nonstationary signal/noise power environments