Adaptive time delay estimation with allpass constraints

A new gradient adaptive time delay estimation (TDE) algorithm is proposed. The algorithm implicitly maintains allpass constraints on the coefficients of the TDE filter without any additional procedures and employs a simple interpolation formula to calculate the fractional delay estimate. Approximate mean- and mean-square analyses of the behaviors of the TDE filter coefficients and the delay estimate are provided. Analyses and simulations verify that the new method outperforms other gradient adaptive TDE approaches in low signal-to-noise ratio environments.