Adaptive techniques for time-delay estimation and tracking

Adaptive time delay estimation in the specific case where the recorded signals are sinusoids with additive noise is discussed. Two simple adaptive techniques which do not require transforms and are capable of tracking a nonstationary, time varying delay are presesnted. First, a method which makes use of a two pole, all pass adaptive filter is introduced. An LMS type of adaptive algorithm is derived, and the associated error surface is discussed. The performance of this adaptive structure is then compared to that of the adaptive delay element. Simulation results are compared on the basis of delay estimate accuracy, rate of convergence, and the ability to track varying phase shifts.