A discrete-time quadrature time-of-arrival estimator for determining the subsample delay between narrowband ultrasound signals

A high-resolution discrete-time delay estimator for determining the delay between two narrowband ultrasonic signals is described. The technique is based upon the principles of analogue quadrature detection and is relatively simple to implement digitally. Simulations in the presence of system noise show that the delay estimator does not exhibit any significant bias and outperforms other estimators across a range of SNR situations.