Adaptive subsample delay estimation using a windowed quadrature phase detector

An on-line delay estimation algorithm based on an analogue quadrature phase detector that is suitable for determining the subsample delay between two noisy sinusoidal signals is introduced. The new estimator uses a windowed discrete-time quadrature technique to update directly the delay estimate, which is in turn used to adapt the coefficients of a simple fractional delay filter (FDF). Simulations show that, in the presence of system noise, the new estimator significantly outperforms conventional fractional delay filter based estimators.