High resolution time delay estimation using sliding discrete Fourier transform

In this paper, we propose a novel time delay estimation approach based on sliding the discrete Fourier transform (DFT) analysis window, sample by sample, over the received short continuous wave (CW) pulse signal with the DFT evaluated successively. This approach uses the maximum magnitude of the spectrum and its corresponding phase offset to estimate the time delay (pulse echo mode) of the signal. We use the corresponding time as the first estimate, which is improved on the basis of the related phase. Examples are given of synthetic signals and simulated delays scenario, with and without added white noise. An underwater application, based on distance and speed of sound measurements using this approach in a water tank is demonstrated. The proposed method is shown to significantly outperform standard correlator-based approaches. Furthermore, the algorithm is simple to use and can be easily implemented, being based on phase detection using the sliding DFT. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.