<title>Joint time delay and signal estimation in subbands with application to underwater target detection</title>

Abstract

Time delay estimation has found applications in diverse fields such as underwater acoustic, radar, speech processing and biomedical signal processing. In underwater target detection in order to identify certain clues in the acoustic backscatter the time delays associated with the multi-specular returns must be estimated. In this paper a new joint time delay and signal estimation (JTDSE) procedure is proposed using the dyadic multi-resolution analysis framework. The multi-resolution analysis of a signal was performed through a discrete wavelet transform which is closely related to sub-band decomposition using filter banks. The goal of the proposed JTDSE scheme is to estimate the time delays corresponding to the multi-specular returns. Once the signals are decomposed, the time delays are estimated iteratively in each sub-band using two different adaptation mechanisms that minimize the sum of squared errors (MSE) between the reference and primary signals in the corresponding sub-band and scale. The localization of the minima of the MSE curves at different scales and sub-bands are used in order to arrive at the time delay estimates. Once the time delay estimates are validated among scales, the specular returns can then be separated from the backscattered signal for more accurate analysis of the residual part. Simulation results on synthesized as well as real data indicate the promise of this scheme for underwater target detection.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.