Iterative maximum-likelihood/cross-correlation algorithm for reflection and pulse TOA estimation

An iterative method that combines a parametric channel model with the maximum likelihood and cross-correlation estimation techniques has been developed to estimate the reflection, creeping wave, and times of arrival (TOAs) from an echo (backscatter) emanating from a rigid acoustic sphere. The modelled echo is assumed to be more complex than a linear combination of delayed and scaled versions of the transmitted pulse, and the individual backscatter pulses need not be disjoint. Experimental results demonstrate that the algorithm is successful in determining the proper time delays of the reflection and the creeping wave for a variety of received signal-to-noise ratios (SNRs)