Efficient wideband signal parameter estimation using combined narrowband and wideband ambiguity functions

In active sonar processing, target signal parameters are usually obtained via the estimation of the peak position of the wideband ambiguity function (WAF). As the peak search of the WAF involves an exhaustive 2-d search in the delay-scale domain, which is computationally intensive, an alternative peak search procedure is proposed in this paper. The proposed method is based on the evaluation of the analytical expressions for the narrowband and wideband ambiguity functions of the transmitted wideband signal. The computational efficiency of this scheme is achieved by reducing a 2-d search problem into two 1-d searches. An FFT- based narrowband ambiguity function (NAF) processing is also proposed for approximately estimating the scale of multipath reflections.