Efficient wideband sonar parameter estimation using a single slice of Radon-ambiguity transform

A novel efficient technique, based on a Radon-ambiguity transform (RAT), for time delay and Doppler stretch estimation is presented. The proposed approach combines the narrowband ambiguity function (NAF), the wideband ambiguity function (WAF), and the Radon transform (RT) to estimate multiple targets in noisy environments. The main ridges of NAF represent straight lines whose slopes depend on the Doppler rates of the moving targets. These lines could be effectively detected by computing the RT of the NAF for all possible angles. However, the computation of RT for all possible angles is computationally exhaustive. It is shown that, without calculating the entire RAT, it is possible to estimate target parameters using only a single slice of RAT, i.e., using an appropriate projection of the NAF. The resolution issue and the effect of the integration length of RAT in complex white Gaussian noise are also discussed. It is demonstrated that the proposed method can successfully separate overlapping targets.