Non-linear Processing for Underwater Detector using Time-Reversal-based Cross-Ambiguity Function

An enhanced cross-ambiguity detector using non-linear processing based on a time-reversal technique is proposed to enhance the delay-Doppler resolution for active sonar systems. We use linear frequency modulated signals to fulfill a model based on signals from certain dolphin species. A channel estimation approach known as the Spectral Projected Gradient for L1 norm (SPGL1) is applied to estimate the channel impulse response. The virtual time-reversal technique employs a family of nonlinear processing methods to enhance the delay-Doppler resolution in a multi-path ocean environment. We also investigate the detection performance of the algorithms. The contribution of the proposed scheme is a significant improvement in the delay-Doppler resolution without a significant increase in the system or computational complexity and without significant degradation to the detection performance.