Adaptive algorithm for combination method of conventional and coherent Doppler sonar

Pulse-to-pulse coherent Doppler sonar has been used to provide accurate velocity information, but the occurrence of “range-velocity” ambiguity seriously limits more general applications. Although multi-frequency and dual-time-interval methods have been used to enlarge the range of ambiguity velocity, it remains limited. Therefore, a combined method of conventional and coherent Doppler sonar using a fixed range of ambiguity velocity has been proposed to provide accurate and precise velocity without velocity ambiguity. The combined method using a fixed range of ambiguity velocity worked well at high SNR, but at low SNR it was not able to provide the same accuracy as seen at high SNR. In order to provide accurate and precise velocities at a wide range of SNR, an adaptive algorithm of ambiguity velocity is proposed. Based on simulation results, the combined method using the adaptive algorithm can provide accurate and precise velocities at a wide range of SNR.