Target detection in sonar system basing on symmetrical LFM impulse

Because of the Range-Doppler coupling, Linear Frequency Modulation (LFM) impulse cannot be used to estimate parameters when time delay and Doppler shift are both unknown. Taking into account the large Doppler shift scale and wideband operation, we propose a processing flow basing on Symmetric LFM impulse for sonar system. Time delays and Doppler shifts are estimated by the coupling error, and re-calculation is suggested to decrease the estimation error. Directions are estimated by split beamforming after confirming the time windows when the echoes being. The method can be realized in sonar real-time system for multiple targets environments. Simulation results indicate the method´s effectiveness.