Range sidelobe suppression for FD-MIMO sonar imaging using multi-ping amplitude weighting

The frequency diverse multiple-input multiple-output (FD-MIMO) sonar can use a group of small-bandwidth FD pulses to synthesize a large bandwidth signal, which brings a higher range resolution than traditional methods. However the range sidelobe level (SLL) is high due to the cross-correlation function (CCF) interferences and the spectrum leakage between auto-correlation functions (ACFs) of transmitting waveforms. To suppress the range SLL, we propose a multi-ping amplitude weighting method using a set of FD continuous wave (FDCW) pulses. In our method these FDCW pulses are divided into several groups, and each group is emitted in the corresponding ping. To suppress CCFs, the band gap between FDCW pulses transmitted in a ping is set to be relatively large. Furthermore, to suppress the spectrum leakage, the amplitude weights calculated via an optimization problem are applied to ACFs of all FDCW pulses. Via numerical simulations, we show the proposed method can suppress the range SLL of FD-MIMO sonar effectively.