Frequency Hopping Waveforms Design and Targets Detection for Continuous Active Sonar

In order to improve the performance of anti-interception and information update rate for continuous active sonar (CAS), frequency hopping linear frequency-modulated (FH-LFM) waveforms were proposed. The expressions of transmitting waveforms and base band signals were presented, and the echo model of underwater moving targets was established. The method of multi-channel quadrature demodulation and matched filtering was proposed to detect sub-pulses of the FH-LFM waveforms. In order to improve sonar detection performance, the output results of matched filters were delayed and processed by non-coherent integration. The proposed algorithm can shorten the update time of target information, and provided enough information for target tracking. To verify detection performance of FHLFM, the receiver operating characteristic (ROC) curves were obtained by simulation. The performance and feasibility of the proposed waveform and signal processing algorithm were verified by sea trial.