Research On Bistatic Sonar Direct Wave Interference Suppression Algorithm

With the continuous upgrading and development of submarine stealth technology,the traditional sonar have exposed many drawbacks in anti-submarine,such as distance reduced and poor concealment.In order to greatly improve the detection capability of the sonar system,a multi-static sonar detection system can be used.Different from the traditional sonar,when the multi-static sonar is working,the receiving base receives direct wave signal from the transmitting base in addition to the target echo.It has a great impact on the target detection.Thus,direct wave suppression is one of the key technologies for signal processing in bistatic sonar system.The main research content of this paper is the direct wave interference suppression algorithm in the bistatic sonar system.The main content has the following aspects:1.A direct wave is defined as a signal that travels directly from the transmitter along the baseline to the receiver without reflection from the target.Since the configuration of the bistatic sonar system is known,direct wave interference can be equivalent to strong coherent interference of the known direction.Direct wave and target echo have certain differences in the time domain,spatial domain,energy and frequency.This paper mainly studies the method of suppressing direct wave in airspace.2.Simulation analysis of several direct wave suppression algorithms.The advantage of the algorithm based on adaptive array signal processing is that it can adaptively form a null trap.The disadvantage is that there is a phenomenon of coherent cancellation.The advantage of the algorithm based on delay compensation is that the calculation amount is small and the method is simple.The disadvantage is that the delay estimation of the direct wave is required to be high;Aiming at the shortcoming of the performance of the direct wave interference direction close to the desired direction,a blocking matrix method is proposed to cancel the interference in the main lobe.When the difference between the direct wave interference and the target echo angle is small,the target back can be correctly estimated.3.The algorithm based on zero constraint has better interference suppression effect and can generate deep nulls in the interference orientation.In order to further control the beam sidelobe height,an improved direct wave suppression algorithm is proposed.Based on the zero constraint,the weighted sparse constraint method is used to reduce the side lobes of the beam.The simulation algorithm is simulated and analyzed when there are in different SNR and ISR.According to the analysis,the weighted sparse constrained zero constraint algorithm has a side lobe reduction of about 6dB compared with the conventional zero constraint algorithm,and has better performance under low SNR conditions,and maintains a conventional beamforming zero constraint algorithm.Stability.Combined with the experimental data,when the ISR is 35 dB,the algorithm can effectively suppress the direct wave interference and correctly estimate the target azimuth.The algorithm is effective.