Method Of Unknown Parametric Underwater Acoustic Pulse Signal Detection Under Strong Interference

Acoustic decoy is one of the means of soft confrontation against torpedoes by surface ships.It has the ability to transmit and receive while transmitting,which is to continuously passively detect pulse signals emitted by torpedo while transmitting wideband noise to jam and deceive torpedo.After the broadband noise propagates through the shallow sea channel with multipath effect,a strong broadband interference background is formed in the device receiving transducer.Under this influence,the detection ability of acoustic decoy to unknown parametric pulse signals decreases sharply.Therefore,it is of great significance to study the adaptive multipath interference cancellation method and the unknown parametric underwater acoustic pulse signal detection method under strong interference to improve the ability of acoustic decoys to receive and receive while transmitting.Aiming at the problem of effective cancellation of strong interference in multipath channels,an adaptive cancellation reference signal generation method based on correlation of transceiver signals is designed in this paper.Firstly,the noise characteristics of acoustic decoy emission,the transmission characteristics of shallow water channel and the characteristics of acoustic decoy received signal are studied theoretically.Then,the correlation between the transmitted jamming sample of acoustic decoy and the multipath jamming component of the receiver pick-up signal is analyzed,and the correlation output is the estimation result of the multipath response of shallow water channel.Based on this,an adaptive interference canceller reference signal generation method is designed,which improves the correlation between the reference signal of the adaptive canceller and the multipath interference component of the pickup signal of the receiver,it can effectively cancel the strong interference in multipath channel.Aiming at the two factors that affect the accuracy of the reference signal of the canceller,the selection of Correlation Peak and the estimation precision of correlation delay,the automatic detection threshold of correlation peak based on alpha filter and the high precision correlation time delay estimation method based on Lagrange polynomial are studied.The simulation results show that the reference signal generation method of adaptive canceller based on the correlation of transceiver signals can effectively cancel the strong interference in shallow water multi-path channels under different hydrological conditions,significantly reduce the interference background in the detection frequency band of the pulse signal.To solve the problem of adaptive canceller design for strong interference cancellation,this paper studies the transverse FIR Adaptive filter structure,LMS algorithm and VSS LMS algorithm based on variable step-size idea.The influence of two adaptive filtering algorithms and the selection of step factor on the performance of adaptive interference canceller is analyzed by simulation.The VSS LMS algorithm is used to simulate and verify the influence of the correlation between the reference sample and the interference component of the received signal and the condition of the signal-to-interference ratio on the performance of the adaptive interference canceller.Simulation results show that VSS LMS algorithm has better interference cancellation performance than LMS algorithm by considering both convergence speed and steady-state error with variable step size.The VSS LMS algorithm combined with the adaptive cancellation reference signal based on correlation of the transceiver signal presented in this paper can achieve a better effect of strong interference cancellation.For the detection of unknown parameter pulse signal in strong jamming background,this paper analyzes two typical torpedo acoustic homing signals,single frequency pulse signal and linear frequency modulated pulse signal.A Short-time Fourier transform detection method based on correlation interference cancellation processing is designed for single-frequency pulse signal detection,a fractional order Fourier transform detection method based on correlation interference cancellation is designed for LFM pulse signal detection.The simulation results show that the above methods have better anti-jamming ability and improve the detection ability of unknown parameter pulse signal under strong interference.