Research On Multistatic Sonar Target Detection And Location Method Based On Doppler Sensitive Signal

Active sonar is easy to expose the position of the platform,and passive sonar detection faces more difficulties,so multistatic sonar has emerged as the times require.It has a series of advantages such as strong concealment and long detection distance.The configuration and array of multistatic sonar,weak target detection under strong interference,multi-base positioning technology,synchronization and high-speed technology have become hot research issues.This paper mainly focuses on the weak target detection problem and the multistatic location problem under the interference of strong direct waves.For the problem of weak target detection,this paper starts from the signal system,selects Doppler sensitive signals,and studies the time-frequency-space joint interference suppression method;for the multi-base positioning problem,this paper studies the least squares positioning solution algorithm and the positioning based on extended Kalman filter method.First of all,this paper studies the characteristics of long CW signal,m-sequence BPSK signal,Gold-sequence BPSK signal and GSFM signal from the ambiguity function.The four kinds of signals are Doppler sensitive signals,which can effectively suppress zero-Doppler interference such as echoes of stationary targets.And compared and analyzed in terms of time-frequency resolution,fuzzy function shape,autocorrelation performance and main application scenarios.Subsequently,this paper studies a moving target detection method based on time-frequency-space joint interference suppression.The frequency domain(Doppler shift)interference suppression method is based on the frequency offset matching of the matched filter bank.When the target signal and the interference signal have different frequency shifts,the output of the interference signal through the matched filter is a low-level side lobe.The spatial interference suppression method is based on beamforming technology.When the target signal and the interference signal come in different directions,the beamformer can further suppress the interference signal.The time-domain interference suppression method is based on the adaptive notch filter of the slow time-dimensional sequence of multi-pulse signals.Passing the slow time-dimensional sequence through the adaptive notch filter can effectively filter the interference signal components near the zero frequency offset.Both the simulation experiment and the lake experiment have verified the effectiveness of the algorithm,which can make the target obtain a detection ability of about 10 d B under experiment condition that the transmitted signal is an 11-order m-sequence signal and an interference signal ratio of nearly 40 d B.Finally,this paper takes the configuration of one transmitter and three receivers as an example,and studies the pure distance least squares positioning solution algorithm and the positioning method based on pure distance extended Kalman filtering in the background of small platform detection.The positioning accuracy of both algorithms is limited by measurement error.Performance comparisons are made in terms of positioning accuracy,initial value selection and prior information through simulation results.The effectiveness of the two algorithms is verified by the lake test data processing results.