Study Of Passive Sonar Buoys Location Technology

Passive location in underwater acoustic has always been the focus of researchers. The passive location system consisting of four buoys with the same depth can detect the targets passively and get the locations of the targets. The main tasks of this paper are the study of the system's detecting technology and targets' location technology.The noise spectrums radiated by targets consist of line spectrum and continuous spectrum, and the former has a higher SNR, so the line spectrum has been selected as detected signal. The simulation results show that the line spectrum whose frequency is unknown can be detected effectively and the noise can be suppressed synchronously by utilizing the Adaptive Line Enhancement (ALE).Hyperbolical join localization technology is employed to get the targets' location, whose locating precision depends on the array configuration. When the array configuration is fixed, the high precision of time delay estimation is the foundation of getting precise locating result. Cross-correlation is the optimal time delay estimation in the ideal condition. Generalized cross-correlation is employed to achieve the time delay estimation. Because the cross-correlation function is quasi-period function, whose cross correlation peaks are not keen-edged enough, the needed time delay estimation precision can't be achieved. So the continuous spectrum component is still employed, although the SNR is lower. And the spectrum whitening is conducted before cross-correlation to reduce the effect of the line spectrum. The skip cross-correlation can improve the processing gain further more when the SNR is lower.And multi-path effect is also one of the factors of affecting location's precision, which can result in multi-peak of correlation, so an expert system is designed according to environment feature of the passive location system, which can pick out the real peak. The simulation results show that the expert system can reduce the probability of selecting the wrong correlation peak and ensure the veracity of location.