Research Of Detection Of Sonar Pulse Signal And Passive Ranging

Underwater target detection and localization shall be conducted by means of sonar.according to the principle sonar can be divided into active sonar and passive sonar. Active sonar transmits sound pulses,detecting objective by it’s reflected echo,this is likely to expose themselves, leading to other attack, affecting their security. The target signal or noise receiver receiving transducer arrays is used by passive sonar to detect target itself .In terms,passive sonar gains good concealment, the role of distance and so on advantages over active sonar.Passive sonar pulse detection is the technology by use of active sonar transmit pulse signals to detect the target. Two main pulse signal of active sonar: CW pulse and LFM pulse,The key of sonar pulse detection technique is highly accurate delay measurements. The main task of sonar pulse detection of active sonar is detection of target operating parameters,tracking target, the azimuth and distance of the target can be estimated by the precise delay measurement.Research work of this paper is divided into two parts: detection of CW pulse signal and detection of LFM signal, these two signals detected mainly TDE (Time Delay Estimation),corresponding to different pulse signals using different time delay estimation method,according to a ternary array ranging principle derived target’s azimuth and distance.In passive ranging sonar, target distance finding is accomplished by estimating the time delay between signals emanating from a remote source and received by three spatially separated array elements. In this paper, three-way symmetric array passive ranging formulas is derived ,the general characteristics of TDE is analyzed .Passive distance measurement model is relatively simple in theory, but in practice, the complexity of underwater acoustic channel leads to propagation time fluctuation , and range time delay estimation of required is the order of microseconds, so a passive ranging be complemented by a series of signal processing for passive ranging technology. For CW pulse signal processing method introduces three methods of zero-frequency measurement and two methods of FFT frequency measurement, adaptive line enhancer (ALE), adaptive phase estimator (Notch). For LFM pulse processing method introduces the generalized cross correlation, three point interpolation method, correlation peak refinement TDE(MCZT-FICP), and phase adjustment method.In this paper, simulation to test the effectiveness of various methods of signal processing, improved edge detection time-delay estimation, front fixed frequency measurement and phase adjustment method TDE estimate the error analysis, and some experimental data validate the time delay estimation structural designs has certain advantages over other structural designs.