The Study On The Echo Characteristics Of Typical Mine

Using the active sonar to obtain the target echo, detecting and recognizing underwater mine according to the target echo characteristic information, is one feasible method of mine-hunting in shallow sea. The effective target echo characteristic and the method of its extraction is the premise and the foundation of recognitionColumniform shell which has a ball coronal head is basal model structure. The material and the structure of target is the reason for producting echo characteristic. In the high frequency situation, the echo may regard as certain sub-echoes iteration, but each sub-echo may be considered that is send out from some scattering highlights, including geometry echo related to the target's structure and elastic echo related to the target's material, and it is emphases of the dissertation that to analyze their characteristic in time domain and in frequency domain. Embarking form target model's structure, the analyzes concretely the situation that echo's change along with the change of an angle of incidence or target azimuth angle, elastic scattered wave is the important difference between underwater mine and non-underwater mine, form to echo contribution aspect, not only in time domain but also in frequency, elastic scattered wave has the obvious difference from geometry echo.The process of the characteristic extraction is a process which maps the target echo signal to different characteristic space and distills category information , it is a process preparing for recognition. Four methods are used for characteristic extraction in this dissertation: extracting highlight information with short pulse, correlation analysis of linear frequency-modulated signal echo from the target, estimating the power spectrum , Short-time Fourier Transform .Through taking short pulse as the emit signal, we can have a kind of target echo signal reflecting each edge or mirror echo's magnitude and delay;...