Optimized Research On Passive-ranging With Cross-spectra

Noise Passive-ranging is always an active research problem in underwater acoustic signal processing domain. However, the pro passive sonar used middle-small integrate circuit with a huge frame, and it can only range far targets and cannot track move fast targets, such as torpedo. It cannot meet the modern naval battle. With acoustics , signal process theory and electron technique developing, we possible can empolder a more advanced ranging system.It first mainly probes into the theory of passive directing and ranging, then analyses some kinds of elements that influence time-delay estimation, finally gets an optimized ranging formula fit both far and near targets in this papers.It tests many ways of the cross-spectra method with simulation, such as chose the weight of least-square estimate, chose the length of correlation window and four frequency domains colligate.It worse to mention about that it will improve greatly the precision of time-delay estimation, if torpedo line spectra exits. Some simulation results is given which the system detecting threshold drops down 3dB and improves both the precision and quality of time-delay estimation, because estimation invariance drops and the mean of estimation approach the true value.The calculate time is cut sharply down in hardware realization with directing system inducting ranging system. One-order linear recursion filter is used to filter the correlation function before post-processor, which improve the time-delay estimation precision to some extent.As well known, it is important to defend torpedo attack for submarine. Then an filter both filtering and tracking well is needed. A tradition sonar often used Kalman-filter as a post-processor which improve precision with long integral time, however it will bring a serious lag if targets move fast. A parameter-estimator with adapt filter is used in this paper, consisting of two α-β filter and an adapt filter. A post-processor can be got if we choose proper α and β coefficient.At last, the cross-spectra optimized method is realized in DSP. It apply to both symmetry array and asymmetry array. The optimized ranging system realizes whole ranging and tracking moving-fast targets. In near targets ranging, the blind zone of submarine tail ranging is shortly cut down. The pro ranging system can range from 30 degree to 150 degree. After optimized, it can range from 20 degree to 160 degree for 3km target and from 10 degree to 170 degree for 300m target, which only has a approximate error least 5%. It is very useful for submarine.