Weak Moving Target Echo Signal Detection And Parameter Estimation

Non-cooperative illuminating passive coherent location system using televisionor fmbroadcast is a kind of radar which employs a television or FM broadcast itter asthe illuminator. Some advantages are obtained from this radar, such asanti-elint ,electronic counter-countermeasure, detection of stealth targets and counteranti-radiation missile, and there is a nicer foreground.The signal received by passive coherent radar contain four-part: direct signal,echos of still object, echos of moving object, and interference. Location of movingobject is by examination and estimation of direction of arrival of signals, time delayand Doppler shift. Considering actual conditions, the target echoes are not only veryweakly but also existing in complex multi-path environment that are covered withstrongly direct wave and fixed echoes. The traditional method is invalid. Inconsequence, it is very difficultly for target echoes to detect, and it's one of keys.Based on analysis of above, in this thesis, the main aim is to study the method forweak signal of detecting and extracting and the direction of arrival of signals,time-delay and Doppler shift, and obtained some valuable results:·Consider to restrain direct wave and fixed echos by hardware to improve SNR·Reserch a method for designing null matrix based on eigenvaluedecomposition.·Give a kind of method that purify direct wave which can be used in follow-upapplication.·Reserch a method for detecting and extracting DOA of weak signal based onfuzzy function.·Improving SNR and estimate DOA with method of cyclostationary andcumulation.