Studying Of Passive Tracking Location Measures

Passive coherent location system based on Non-cooperative illuminating target of passive detection technology, which has strong concealment, the ability of detecting covered target and guarding against low altitude raid. Therefore, it is very strategic for the modernization of Chinese national defense in the modern war condition. And studying of passive tracking location method is very vital to realize this system.The basic parameters which can be measured by receiver are direction of arrival (DOA), time delay and Doppler shift. These parameters are the main references of target locating and tracking. From the global research actuality of passive coherent locating technique, we can find that the measurements of these parameters is mainly depended on the signal processing ability, and array signal processing is a main method in space signal processing. Besides, considering actual application, signals reflected by the target not only have low signal noise ratio, but also exist in the complicated multi-path environment which are covered by strong direct arrival wave and reflected wave. So, the detection and extraction of signals reflected by the target are difficulties and the key technology of passive tracking location. Based on above analysis, according to array signal processing, the complicated environment of target signal is considered and some research on time delay of weak target signals, detection of Doppler shift and estimating on direction of arrival are done in the paper, and some valuable results are obtained. The effect of weak signal detection is enhanced by adopting the method of designing null matrix based on singular value decomposition. The Signal-to-Noise Ratio is improved by restraining the strong signal, such as direct arrival wave in hardware. The locating precision of direction of arrival is increased by improving the MUSIC and ESPRIT algorithm. Doppler shift is estimated by using multi-beam direction-finding algorithm based on FFT. The exact space location of moving target can be obtained by using 3 points location method to measure the distance.