Ground Moving Target Detection And Velocity Ambiguity Resolution Based On VSAR System

As an indispensable part for target imaging, detection and location, besides withgreat potential prospect, synthetic aperture radar/ground moving target indication(SAR/GMTI) on high speed motion platform has been widely used in the field of targetdetection. Problems related with moving target detection and parameters estimation instrong ground clutter environment can be resolved effectively followed by cluttersuppression with multichannel system, performance of slowly moving target detectionwill be improved dramatically in this case. In this dissertation, ground moving targetdetection and velocity ambiguity resolution are studied based on velocity syntheticaperture radar (VSAR) system. On this basis, a revised method is also proposed. Withthis novel method, the estimation accuracy of moving target velocity is greatlyimproved besides velocity ambiguity is eradicated effectively.1. With respect to the low estimation accuracy of target velocity with traditionalmethods, subspace fitting method is used to estimate the velocity of moving target inthis dissertation. In the case of ideal and with jamming situation, signal and noisesubspace fitting methods are employed for velocity estimation of moving target,respectively. After clutter suppression, the signal-clutter-noise-ratio (SCNR) isimproved effectively in the stationary clutter scene. The stationary clutter can be furthersuppressed with space information provided by subspace fitting, under which accuracyof velocity estimation improves more.2. To ensure the accuracy of velocity estimation and avoid the velocity ambiguitycaused by the limitation of pulse repetition frequency (PRF) for fast moving target, themulti-look beat frequency method is used for ambiguity resolution with Dopplercentroid of beat signal extracted from signal phase. Iteration is modified to decrease thecomputational loads, shorten the execute time and then improve the detection possibility.Combining with Doppler ambiguity and velocity estimation, the radial velocity withoutambiguity is acquired and target location is realized. Performance analysis of traditionalmethods and the proposed method in this dissertation are made by simulationexperiments. The effectiveness and reliability of the proposed method are validated bythe proposed method.