Study On The Cross-track Velocity Ambiguity Resolution Of SAR Ground Moving Target

Synthetic aperture radar (SAR) can obtain two-dimensional (2-D) image of thetarget, through wideband pulse compression to improve the resolution of range andazimuth. The radial velocity causes the migration of target location and increase theDoppler frequency complexity of echoes, the along-track velocity leads to defocusing inazimuth. Therefore, it is important to detect moving targets and relocate them. Thispaper deals with the Doppler ambiguity resolution of cross-track velocity for groundmoving target estimation, which is an important parameter for target relocation.Two methods for estimating the ambiguity number of radial velocity for groundmoving targets from a single SAR sensor are analyzed. In the first method, wetransform the target signatures into range and azimuth2-D frequency domain and thencompress it for each range frequency. The resulting compressed envelope exhibits astraight line with its slope just proportional to the ambiguity number of the inducedDoppler centroid. Then we can estimate its slope and accurately obtain the ambiguitynumber by linear features detection techniques. The other method is based on amplitudeand phase to estimate the ambiguity number of radial velocity. When range migrationcorrection is done, similar with the first method, the ambiguity number of the inducedDoppler centroid is obtained by estimating the slope of the line that the resultingcompressed envelope exhibits. At last, the two methods are proved correct and effectiveby simulations. The resulting compressed envelope exhibits a straight line with its slopejust proportional to the ambiguity number of the induced Doppler centroid. Then we canestimate its slope and accurately obtain this number by linear features detectiontechniques.