A Fast Two-Dimensional Velocity Estimation Method for Multi-Channel UWB SAR

Moving target detection in ultra-wideband synthetic aperture radar (UWB SAR) has to accumulate target energy with long integration time to improve the probability of target detection. The traditional detection and parameters estimation algorithms usually rely on parameter searching, leading to a heavy computing burden. In this paper, a fast two-dimensional velocity estimation method of moving target for multi-channel UWB SAR is proposed. The method processes the multi-channel data separately to realize the target's coherent accumulation and one-dimensional velocity estimation. Then the multi-channel signals are processed jointly to realize the two-dimensional velocity estimation. Specifically, for each channel, the second-order keystone transform is used to correct the range curvature. The symmetric autocorrelation function in the range-frequency domain is used to accumulate the moving-target energy, achieving the target detection and target's azimuth signal extraction. Next, considering the long integration time, the azimuth signal is processed by the non-uniform cubic phase function (NUCPF) based on the fourth-order phase signal to estimate the relative velocity. The azimuth signal is transformed into the Doppler domain for multi-channel data, and the interferometric signal is calculated. The phase generated by the interferometric signal is related to the radial velocity of the target. Thus, the two-dimensional velocity of the target is obtained. Finally, the effectiveness of the algorithm is verified by simulation experiments.