Computational Efficient Refocusing and Estimation Method for Radar Moving Target With Unknown Time Information

摘要

In the real application scenario, the time information when a moving target enters/leaves the radar coverage is often unknown, which would lead to severe performance loss for target refocusing, parameter estimation and imaging. We address the refocusing and motion parameters estimation problem for a moving target with unknown entry/departure time, involving range cell migration (RCM) and Doppler frequency migration (DFM) within the coherent refocusing period. A computationally efficient refocusing method based on extended generalized Radon Fourier transform (EGRFT) and window Fractional Fourier transform (WFRFT), i.e., EGRFT-WFRFT, is proposed. By employing the four-dimensional searching in the parameter space, the proposed EGRFT-WFRFT method could extract and match the target signal very well, resulting in good refocusing output, where the target's entry time, radial acceleration, velocity and initial range could be estimated. Then the radar echoes corresponding to the “entry time” are extracted. After quadratic phase term compensation, WFRFT is performed on the extracted echoes to obtain the estimation of target's departure time. Numerical experiments and real radar dataset processing are carried out to evaluate the performance of the proposed method. The results show that EGRFT-WFRFT could achieve superior focusing performance.