Novel Method of ISAR Cross-Range Scaling for Slowly Rotating Targets Based on the Iterative Adaptive Approach and Discrete Polynomial-Phase Transform

The cross-range scaling is quite important for inverse synthetic aperture radar (ISAR) because the cross-range resolution cannot be acquired directly for non-cooperative targets. Its essence is to estimate the relative rotating velocity of the target to radar and calculate the cross-range resolution. Since the rotating velocity is involved in the slow-time domain of the signals and relative with the frequency-modulation rate, the problem of cross-range scaling can be considered as the task to estimate the frequency-modulation rate of the slow-time signals. Considering the common methods of this kind are always limited by the resolution of Fourier transform and cannot get good performances in the situations of slowly rotating targets, a novel method of scaling based on the iterative adaptive approach and the discrete polynomial-phase transform is proposed in this paper. The results of the simulated and real-measured data experiments verify the effectiveness of this method on scaling the ISAR images of slowly rotating targets.