An Efficient ISAR Imaging Method for Rapidly Spinning Targets

摘要

Due to the large range cell migration (RCM) and highly-nonstationary Doppler frequency modulation (DFM) of rapidly spinning targets, it is difficult to efficiently obtain well-focused inverse synthetic aperture (ISAR) images via conventional methods. Inspired by the azimuth spatial invariance in strip-map synthetic aperture radar (SAR) imaging mode, in this paper, an efficient range-Doppler domain ISAR imaging methods for rapidly spinning target is proposed. First, the echo signal is transformed into range-Doppler domain and its precise analytical expression in range-Doppler domain is derived according to the principle of stationary phase (POSP). Second, the energy of scatterers distributed in different range cells is extracted along the rotating radius to concentrate it into the same range cell. After that, the high-order phase terms of signal are compensated. Finally, the scatterer is focused in two-dimensional time domain. The simulated results demonstrate the effectiveness of the proposed method.