Stepped frequency synthetic preprocessing algorithm for inverse synthetic aperture radar imaging in fast moving target echo model

This paper first introduces an accurate inverse synthetic aperture radar echo model for the fast moving targets. In this model, the target´s motion during the time periods of the pulse transmitting, propagating and receiving have been taken into account, and some problems, which have been ignored in the `stop-go´ model, may occur, for example, the varied ambiguity numbers and the drifted frequency centre. These problems will cause many difficulties in obtaining a high resolution range profile (HRRP) synthesis. To deal with these problems, a stepped frequency synthetic preprocessing (SFSP) algorithm is presented. The key of the proposed algorithm is synthetic preprocessing, including Doppler ambiguity suppression, echo coherence restoration and frequency centre correction, respectively. By completing the preprocessing, the HRRP can be achieved by a bandwidth synthesis and a well-focused image can be obtained by a keystone transform and an azimuth process, respectively. The simulation results validate the proposed SFSP algorithm by comparing it with the algorithm in the existing extended `stop-go´ model.