Effects and Compensation of High-Speed Motion in ISAR Imaging

Traditional ISAR imaging algorithms are based on the “stop-and-go” assumption and lack theoretical analysis, accurate simulation, and effective compensation regarding the high-speed motion of the target or the platform. In response to this issue, a theoretical analysis of the high-speed motion of the target or the platform in ISAR imaging is first conducted, indicating that when a chirp is transmitted, the echo from a scatterer can be approximated as a chirp with its central frequency and chirp rate changed, and this will lead to the shift and the blurring of the scatterer in range. A method is then proposed to estimate the central frequency and the chirp rate, which are used to adjust the central frequency and the chirp rate of the matched filter. The central frequency is estimated to maximize the normalized correlation of the amplitude spectrum and its nominal form, and the chirp rate is derived from the central frequency. Moreover, in order to show the rationality of our theoretical analysis and the effectiveness of our compensation method, a scheme is presented to simulate the received signal under the high-speed motion of the target or the platform. This scheme assumes that the target and the platform move continuously with time and reflects the effects of the high-speed motion on the received signal accurately.