Varied PRF Sequence Design Method for Space-borne UHRSL-SAR

Sliding spotlight synthetic aperture radar (SAR) is suitable for ultra-high resolution remote sensing with wide angle azimuth beam steering. However, it will cause large echo range cell migration (RCM), which needs wider echo receive window or lower pulse repetition frequency (PRF) to prevent transmit and nadir interference. In this case, conventional echo timing with fix PRF no longer works. To solve the problem, this paper proposes a varied PRF sequence design method for space-borne ultra-high resolution sliding spotlight SAR (UHRSL-SAR). In this method, a PRF step change strategy is presented to prevent the transmitting and nadir interference in different azimuth time. In order to determine PRF changing points along azimuth, a burst division rule is raised based on RCM variation curve obtained from beam steering geometry. For each burst, the corresponding RCM variations are greatly reduced compared with the whole RCM. Therefore, the PRF values for all bursts can be designed successively without contradiction. Simulation experiments are conducted to demonstrate the effectiveness of the proposed method.