A noise-robust ISAR imaging method for GEO satellite-based passive ISAR

The geosynchronous broadcasting satellite-based passive ISAR (GEO satellite-based P-ISAR) always suffers from the extremely low signal-to-noise ratio (SNR) condition, which is caused by the great distance between the satellite transmitter and the terrestrial receiver. The low SNR condition yields the main challenge on ISAR imaging of the target. In the case where the SNR is so low that the target information in the range profiles is submerged by noise, the existing ISAR imaging methods will no longer be valid, and novel methods are required. In this paper, a batch width extension (BWE) method is proposed to deal with the extremely low SNR condition, where the batch width refers to the duration of the signal that generates a range profile. By extending the batch width and using a target shift compensation process, the energy of the target signal can be well accumulated to corresponding range cells so that the SNR of the range profiles can be improved. Then the conventional autofocusing method can be employed to obtain the target image. Simulation results validate the effectiveness of the proposed method.