Time-frequency-based ISAR image formation technique

Conventional radar range-Doppler imaging uses the Fourier transform to retrieve Doppler information. Due to a target's complex motion, the Doppler frequency shifts are actually time-varying. By using the Fourier transform, the Doppler spectrum becomes smeared and the image becomes blurred. In this paper, we propose a time-frequency based ISAR image formation technique to replace the Fourier based ISAR image formation for resolving image blurring problem without resorting to sophisticated motion compensation algorithms. Some high resolution time-frequency transforms are discussed and examples of applying the time-frequency based image formation to simulated ISAR data are given.