Research On ISAR Imaging Of Non-uniformly Rotational Targets

Inverse Synthetic Aperture Radar (ISAR) imaging could supply important character for target identification, so it is valuable for both legionary and civil purpose. Relying on the National 973 Project, this paper studies the ISAR imaging for non-uniformly rotational targets.At first, the background and worthiness of the research is introduced, and the research state in quo and the development is summarized, following with the framework and the content of the thesis.In the second chapter, the rationale of ISAR imaging is introduced, and the Range-Doppler imaging arithmetic is expatiated detailed, which is the basic of ISAR imaging and based on a uniformly rotational table model, using DFT for cross-range focus.In the third chapter, the ISAR imaging matter of equably accelerative rotating targets is studied, and the characteristic of echo is analyzed, aiming which an ISAR imaging method for equably accelerative rotating targets based on match FFT is presented. Using this method, the results of experiments for emulational data and real data are excellent, which proves the validity of the method.In the fourth chapter, the matter of scatter's migration through resolution cells when equably accelerative rotation is studied, and an improved Keystone Transform for MTRC compensation aiming at equably accelerative rotational target is presented, following with its fast arithmetic. Then the matter of scatter's migration through Doppler cell is analyzed and a compensation method is presented. The compensation for emulational data and Mig.25 data proves the validity of the method.In the fifth chapter, the echo of unequally accelerative rotating targets is calculated and analyzed and time-frequency method is used for imaging. The subsection approximately parameter estimation method and the non-parameter time-frequency method are introduced and used for the imaging of unequally accelerative rotating targets.The content of the dissertation is summarized and the problems needed for further research of the ISAR imaging for non-uniformly rotational targets are pointed out in Chapter 6.