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An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect
EURASIP Journal on Advances in Signal Processing volume 2006, Article number: 083727 (2006)
Distortion in the ISAR image of a target is a result of nonuniform rotational motion of the target during the imaging period. In many of the measured ISAR images from moving targets, such as those from in-flight aircraft, the distortion can be quite severe. Often, the image integration time is only a few seconds in duration and the target's rotational displacement is only a few degrees. The conventional quadratic phase distortion effect is not adequate in explaining the severe blurring in many of these observations. A numerical model based on a time-varying target rotation rate has been developed to quantify the distortion in the ISAR image. It has successfully modelled the severe distortion observed; the model's simulated results are validated by experimental data. Results from the analysis indicate that the severe distortion is attributed to the phase modulation effect where a time-varying Doppler frequency provides the smearing mechanism. For target identification applications, an efficient method on refocusing distorted ISAR images based on time-frequency analysis has also been developed based on the insights obtained from the results of the numerical modelling and experimental investigation conducted in this study.
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Wong, S.K., Riseborough, E. & Duff, G. An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect. EURASIP J. Adv. Signal Process. 2006, 083727 (2006) doi:10.1155/ASP/2006/83727
- Rotation Rate
- Rotational Motion
- Doppler Frequency
- Target Identification
- Image Distortion