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Open Access

An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect

EURASIP Journal on Advances in Signal Processing20062006:083727

https://doi.org/10.1155/ASP/2006/83727

Received: 28 April 2005

Accepted: 16 December 2005

Published: 11 May 2006

Abstract

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.

Keywords

Rotation RateRotational MotionDoppler FrequencyTarget IdentificationImage Distortion

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Authors’ Affiliations

(1)
Defence R&D Canada - Ottawa, Ottawa, Canada

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Copyright

© Wong et al. 2006

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