tailieunhanh - Báo cáo hóa học: "An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect | Hindawi Publishing Corporation EURASIP Journal on Applied Signal Processing Volume 2006 Article ID 83727 Pages 1-16 DOI ASP 2006 83727 An Analysis of ISAR Image Distortion Based on the Phase Modulation Effect S. K. Wong E. Riseborough and G. Duff Defence R D Canada - Ottawa 3701 Carling Avenue Ottawa ON Canada K1A 0Z4 Received 28 April 2005 Revised 26 August 2005 Accepted 16 December 2005 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. Copyright 2006 Hindawi Publishing Corporation. All rights reserved. 1. INTRODUCTION Inverse synthetic aperture radar ISAR imaging provides a 2-dimensional radar image of a target. A 2-dimensional picture can potentially offer crucial information about the features of the target and provide improved discrimination leading to more accurate target identification. .