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: Target Identification Using Harmonic Wavelet Based ISAR Imaging | Hindawi Publishing Corporation EURASIP Journal on Applied Signal Processing Volume 2006 Article ID 86053 Pages 1-13 DOI ASP 2006 86053 Target Identification Using Harmonic Wavelet Based ISAR Imaging B. K. Shreyamsha Kumar B. Prabhakar K. Suryanarayana V. Thilagavathi and R. Rajagopal Central Research Laboratory Bharat Electronics Limited Bangalore-560013 India Received 30 April 2005 Revised 21 November 2005 Accepted 23 November 2005 A new approach has been proposed to reduce the computations involved in the ISAR imaging which uses harmonic wavelet- HW based time-frequency representation TFR . Since the HW-based TFR falls into a category of nonparametric time-frequency T-F analysis tool it is computationally efficient compared to parametric T-F analysis tools such as adaptive joint time-frequency transform AJTFT adaptive wavelet transform AWT and evolutionary AWT EAWT . Further the performance of the proposed method of ISAR imaging is compared with the ISAR imaging by other nonparametric T-F analysis tools such as short-time Fourier transform STFT and Choi-Williams distribution CWD . In the ISAR imaging the use of HW-based TFR provides similar better results with significant 92 computational advantage compared to that obtained by CWD. The ISAR images thus obtained are identified using a neural network-based classification scheme with feature set invariant to translation rotation and scaling. Copyright 2006 Hindawi Publishing Corporation. All rights reserved. 1. INTRODUCTION Inverse synthetic aperture radar ISAR is an imaging radar that uses the target s pitch roll and yaw motions to generate an image in the range-Doppler plane. Primarily the Fourier transform FT was used for the ISAR imaging with the assumption that Doppler frequency is constant over the imaging time duration 1 2 . However the assumption of constant Doppler frequency is not true as the Doppler frequency varies in time because of the nonuniform motion of the target due to maneuvers. Hence the
