New range alignment algorithm for ISAR based on high order moment

Abstract

A new technique is proposed for range alignment in Inverse Synthetic Aperture Radar (ISAR). The basic idea is to perform range alignment using a maximum kurtosis (fourth-order central moment) criterion. After maximizing the kurtosis of the combined range profile of two adjacent echoes, the amount of range shift between them can be automatically tracked out. The combined range profile is constructed by a max operation, which only reserves the larger elements of the two echoes, and the echoes' amplitudes are limited before they are combined. This algorithm has been used to process real ISAR data and the results demonstrate the effectiveness of the method. Compared with the correlation method and the minimum entropy method, the proposed algorithm obtains much better results in both examples in this paper. Its computation complexity has the same order of magnitude as the minimum entropy method.

Inverse synthetic aperture radar imaging compensation method based on coherent processing of intermediate frequency direct sampling data

“…To acquire high-quality imaging results, the speed in the fast time should be compensated. The HSMC can be easily achieved to the stretch echo since the phase term induced by high-speed movement can be separated 12 , 13 . Nevertheless, the method is not effective for the IF direct sampling data, from which the phase term could not be separated.…”

“…If no prior translational information is available, the range alignment processing could be accomplished in accordance with the similarity of the range profile envelopes of adjacent pulses. The algorithms based on maximum-correlation 1 , 13 and minimum-entropy 14 , 15 are traditional ways to deal with range alignment. However, these algorithms do not take the noise effects and optimization process into account.…”

Robust Phase Bias Estimation Method for Azimuth Multi-Channel HRWS SAR System Based on Maximum Modified Kurtosis

“…The algorithm uses the principle following which the total amplitude of all targets represented by the L 1 -norm is minimized if there is no phase bias between channels. Wang et al [19] proposed a new range alignment method for ISAR based on maximum modified kurtosis (MMK); the kurtosis definition applied to discrete signal sequences is modified to measure the alignment between echo envelopes. Inspired by this, this paper proposes a phase bias estimation approach based on MMK.…”