Low SNR isar Imaging Method Based on Echo Downsampling and Accumulation

Abstract

The invention relates to the ISAR imaging signal processing technology and particularly relates to a low signal-to-noise ratio ISAR imaging method based on echo downsampling accumulation. The method comprises steps of S1, determining an imaging angle and an imaging total echo pulse; S2, determining an echo downsampling factor; S3, echo downsampling segmentation; S4, echo joint motion compensationand phase-coherent accumulation in various subsegments; S5, subsegment phase-coherent accumulation data recombination; S6, inter-segment echo motion compensation; and S7, azimuth compression for obtaining ISAR images. The method is advantaged in that echoes within the imaging time are subjected to downsampling segmentation according to downsampling conditions, parametric motion compensation is performed in subsegments, through Fourier transform, phase-coherent accumulation is achieved to improve the signal-to-noise ratio, the number of echoes in the azimuth direction is greatly reduced after echo pulses are accumulated in the subsegments, further nonparametric motion compensation is utilized among the subsegments, and lastly, azimuth compression is performed to achieve low signal-to-noiseratio ISAR imaging, and the method plays an important role in promoting development of broadband radar target identification in the practical and refined direction.

Description

technical field [0001] The invention relates to an inverse synthetic aperture radar (Inverse Synthetic Aperture Radar, ISAR) imaging signal processing technology, in particular to an ISAR imaging method with low signal-to-noise ratio based on echo down-sampling accumulation. Background technique [0002] ISAR imaging is one of the most effective ways to identify space targets, but space targets are often characterized by long distances and small targets, and radar observation echoes are in a state of low signal-to-noise ratio. The biggest impact of low signal-to-noise ratio on ISAR imaging is to make the performance of translation compensation algorithm deteriorate or even fail, so that the subsequent ISAR image reconstruction algorithm cannot be carried out. Translation compensation is divided into two steps of envelope alignment and initial phase correction. The traditional method is carried out in two steps, and the joint compensation method is carried out at the same tim...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problems existing in the above-mentioned prior art, the present invention proposes a low SNR imaging method based on echo down-sampling accumulation to solve the problem of ISAR imaging processing of space targets with low SNR under actual observation conditions. There is oversampling, and the echoes in the imaging time are downsampled and segmented according to the downsampling conditions, and parametric translation compensation is performed within the segment to achieve coherent accumulation to improve the signal-to-noise ratio, so that non-parametric translation compensation can be used between segments , and finally achieve low signal-to-noise ratio ISAR imaging

Images