Accurate locating method for onboard tri-channel SAR-GMTI (Synthetic Aperture Radar-Ground Moving Target Indication)

Abstract

The invention discloses an accurate locating method for onboard tri-channel SAR-GMTI (Synthetic Aperture Radar-Ground Moving Target Indication). The accurate locating method has the main ideas of sequentially carrying out range pulse compression processing, conventional motion error compensation and channel equilibrium processing on an echo signal of an original moving target received by a channel of an onboard tri-channel SAR at first; then, carrying out time-shifting rectification on all channels which are sequentially subjected to the range pulse compression processing, the conventional motion error compensation and the channel equilibrium processing according to DPCA (Displaced Phase Center Antenna) technology; respectively carrying out cancellation on every two channel signals of all channel signals which are subjected to the time-shifting rectification, and obtaining a first moving target signal and a second moving target signal; respectively carrying out phase compensation and range migration compensation on the first moving target signal and the second moving target signal; then, respectively carrying out interference processing on the first moving target signal and the second moving target signal, and obtaining an accurate focusing and imaging position of the original moving target; marking the accurate focusing and imaging position of the original moving target in a scene.

Description

technical field [0001] The invention belongs to the field of radar signal processing, and in particular relates to an airborne three-channel SAR-GMTI precise positioning method, that is, an airborne three-channel synthetic aperture radar-ground moving target detection (Synthetic Aperture Radar-Ground Moving Target Indication, SAR- GMTI) precise positioning method, which is suitable for SAR imaging processing of airborne platforms or spaceborne platforms. Background technique [0002] At present, SAR imaging technology has been widely used in civil and military fields including moving target detection and high-resolution radar imaging. However, when the moving target position in SAR imaging technology moves, SAR imaging technology cannot correctly reflect the moving target. At this time, it is required to re-detect and re-position the moving target, and even re-SAR imaging. [0003] In SAR imaging technology, for moving targets, because the motion parameters of multiple movi...

AI Technical Summary

Problems solved by technology

[0002] At present, SAR imaging technology has been widely used in civil and military fields including moving target detection and high-resolution radar imaging, but when the moving target position in SAR imaging technology moves, SAR imaging technology cannot correctly reflect the moving target At this time, it is required to re-detect and re-position the moving target, and even perform re-SAR imaging

[0003] In SAR imaging technology, for moving targets, since the motion parameters of multiple moving targets in the scene are different, and each moving parameter within the synthetic aperture time of each moving target will change over time, and It is difficult to effectively solve the range migration (RCM) and azimuth defocusing problems of moving targets using conventional algorithms, and it is also difficult to achieve fine focusing of moving targets, which affects the positioning accuracy of moving targets

[0004] In order to solve the defects of the conventional algorithm, scholars try to use the airborne multi-channel synthetic aperture radar-ground moving target detection (SAR-GMTI) method to solve the azimuth defocus problem by estimating the azimuth modulation frequency of the moving target. The method of estimating the azimuth modulation frequency of moving targets usually uses time-frequency analysis method and fractional Fourier transform method; the airborne multi-channel SAR-GMTI method mainly uses Keystone transform, Keystone Although the transformation can realize the linear distance walking correction in the range migration (RCM) of the moving target under the condition that the motion parameters of the moving target are unknown, it cannot perform the quadratic range bending correction in the range migration (RCM), and The Keystone transform is only applicable to the situation where the moving target has no ambiguous radial velocity; in addition, although the time-frequency analysis method and the fractional Fourier transform method can estimate the moving target orientation with higher precision under ideal conditions frequency modulation, but when the signal-to-noise ratio (SNR) of the moving target decreases or other moving targets interfere with the moving target, the estimation accuracy of the azimuth modulation frequency of the moving target will be severely reduced, and the azimuth velocity of the moving target is time-varying, only compensation The secondary frequency modulation term caused by the azimuth velocity of the moving target is not enough to achieve the complete focus of the moving target

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