A Target Equivalent Rotation Center Estimation Method for Bistatic ISAR

Abstract

The invention provides a target equivalent rotation center estimation method for a double-base ISAR and relates to the field of radar signal processing technology. According to echoes received by a double-base radar, a one-dimensional distance image sequence is generated. Through grouping, a first image and a second image are generated and the observation view angle difference of the first image and the second image is calculated. According to a distortion angle calculating formula, a first average distortion angle and a second average distortion angle are calculated. According to the averagedistortion angles, the first image and the second image are corrected and are recorded as a first corrected image and a second corrected image. Further, according to the second corrected image and a rotation conversion formula, a rotation image is generated. Finally, according to the first corrected image and the rotation image, the correlation index of the first corrected image and the rotation image is calculated and the equivalent rotation center is determined. By adopting the technical scheme provided by the invention, the estimation precision of the equivalent rotation center is improved;through introduction of the average distortion angles, the application range of equivalent rotation center estimation is improved.

Description

technical field [0001] The present invention relates to the technical field of radar signal processing, in particular to a target equivalent rotation center estimation method for bistatic ISAR. Background technique [0002] The bistatic inverse synthetic aperture radar (Inverse Synthetic Aperture Radar, ISAR) system, while possessing the characteristics of "four resistances", uses the received non-backscattered echoes of the target for imaging, and can obtain more abundant target information than the monostatic radar . The Range-Doppler (RD) algorithm is a classic algorithm for bistatic ISAR imaging. Because of its clear physical meaning and easy operation, it is widely used in imaging simulation and processing of measured data. When the rotation angle is too large or the imaging cumulative rotation angle is too large, the algorithm has the problem of migration of more resolution units, resulting in image defocusing. The farther away from the rotation center, the more serio...

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Problems solved by technology

[0003] However, in the prior art, the following methods are usually adopted: (1) The equivalent rotation center of the target is approximated by the motion compensation method based on a single characteristic point. , in the measured data, the signal-to-noise ratio of the echo is generally very low, and it is difficult to find a single characteristic point; (2) Use the position tracking of several scattering points to extract the equivalent rotation center of the target. On the one hand, this method uses less information about the scattering points , the estimation accuracy of the rotation center is low. On the other hand, the characteristics of the bistatic angle changing with time are not considered, and the application range is limited.

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