ISAR (inverse synthetic aperture radar) imaging orientation calibration method

Abstract

The invention provides an ISAR (inverse synthetic aperture radar) imaging orientation calibration method, which comprises the following steps that a radar records echo to obtain echo data using the distance as the line vector and the orientation as the row vector; distance units are selected for forming a new echo matrix; a frequency domain windowing technology is adopted for extracting the scattering point echo; the phase quadratic term factor of the distance unit echo is estimated; the orientation resolution ratio of the ISAR image is calculated on the basis of a least squares estimation method; the orientation calibration on the ISAR images is completed according to the orientation resolution ratio of the ISAR image. The method provided by the invention has the advantages that 2-order DPT conversion is adopted for estimating the phase quadratic term factor of the distance-dimension echo, the defects of real-time application inconvenience and great calculation quantity during the phase quadratic term estimation of the traditional method based on LPFT and image contrast ratio are overcome, and in addition, the rotating angular speed of a target is obtained through the least squares estimation method, so the orientation calibration of the ISAR images is realized.

Description

technical field [0001] The invention belongs to the technical field of signal processing, in particular to an inverse synthetic aperture radar imaging azimuth calibration method in radar signal processing. Background technique [0002] Inverse Synthetic Aperture Radar (Inverse Synthetic Aperture Radar, hereinafter referred to as ISAR) has the advantages of all-weather, all-weather, long-range, high-resolution, etc., and has a wide range of applications in military and civilian fields. In order to determine the real size of the target, and then identify and classify the target, it is necessary to calibrate the range and azimuth of the ISAR image. The calibration of the distance dimension is only related to the bandwidth of the radar emission signal and the sampling frequency, which can be obtained in advance, but the calibration of the azimuth dimension is related to the rotation angle of the target relative to the radar. Since the target of ISAR imaging is generally a non-c...

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Problems solved by technology

However, the disadvantage of the above method is that when estimating the modulation frequency of the echo signal containing prominent points, the local polynomial phase transform (LPFT) combined with the method of the maximum contrast criterion is used. Therefore, in order to obtain a high estimation accuracy, It is necessary to set a small search interval and search repeatedly in the solution space, which brings a huge amount of calculation and is not convenient for real-time application

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