Large-squint high-resolution SAR imaging method based on distance-azimuth circle model

Abstract

The invention discloses a large-squint high-resolution SAR imaging method based on a distance-azimuth circle model. The method comprises the following steps: 1, constructing an SAR system geometric model to obtain an echo signal; 2, carrying out the range direction preprocessing of the signal in a frequency domain; 3, constructing the distance-azimuth circle model according to a range direction preprocessing result, and describing the azimuth space-variant characteristics of the SAR signal; 4, modeling an azimuth space-variant part in a remaining high-order RCM through a result given by the distance-azimuth circle model, and constructing a new variable-scale function to implement QRCMC, and then designing a distance compressing filter and completing all the processing in the distance direction; 5, modeling the azimuth space-variant characteristics of a Doppler phase according to the distance-azimuth circle model, achieving azimuth equalization through using an ENLCS algorithm, finallydesigning a filter for azimuth compression, and obtaining a final focused image. The method has a better focusing effect during the processing of large-squint and high-resolution echo data.

Description

technical field [0001] The invention belongs to the field of signal processing, and relates to a high-resolution imaging algorithm of high-squint synthetic aperture radar, specifically on the basis of constructing a new range-azimuth circle model, a new residual second-order range cell migration correction (QRCMC) is proposed , that is, the QRCMC processing method for the remaining distance migration of the azimuth space variation, and the improved azimuth ENLCS equalization process. Background technique [0002] The idea of ​​constructing an equivalently long antenna through signal analysis technology is called Synthetic Aperture Radar (SAR, Synthetic Aperture Radar). In remote sensing, SAR obtains surface images with the help of airborne or spaceborne platforms. This process uses the radar beam to transmit phase-modulated pulses in a direction that is nearly perpendicular to the movement of the sensor or has a large angle, and receives and records the reflections from the ...

AI Technical Summary

Problems solved by technology

However, under the requirement of high-resolution imaging, the remaining high-order RCM will seriously deteriorate the final focusing result

Although many existing technical solutions have used the consistent RCMC (bulk RCMC) method to compensate the non-spatial-variant part of the remaining high-order RCM, the unprocessed azimuth-spatial-variant part still cannot meet the high-resolution requirements of the range migration correction result. Require

At the same time, in the process of applying the ENLCS algorithm for Doppler phase equalization in the azimuth direction, the first-order original model describing the azimuth space-varying characteristics of the signal cannot completely match the processing results in the range direction, and cannot perform the Doppler phase of the azimuth space-varying Accurate modeling, leading to misalignment of azimuth equalization and defocusing of azimuth compression results

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