Curve synthetic aperture radar (CSAR) ground moving target refocusing imaging method

Abstract

The invention belongs to the field of synthetic aperture radar (SAR) ground moving target indication, and relates to a curve SAR (CSAR) ground moving target refocusing imaging method. The method comprises the following steps: S1, receiving a radar echo signal of a moving target, and preprocessing the radar echo signal; S2, dividing the radar echo signal into a plurality of sub-aperture echo signals along the azimuth direction; S3, transforming the sub-aperture echo signals into a distance frequency domain, and extracting phases of the signals along the azimuth direction one frequency point after another; S4, calculating a distance estimated value according to the extracted phases, and constructing a phase compensation factor by quadratic curve fitting; S5, performing motion compensation bythe phase compensation factor; S6, compensating for a phase estimation error by a map-drift (MD) self-focusing method; S7, performing Fourier transform along the azimuth direction and performing inverse Fourier transform along the distance direction respectively to obtain a moving target re-focusing result under a current sub-aperture; and S8, repeating the steps S3 to S7 to obtain a moving target re-focusing image sequence under a plurality of sub-apertures. Through adoption of the method, motion compensation is realized under the situation that target motion parameters are unknown.

Description

technical field [0001] The invention belongs to the field of ground moving target indication (GMTI) of synthetic aperture radar (Synthetic Aperture Radar, SAR), and relates to a ground moving target refocusing (Ground Moving Target Indication) suitable for curve synthetic aperture radar (Curve SAR, CSAR). Moving Target Refocusing, GMTR) imaging method. Background technique [0002] Synthetic Aperture Radar (SAR) is a radar technology that can perform high-resolution microwave imaging on the observation scene. CSAR is a new SAR imaging system, that is, the radar platform makes a large curve or wide-angle arc around the observation scene. A radar system whose beam is always pointing to the target scene for observation and imaging. CSAR can achieve sub-wavelength resolution of stationary targets on the ground, and can observe targets from multiple angles in all directions to obtain more detailed target azimuth scattering information. In order to improve battlefield awareness,...

AI Technical Summary

Problems solved by technology

[0003] Ground moving targets are generally non-cooperative targets, and it is difficult to accurately obtain information about their motion parameters, which increases the difficulty of refocusing imaging

In addition, while the special motion geometry of CSAR brings the advantages of omni-directional multi-aperture angle observation, it also introduces complex azimuth and distance coupling, which makes the moving target refocusing method under traditional linear SAR invalid.

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