Time-frequency scale changing curve track bistatic foresight SAR imaging method

Abstract

The invention discloses a time-frequency scale changing curve track bistatic foresight SAR imaging method, and mainly solves the problem that in the existing curve track bistatic foresight SAR imaging technology, parameter space-variant is serious, so that an image edge region cannot be focused at high resolution. According to the implementation scheme, the method comprises the following steps: acquiring a curve track bistatic forward-looking SAR echo signal, and performing range walking correction and second-order wedge-shaped time-frequency transformation on the echo signal; performing high-order migration correction and distance compression on the signals after time-frequency transformation, and completing distance direction processing of the echo signals; and constructing a high-order disturbance factor and a nonlinear scaling factor based on an azimuth space-variant model to reconstruct a signal azimuth frequency spectrum after range processing, obtaining echo signals with consistent Doppler parameters, and performing unified focusing on the echo signals to obtain a focused SAR image. According to the method, the edge region focusing depth of the curve track bistatic foresight SAR imaging image is improved, the image quality is improved, and the method can be used for foresight high-resolution detection.

Description

technical field [0001] The invention belongs to the technical field of digital signal processing, and in particular relates to a curved track double-base forward-looking SAR imaging method, which can be used for forward-looking high-resolution detection. Background technique [0002] Bistatic forward-looking SAR refers to the curved motion trajectory during the imaging process formed by multiple aircraft at different altitudes, speeds, acceleration directions, and sizes. Carry out research on the forward-looking imaging method of bistatic SAR with heterogeneous and different-velocity curve trajectories, and obtain high-resolution radar images by performing frequency-domain pulse compression on the echoes recorded by the receiver directly in front of the observation area, so as to realize high-resolution forward-looking detection of the receiver. It is of great research significance to expand the existing remote sensing detection field and enhance the detection and strike cap...

AI Technical Summary

Problems solved by technology

Although these three methods can achieve image focusing under curved trajectories, they do not consider the depth of range bending space variation and Doppler parameter space variation under curved trajectories, that is, ignore the situation that the high-order phase is much larger than the threshold, so the Causes the depth of focus to decrease in the edge area of ​​​​the image and the lack of image blur

Images