SAS imaging and motion compensation method suitable for non-uniform straight-line flight path

Abstract

The invention relates to an SAS imaging and motion compensation method suitable for a non-uniform linear trajectory. The method comprises the steps of establishing a rectangular coordinate imaging grid of a final output image and recording coordinates of each pixel on the rectangular coordinate imaging grid, wherein for a scene with fluctuations in elevation, the recording of elevation information of each pixel on the rectangular coordinate imaging grid is also required; establishing a global polar coordinate grid for sub-aperture image fusion; recursively achieve multi-level sub-aperture merging, imaging area decomposition and sub-image fusion; and after the recursion process is terminated, transforming a polar coordinate system image into the rectangular coordinate imaging grid, and finally obtaining an image with full spatial resolution.

Description

technical field [0001] The invention relates to the field of sonar imaging, in particular to a SAS imaging and motion compensation method suitable for non-uniform straight-line tracks. Background technique [0002] Synthetic aperture sonar (Synthetic Aperture Sonar: SAS) uses the movement of the small-sized matrix in the azimuth direction to form a virtual large aperture, and obtains high-resolution sonar images by coherently processing the sonar echo signals at different positions. Motion errors have a great influence on synthetic aperture sonar imaging. The main factors that generate motion errors include: the influence of wind, waves, and currents, the irregular motion of the carrier platform, the instability of the sound propagation medium, the non-uniform sound velocity, and the positioning sensor GPS and speed sensor The precision of ADL is not enough and so on. [0003] Motion error estimation and compensation is one of the important components of synthetic aperture ...

AI Technical Summary

Problems solved by technology

Especially for some SAS systems working at high speed and with large sea waves, the carrier platform will move sideways to the planned straight track, which will inevitably have a negative impact on the imaging quality

The frequency-domain imaging algorithms in the prior art generally need to work on a uniform-velocity straight-line track. When processing one or more complete synthetic aperture blocks, the average value of the azimuth velocity within the entire synthetic aperture length is generally taken as the imaging processing parameters, including certain approximate components; when the actual SAS system is working, the multiple complete synthetic apertures contained in the block processing can be as long as tens of meters, and the number of sub-apertures included is as many as hundreds or thousands. Among them, the non-uniformity of the azimuth velocity will have a non-negligible impact on the quality of the imaging in some special application scenarios.

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