SAR Image Phase Reference Shift for Coherent Change Detection
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Solution Overview
Problem
Synthetic aperture radar (SAR) images processed using sub-aperture algorithms (SAA) lack a phase component, making it difficult to apply coherent change detection and autofocus processes, as the phase differences between images from repeat passes are challenging to manage and can lead to interference issues.
Innovation Solution
A phase shift is applied to intermediate images generated using SAA to create an output image, mimicking the phase component present in full aperture algorithm (FAA) images, thereby enabling consistent phase reference across images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sub-aperture algorithms are used to generate SAR images, then image processing complexity is reduced, but phase consistency is lost
Solution Approach 1:
The patent applies a phase shift parameter to the intermediate image generated by sub-aperture algorithms. This parameter change restores the phase component that was lost during sub-aperture processing, enabling phase consistency to be achieved while maintaining the computational advantages of SAA methods
2Productivity
If phase component is removed in SAA processing, then processing speed is improved, but coherent change detection capability deteriorates
Solution Approach 1:
The patent applies the phase shift in advance to the intermediate image before performing coherent change detection. This preliminary action ensures that phase consistency is established beforehand, enabling accurate CCD while maintaining the processing efficiency of sub-aperture algorithms
3Use of energy by moving object
If sub-aperture algorithms are used, then computational load is reduced, but phase error measurement becomes difficult
Solution Approach 1:
The patent introduces an intermediate image as a mediator between the sub-aperture processing and the final output. This intermediate representation maintains computational efficiency while providing a structured format that facilitates phase error measurement and correction through the applied phase shift
Data Source
AI summary
Embodiments are directed to generating a plurality of sub-images associated with a target via a synthetic aperture radar, processing, by a processor, the sub-images using a sub-aperture algorithm to generate an intermediate image, and applying, by the processor, a phase shift to the intermediate image to generate an output image.