Synchronous orbit SAR imaging method based on high-order polynomial range equation

Abstract

The invention discloses a synchronous orbit SAR (Synthetic Aperture Radar) imaging method based on high-order polynomial range equation. The implementation process thereof is as follows: 1. establishing a synchronous orbit SAR high-order polynomial range equation; 2. solving a Cardan equation and deducing the precise analytical expression of a synchronous orbit SAR echo signal two-dimensional frequency spectrum; 3. structuring a two-dimensional frequency domain compensation function and finishing a scene centre point matching processing in the two-dimensional frequency domain; 4. performing arange IFFT (Inverse Fast Fourier Transform) processing on a result after finishing the centre point matching and transforming the result to a range-Doppler domain from the two-dimensional frequency domain; 5. structuring an error phase spatially variant with range and compensating for a range spatially variant phase in the range-Doppler domain; and 6. performing an azimuth IFFT processing to obtain a focused synchronous orbit SAR image. All the operations in the invention are finished by fast Fourier transform and phase dot product, and the method is high in efficiency and suitable for engineering implementation; and moreover, the two-dimensional frequency spectrum is a precise analytic solution capable of realizing full-aperture and high-resolution imaging.

Description

technical field [0001] The invention belongs to the technical field of spaceborne radar, and further relates to a synchronous orbit SAR imaging method based on a high-order polynomial distance equation, which can be used for synchronous orbit SAR to realize high-resolution imaging of ground scenes. Background technique [0002] Since the orbit height of the synchronous orbit SAR is 35,768km, it has strong anti-strike and destruction capabilities, and has strong battlefield survivability. At the same time, the ultra-long synthetic aperture makes it possible to carry out continuous tracking and high-resolution imaging of moving targets, which can meet the needs of large-scale strategic surveillance, early warning and battlefield reconnaissance. In addition, geosynchronous orbit SAR also has the advantages of short reentry period, wide coverage and high time resolution, and has potential advantages in earthquake and volcano forecasting, marine application research, etc. The em...

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Problems solved by technology

For example, Li Caipin, Zhang Hongtai, and Tan Xiaomin proposed an RD algorithm after compensating the curved trajectory to a straight line in "An Improved CS Algorithm Applicable to Geosynchronous Orbit SAR" "Acta Astronautics" 2011, 32(1): 179-186 The method of imaging, but because it is compensated according to the center point of the scene, its focusing effect on the edge points of the scene is poor, and it is only applicable to low-resolution situations

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