Self-focusing method for compensating geosynchronous synthetic aperture radar (GEO SAR) ionized layer scintillation amplitude-phase errors

Abstract

The invention discloses a self-focusing method for compensating geosynchronous synthetic aperture radar (GEO SAR) ionized layer scintillation amplitude-phase errors. The self-focusing method includes firstly partitioning initial echo data acquired by a GEO SAR to obtain a plurality of sub-scenes, subjecting each sub-scene to compensation processing, and performing splicing to obtain a self-focusing result, wherein the compensation processing includes performing dechirp processing to the initial echo data to obtain S<de>(n, m), initializing an amplitude compensation value alpha<n> and a phase compensation value psi<n> to be 0, respectively establishing an amplitude error model and a phase error compensation model as to the S<de>(n, m), respectively calculating an image entropy E and an image entropy E, using the E and the E as cost functions to perform iteration updating on the alpha<n> and the psi<n> until a minimum value of the cost functions are reached, and using an ultimately updated amplitude compensation value and phase compensation value to compensate the S<de>(n, m) and perform fast Fourier transform (FFT) imaging to obtain a compensation processing result of a current sub-scene. The self-focusing method is capable of accurately estimating and compensating amplitude fluctuation and phase errors of echo data introduced by ionized layer scintillation.

Description

technical field [0001] The invention relates to the field of geosynchronous orbit synthetic aperture radar GEO SAR imaging, in particular to a self-focusing method for compensating amplitude and phase errors of GEO SAR ionospheric scintillation. Background technique [0002] In GEO SAR imaging, ionospheric scintillation will cause sharp fluctuations in the amplitude and phase history of target echo signals, which will lead to a serious decrease in imaging focus quality. Ionospheric scintillation mainly occurs in the equatorial and polar regions of the earth, and the probability of occurrence in mid-latitude regions is low. However, the long synthetic aperture time and large observation area of ​​GEO SAR greatly increase the probability of being affected by scintillation. Therefore, the research on ionospheric scintillation compensation method for GEO SAR is very necessary. [0003] Ionospheric scintillation is mainly caused by ionospheric irregularities and is most severe b...

AI Technical Summary

Problems solved by technology

However, due to the randomness of the ionospheric scintillation error, the SAR error compensation method based on the parameter model needs a higher order to accurately describe the random error, which will greatly increase the computational burden

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