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Sub-aperture large squint SAR imaging processing method based on time-varying scales

A technology of imaging processing and large squint, applied in the direction of radio wave reflection/re-radiation, using re-radiation, measuring devices, etc., can solve problems such as defocusing of imaging results, and achieve the effect of increasing usability

Active Publication Date: 2020-01-10
XIDIAN UNIV
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Problems solved by technology

[0003] Since the large squint imaging mode will lead to deep coupling of distance and azimuth dimensions, it is necessary to introduce squint minimization processing in the preprocessing to eliminate most of the coupling, but this will cause the imaging coordinate system to rotate, causing Doppler modulation frequency and high-order The Doppler coefficient changes with the azimuth position of the target, which leads to a large approximation when the conventional SAR imaging method is directly applied to the high squint SAR imaging processing, and in severe cases, the imaging result will be defocused

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  • Sub-aperture large squint SAR imaging processing method based on time-varying scales
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[0027] The embodiments and effects of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0028] refer to figure 1 , a sub-aperture large squint SAR subduction imaging method of the present invention is implemented according to the following steps:

[0029] Step 1: Establish the imaging geometric model of the submerged high squint SAR, and obtain the expression of the slant distance from the submerged high squint SAR to the target in the beam coverage area; construct the fundamental frequency echo signal ss 0 (t r ,t m ; 0 );

[0030] To establish a high squint SAR imaging geometric model such as figure 2 As shown, the radar platform moves along the trajectory AC, and its velocity in the X direction is v. Considering the short accumulation time of the sub-aperture imaging azimuth, the velocity of the platform and the change of the moving direction are ignored here, that is, the carrier is considered to move in ...

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Abstract

The invention discloses a sub-aperture large squint SAR imaging processing method based on time-varying scales, and belongs to the technical field of radar signal processing; specifically, the methodcomprises the steps of firstly establishing a large squint SAR imaging geometric model; then, performing range walk correction in a range frequency domain, and performing range-to-range pulse pressure-range warp correction-secondary range pulse pressure in a two-dimensional frequency domain; and finally, introducing a predistortion compensation factor in an azimuth time domain, introducing a nonlinear scaling varying factor in a range-Doppler domain and introducing a Deramp slope removal factor in a range time domain to complete azimuth pulse pressure, so that two-dimensional focusing in the range-Doppler domain is realized. An inclined plane SAR image obtained by the sub-aperture large squint SAR imaging processing method has no geometric distortion, and can reflect ground scene information more truly, thereby increasing the usability of the inclined plane image; and the operation amount is not increased.

Description

technical field [0001] The invention belongs to the technical field of radar signal processing, and in particular relates to a sub-aperture high squint SAR imaging processing method based on time scaling, which introduces a predistortion compensation factor in the azimuth time domain and a nonlinear scaling factor in the range Doppler domain. , to achieve azimuth time scaling, Doppler center space correction and azimuth focusing. It can be used for SAR imaging of airborne and missile-borne platforms. Background technique [0002] Synthetic Aperture Radar (SAR) is an active microwave imaging radar. It transmits a pulse signal with a large time-width-bandwidth product to achieve high resolution in the distance dimension. The virtual antenna aperture is formed by the continuous movement of the platform to achieve high resolution in the azimuth dimension. This feature shows great application value in the military. With the continuous development of radar imaging technology and...

Claims

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Application Information

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IPC IPC(8): G01S13/90G01S7/41
CPCG01S13/9094G01S13/90G01S7/418G01S13/9041
Inventor 梁毅梁宇杰秦翰林张罡
Owner XIDIAN UNIV
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