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Spotlight SAR (synthetic aperture radar) imaging method based on NFS (nonlinear frequency scaling) of subduction mode

A technology of synthetic aperture radar and imaging method, applied in the field of signal processing, to achieve the effect of solving azimuth spectrum aliasing, increasing the depth of focus, and high-precision imaging

Active Publication Date: 2013-04-17
BEIHANG UNIV
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Problems solved by technology

[0006] The present invention aims at the problem that the imaging accuracy needs to be further improved in the existing spotlight SAR imaging method, and according to the inherent characteristics of the echo signal under the subduction model, a spotlight synthetic aperture radar imaging method with non-linear frequency scaling of the subduction model is proposed , the method can process the full-aperture echo data of the spotlight synthetic aperture radar (SAR) under the subduction model, and realize high-precision spotlight imaging with a large oblique angle of view

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  • Spotlight SAR (synthetic aperture radar) imaging method based on NFS (nonlinear frequency scaling) of subduction mode
  • Spotlight SAR (synthetic aperture radar) imaging method based on NFS (nonlinear frequency scaling) of subduction mode
  • Spotlight SAR (synthetic aperture radar) imaging method based on NFS (nonlinear frequency scaling) of subduction mode

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Embodiment

[0152] The radar parameters are shown in Table 1.

[0153] Table 1 Radar parameters

[0154]

[0155] According to the parameters in Table 1, the echo simulation of the 3×3 lattice target located on the ground within the range of 300m×300m is carried out to obtain the full-aperture echo data. Use the parameters in Table 1 to perform the following steps on the full-aperture echo data Imaging processing.

[0156] Step 1: Azimuth deramp processing;

[0157] For SAR raw echo data s 0 (τ, t) carry out azimuth deramp processing, that is, echo data and azimuth deramp factor H DER (t) Convolution operation is performed to complete the azimuth deramp processing.

[0158] Will K r =Bw / T p Substituting into formula (7) to obtain the original SAR echo data, and combining it with the azimuth deramp factor H expressed in formula (8) DER (t) Perform convolution operation to obtain data s 1 (τ,t), complete the azimuth deramp processing.

[0159] Step 2: distance dechirp processing...

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Abstract

The invention provides a spotlight SAR (synthetic aperture radar) imaging method based on NFS (nonlinear frequency scaling) of a subduction mode. Collected spotlight full-aperture echo data of radar is sequentially subjected to the following processes: direction deramp process, distance dechirp process, residual video phase correction, three-time phase compensation, frequency scaling, distance compensation, direction compensation, and consistent compensation; and finally, azimuth IFFT (inverse fast fourier transform) is carried out on the data after the consistent compensation so that a final SAR image is obtained. According to the spotlight SAR imaging method based on NFS of the subduction mode, disclosed by the invention, a direction spectrum aliasing problem of a spotlight SAR is solved through an azimuth deramp process, the focus depth of range direction is increased by utilizing an NFS process, and high-precision spotlight SAR imaging under larger-distance focus depth is realized based on the subduction mode.

Description

technical field [0001] The invention relates to a spotting synthetic aperture radar (SAR) imaging method with nonlinear frequency scaling of a dive model, belonging to the technical field of signal processing. Background technique [0002] Synthetic Aperture Radar (SAR) is a microwave imaging radar with high resolution capability. Applying SAR to missile terminal guidance, the SAR seeker matches the acquired image containing ground scene information with its own electronic image, calculates the position coordinates of the seeker from the spatial geometric relationship, and corrects the inertial navigation system. Accumulate errors to improve guidance accuracy and carry out precise strikes. [0003] In the terminal guidance stage of the missile, since the SAR works in the dive mode, the biggest difference between it and the conventional airborne SAR is that the vertical height between the radar platform and the ground target changes with time, which makes the SAR echo under ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S13/90G01S7/02
Inventor 徐华平肖忠源李春升
Owner BEIHANG UNIV
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