FFBP SAR imaging-based autofocus method

A self-focusing and imaging technology, which is applied in the reflection/re-radiation of radio waves, the use of re-radiation, and measurement devices, can solve problems such as redundancy and increase the complexity of algorithms, and achieve small increases in computation, save memory, and Avoiding the effect of overlapping subapertures

Active Publication Date: 2016-08-10
CHINA ELECTRONIC TECH GRP CORP NO 38 RES INST
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This will not only cause nearly double the redundant calculat

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  • FFBP SAR imaging-based autofocus method
  • FFBP SAR imaging-based autofocus method
  • FFBP SAR imaging-based autofocus method

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[0118] The present invention mainly adopts the method of simulation experiment for verification, and all steps and conclusions are verified correctly on Visual Studio2010. This invention can be used for self-focusing processing of strip, spotlight, and sliding spotlight SAR FFBP imaging. Here, the ultra-high resolution (better than 0.1m) spotlight SAR is used as an example for simulation. figure 1 It is a flowchart of the present invention. Concrete implementation steps are as follows:

[0119] Step 1: SAR system parameters and observation scene parameter settings. figure 2 is a schematic diagram of the ground polar coordinate system adopted by the FFBP algorithm, image 3 is the simulation parameter of the spotlight SAR system. 5 point targets are placed near the center of the scene with an elevation of 0m. Add a sinusoidal error with an amplitude of 0.005m and a period of 10s in the y and z directions of the platform, see Figure 4 , the results obtained without autofo...

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Abstract

The invention provides an FFBP SAR imaging-based autofocus method through which accurately focused SAR images can be obtained in eight steps. The method is based on an FFBP frame, phase gradient information of movement error is extracted by using phase difference information of adjacent sub-apertures of point targets, and movement error is estimated through an integration method and compensated to realize autofocus processing of high-accurate SAR images. Compared with conventional methods, the method is not affected by error order. Movement error of any orders can be estimated, and the robustness of autofocus algorithm is substantially improved. Error information is extracted by using phase difference of adjacent sub-apertures, which avoids repeated calculation of a nested overlapping sub-aperture method. Large-scale optimized searching is not required, computational burden is greatly reduced, and imaging time is shortened.

Description

technical field [0001] The invention belongs to the field of SAR signal processing, and relates to synthetic aperture radar (SAR) imaging processing, in particular to the self-focusing processing of SAR images, specifically a self-focusing method based on FFBP SAR imaging. Background technique [0002] SAR imaging algorithms can be basically divided into two categories: time-domain imaging algorithms and frequency-domain imaging algorithms. The frequency domain imaging algorithm is a method of uniform compression in the range-Doppler domain or two-dimensional frequency domain by using the same or similar Doppler frequency characteristics of the targets in the scene. Since this method compresses all objects at once, it is very computationally efficient. Common frequency-domain imaging methods include Range Doppler (RD) algorithm, CS (Chirp Scaling) algorithm, wavenumber domain (ω-k) algorithm, and the commonly used spectrum analysis (SPECAN) algorithm in ScanSAR. These freq...

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Application Information

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IPC IPC(8): G01S13/90
CPCG01S13/904G01S13/9017G01S13/9019
Inventor 钟雪莲邓海涛陈仁元杨然谈璐璐马志娟雍延梅郝慧军王金峰
Owner CHINA ELECTRONIC TECH GRP CORP NO 38 RES INST
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