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Fractional order Fourier transform-based SAR imaging method

An imaging method and fractional-order technology, applied in the direction of reflection/re-radiation of radio waves, utilization of re-radiation, measurement devices, etc., can solve problems such as low imaging performance, and achieve reduced side lobe level, good clarity, and excellent focusing. performance effect

Active Publication Date: 2020-11-20
JIANGSU POLICE INST
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Problems solved by technology

[0007] Purpose of the invention: The present invention proposes a SAR imaging method FrFT-RD based on the fractional Fourier transform, which is constructed according to the order of range and azimuth, which improves the performance of SAR imaging, and overcomes the traditional range in the prior art. Technical Problems of Low Imaging Performance of Doppler Method

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  • Fractional order Fourier transform-based SAR imaging method
  • Fractional order Fourier transform-based SAR imaging method
  • Fractional order Fourier transform-based SAR imaging method

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Embodiment Construction

[0071] Such as figure 1 , figure 2 Shown, the present invention comprises the following steps based on the SAR imaging method of fractional order Fourier transform:

[0072] (1) Use the fractional Fourier transform analysis to obtain the optimal transformation order of the range of the SAR original echo signal; specifically include the following steps:

[0073] ① Signal transformation analysis

[0074] The fractional Fourier transform of the SAR range echo signal can be obtained

[0075]

[0076] In the formula: K α (u,x) is the kernel function of fractional Fourier transform; α is the rotation angle and μ is the order of fractional Fourier transform; τ is the fast time variable; T P is the pulse width; f c is the carrier frequency; κ r is the modulation frequency of the SAR echo signal; c is the speed of light; rect(·) is the rectangular window function; R(t) is the slope distance, and t is the slow time variable.

[0077] ②Simplified calculation

[0078] Formul...

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Abstract

The invention discloses a fractional order Fourier transform-based SAR (Synthetic Aperture Radar) imaging method FrFT-RD. The construction of a FrFT-RD method in a fractional order Fourier transform domain is completed according to the calculated optimal orders in the distance direction and the azimuth direction. The method specifically comprises the following steps of obtaining a distance direction transform order of an SAR original echo signal by applying fractional order Fourier transform analysis, carrying out fractional order Fourier transform analysis to obtain an azimuth direction transform order of the SAR original echo signal, adjusting the optimal rotation angle of the time-frequency rotation plane to obtain a corresponding order, and constructing a high-resolution SAR imaging method based on fractional order Fourier transform. According to the method, the problem of low imaging performance of a traditional distance Doppler method is solved in synthetic aperture radar imaging, and the SAR imaging resolution is improved.

Description

technical field [0001] The present invention relates to synthetic aperture radar (Synthetic Aperture Radar, SAR) imaging method, relate in particular to a kind of SAR imaging method based on fractional Fourier transform. Background technique [0002] As an effective air-to-ground observation tool, SAR imaging reconnaissance can provide long-distance, all-weather and all-weather detection activities, and plays a pivotal role in the civil and military fields. Common SAR imaging methods include Range Doppler (RD) method, CS (Chirp Scaling) method, wavenumber domain (ωk) method and Spectra Analysis (SPECAN) method. [0003] Due to the advantages of easy implementation and high processing efficiency, the RD method has become the most intuitive and classic method in SAR imaging processing. This method uses the traditional Fast Fourier Transform (FFT) to complete range pulse compression (Pulse Compression), range migration correction (Range Cell MigrationCorrection, RCMC) and azim...

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Application Information

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IPC IPC(8): G01S13/90
CPCG01S13/90
Inventor 王振力马如坡王群李馥娟顾海艳
Owner JIANGSU POLICE INST