SAR imaging method based on sampling sequence length constraint condition

A sampling sequence, length-constrained technology, applied in the field of SAR imaging, can solve problems such as low imaging accuracy, achieve high distinguishability, improve range and azimuth resolution, and improve focusing performance.

Pending Publication Date: 2021-02-02
JIANGSU POLICE INST
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Problems solved by technology

[0006] Purpose of the invention: The present invention proposes a SAR imaging method based on the constraints of the sampling sequence length, that is, constructing a high-resolution SAR imaging method based on the constraints of the optimal sampling length in the range and azimuth directions, aiming at solving the problem of traditional range Doppler The problem of low imaging precision of the method

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  • SAR imaging method based on sampling sequence length constraint condition
  • SAR imaging method based on sampling sequence length constraint condition
  • SAR imaging method based on sampling sequence length constraint condition

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Embodiment Construction

[0056] Such as figure 1 As shown, the present invention is based on the SAR imaging method under the sampling sequence length constraint condition and comprises the following steps:

[0057] Step (1), the SAR echo signal is calculated using the order of the fractional Fourier transform; specifically includes the following:

[0058] (1.1) Signal model construction

[0059] Assume that the LFM (Linear Frequency Modulation) signal transmitted by the SAR at any position is shown in formula (1):

[0060]

[0061] where τ is the fast time variable, T r 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, and rect(·) is the rectangular window function.

[0062] (1.2) Definition of Fractional Fourier Transform

[0063] The definition of fractional Fourier transform of continuous signal f(x) is

[0064]

[0065] where K α (u,x) is the kernel function of fractional Fourier transform, α is the rot...

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Abstract

The invention discloses an SAR imaging method based on an optimal sampling sequence length constraint condition, and the method comprises the steps: a calculation formula of an initial sampling sequence length is designed according to related imaging parameters in an SAR distance direction and an azimuth direction; the obtained initial sampling sequence length and the corresponding criterion of SAR image quality performance evaluation are utilized, the optimal sampling sequence length in the distance direction and the optimal sampling sequence length in the azimuth direction are determined within the reasonable interval change range in combination with curve extreme values, the optimal sampling data length support is provided for global optimal imaging, and a high-resolution SAR imaging method is constructed on the basis of the optimal sampling data length support; the SAR imaging method comprises the steps of order calculation of fractional Fourier transform applied to SAR echo signals, setting of sampling sequence length constraint conditions and construction of the high-resolution SAR imaging method. According to the method, the problem of low imaging quality of a traditional distance Doppler method is solved in synthetic aperture radar imaging, and the range resolution and the azimuth resolution of the SAR image are remarkably improved.

Description

technical field [0001] The invention relates to a synthetic aperture radar imaging method, in particular to a SAR imaging method based on the constraint condition of sampling sequence length. Background technique [0002] Synthetic Aperture Radar (SAR) is widely used in military and civilian fields. Although the Range Doppler (RD) method is still widely used in many modes of SAR imaging processing, especially in front-looking and side-looking SAR imaging processing, its low-precision SAR image quality is increasingly unable to meet the current requirements. practical application needs. [0003] The Fractional Fourier Transform (FrFT) is a generalized Fourier transform, which is a unified time-frequency transform. As the transform order increases continuously from 0 to 1, it shows that the signal gradually changes from the time domain to All features in the frequency domain. In recent years, the fractional Fourier transform has been applied to SAR imaging processing. In th...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S13/90
CPCG01S13/9021
Inventor 王振力王群马如坡印杰郁烨刘家银
Owner JIANGSU POLICE INST
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