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Equivalent range equation based SAR (synthetic aperture radar) ground motion target imaging method

A ground moving target and equivalent distance technology, applied in the field of radar, can solve problems such as azimuth defocusing, inaccurate focusing of moving targets, and affecting the recognition and classification of moving targets by the system

Inactive Publication Date: 2013-09-11
XIDIAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above methods all perform a second-order Taylor approximation to the target distance equation
The effect of this approximation on range migration correction is negligible, but the effect on signal phase bending compensation cannot be ignored, especially for airborne SAR systems with long synthetic aperture time, this approximation will lead to serious azimuth defocusing and Azimuth side lobes are asymmetrical, making the system's focus on moving targets inaccurate, which will seriously affect the system's identification and classification of moving targets

Method used

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  • Equivalent range equation based SAR (synthetic aperture radar) ground motion target imaging method
  • Equivalent range equation based SAR (synthetic aperture radar) ground motion target imaging method

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Embodiment 1

[0039] The airborne SAR-GMTI system is an advanced earth observation equipment, which has been widely used in both civil and military fields. Among them, ground moving target detection and ground moving target imaging play an important role in traffic monitoring and battlefield reconnaissance. Traditional imaging algorithms for moving targets usually make second-order approximation to the range equation of the target, but this approximation will lead to target azimuth defocus and asymmetry of azimuth side lobes. In order to solve the above problems, the present invention proposes a new imaging method for ground moving targets.

[0040]The invention is a SAR ground moving target imaging method based on the equivalent distance equation, which can be used in the airborne SAR-GMTI system working in the side-view mode. In this system, according to the motion characteristics of the radar and the target, a Observation geometry of slant range plane SAR. In this example, the carrier ...

Embodiment 2

[0065] The SAR ground moving target imaging method based on the equivalent distance equation is the same as that in Embodiment 1.

[0066] refer to figure 1 , the implementation steps of the present invention are further described in detail as follows:

[0067] Step 1, the ground moving target is equivalent to a stationary target and the equivalent signal model is established.

[0068] The observation geometry of slant range plane airborne SAR system is as follows: figure 2 shown. The radar works in the front and side view mode, and the speed of the radar platform is v a , the azimuth velocity of the ground moving target is v x , the range velocity projected onto the slant distance plane is v y , regardless of the target acceleration, set at t a = 0 moment, the radar is at the coordinate origin, and the target is at (x 0 ,y 0 ).

[0069] Therefore, t a The instantaneous distance from the target to the radar at any time can be expressed as:

[0070] R ...

Embodiment 3

[0116] The SAR ground moving target imaging method based on the equivalent distance equation is the same as that in Embodiment 1-2.

[0117] Simulation 1, the imaging simulation of ground moving targets based on the second-order Taylor approximation in the prior art.

[0118] The parameters of the SAR system are shown in Table 1, the target is located in the center of the scene, v x =5m / s, v y = 2m / s. The simulation considers that the target motion parameters are known. image 3 The literature [S.Q.Zhu, G.S.Liao, Y.Qu, Z.G.Zhou, and X.Y.Liu, "Ground moving targets imaging algorithm for synthetic aperture radar", IEEE Trans.Geosci.Remote Sens., vol.49, no.1 , pp.462-477, Jan.2011.] is a simulation result diagram of the ground moving target imaging method based on the second-order Taylor approximation, where: image 3 (a) is an azimuth plan view, image 3 (b) is the enlarged target contour map. In order to further analyze the focusing performance, Table 2 gives the image...

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Abstract

The invention discloses an equivalent range equation based SAR (synthetic aperture radar) ground motion target imaging method. The equivalent range equation based SAR ground motion target imaging method includes: subjecting a ground motion target to being equivalent to a static target by means of the equivalent range equation and building an equivalent signal model; subjecting target signals to Fourier transform in range and direction and transforming the signals to a two-dimensional field; matching filter in range of the two-dimensional field; performing inverse Fourier transform in range and correcting range migration; matching filter in direction; performing inverse Fourier transformer in direction and completing motion target imaging. The motion target is equivalent to the static target, the motion target is imaged by means of a static target imaging method, the problems that target direction is defocused and direction sidelobe is asymmetric in the prior art are solved, and the target can be imaged in high quality. The motion target can be imaged by the static target imaging technology, imaging of the motion target is simplified, and the equivalent range equation based SAR (synthetic aperture radar) ground motion target imaging method is easy to implement on engineering and can be used for an onboard SAR-GMTI (ground motion target imaging) to image the ground motion target.

Description

technical field [0001] The invention belongs to the technical field of radar, and relates to an airborne synthetic aperture radar (Synthetic Aperture Radar, SAR) imaging method, specifically a kind of SAR ground moving object imaging method based on the equivalent distance equation, which is used for airborne SAR to ground movement target imaging. Background technique [0002] SAR is an all-day, all-weather, multi-functional microwave remote sensing imaging device, which has been widely used in civilian and military fields. Among them, airborne SAR ground moving target detection GMTI and ground moving target imaging GMTIm have become a research hotspot because of their important role in traffic monitoring and battlefield reconnaissance. [0003] For the airborne SAR-GMTI system, the wide operating bandwidth and long coherent accumulation time enable it to perform high-resolution imaging of the observation area. However, due to the long coherent accumulation time, the imagi...

Claims

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Application Information

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IPC IPC(8): G01S7/41G01S13/90
Inventor 王彤李永康刘保昌吴建新
Owner XIDIAN UNIV
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