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Satellite-borne bunching synthetic aperture radar high-resolution real-time imaging method

A technology of synthetic aperture radar and real-time imaging, which is applied in the direction of radio wave reflection/re-radiation, utilization of re-radiation, measurement devices, etc., which can solve the problem that the slant range model is no longer accurate, shortens the generation time of imaging results, and the equivalent velocity space variation and other problems, to achieve the effect of good real-time, high-efficiency and high-resolution real-time imaging algorithm

Pending Publication Date: 2022-01-04
XIDIAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The first problem is the azimuth spectrum aliasing caused by the azimuth bandwidth of the signal in the spaceborne SAR spotlight mode is greater than the pulse repetition frequency
The second problem is the space variation of the equivalent velocity caused by the curved orbit of the spaceborne SAR
In the high-resolution imaging of space-borne SAR spotlight mode, the real orbit of space-borne SAR in the long synthetic aperture time is no longer an approximate straight line orbit, but a curved orbit; the curved orbit will cause the space variation of the equivalent velocity, making The traditional slant distance model is no longer accurate and affects the focusing effect
The third problem is to improve the real-time performance of imaging processing and shorten the generation time of imaging results after echo data acquisition
[0004] However, most of the existing imaging algorithms can only solve the first two problems, and cannot realize real-time imaging processing. Therefore, more efficient high-resolution real-time imaging algorithms need to be studied in actual processing.

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  • Satellite-borne bunching synthetic aperture radar high-resolution real-time imaging method
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  • Satellite-borne bunching synthetic aperture radar high-resolution real-time imaging method

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Embodiment 1

[0070] See figure 1 and figure 2 , figure 1 It is a schematic flow chart of a space-borne spotlight synthetic aperture radar high-resolution real-time imaging method provided by an embodiment of the present invention, figure 2 It is a schematic flowchart of a high-resolution real-time imaging method for a spaceborne spotlight synthetic aperture radar provided by an embodiment of the present invention. The real-time imaging method includes the steps of:

[0071] S1. Sub-aperture division is performed on the spaceborne SAR spotlight mode echo signal in the azimuth direction to obtain sub-aperture echo signals.

[0072] Specifically, taking the echo signal with 1024 points as an example, it is divided into 8 apertures by equal points, and each aperture includes 128 points.

[0073] This embodiment solves the azimuth spectrum aliasing problem caused by the azimuth bandwidth of the signal being greater than the pulse repetition frequency in the spaceborne SAR beamforming mode...

Embodiment 2

[0154] On the basis of the first embodiment, this embodiment further verifies the effect of the real-time imaging method through simulation.

[0155] Simulation 1: Point simulation effect in spotlight mode

[0156] Table 1 Simulation parameter list of spotlight mode

[0157] model Spotlight mode Orbit height (km) 755 wavelength(m) 0.055 Equivalent speed 7063 Scene center distance (km) 928 Rotation center distance (km) 928 Pulse repetition frequency (Hz) 3549 Sampling rate(MHz) 360 Bandwidth (MHz) 300 Azimuth scene (Km) 4 Distance from scene(Km) 2

[0158] The point target simulation parameters of spotlight mode are shown in Table 1, and the dot matrix is ​​distributed according to 3 (distance)×3 (direction). Figure 4 It is the point target imaging result in spotlight mode obtained by the high-resolution real-time imaging method of spaceborne spotlight synthetic aperture radar in this embodiment. Fi...

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Abstract

The invention relates to a satellite-borne bunching synthetic aperture radar high-resolution real-time imaging method. The method comprises the following steps of: performing sub-aperture division on a satellite-borne SAR bunching mode echo signal in an azimuth direction to obtain a sub-aperture echo signal; carrying out azimuth time scale transformation on the sub-aperture echo signal to obtain an azimuth time scale transformation signal; performing high-order phase compensation on the azimuth time scale signal to obtain a high-order phase compensation signal; performing range migration correction and range pulse pressure equal range direction processing on the high-order phase compensation signal to obtain a range direction processing signal; converting the hyperbolic phase of the distance direction processing signal into a standard secondary phase to obtain a phase conversion signal; performing de-chirp operation and residual phase compensation on the phase conversion signal in sequence to obtain a target sub-aperture image; and performing coherent superposition on the plurality of target sub-aperture images to obtain a full-resolution image. According to the method, imaging processing can be carried out while sub-aperture data are recorded, and good real-time performance is achieved.

Description

technical field [0001] The invention belongs to the technical field of radar signal processing, and in particular relates to a high-resolution real-time imaging method of a space-borne spotlight synthetic aperture radar. Background technique [0002] As an active microwave imaging system, spaceborne synthetic aperture radar (SAR) can perform high-resolution imaging of ground scenes all-weather and all-time. With its superior global observation capability, spaceborne SAR has been widely used in fields such as terrain surveying and mapping, resource detection, disaster monitoring and target recognition. With the continuous improvement of application requirements, spaceborne SAR technology is also developing. In order to quickly and efficiently complete some urgent observation tasks, spaceborne SAR needs to conduct high-resolution real-time observations of specific areas, so the high-resolution real-time imaging processing of the spotlight imaging mode has been developed in sp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S13/90
CPCG01S13/9021
Inventor 刘彦斌孙光才邢孟道王石语
Owner XIDIAN UNIV