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Ionized layer time-dependent effect impact determining method for GEOSAR orientation imaging

An ionospheric and imaging technology, which is applied in the cross-field of aerospace and microwave remote sensing, can solve the problems of azimuth imaging quality degradation, non-detection, and reduced coherence of GEOSAR echo signals.

Active Publication Date: 2016-07-20
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

GEOSAR synthetic aperture times up to 10 2 ~10 3 seconds, so the time-varying effect of the ionosphere will reduce the coherence of the GEOSAR echo signal, which may lead to a decrease in the quality of its azimuth imaging
[0004] The impact of ionospheric time-varying effect on GEOSAR azimuth imaging is reflected in the change of STEC (SlantTotalElectronContent, slant total electron content) within the synthetic aperture time, and the corresponding impact judgment method has not yet been found

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  • Ionized layer time-dependent effect impact determining method for GEOSAR orientation imaging
  • Ionized layer time-dependent effect impact determining method for GEOSAR orientation imaging
  • Ionized layer time-dependent effect impact determining method for GEOSAR orientation imaging

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Embodiment Construction

[0027] The method provided by the present invention will be described in detail below in conjunction with the accompanying drawings.

[0028] figure 1 The time-varying effect of the ionosphere in the GEOSAR azimuth imaging provided by the present invention affects the decision flow chart, which is divided into four steps in total. Taking GEOSAR system parameters as input, the first step: for any target point P in the observation scene, calculate its synthetic aperture center time t 0 The coordinates of the ionospheric piercing point Step 2: Use the online IRI model to obtain the azimuth slow time t n The ionosphere at the coordinates of the puncture point at time Step 3: Get what you got Perform polynomial fitting to obtain the first-order component coefficient k 1 The value of and the second-order component coefficient k 2 The value of; the fourth step: judge k 1 and k 2 and the size of the threshold value to obtain the judgment result.

[0029] figure 2 It is a...

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Abstract

The invention discloses an ionized layer time-dependent effect impact determining method for GEOSAR orientation imaging. The technical scheme is that the method takes a GEOSAR system parameter as the input, and comprises the steps: 1, obtaining the coordinates of a puncture point of an ionized layer at a synthetic aperture center moment t0; 2, obtaining an ionized layer (shown in the description) at the coordinates of the puncture point in an azimuth direction at a slow moment tn through employing an online IRI model; 3, carrying out the polynomial fitting of the obtained ionized layer (shown in the description), and obtaining the value of a first-order component coefficient k1 and the value of a second-order component coefficient k2; 4, comparing k1 and k2 with a threshold value, and obtaining a judgment result. The method aims at the spaceborne SAR orientation imaging processing, gives a judgment threshold vale and a judgment method, and is widely used in the analysis and correction of the spaceborne SAR ionized layer impact.

Description

technical field [0001] The invention belongs to the cross-technical field of the combination of aerospace and microwave remote sensing, and in particular relates to a method for judging the impact of ionospheric time-varying effects in GEOSAR (Geosynchronous Synthetic Aperture Radar, Geosynchronous Synthetic Aperture Radar) azimuth imaging. Background technique [0002] With the development of aerospace technology and microwave detection technology, spaceborne SAR system is playing an increasingly important role as an important means of space detection. At present, the orbital height and frequency range of the spaceborne SAR system have been further expanded, and the functions have been further enhanced. The GEOSAR system is a new spaceborne SAR system obtained when the orbit is extended to geosynchronous orbit. Compared with the traditional low-orbit spaceborne SAR system, the GEOSAR system has the technical advantages of wide observation scene, wide coverage area, and hig...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S7/40G01S13/90
CPCG01S7/40G01S13/90G01S13/9058
Inventor 张启雷计一飞张永胜董臻余安喜何志华黄海风何峰孙造宇金光虎
Owner NAT UNIV OF DEFENSE TECH