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A method for determining azimuth ambiguity in geoSAR staring imaging mode

A technology of azimuth ambiguity and determination method, applied in the field of radar, to achieve the effect of accurate calculation

Active Publication Date: 2019-11-29
XIAN INSTITUE OF SPACE RADIO TECH
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  • Claims
  • Application Information

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Problems solved by technology

The above characteristics inevitably lead to the difference between the azimuth ambiguity calculation in GEO SAR staring imaging mode and the azimuth ambiguity calculation in low-orbit conventional imaging mode.

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  • A method for determining azimuth ambiguity in geoSAR staring imaging mode
  • A method for determining azimuth ambiguity in geoSAR staring imaging mode
  • A method for determining azimuth ambiguity in geoSAR staring imaging mode

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Embodiment Construction

[0042] For the GEO SAR staring working mode, the antenna beam pointing is no longer fixed perpendicular to the flight direction, but its beam pointing is constantly adjusted over time to ensure that the beam center is always pointing to the imaging observation area during the entire synthetic aperture time. Compared with the strip mode, the relative motion between the radar and the imaging target can no longer be equivalent to the motion between the antenna pattern and the imaging target. For a fixed point in the imaging area, the antenna azimuth gain factor Basically unchanged. Therefore, the traditional classic strip azimuth ambiguity calculation method cannot be used.

[0043] The ambiguity of the azimuth mode is due to the limited sampling rate in the azimuth direction and the non-band-limited Doppler spectrum of SAR, which makes the ambiguous signal superimposed on the desired signal. The size of the azimuth ambiguity is usually expressed by the azimuth ambiguity ratio, ...

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Abstract

The invention relates to an orientation fuzziness determining method for a staring imaging mode of a GEO SAR. The method can be used to calculate the orientation fuzziness of different orbit positionsand different scene target points in the staring imaging mode of the GEO SAR accurately. The method comprises the steps that 1) satellite orbit time and a target point scene position during staring observation are determined; 2) GEO SAR characteristics are combined to calculate orientation Doppler frequencies corresponding to different orbit time and different scene objects; 3) according to an antenna orientation directional diagram, radiation gains of a target point antenna in different scene positions during staring observation are calculated; and 4) the orientation fuzziness of the starting model is calculated according to a staring-mode orientation fuzziness formula. The orientation fuzziness determining method can be popularized to accurately calculate the orientation fuzziness in staring imaging observation of speed and time varying low-orbit SAR and medium-orbit SAR.

Description

technical field [0001] The invention belongs to the technical field of radar, and relates to a method for determining the azimuth ambiguity of a GEO SAR staring imaging mode, which can be used for the azimuth ambiguity of the GEO SAR staring imaging mode. The calculation method of the azimuth ambiguity can also be extended to the accurate calculation of the azimuth ambiguity of staring imaging observation under low-orbit SAR\medium-orbit SAR velocity time-varying. Background technique [0002] GEO SAR has the characteristics of short revisit period, wide observation range, and flexible staring observation of specific areas, and has become a research hotspot. GEO SAR staring observation imaging mode can be realized through small-angle antenna phase scanning or satellite attitude maneuvering. Realize staring observation of a specific area at the hour level, and even achieve 24-hour uninterrupted continuous observation of a specific area through a certain orbital design. [0...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01S13/90
CPCG01S13/90G01S13/9058
Inventor 李财品刘娇
Owner XIAN INSTITUE OF SPACE RADIO TECH