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Spaceborne sliding spotlight SAR (Synthetic Aperture Radar) satellite attitude and PRF (Pulse Repetition Frequency) sequence design method

A satellite attitude and sliding beamforming technology, applied in the direction of radio wave reflection/re-radiation, use of re-radiation, measurement devices, etc., can solve the problem of small azimuth resolution, lack of roll angle control, and azimuth resolution and other problems, to achieve the effect of reducing the azimuth resolution space, reducing the Doppler bandwidth and Doppler bandwidth bandwidth

Active Publication Date: 2019-03-26
XIDIAN UNIV
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0004] There are two main problems in the parameter design of the existing spaceborne sliding spotlight SAR system: the first problem is to adopt a flexible attitude maneuver strategy to ensure that the azimuth resolution becomes smaller and avoid the curvature of the illuminated scene; the second problem is to launch In the case of serious distance migration, a fixed PRF cannot guarantee that all echoes fall within the "receiving window"
[0005] The existing space-borne sliding spotlight SAR attitude maneuver strategy only controls the single-axis or two-axis attitude, lacks the control of the roll angle, and has the problem of bending the irradiation scene; the focus center position remains unchanged, and the Doppler bandwidth is wide , there is a problem that the azimuth resolution space changes obviously; the PRF is fixed, and there is a problem that all echoes cannot fall within the "receiving window"

Method used

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  • Spaceborne sliding spotlight SAR (Synthetic Aperture Radar) satellite attitude and PRF (Pulse Repetition Frequency) sequence design method
  • Spaceborne sliding spotlight SAR (Synthetic Aperture Radar) satellite attitude and PRF (Pulse Repetition Frequency) sequence design method
  • Spaceborne sliding spotlight SAR (Synthetic Aperture Radar) satellite attitude and PRF (Pulse Repetition Frequency) sequence design method

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Embodiment 1

[0031] Synthetic aperture radar has the characteristics of all-day and all-weather, and plays an important role in military and civil fields. Due to the unique advantages of high resolution, spaceborne sliding spotlight SAR has become a research hotspot in the field of SAR at home and abroad. For space-borne sliding spotlight SAR, the existing single-axis or dual-axis attitude control will cause the problem of scene curvature; the single data acquisition usually takes more than tens of seconds, the distance migration is serious, and some echoes will fall in the "blind zone" within, so that part of the echo is lost. The present invention has launched research on the above-mentioned problems, and proposes a space-borne sliding spotlight SAR satellite attitude maneuver strategy and a PRF sequence design method, see figure 1 , the present invention performs three-axis attitude maneuvering control, and there is no problem that the irradiation scene is curved and the azimuth resolu...

Embodiment 2

[0038] The attitude maneuver strategy and PRF sequence design method of the spaceborne sliding spotlight SAR satellite are the same as in Example 1, and the initial data acquisition time T described in step 1 is calculated. on method, its sub-steps are:

[0039] 1a) Determine the slip factor α

[0040] The sliding beamforming geometric model such as figure 2 As shown in , it is assumed that the working mode of the spaceborne sliding spotlight SAR is right-looking, and the satellite moves from left to right along the trajectory, t s is the start time of data acquisition, t m Get intermediate instants for the data, t e It is the end time of data acquisition. θ s (t) indicates that the satellite is at t s Beam center oblique angle at time, R rot means t m The slant distance from the moment focus center to the satellite, R st means t m The slant distance from the center of the scene to the satellite at any moment, X s Indicates the effective width of the azimuth direct...

Embodiment 3

[0057] The spaceborne sliding spotlight SAR satellite attitude maneuver strategy and the PRF sequence design method are the same as those in Embodiment 1-2, the method for determining the satellite attitude angle described in step 2, and its sub-steps are:

[0058] 2a) Determine the direction of the coordinate axes of the satellite body coordinate system under the ground-fixed system. The satellite body coordinate system is a Cartesian rectangular coordinate system, and the coordinate axes conform to the right-hand rule. image 3 Obtain geometric schematics for squint radar data, where R S is the current position vector of the satellite, V S is the satellite velocity vector, T n is the position vector of the near end point of the beam coverage area at the current moment, T f is the position vector of the far end of the beam coverage area at the current moment, X B , Y B and Z B are the three coordinate axes of the satellite body coordinate system.

[0059] 2a.1) Find the...

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Abstract

The invention discloses a spaceborne sliding spotlight SAR (Synthetic Aperture Radar) satellite attitude and PRF (Pulse Repetition Frequency) sequence design method, which solves the problems of irradiation scene bending, obvious space variation of the azimuth resolution and the failing of an echo into a blind area of the spaceborne sliding spotlight SAR. The implementation comprises the steps ofcalculating the initial data acquisition time; determining the satellite attitude angle according to the beam pointing and the minimum constrained Doppler center frequency distance space variation; determining the final data acquisition time; and dividing the data acquisition time into multiple bursts, wherein each burst adopts a different PRF so as to complete PRF sequence design. According to the invention, the control for the roll angle is increased so as to avoid the irradiation scene bending; the focus center position changes, so that the space variation of the azimuth resolution is reduced; and the PRF changes, so that the echo is avoided from falling into the blind area. The method disclosed by the invention is free of irradiation scene bending, reduced in space variation of the azimuth resolution and capable of enabling the echo to be completely falling into a receiving window. The method is used for system parameter design of the spaceborne sliding spotlight SAR, and achievesthe purposes of being free of irradiation scene bending and acquiring the complete echo.

Description

technical field [0001] The present invention relates to the technical field of parameter design of a spaceborne synthetic aperture radar system, in particular to the parameter design of a spaceborne sliding spotlight SAR satellite system, in particular to a spaceborne sliding spotlight SAR satellite attitude and PRF sequence design method, which can be used for spaceborne sliding Parameter Design of Spotlight Synthetic Aperture Radar System. Background technique [0002] Synthetic aperture radar can observe the earth all-weather and all-weather, and can penetrate natural vegetation and artificial camouflage to discover important military targets. Synthetic aperture radar has a variety of working modes, among which the sliding spotlight mode is a mixed mode of the strip mode and the spotlight mode, and its azimuth resolution is better than that of the strip mode, and the azimuth mapping bandwidth is larger than that of the spotlight mode, which can accurately obtain local Im...

Claims

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Application Information

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IPC IPC(8): G01S13/90
CPCG01S13/9094G01S13/9052
Inventor 李真芳郑成鑫楼嘉晗周超伟
Owner XIDIAN UNIV
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