Strabismus spaceborne bunching SAR PRT calibration distance changing migration method

A technology of distance migration and squint star, which is applied in the field of radar to achieve the effect of small amount of computation, avoiding the loss of imaging swath width, and reducing the difficulty of imaging processing

Inactive Publication Date: 2013-07-24
BEIHANG UNIV
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  • Abstract
  • Description
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Problems solved by technology

[0005] In view of the fact that spaceborne SAR cannot solve the problem of distance migration simply through "sliding window processing" under squint conditions, the invention proposes a method of correcting distance migration by changing the pulse repetition time (PRT)

Method used

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  • Strabismus spaceborne bunching SAR PRT calibration distance changing migration method
  • Strabismus spaceborne bunching SAR PRT calibration distance changing migration method
  • Strabismus spaceborne bunching SAR PRT calibration distance changing migration method

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Embodiment

[0050] Step 1. Set the initial pulse repetition time T 0 , input the discrete time-distance data D between the spaceborne SAR and the target, use the polyfit function in MATLAB software to obtain the slope distance-time variation function R(t) between the radar and the target, and calculate the initial moment distance R between the satellite and the target 0 , according to the distance R at the initial moment 0 with the initial pulse repetition time T 0 , calculate the distance ambiguity number n.

[0051] Specifically:

[0052] (i) Set the initial pulse repetition time T 0 =492.6×10 -6 s, input the discrete time-distance data between the spaceborne SAR and the target such as image 3 As shown, using the polyfit function in the MATLAB software, the fitting order is set to 2, and the slope distance-time variation function R(t) between the radar and the target is obtained as shown in formula (6)

[0053] R(t)=0.0163t 2 -0.7946t+1499.7 (6)

[0054] (ii) Substitute t=0 int...

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Abstract

The invention discloses a strabismus spaceborne bunching SAR PRT calibration distance changing migration method which includes the following steps. Firstly, a slope-distance-time change function R(t) and a distance fuzzy number n between a radar and a target are obtained. Secondly, a distance error square and the minimal rule are used and a target function F (delta, delta one and delta two) is simultaneously obtained. By solving the minimal value of the target function, ith impulse repetition time Ti and echoing window opening time delta are obtained. Thirdly, according to the ith impulse repetition time Ti and the echoing window opening time delta which are obtained in the second step, signal impulses are sequentially emitted and echoing signals are received. According to the strabismus spaceborne bunching SAR PRT calibration distance changing migration method, effective compensation for distance migration momentum is achieved by changing radar PRT; operation quantity of the method is little; after calibration, echoing waves of the same target appear within the same distance; and imaging processing difficulties are lowered. With the PRT calibration distance changing migration method, the phenomenon that width of an imaging mapping belt is lost due to distance migration is avoided and the width of the mapping belt of a satellite is increased.

Description

technical field [0001] The present invention relates to the field of radar technology, in particular to a squint-looking spaceborne spotlight synthetic aperture radar (Synthetic Aperture Radar, referred to as SAR) variable pulse repetition time (Pulse Repetition Time, referred to as PRT) correction distance migration method. Background technique [0002] Synthetic aperture radar is a two-dimensional imaging radar that relies on the Doppler effect generated by the relative motion between the radar and the target to obtain high resolution in the azimuth direction, and relies on transmitting large time-band product signals to obtain high resolution in the range direction. Due to the relative motion between the radar and the target during the synthetic aperture process, the slant range between them changes beyond a range resolution unit, resulting in the echo signals from the same target being distributed in different range units in the range direction, so produce distance migra...

Claims

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Application Information

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IPC IPC(8): G01S13/90
Inventor 孙兵李星辉李景文
Owner BEIHANG UNIV
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