基于Chirp_z變換與方位變標(biāo)地球同步軌道SAR成像算法
doi: 10.11999/JEIT141491
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2.
(西北工業(yè)大學(xué)電子信息學(xué)院 西安 710129) ②(中國(guó)空間技術(shù)研究院西安分院 西安 710100)
Imaging Algorithm for Geosynchronous Orbit SAR Based on Chirp_z Transform and Azimuth Scaling
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2.
(School of Electronics and Information, Northwestern Polytechnical University, Xi&rsquo
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摘要: 針對(duì)地球同步軌道合成孔徑雷達(dá)(GEO SAR)成像距離向處理復(fù)雜，方位向空變性強(qiáng)問題，該文提出一種基于Chirp_z變換與方位變標(biāo)的成像算法。首先在回波模型中考慮停-走-停假設(shè)帶來的相位誤差，然后給出目標(biāo)點(diǎn)的斜距表達(dá)式，并利用泰勒級(jí)數(shù)對(duì)斜距進(jìn)行了高階展開，通過級(jí)數(shù)反演法得到信號(hào)頻譜表達(dá)式，利用高效的Chirp_z變換校正距離走動(dòng)，簡(jiǎn)化距離向處理，利用改進(jìn)的變標(biāo)因子校正方位向信號(hào)一次，二次，三次展開項(xiàng)系數(shù)線性時(shí)變性，并在方位頻域內(nèi)補(bǔ)償變標(biāo)操作引入的相位誤差。仿真結(jié)果表明該算法能夠?qū)崿F(xiàn)地球同步軌道SAR聚集成像。
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關(guān)鍵詞:
- 地球同步軌道合成孔徑雷達(dá) /
- 成像算法 /
- Chirp_z變換 /
- 方位變標(biāo)
Abstract: Aiming at the problem of complex range processing and strong azimuth variant in GEosynchronous Orbit SAR (GEO SAR) imaging processing, an imaging algorithm based on Chirp_z transform and the azimuth scaling is proposed. Firstly, the stop-go-stop phase error is considered in the echo model, and then the slant distance expression which is expanded using the Taylor series is given. After that, a series of inversion method is used to get the signal spectrum expression. In order to simplifying the imaging processing at range direction, the Chirp_z transform is used to correct the range walk. And then, an improved scale factor is used to correct the linear time-varying coefficient of signal expand included the first order, the second order and the three order. The phase error introduced by scaling operation is compensated in frequency domain. Finally, the simulation results show that the algorithm can realize geosynchronous orbit SAR imaging. -
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