基于分数阶Fourier变换的高性能SAR成像算法

doi:10.12082/dqxxkx.2020.190792

地球信息科学学报 ›› 2020, Vol. 22 ›› Issue (11): 2247-2255.doi: 10.12082/dqxxkx.2020.190792

基于分数阶Fourier变换的高性能SAR成像算法

王振力¹^,^*(), 王群¹, 陈先意², 马如坡¹, 刘晓迁¹

1.江苏警官学院计算机信息与网络安全系,南京 210031
2.南京信息工程大学计算机与软件学院,南京 2100442

收稿日期:2019-12-23 修回日期:2020-05-19 出版日期:2020-11-25 发布日期:2021-01-25
通讯作者: 王振力 E-mail:dongwen3619@sina.com
作者简介:王振力（1977— ）,男,安徽寿县人,博士,副教授,研究方向为非平稳信号分析及成像处理。E-mail: dongwen3619@sina.com
基金资助:
国家科技攻关计划项目(2018YFB1003205);国家自然科学基金项目(61502242);江苏省教育科学“十三五”规划2020年度课题(D/2020/01/22);江苏省高等学校自然科学研究面上项目(19KJB510022);江苏警官学院高层次引进人才科研项目(JSPI19GKZL405)

Research on a High-performance Imaging Algorithm of Synthetic Aperture Radar via Fractional Fourier Transform

WANG Zhenli¹^,^*(), WANG Qun¹, CHEN Xianyi², MA Rupo¹, LIU Xiaoqian¹

1. Computer Information and Network Security Department, Jiangsu Police Institute, Nanjing 210031, China
2. School of computer and software, Nanjing University of Information Science&Technology, Nanjing 210044, China

Received:2019-12-23 Revised:2020-05-19 Online:2020-11-25 Published:2021-01-25
Contact: WANG Zhenli E-mail:dongwen3619@sina.com
Supported by:
The National Key R&D Program of China(2018YFB1003205);The National Natural Science Foundation of China(61502242);The 13th Five-Year Plan for Jiangsu Education Science(D/2020/01/22);Natural Science Research Projects of Colleges and Universities in Jiangsu Province(19KJB510022);JSPIGKZ(JSPI19GKZL405)

摘要/Abstract

摘要：

传统距离多普勒算法（RD）较低精度的SAR成像质量越来越不能满足当前实际应用的需要。为解决传统距离多普勒算法成像性能低的问题,本文提出基于分数阶Fourier变换的高性能SAR成像算法（FrFT-RD）。本文详细推导SAR距离向信号运用分数阶Fourier变换时最佳阶数的计算表达式,同时给出方位向相应的计算式。理论分析表明距离（方位）向最佳阶数均取决于SAR成像参数并具有唯一性,无须迭代运算,可极大提高FrFT-RD算法的工程实用性。根据计算得到的距离向和方位向上最优阶数,在分数阶Fourier变换域完成FrFT-RD算法的构建。机载SAR模拟数据和星载SAR实测数据测试表明,FrFT-RD算法在分辨率、峰值旁瓣比（PSLR）成像性能方面比传统RD算法均得到显著提高,其中距离向和方位向分辨率提高比值分别为45.92%和48.06%;距离向PSLR和ISLR降低幅度为1.45 dB和2.59 dB,而FrFT-RD算法在方位向PSLR和ISLR成像性能方面与传统RD算法相当。

关键词: Fourier变换, 分数阶Fourier变换, 合成孔径雷达, 距离多普勒算法, 峰值旁瓣比, 积分旁瓣比, 脉冲压缩

Abstract:

The Traditional Range Doppler (RD) algorithm has become the most classic method in Synthetic Aperture Radar (SAR) image processing because of its advantages of easy implementation and high efficiency. However, its low imaging quality is unable to meet the needs of practical applications nowadays. To resolve this problem, we propose a high-performance imaging procesing algorithm (FrFT-RD) in this paper. The expression of optimal order of SAR range signals using fractional Fourier transform is deduced, and the corresponding formula of the azimuth direction is also given. The theoretical analysis shows that the optimal orders of the range and azimuth direction both depend on the SAR imaging parameters and are unique. Thus, the engineering practicability of FrFT-RD algorithm are large without iteration approaches. The construction of the FrFT-RD algorithm includes: Firstly, the FrFT-RD algorithm based on the traditional range Doppler algorithm is established in the fractional Fourier transform domain using the calculated optimal orders of the range and azimuth direction; Secondly, the fractional Fourier transform of corresponding order is used to process the range signals and the reference function of the range direction to complete the range pulse compression and the range cell migration correction (RCMC). The range signals are reconstructed by the inverse fractional Fourier transform (IFrFT) with the order of 1; Thirdly, the fractional Fourier transform of the corresponding order is used to process the azimuth signals and the reference function of the azimuth direction to complete the azimuth pulse compression. The azimuth signals are finally reconstructed by the inverse fractional Fourier transform (IFrFT) with the order of 1. By comparing results of airborne SAR simulation with spaceborne SAR measurement data, we find that the FrFT-RD algorithm significantly improves the imaging performance on resolution, and peak side lobe ratio (PSLR) compared to traditional RD algorithm. The resolutions of the range and azimuth directions are increased by 45.92% and 48.06%, respectively, and the PSLR and ISLR of the range and direction are decreased by 1.45 dB and 2.59 dB, respectively. While the Frft-RD algorithm almost has the same imaging performance as the traditional RD algorithm in PSLR and ISLR on the azimuth direction.

Key words: Fourier transform, fractional Fourier transform, Synthetic Aperture Radar, range doppler algorithm, peak side lobe ratio, integrated side lobe ratio, pulse compression

王振力, 王群, 陈先意, 马如坡, 刘晓迁. 基于分数阶Fourier变换的高性能SAR成像算法[J]. 地球信息科学学报, 2020, 22(11): 2247-2255.DOI:10.12082/dqxxkx.2020.190792

WANG Zhenli, WANG Qun, CHEN Xianyi, MA Rupo, LIU Xiaoqian. Research on a High-performance Imaging Algorithm of Synthetic Aperture Radar via Fractional Fourier Transform[J]. Journal of Geo-information Science, 2020, 22(11): 2247-2255.DOI:10.12082/dqxxkx.2020.190792

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参数	数值	单位
光速	2.988×10⁸	m/s
载波频率	4	GHz
信号带宽	120	MHz
信号脉宽信号抽样频率	5 192	μs MHz
脉冲重复频率方位向天线尺寸	140 3	Hz m
载机飞行速度	150	m/s
中心点斜距	6000	m

算法		分辨率 /m	峰值旁瓣比 /（PSLR/dB）	积分旁瓣比 /（ISLR/dB）
RD	距离向	1.11	-13.29	-10.19
RD	方位向	1.34	-13.38	-10.17
FrFT-RD	距离向	0.71	-13.64	-10.78
FrFT-RD	方位向	0.97	-13.69	-10.18

算法		分辨率 /m	峰值旁瓣比 /（PSLR/dB）	积分旁瓣比 /（ISLR/dB）
RD	距离向	9.32	-13.19	-8.96
RD	方位向	29.32	-13.34	-10.93
FrFT-RD	距离向	5.04	-14.64	-11.55
FrFT-RD	方位向	15.23	-12.25	-11.06

基于分数阶Fourier变换的高性能SAR成像算法

Research on a High-performance Imaging Algorithm of Synthetic Aperture Radar via Fractional Fourier Transform

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