频域宽带下视多波束三维声成像算法
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摘要
为解决下视多波束三维成像声呐跨航向分辨率差、旁瓣级高的问题,提出一种频域宽带下视多波束三维声成像算法。该算法将阵元域回波信号通过二维傅里叶变换直接变换到波数-频率域,之后进行深度向匹配滤波,同时选取带宽内的频点进行频域宽带信号的相位补偿,再进行二维逆傅里叶变换回阵元域,实现跨航向-深度向成像处理。沿航向采用时域合成孔径方法,得到三维图像结果.计算机仿真和海上实验结果表明,相比于常规的下视多波束三维成像声呐处理算法,改进的方法跨航向主瓣变窄,角分辨率明显提高,旁瓣降低10～30 dB。相比于传统基于分块DFT的频域宽带波束形成,改进的频域宽带方法避免了跨航向处理中的时域分块插值和多次变换域,复数加法和乘法次数显著降低。改进的频域宽带下视多波束三维声成像算法可以有效地获取水下三维高分辨图像,抑制虚影,明显改善成像质量。同时,计算效率高,更适合于实时成像系统实现。
A broadband downward-looking multi-beam 3 D imaging algorithm in frequency domain is proposed.Echo in array-element domain is transferred into wave number-frequency domain through 2 D Fourier Transformation.Vertical match filtering and phase compensation of broadband signal are subsequently applied.The result is then transferred into array-element domain through 2 D Inverse Fourier Transformation to complete the across-track-vertical imaging processing.Synthetic aperture method is used for along-track processing to obtain the 3 D image.Computer simulation and sea trial results demonstrate that across-track resolution has obvious improvement and the side lobe level is significantly reduced of 10～30 dB compared with the conventional narrowband downward-looking multi-beam 3 D imaging algorithm.Compared to the traditional broadband beamforming,the computational complexity of the presented method is significantly reduced,which is more suitable for real time application.
A broadband downward-looking multi-beam 3 D imaging algorithm in frequency domain is proposed.Echo in array-element domain is transferred into wave number-frequency domain through 2 D Fourier Transformation.Vertical match filtering and phase compensation of broadband signal are subsequently applied.The result is then transferred into array-element domain through 2 D Inverse Fourier Transformation to complete the across-track-vertical imaging processing.Synthetic aperture method is used for along-track processing to obtain the 3 D image.Computer simulation and sea trial results demonstrate that across-track resolution has obvious improvement and the side lobe level is significantly reduced of 10～30 dB compared with the conventional narrowband downward-looking multi-beam 3 D imaging algorithm.Compared to the traditional broadband beamforming,the computational complexity of the presented method is significantly reduced,which is more suitable for real time application.
引文
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2王朋,任宇飞,黄勇等.基于TMS320C6678三维成像声呐信号处理算法的设计与实现.海军工程大学学报,2014; 26(2):85-90
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5 YAN Shefeng.Designs and implementations of broadband beamformers.Chinese Journal of Acoustics,2016; 35(4):329—347
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13 ZHU Weijie,SUN Jincai,ZENG Xiangyang.Adaptive synthesis method for broadband array with frequency invariant beam pattern.Chinese Journal of Acoustics,2003;22(4):352-359
14杨益新,孙超,马远良.宽带低旁瓣时域波束形成.声学学报,2003; 28(4):331-338
15马远良,赵俊渭,张全.用FIR数字滤波器实现高精度时延的一种新方法.声学学报,1995; 20(2):121-126
16王静,黄清,黄建国.稳健宽带自适应波束形成.声学技术,2003;22(2):90-94
17穆鹏程,殷勤业,张建国.一种基于有向均匀圆阵的宽带波束形成方法.中国科学:信息科学,2011;41(2):246-256
18赵拥军,陈辉,刘成城等.宽带波束形成结构及算法研究.电子测量与仪器学报,2014(7):687-694
19蒋留兵,罗良桂,车俐.频率不变约束的对角加载稳健宽带波束形成算法.现代雷达,2012; 34(12):41—44
20吴凯,苏涛,靳标等.具有固定反馈权的自适应宽带波束形成器设计.吉林大学学报(工学版),2016;46(1):303—310
21庞金城,林京,黄晓砥.宽带信号时域波束形成方位估计算法改进.声学技术,2007; 26(5):1044-1045
22 Koca M,Levy B C.Broadband beamforming with power complementary filters.IEEE Trans.Signal Process.,2002;50(7):1573-1582
23 Mitchell M A,Howard R L,Tarran C.Adaptive digital beamforming(ADBF)architecture for wideband phasedarray radars.Proceedings of Spie the International Society for Optical Engineering,1999; 3704:36—47
24 Ward D B,Kennedy R A,Williamson R C.An adaptive algorithm for broadband frequency invariant beamforming.IEEE International Conference on Acoustics,Speech,and Signal Processing,IEEE,1997;5:3737-3740
25刘伯胜,雷家煜.水声学原理.哈尔滨:哈尔滨工程大学出版社,2010
2王朋,任宇飞,黄勇等.基于TMS320C6678三维成像声呐信号处理算法的设计与实现.海军工程大学学报,2014; 26(2):85-90
3杜磊,王彦平,洪文等.机载下视三维成像合成孔径雷达空间分辨特性.测试技术学报,2010; 24(2):175-181
4邵杰.一种改进的宽带波束形成方法.工程科学与技术,2006;38(4):126—130
5 YAN Shefeng.Designs and implementations of broadband beamformers.Chinese Journal of Acoustics,2016; 35(4):329—347
6李加庆,陈进,杨超,薛玮飞,董广明.基于波束形成和波叠加法的复合声全息技术.声学学报,2008; 33(2):152-158
7陈朋,陈耀武.三维声呐频域波束形成算法的优化及实现.吉林大学学报(工学版),2010; 40(3):830-835
8 Liu W,Weiss S.Wideband beamforming:Concepts and techniques.Wiley Publishing,2010
9 Yang Y,Wan C,Sun C.Adaptive design of FIR filter with applications in broadband beamforming.Tencon IEEE Region 10 Conference,IEEE,2004
10 FAN Zhan LIANG Guolong.Frequency-invariant robust adaptive beamforming based on interference covariance matrix reconstruction.Chinese Journal of Acoustics,201433(4):359-368
11 Weiss S,Koh C L,Liu W.A comparison of adaptive beamforming implementations for wideband scenarios.Presented at the 2nd IEE/EURASIP Conf.DSP Enabled Radio,2005
12 Klemm R.Applications of space-time adaptive processing IET Digital Library,2004
13 ZHU Weijie,SUN Jincai,ZENG Xiangyang.Adaptive synthesis method for broadband array with frequency invariant beam pattern.Chinese Journal of Acoustics,2003;22(4):352-359
14杨益新,孙超,马远良.宽带低旁瓣时域波束形成.声学学报,2003; 28(4):331-338
15马远良,赵俊渭,张全.用FIR数字滤波器实现高精度时延的一种新方法.声学学报,1995; 20(2):121-126
16王静,黄清,黄建国.稳健宽带自适应波束形成.声学技术,2003;22(2):90-94
17穆鹏程,殷勤业,张建国.一种基于有向均匀圆阵的宽带波束形成方法.中国科学:信息科学,2011;41(2):246-256
18赵拥军,陈辉,刘成城等.宽带波束形成结构及算法研究.电子测量与仪器学报,2014(7):687-694
19蒋留兵,罗良桂,车俐.频率不变约束的对角加载稳健宽带波束形成算法.现代雷达,2012; 34(12):41—44
20吴凯,苏涛,靳标等.具有固定反馈权的自适应宽带波束形成器设计.吉林大学学报(工学版),2016;46(1):303—310
21庞金城,林京,黄晓砥.宽带信号时域波束形成方位估计算法改进.声学技术,2007; 26(5):1044-1045
22 Koca M,Levy B C.Broadband beamforming with power complementary filters.IEEE Trans.Signal Process.,2002;50(7):1573-1582
23 Mitchell M A,Howard R L,Tarran C.Adaptive digital beamforming(ADBF)architecture for wideband phasedarray radars.Proceedings of Spie the International Society for Optical Engineering,1999; 3704:36—47
24 Ward D B,Kennedy R A,Williamson R C.An adaptive algorithm for broadband frequency invariant beamforming.IEEE International Conference on Acoustics,Speech,and Signal Processing,IEEE,1997;5:3737-3740
25刘伯胜,雷家煜.水声学原理.哈尔滨:哈尔滨工程大学出版社,2010