结合通道均衡的SAR距离DBF方法
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摘要
利用距离数字波束形成(digital beam-forming,DBF)技术可以扩展有效观测幅宽,缓解传统合成孔径雷达系统方位向高分辨与距离向宽测绘带的矛盾,而距离向各通道间的通道误差会使合成波束方向图偏离理想状态,降低系统的性能。针对该问题,提出了结合通道均衡的DBF方法,首先简单介绍传统距离DBF处理技术的原理;然后对实际系统中通道接收信号存在的通道误差进行分析;最后根据分析结果,将通道均衡算法与传统DBF处理技术相结合。该处理方法可以有效消除通道间幅相误差,提升DBF处理效果。利用机载距离向八通道实测数据验证了算法的有效性。
Using digital beam-forming(DBF)can relieve the contradiction between high resolution in azimuth and wide measuring range of conventional synthetic aperture radar(SAR)system by increasing the measurement swath,while deviations between range channels will deviate the synthetic beam pattern from the expected form and impair the performance of the system.To address the issue,a method of DBF combined with channel equalization algorithm is presented.Firstly,the traditional DBF method is introduced briefly;then,the form of deviations between range channels is analyzed;finally,channel equalization algorithm is combined into traditional DBF method according to the analysis.The method can compensate deviations between channels validly and improve the result of DBF processing.Airborne flight experiments with eight range channels validate the proposed method.
Using digital beam-forming(DBF)can relieve the contradiction between high resolution in azimuth and wide measuring range of conventional synthetic aperture radar(SAR)system by increasing the measurement swath,while deviations between range channels will deviate the synthetic beam pattern from the expected form and impair the performance of the system.To address the issue,a method of DBF combined with channel equalization algorithm is presented.Firstly,the traditional DBF method is introduced briefly;then,the form of deviations between range channels is analyzed;finally,channel equalization algorithm is combined into traditional DBF method according to the analysis.The method can compensate deviations between channels validly and improve the result of DBF processing.Airborne flight experiments with eight range channels validate the proposed method.
引文
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[2]WANG B L,WANG W D,LI J J,et al.Ground moving target detection and imaging using a virtual multichannel scheme in HRWS mode[J].IEEE Trans.on Geoscience and Remote Sensing,2016,54(9):5028-5043.
[3]LUN M,LIAO G S,LIU A F,et al.Array-error estimation method for multi-channel SAR systems in azimuth[J].Journal of Systems Engineering and Electronics,2016,27(4):815-821.
[4]YANG T L,WANG Y,CHEN G Z.Digital beamforming in elevation for spaceborne HRWS SAR based on sparse DOA estimation[J].Remote Sensing Letters,2017,8(5):448-457.
[5]李杨,黄杰文,禹卫东.高分辨率宽测绘带星载SAR距离向DBF处理[J].电子与信息学报,2011,33(6):1510-1514.LI Y,HUANG J W,YU W D.Range DBF processing for highresolution wide-swath spaceborne SAR[J].Journal of Electronics&Information Technology,2011,33(6):1510-1514.
[6]ARUN K,PIYUSH V,MANISHA G,Design,analysis of 4X4and 8X8MIMO system with ZF,MMSE and BF techniques[J].Scientific Bulletin of Electrical Engineering Faculty,2017,17(2):16-19.
[7]RAFAEL F R,MANUEL A V,MANUEL B,et al.NASA’s L-band digital beamforming synthetic aperture radar[J].IEEE Trans.on Geoscience and Remote Sensing,2011,49(10):3622-3628.
[8]ROBERT W,WANG W,SHAO Y F,et al.First bistatic demonstration of digital beamforming in elevation with TerraSAR-X as an illuminator[J].IEEE Trans.on Geoscience and Remote Sensing,2016,54(2):842-849.
[9]WANG W,ROBERT W,DENG Y K,et al.A processing scheme for LFM-based waveform MIMO SAR with digital beam-forming in elevation[J].Remote Sensing Letters,2015,6(11):874-883.
[10]KARL G.The effects of IF bandpass mismatch errors on adaptive cancellation[J].IEEE Trans.on Aerospace&Electronic Systems,1990,26(3):455-468.
[11]吕孝雷.机载多通道SAR-GMTI处理方法的研究[D].西安:西安电子科技大学,2008.LX L.Study on new methods for airborne multichannel SAR-GMTI processing[D].Xi’an:Xidian University,2008.
[12]CHEN J L,SUN G C,WANG Y,et al.A TSVD-NCS algorithm in range-Doppler domain for geosynchronous synthetic aperture radar[J].IEEE Geoscience and Remote Sensing Letters,2016,13(11):1631-1635.
[13]LIU W K,SUN G C,XIA X G,et al.A modified CSA based on joint time-Doppler resampling for MEO SAR stripmap mode[J].IEEE Trans.on Geoscience and Remote Sensing,2018,56(6):3573-3586.
[14]XING M D,JIANG X W,WU R B,Motion compensation for UAV SAR based on raw radar data[J].IEEE Trans.on Geoscience and Remote Sensing,2009,47(8):2870-2883.
[15]CHEN J L,XING M D,SUN G C,et al.A 2Dspace-variant motion estimation and compensation method for ultrahigh-resolution airborne stepped-frequency SAR with long integration time[J].IEEE Trans.on Geoscience and Remote Sensing,2017,PP(99):1-12.
[16]WANG G Y,ZHANG L,LI J,et al.Range cell migration correction analysis of one-step and two-step motion compensation for millimeter-wave airborne SAR imaging[J].EURASIP Journal on Advances in Signal Processing,2016,2016(1):115-126.
[17]JAMAL S,SEYED M A.Improved navigation-based motion compensation for LFMCW synthetic aperture radar imaging[J].Signal Image&Video Processing,2015,10(2):1-8.