短程宽带FMCW雷达信号非线性校正方法研究
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摘要
调频连续波(Frequency Modulated Continuous Wave,FMCW)合成孔径雷达(Synthetic Aperture Radar,SAR)具有重量轻、截获概率低、高分辨率成像等优点,但其发展受到限制的一个重要因素是发射信号中存在的非线性误差。本文针对一部X波段4.8 GHz带宽短程调频连续波成像雷达系统中非线性误差较大的问题,提出了一种基于高阶模糊函数(High-order Ambiguity Function,HAF)和重采样的非线性误差校正方法。该方法结合压控振荡器(Voltage Controlled Oscillator,VCO)的频率电压特性将非线性差频信号拟合为多项式相位信号(Polynomial Phase Signals,PPS),利用HAF对多项式相位系数进行估计,并利用插值完成非线性误差校正。仿真和实测数据处理结果表明,该方法能准确有效地校正FMCW系统中的非线性误差,且工程适用性强。
The combination of frequency-modulated continuous-wave( FMCW) technology and synthetic aperture radar( SAR) techniques have a lot of advantages,such as light weight,low probability of intercept and high resolution imaging.One limiting factor to the use of FMCW sensors is the presence of nonlinearities in the transmitted signal. In order to analyze the problem of large nonlinear error in frequency modulated continuous wave imaging system with X-band and 4. 8 GHz bandwidth,a nonlinear correction algorithm based on high order ambiguity function and resampling is proposed. Polynomial-phase signals are fitted by the nonlinear beat-frequency signals combing with frequency-voltage character of voltage controlled oscillator in this paper. Polynomial-phase coefficients are estimated by HAF,and then nonlinear error is corrected by interpolation method. The experimental results based on simulation and real data indicate that this method can correct the nonlinear error with high precision and strong engineering applicability can solidly and effectively corrects the nonlinear error in FMCW system.
The combination of frequency-modulated continuous-wave( FMCW) technology and synthetic aperture radar( SAR) techniques have a lot of advantages,such as light weight,low probability of intercept and high resolution imaging.One limiting factor to the use of FMCW sensors is the presence of nonlinearities in the transmitted signal. In order to analyze the problem of large nonlinear error in frequency modulated continuous wave imaging system with X-band and 4. 8 GHz bandwidth,a nonlinear correction algorithm based on high order ambiguity function and resampling is proposed. Polynomial-phase signals are fitted by the nonlinear beat-frequency signals combing with frequency-voltage character of voltage controlled oscillator in this paper. Polynomial-phase coefficients are estimated by HAF,and then nonlinear error is corrected by interpolation method. The experimental results based on simulation and real data indicate that this method can correct the nonlinear error with high precision and strong engineering applicability can solidly and effectively corrects the nonlinear error in FMCW system.
引文
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[11]江志红,程翥,万建伟,等.调频连续波SAR MCM成像算法[J].信号处理,2009,25(1):81-86.Jiang Z H,Cheng Z,Wan J W,et al.MCM Algorithm for FMCW SAR Data Processing[J].Signal Processing,2009,25(1):81-86.(in Chinese)
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[14]Wang Y,Zhou G.On the use of high order ambiguity function for multicomponent polynomial phase signals[C]∥Acoustics,Speech,and Signal Processing,1997.ICASSP-97,1997 IEEE International Conference on.IEEE,1997:3629-3632.
[15]Peleg S,Porat B.Estimation and Classification of Signals With Polynomial Phase[C]∥Electrical and Electronics Engineers in Israel,1989.The Sixteenth Conference of.1989:1-4.
[2]李瑶,章军,林大勇.一种FMCW信号非线性估计方法[J].现代电子技术,2012,35(9):7-9.Li Y,Zhang J,Lin D Y.Method for non-linearity estimation of FMCW signal[J].Modern Electronics Technique,2012,35(9):7-9.(in Chinese)
[3]潘磊,刘光炎.FMCW信号的频率非线性校正分析[J].中国电子科学研究院学报,2010,5(1):74-77.Pan L,Liu G Y.Analysis of Non-linear Frequency Correction Way for FMCW Signal[J].Journal of CAEIT,2010,5(1):74-77.(in Chinese)
[4]王虹,李兴国.FMCW雷达差频信号的非线性分析[J].电光与控制,2010,17(10):33-36.Wang H,Li X G.Analysis to Nonlinearity of Difference Frequency Signal for FMCW Radar[J].Electronics Optics&Control,2010,17(10):33-36.(in Chinese)
[5]易天柱,何志华,董臻.调频连续波SAR非线性误差的开环校正方法[J].电子学报,2015,43(3):550-556.Yi T Z,He Z H,Dong Z.Open-Loop Correction Method for Nonlinear Error of Frequency Modulated Continuous Wave SAR[J].Acta Electronica Sinica,2015,43(3):550-556.(in Chinese)
[6]Meta A,Hoogeboom P,Ligthart L P.Signal Processing for FMCW SAR[J].Geoscience&Remote Sensing IEEE Transactions on,2007,45(11):3519-3532.
[7]曲长文,王颖,苏峰,等.LFMCW SAR非线性校正成像方法研究[J].中国电子科学研究院学报,2009,4(1):50-53.Qu C W,Wang Y,Su F,et al.Research on Nonlinearity Correction Imaging Method of LFMCW SAR[J].Journal of CAEIT,2009,4(1):50-53.(in Chinese)
[8]Andrei A,Gabriel V,Remus C,et al.Short-Range Wideband FMCW Radar for Millimetric Displacement Measurements[J].IEEE Transactions on,2014,52(9):5633-5642.
[9]董勇伟,梁兴东,丁赤飚.调频连续波SAR非线性处理方法研究[J].电子与信息学报,2010,32(5):1034-1039.Dong Y W,Liang X D,Ding C B.Non-linear Signal Processing for FMCW SAR[J].Journal of Electronics&Information Technology,2010,32(5):1034-1039.(in Chinese)
[10]程普,王展,方凌江,等.调频连续波SAR方位多波束成像[J].现代电子技术,2013,36(3):12-15.Cheng P,Wang Z,Fang L J,et al.Imaging of FMCW SAR using multiple azimuth beams[J].Modern Electronics Technique,2013,36(3):12-15.(in Chinese)
[11]江志红,程翥,万建伟,等.调频连续波SAR MCM成像算法[J].信号处理,2009,25(1):81-86.Jiang Z H,Cheng Z,Wan J W,et al.MCM Algorithm for FMCW SAR Data Processing[J].Signal Processing,2009,25(1):81-86.(in Chinese)
[12]Barbarossa S,Scaglione A,Giannakis G B.Product highorder ambiguity function for multicomponent polynomialphase signal modeling[C]∥IEEE Trans.on Signal Processing,1998:691-708.
[13]Porat B,Friedlander B.Accuracy analysis of estimation algorithms for parameters of multiple polynomial-phase signals[C]∥Acoustics,Speech,and Signal Processing,1995.ICASSP-95,1995 International Conference on.IEEE,1995:1800-1803.
[14]Wang Y,Zhou G.On the use of high order ambiguity function for multicomponent polynomial phase signals[C]∥Acoustics,Speech,and Signal Processing,1997.ICASSP-97,1997 IEEE International Conference on.IEEE,1997:3629-3632.
[15]Peleg S,Porat B.Estimation and Classification of Signals With Polynomial Phase[C]∥Electrical and Electronics Engineers in Israel,1989.The Sixteenth Conference of.1989:1-4.