无线电无源定位中窄带信号时延估计方法研究
摘要
本文主要研究了无线电信号无源定位技术中的时延估计(Time Delay Estimation,TDE)问题。研究目标为寻找针对射频窄带信号的高精度时延估计算法。随着无线技术的迅猛发展,无线定位服务已逐渐与人们的生活息息相关,如移动定位业务(LBS)经由移动网络,利用无线定位,并结合GIS地理信息系统,为用户提供各种位置信息。时间延迟估计在无线电信号无源定位中扮演着重要的角色,其精度和效率直接影响着整个定位系统的性能,因此研究时延估计算法具有重要的理论意义和应用价值。
本文深入分析了影响射频窄带信号时延估计精度的三个主要因素,中频偏差、信号带宽及信噪比。针对这三个主要影响因素进行一一研究,提出了一种中频偏差的解决方案及三种时延估计方法。具体内容介绍如下:
第一,理论推导了中频偏差存在下的时延估计模型,并与不考虑中频偏差情况下的经典时延估计模型进行比较,理论上得出中频偏差对时延估计精度的重要影响,提出了基于频差补偿的中频偏差解决方案及改进的频域相关频差估计法,理论分析和计算机仿真均验证了该方法可以在较低的信噪比下对窄带信号进行较高精度的频差估计。
第二,针对射频窄带信号的带宽及信噪比问题,提出了一种基于连续小波变换的波形比较时延估计法。首先从连续小波变换移不变性的角度推导出连续小波变换与其他时延估计方法联合使用的合理性,扩展了连续小波变换在时延估计算法中的应用范围;同时考虑到波形比较法对信号带宽不敏感的特点,将其与连续小波变换结合形成一种联合时延估计算法,计算机仿真验证了该算法的时延估计精度较高。
第三,对相位谱时延估计法进行了深入研究,推导出中频偏差存在下的相位谱时延估计模型,同时针对射频窄带信号的带宽及信噪比问题,提出了一种基于频差补偿的相位谱时延估计法。该方法采用CZT变换来增加相位法在有限带宽内用于时延估计的有效点数,同时利用Kalman滤波器对相位谱进行线性拟合,提高信号的信噪比。
第四,对DOA估计模型、谐波频率估计模型及时延估计模型三者之间的关系进行了研究,从理论上推导出经典的MUSIC方法可应用于时延估计问题中,并给出频差存在下的MUSIC频率检测时延估计模型,从而提出了基于频差补偿的MUSIC频率检测时延估计法,计算机仿真及实际数据测试均验证了该算法的有效性。
第五,改进了在Matlab环境下运行的窄带无线电信号时差测量系统软件,并通过实际采集的数据测试了各种时延估计方法的性能。
This thesis studies the time delay estimation (TDE) under the situation of passive source positioning based on the received wireless signals. The research object is to find algorithms aimed at the TDE of narrow-band signals. With the rapid development of wireless technology, wireless positioning service is more and more bound up with people's daily life. For instance, LBS can provide people with various kinds of location information with the help of combining mobile network, wireless positioning and GIS. TDE plays an important role in passive wireless positioning, of which the precision and efficiency directly determines the performance of the entire positioning system. Thus, it is of great value to research into the topic of TDE not only in theory but also in application.
Three main factors that deeply affect the TDE precision of narrow-band RF signals have been thoroughly analyzed; they are frequency difference (FD), bandwidth and SNR. Considering the above factors, a frequency difference solution and three TDE methods have been proposed in this thesis, which will be introduced briefly as follows:
Firstly, the TDE model under the existence of frequency difference is derived and compared with the classical TDE model, obtaining the important influence of frequency difference to TDE precision. Thus a frequency difference compensation (FDC) solution and an improved frequency difference estimation method based on frequency domain correlation are proposed here. Theoretical analysis and simulation experiments show that this frequency estimation method can give satisfactory results for narrow-band signals under relatively low SNR.
Secondly, considering the problem of bandwidth and SNR for narrow-band RF signals, a waveform comparison TDE method based on continuous wavelet transform (CWT) is proposed. This method at first proves the feasibility of combination between CWT and other TDE methods using the shift-invariance characteristic of CWT, thus enlarging the application scope of CWT in solving TDE problem. At the same time, this method is insensitive to bandwidth due to the adoption of waveform comparison (WFC) method. Simulation experiments verify that this method has a relatively high TDE precision.
Thirdly, the phase spectrum TDE model under the existence of frequency difference is derived in this thesis. Considering also the factors of bandwidth and SNR, a phase spectrum TDE method based on FDC is proposed. In this method, CZT transform is applied to increase the available frequency bins within a limited bandwidth. Meanwhile, kalman filter is also adopted here because of its excellent anti-noise characteristics.
Fourthly, this thesis theoretically proves that MUSIC method is applicable in solving TDE problem after comparing TDE model with DOA estimation model and harmonic frequency estimation model. Thus a MUSIC TDE method based on FDC is proposed, and the MUSIC TDE model under the existence of frequency difference is also derived. Simulation experiments and real date tests demonstrate the effectiveness of this method.
Finally, the TDOA measuring system for narrow-band RF signals is improved, which is operated under the environment of Matlab. Real data have also been adopted to verify the ability of various kinds of TDE methods.
本文深入分析了影响射频窄带信号时延估计精度的三个主要因素,中频偏差、信号带宽及信噪比。针对这三个主要影响因素进行一一研究,提出了一种中频偏差的解决方案及三种时延估计方法。具体内容介绍如下:
第一,理论推导了中频偏差存在下的时延估计模型,并与不考虑中频偏差情况下的经典时延估计模型进行比较,理论上得出中频偏差对时延估计精度的重要影响,提出了基于频差补偿的中频偏差解决方案及改进的频域相关频差估计法,理论分析和计算机仿真均验证了该方法可以在较低的信噪比下对窄带信号进行较高精度的频差估计。
第二,针对射频窄带信号的带宽及信噪比问题,提出了一种基于连续小波变换的波形比较时延估计法。首先从连续小波变换移不变性的角度推导出连续小波变换与其他时延估计方法联合使用的合理性,扩展了连续小波变换在时延估计算法中的应用范围;同时考虑到波形比较法对信号带宽不敏感的特点,将其与连续小波变换结合形成一种联合时延估计算法,计算机仿真验证了该算法的时延估计精度较高。
第三,对相位谱时延估计法进行了深入研究,推导出中频偏差存在下的相位谱时延估计模型,同时针对射频窄带信号的带宽及信噪比问题,提出了一种基于频差补偿的相位谱时延估计法。该方法采用CZT变换来增加相位法在有限带宽内用于时延估计的有效点数,同时利用Kalman滤波器对相位谱进行线性拟合,提高信号的信噪比。
第四,对DOA估计模型、谐波频率估计模型及时延估计模型三者之间的关系进行了研究,从理论上推导出经典的MUSIC方法可应用于时延估计问题中,并给出频差存在下的MUSIC频率检测时延估计模型,从而提出了基于频差补偿的MUSIC频率检测时延估计法,计算机仿真及实际数据测试均验证了该算法的有效性。
第五,改进了在Matlab环境下运行的窄带无线电信号时差测量系统软件,并通过实际采集的数据测试了各种时延估计方法的性能。
This thesis studies the time delay estimation (TDE) under the situation of passive source positioning based on the received wireless signals. The research object is to find algorithms aimed at the TDE of narrow-band signals. With the rapid development of wireless technology, wireless positioning service is more and more bound up with people's daily life. For instance, LBS can provide people with various kinds of location information with the help of combining mobile network, wireless positioning and GIS. TDE plays an important role in passive wireless positioning, of which the precision and efficiency directly determines the performance of the entire positioning system. Thus, it is of great value to research into the topic of TDE not only in theory but also in application.
Three main factors that deeply affect the TDE precision of narrow-band RF signals have been thoroughly analyzed; they are frequency difference (FD), bandwidth and SNR. Considering the above factors, a frequency difference solution and three TDE methods have been proposed in this thesis, which will be introduced briefly as follows:
Firstly, the TDE model under the existence of frequency difference is derived and compared with the classical TDE model, obtaining the important influence of frequency difference to TDE precision. Thus a frequency difference compensation (FDC) solution and an improved frequency difference estimation method based on frequency domain correlation are proposed here. Theoretical analysis and simulation experiments show that this frequency estimation method can give satisfactory results for narrow-band signals under relatively low SNR.
Secondly, considering the problem of bandwidth and SNR for narrow-band RF signals, a waveform comparison TDE method based on continuous wavelet transform (CWT) is proposed. This method at first proves the feasibility of combination between CWT and other TDE methods using the shift-invariance characteristic of CWT, thus enlarging the application scope of CWT in solving TDE problem. At the same time, this method is insensitive to bandwidth due to the adoption of waveform comparison (WFC) method. Simulation experiments verify that this method has a relatively high TDE precision.
Thirdly, the phase spectrum TDE model under the existence of frequency difference is derived in this thesis. Considering also the factors of bandwidth and SNR, a phase spectrum TDE method based on FDC is proposed. In this method, CZT transform is applied to increase the available frequency bins within a limited bandwidth. Meanwhile, kalman filter is also adopted here because of its excellent anti-noise characteristics.
Fourthly, this thesis theoretically proves that MUSIC method is applicable in solving TDE problem after comparing TDE model with DOA estimation model and harmonic frequency estimation model. Thus a MUSIC TDE method based on FDC is proposed, and the MUSIC TDE model under the existence of frequency difference is also derived. Simulation experiments and real date tests demonstrate the effectiveness of this method.
Finally, the TDOA measuring system for narrow-band RF signals is improved, which is operated under the environment of Matlab. Real data have also been adopted to verify the ability of various kinds of TDE methods.
引文
[1]孙仲康,郭福成,冯道旺.单站无源定位跟踪技术[M].北京:国防工业出版社,2008.
[2]熊群力,陈润生,杨小牛,田宏.综合电子战[M].北京:国防工业出版社,2008.
[3]王宏禹,邱天爽.自适应噪声抵消与时间延迟估计[M].大连:大连理工大学出版社,1999.
[4]邱天爽,魏东兴,唐洪,张安清.通信中的自适应信号处理[M].北京:电子工业出版社,2005.
[5]解家宝,李坤,胡博.时差定位系统中时延估计的研究[J].电子工程,2008,3:40-44.
[6]Zheng C,Tjeng T T.A New Time Delay Estimator Based on ETDE[J].IEEE Transactions on Signal Processing,2003,51(7):1859-1869.
[7]So H C,Ching P C,Chan Y T.A New Algorithm for Explicit Adaptation of Time nelay[J].IEEE Transactions on Signal Processing,1994,42(7):1816-1820.
[8]Weiss A J,Weinstein E.Fundamental Limitations in Passive Time Delay Estimation-Part Ⅰ:Narrow-Band Systems[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1983,31(2):472-486.
[9]Sharma K K,Joshi S D.Time Delay Estimation Using Fractional Fourier Transform[J].Signal Processing,2007,87(5):853-865.
[10]四阶统计量在时差定位中的应用[J].雷达与对抗,2002(2):27-31.
[11]Burrus CS,Gopinath RA,Haitao G.Introduction to Wavelets and Wavelet Transforms[M],第一版.北京:机械工业出版社,2008.
[12]郭莹,邱天爽,张艳丽等.脉冲噪声环境下基于分数低阶循环相关的自适应时延估计方法[J].通信学报,2007,28(3):8-14.
[13]Chen J D,Benesty J,Huang Y et al.New Insights Into the Noise Reduction Wiener Filter[J].IEEE Transactions on Audio,Speech,and Language Processing,2006,14(4):1218-1234.
[14]G.Clifford Carter.Time Delay Estimation for passive sonar signal processing[J].IEEE transactions on acoustics,speech,and signal processing,1981,29(3):463-469.
[15]Alfred M.Bruckstein,Shan Tiejun,Thomas Kailath.The Resolution of Overlapping Echos[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1985,33(6):1357-1367.
[16]杨德森,时洁,刘伯胜.基于倒谱分析的水声信号被动定位时延估计算法研究[J].系统仿真学报,2009,21(2):610-616.
[17]贾颖.移动位置服务的技术原理及市场前景[J].邮电规划,2003(1):14-18.
[18]毛汉领,陈仲仪,庄红宇.能量比时间延迟估计法及在定位仲的应用[J].广西工学院学报,1994,5(2):12-17.
[19]Alfred O.Hero,Stuart C.Schwartz.A New Generalized Cross Correlator[J].IEEE transactions on acoustics,speech,and signal processing,1985,33(1):38-45.
[20]Knapp C H,Carter G C.The Generalized Correlation Method for Estimation of Time Delay[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1976,24(4):320-327.
[21]Piersol A G.Time Delay Esitmation Using Phase Data[J].IEEE Transactions on Acoustics,Speech,and Processing,1981,29(3):471-477.
[22]Viola F,Walker W F.A Comparison Between Spline-Based and Phase-Domain Time-Delay Estimators[J].IEEE Transactions on Ultrasonics,Ferroelectrics and Frequency Control,2006,53(3):515-517.
[23]王江,杨景曙.频差存在时广义相关时延估计方法研究[J].信号处理,2008,24(1):112-114.
[24]Cabot R.A Note on the Application of the Hilbert Transform to Time Delay Estimation[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1981,29(3):607-609.
[25]Gao Yang,Qiu Tianshuang,Sha Lan,Zhao Yanbin.A Narrowband Time Delay Estimating Based on Correlation Coefficient[J].Journal of Systems Engineering and Electronics,2009,20(2):1-5.
[26]行鸿彦,刘照泉,万明习.基于小波变换的广义相关时延估计法[J].声学学报,2002,27(1):88-93.
[27]Nandi A K.On the Subsample Time Delay Estimation of Narrowband Ultrasonic Echoes[J].IEEE Transactions on Ultrasonics,Ferroelectrics,and Frequency Control,1995,42(6):993-1001.
[28]Dooley S R,Nandi A K.Comparison of discrete subsample time delay estimation methods applied to narrowband signals[J].Meas.Sci.Technol.,1998(9):1400-1408.
[29]Zhao Z,Hou Z Q.The generalized phase spectrum method for time delay estimation[J].Acoustics,Speech,and Signal Processing,IEEE International Conference on ICASSP,1984,9(1):459-462.
[30]郭莹,邱天爽,张艳丽.基于共变谱的CZT多源时延估计新方法[J].大连理工大学学报,2007,47(5):746-750.
[31]Kalman R E.A New Approach to Linear Filtering and Prediction Problems[J].Transactions of the ASME-Journal of Basic Engineering,1960,82(D):35-45.
[32]Shaw S R,Laughman C R.A Kalman-Filter Spectral Envelope Preprocessor[J].IEEE Transactions on Instrumentation and Measurement,2007,56(5):2010-2017.
[33]张贤达.现代信号处理,第二版[M].北京:清华大学出版社,2002.
[34]GE Fengxiang,Shen Dongxu,Peng Yingning,Victor O.K.Li.Super-Resolution Time Delay Estimation in Multipath Environments[J].IEEE Trans on circuits and systems.2007,54(9):1977-1985.
[35]O.Besson,P.Stoica.Analysis of MUSIC and ESPRIT frequency estimates for sinusoidal signals with lowpass envelopes[J].IEEE Transactions Signal Process,1996,44(9):2359-2364.
[36]高阳.无线电被动定位中射频窄带信号时延估计研究[D].大连:大连理工大学电信学院,2008.
[2]熊群力,陈润生,杨小牛,田宏.综合电子战[M].北京:国防工业出版社,2008.
[3]王宏禹,邱天爽.自适应噪声抵消与时间延迟估计[M].大连:大连理工大学出版社,1999.
[4]邱天爽,魏东兴,唐洪,张安清.通信中的自适应信号处理[M].北京:电子工业出版社,2005.
[5]解家宝,李坤,胡博.时差定位系统中时延估计的研究[J].电子工程,2008,3:40-44.
[6]Zheng C,Tjeng T T.A New Time Delay Estimator Based on ETDE[J].IEEE Transactions on Signal Processing,2003,51(7):1859-1869.
[7]So H C,Ching P C,Chan Y T.A New Algorithm for Explicit Adaptation of Time nelay[J].IEEE Transactions on Signal Processing,1994,42(7):1816-1820.
[8]Weiss A J,Weinstein E.Fundamental Limitations in Passive Time Delay Estimation-Part Ⅰ:Narrow-Band Systems[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1983,31(2):472-486.
[9]Sharma K K,Joshi S D.Time Delay Estimation Using Fractional Fourier Transform[J].Signal Processing,2007,87(5):853-865.
[10]四阶统计量在时差定位中的应用[J].雷达与对抗,2002(2):27-31.
[11]Burrus CS,Gopinath RA,Haitao G.Introduction to Wavelets and Wavelet Transforms[M],第一版.北京:机械工业出版社,2008.
[12]郭莹,邱天爽,张艳丽等.脉冲噪声环境下基于分数低阶循环相关的自适应时延估计方法[J].通信学报,2007,28(3):8-14.
[13]Chen J D,Benesty J,Huang Y et al.New Insights Into the Noise Reduction Wiener Filter[J].IEEE Transactions on Audio,Speech,and Language Processing,2006,14(4):1218-1234.
[14]G.Clifford Carter.Time Delay Estimation for passive sonar signal processing[J].IEEE transactions on acoustics,speech,and signal processing,1981,29(3):463-469.
[15]Alfred M.Bruckstein,Shan Tiejun,Thomas Kailath.The Resolution of Overlapping Echos[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1985,33(6):1357-1367.
[16]杨德森,时洁,刘伯胜.基于倒谱分析的水声信号被动定位时延估计算法研究[J].系统仿真学报,2009,21(2):610-616.
[17]贾颖.移动位置服务的技术原理及市场前景[J].邮电规划,2003(1):14-18.
[18]毛汉领,陈仲仪,庄红宇.能量比时间延迟估计法及在定位仲的应用[J].广西工学院学报,1994,5(2):12-17.
[19]Alfred O.Hero,Stuart C.Schwartz.A New Generalized Cross Correlator[J].IEEE transactions on acoustics,speech,and signal processing,1985,33(1):38-45.
[20]Knapp C H,Carter G C.The Generalized Correlation Method for Estimation of Time Delay[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1976,24(4):320-327.
[21]Piersol A G.Time Delay Esitmation Using Phase Data[J].IEEE Transactions on Acoustics,Speech,and Processing,1981,29(3):471-477.
[22]Viola F,Walker W F.A Comparison Between Spline-Based and Phase-Domain Time-Delay Estimators[J].IEEE Transactions on Ultrasonics,Ferroelectrics and Frequency Control,2006,53(3):515-517.
[23]王江,杨景曙.频差存在时广义相关时延估计方法研究[J].信号处理,2008,24(1):112-114.
[24]Cabot R.A Note on the Application of the Hilbert Transform to Time Delay Estimation[J].IEEE Transactions on Acoustics,Speech,and Signal Processing,1981,29(3):607-609.
[25]Gao Yang,Qiu Tianshuang,Sha Lan,Zhao Yanbin.A Narrowband Time Delay Estimating Based on Correlation Coefficient[J].Journal of Systems Engineering and Electronics,2009,20(2):1-5.
[26]行鸿彦,刘照泉,万明习.基于小波变换的广义相关时延估计法[J].声学学报,2002,27(1):88-93.
[27]Nandi A K.On the Subsample Time Delay Estimation of Narrowband Ultrasonic Echoes[J].IEEE Transactions on Ultrasonics,Ferroelectrics,and Frequency Control,1995,42(6):993-1001.
[28]Dooley S R,Nandi A K.Comparison of discrete subsample time delay estimation methods applied to narrowband signals[J].Meas.Sci.Technol.,1998(9):1400-1408.
[29]Zhao Z,Hou Z Q.The generalized phase spectrum method for time delay estimation[J].Acoustics,Speech,and Signal Processing,IEEE International Conference on ICASSP,1984,9(1):459-462.
[30]郭莹,邱天爽,张艳丽.基于共变谱的CZT多源时延估计新方法[J].大连理工大学学报,2007,47(5):746-750.
[31]Kalman R E.A New Approach to Linear Filtering and Prediction Problems[J].Transactions of the ASME-Journal of Basic Engineering,1960,82(D):35-45.
[32]Shaw S R,Laughman C R.A Kalman-Filter Spectral Envelope Preprocessor[J].IEEE Transactions on Instrumentation and Measurement,2007,56(5):2010-2017.
[33]张贤达.现代信号处理,第二版[M].北京:清华大学出版社,2002.
[34]GE Fengxiang,Shen Dongxu,Peng Yingning,Victor O.K.Li.Super-Resolution Time Delay Estimation in Multipath Environments[J].IEEE Trans on circuits and systems.2007,54(9):1977-1985.
[35]O.Besson,P.Stoica.Analysis of MUSIC and ESPRIT frequency estimates for sinusoidal signals with lowpass envelopes[J].IEEE Transactions Signal Process,1996,44(9):2359-2364.
[36]高阳.无线电被动定位中射频窄带信号时延估计研究[D].大连:大连理工大学电信学院,2008.