数字通信信号的源码解调技术研究
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摘要
本文主要研究了数字通信信号MASK，MFSK，MPSK信号的解调技术，重点研究了盲信号处理中通信信号的软件解调。
本文讨论了利用希尔伯特变换提取ASK信号包络，利用高阶累积量估计PSK信号正交解调时的载波相位偏差，利用短时傅立叶变换对任意调制的FSK信号进行软件解调的技术，以及利用小波变换估计基带码元宽度等盲信号处理中解调前必需的参数估计方法。其中包括以下几个关键技术：载波频率估计，相位偏差估计和码元宽度估计。本文重点对利用STFT解调MFSK信号的算法进行了探讨。
考虑到PSK信号是一种抑制载波的调制方式，其解调对载波同步的要求较高，本文总结了现有的基本载波同步方法，包括各种环路提取载波的方法，谱估计方法，频率居中法，并给出了一种多次相关谱估计的PSK载频估计方法，实验证明这种方法对于PSK信号的频率估计具有良好的抗噪声性能。
在工程实践中，本文用MATLAB对上述算法进行了仿真并给出了工程应用的效果，理论分析和工程实践证明了本文提出算法的可行性。
Demodulation techniques on digital communication signals, such as MASK, MFSK and MPSK signals, is discussed in this paper. And software demodulation of communication signals in unknown signal processing is mainly dealt with.
This paper introduces methods of obtain ASK signal's envelope using Hilbert transform, compute deviation of PSK signal's carrier when demodulated in quadrature using higher order cumulant, demodulate FSK signals using STFT and estimation of baseband code width using wavelet transform. There are several key techniques, estimation of carrier frequency, estimation of carrier phase deviation and estimation of code width.
Considered that PSK signal is a kind of signal whose carrier is suppressed after modulated, it's demodulation requires more precision of carrier synchronization. This paper introduces methods of carrier synchronization, including methods of circuit loops, spectrum estimation, frequency mediacy and multi-correlated spectrum estimation. It has a better performance in noise background.
In engineering practice, the algorithms above are realized by MATLAB. Both theoretical analysis and engineering practice justify the effectiveness of the algorithms.
本文讨论了利用希尔伯特变换提取ASK信号包络，利用高阶累积量估计PSK信号正交解调时的载波相位偏差，利用短时傅立叶变换对任意调制的FSK信号进行软件解调的技术，以及利用小波变换估计基带码元宽度等盲信号处理中解调前必需的参数估计方法。其中包括以下几个关键技术：载波频率估计，相位偏差估计和码元宽度估计。本文重点对利用STFT解调MFSK信号的算法进行了探讨。
考虑到PSK信号是一种抑制载波的调制方式，其解调对载波同步的要求较高，本文总结了现有的基本载波同步方法，包括各种环路提取载波的方法，谱估计方法，频率居中法，并给出了一种多次相关谱估计的PSK载频估计方法，实验证明这种方法对于PSK信号的频率估计具有良好的抗噪声性能。
在工程实践中，本文用MATLAB对上述算法进行了仿真并给出了工程应用的效果，理论分析和工程实践证明了本文提出算法的可行性。
Demodulation techniques on digital communication signals, such as MASK, MFSK and MPSK signals, is discussed in this paper. And software demodulation of communication signals in unknown signal processing is mainly dealt with.
This paper introduces methods of obtain ASK signal's envelope using Hilbert transform, compute deviation of PSK signal's carrier when demodulated in quadrature using higher order cumulant, demodulate FSK signals using STFT and estimation of baseband code width using wavelet transform. There are several key techniques, estimation of carrier frequency, estimation of carrier phase deviation and estimation of code width.
Considered that PSK signal is a kind of signal whose carrier is suppressed after modulated, it's demodulation requires more precision of carrier synchronization. This paper introduces methods of carrier synchronization, including methods of circuit loops, spectrum estimation, frequency mediacy and multi-correlated spectrum estimation. It has a better performance in noise background.
In engineering practice, the algorithms above are realized by MATLAB. Both theoretical analysis and engineering practice justify the effectiveness of the algorithms.
引文
[1] 张贤达、保铮，非平稳信号分析与处理，第三版，北京：国防工业出版社，1998，P14
[2] 陈卫东，数字通信信号调制识别算法研究，学位论文．2001，P39
[3] 张贤达，时间序列分析——高阶统计量方法[M]，北京：清华大学出版社，1996
[4] 张辉、曹丽娜，现代通信原理与技术，西安电子科技大学出版社，2002，P197
[5] 冯重熙、钱亚生等编著，现代数字通信技术，人民邮电出版社，1987，P411
[6] 徐迅，一种频移键控信号(FSK)的解调方法，北方交通大学学报，P69
[7] 冯小平、李红娟、罗明，用离散STFT实现FSK调制信号的数字解调方法，西安电子科技大学学报，P813
[8] N.A.D'Andrea,U.Mengali and Reggiannini, COMPARISON OF CARRIER ECOVERY METHODS FOR NARROW-BAND PLOYPHASE SHIFT KEYD SIGNALS, GLOBECOM '88.,IEEE 28Nov.-1 Dec. 1988
[9] [美]S．M．凯依，现代谱估计，科学出版社，1994，P176-178，P335
[10] Lang,S.W.and J.H.McClellan, Frequency Estimation with Maximum Entropy Spectral Estimators, IEEE Trans .Acouss. ,Speech Signal Process, Vol.ASSP28, 1980, P716-724
[11] Tufts,D.W.and R.Kumaresan, Estimation of Frequencies of Multiple Sinusoids Making Linear Prediction Perform Like Maximum Likelihood , Proc,IEEE, 1982, Vol.70,P975-989
[12] E．E．Azzouz A．K．Nandi，通信信号调制的自动识别，中国人民解放军57394部队，1998，P172，P173
[13] [美]John G．Proakis，数字通信(第三版)，电子工业出版社，P244
[2] 陈卫东，数字通信信号调制识别算法研究，学位论文．2001，P39
[3] 张贤达，时间序列分析——高阶统计量方法[M]，北京：清华大学出版社，1996
[4] 张辉、曹丽娜，现代通信原理与技术，西安电子科技大学出版社，2002，P197
[5] 冯重熙、钱亚生等编著，现代数字通信技术，人民邮电出版社，1987，P411
[6] 徐迅，一种频移键控信号(FSK)的解调方法，北方交通大学学报，P69
[7] 冯小平、李红娟、罗明，用离散STFT实现FSK调制信号的数字解调方法，西安电子科技大学学报，P813
[8] N.A.D'Andrea,U.Mengali and Reggiannini, COMPARISON OF CARRIER ECOVERY METHODS FOR NARROW-BAND PLOYPHASE SHIFT KEYD SIGNALS, GLOBECOM '88.,IEEE 28Nov.-1 Dec. 1988
[9] [美]S．M．凯依，现代谱估计，科学出版社，1994，P176-178，P335
[10] Lang,S.W.and J.H.McClellan, Frequency Estimation with Maximum Entropy Spectral Estimators, IEEE Trans .Acouss. ,Speech Signal Process, Vol.ASSP28, 1980, P716-724
[11] Tufts,D.W.and R.Kumaresan, Estimation of Frequencies of Multiple Sinusoids Making Linear Prediction Perform Like Maximum Likelihood , Proc,IEEE, 1982, Vol.70,P975-989
[12] E．E．Azzouz A．K．Nandi，通信信号调制的自动识别，中国人民解放军57394部队，1998，P172，P173
[13] [美]John G．Proakis，数字通信(第三版)，电子工业出版社，P244