The design of classifier is dealt with and the support vector machine ( svm ) , a new result of statistics learning theory , is used in modulation recognition firstly . the choice of classification feature is analyzed . the classification feature vectors are extracted from multi - level wavelet decomposition ( mwd ) and hoc of the received signals 在调制识别分类器的设计上，首次将统计学习理论的新成果? ?支撑矢量机应用在通信信号调制识别中；讨论了分类特征的选取，把接收信号的小波特征或高阶统计量特征作为识别特征，利用支撑矢量机分类器实现信号的调制识别。
Secondly , comparing with the algorithm that was given by english scholars a . k . nandi and e . e . azzouz in 1995 , this dissertation presents a modified automatic recognition algorithm of six kind of digital modulation types such as 2ask , 4ask , 2psk , 4psk , 2fsk and 4fsk , which only uses four key features , and has a very great exaltation in the rate of correct recognition and the performance of signal to noise , we puts forward the constitution of the best threshold which is applicable to the signal that changes within the scope of the signal to noise rate ( snr ) from 5db to 30db , and the overall success rate is not lower than 92 % when snr is over 7db 其次,针对1995年英国学者a . k . nandi和e . e . azzouz提出的针对2ask 、 4ask 、 2psk 、 4psk 、 2fsk和4fsk这六种常用的数字调制信号识别的算法,提出了一种数字信号调制方式识别算法( dmra )的改进算法。该算法仅利用四个特征参数,就可以识别这六种调制方式,而且在调制识别率和信噪比性能上都有了很大的提高,能够在信噪比不低于7db时,对实际信号的识别正确率高于92 % 。并且提出了最佳门限的设置方法,设置的门限适用于信噪比在5db ~ 30db范围内变化的信号。
Asymmetrical digital subscriber loop ( adsl ) is a prevalence fashion of broadband solutions today . it uses the installed base of copper telephone line as the transmission medium . with the combined use of sophisticated signal modulate methods and the high speed digital signal process technology , it ' s upstream speed can be 100kbps to 800kbps and the downstream delivers from 1mbps to 8mbps 不对称数字用户线（ adsl ， asymmetricaldigitalsubscriberloop ）是目前比较流行的宽带接入方式，它使用现有的铜质电话线作为传输介质，采用先进的信号调制方式和高速的数字信号处理技术相结合，上行速度为100kbps 800kbps ，下行速度为1mbps 8mbps 。
Abstract : according to appearances of multi - frequency grinding chatter and signal - modulating principle , the regenerative modulating chatter based on amplitude - modulating principle in grinding process is advanced , and further theoretical analyses and experimental researches about regenerative modulating chatter are carried out 文摘:根据对颤振多频现象的分析及信号调制原理，提出了磨削加工中基于幅值调制原理的再生调制型颤振，并对再生调制型颤振进行了理论分析和试验研究。
This paper divides into six chapters : the first chapter - base on the analyses of the origin , conception and development status of sr , this chapter discusses the key technology and realize difficulties of sr and advances the intention and meaning of the paper . the second chaptei - the sr system with radio frequency band - pass sampling architecture is a design scheme close to software wireless radio ( swr ) , this chapter introduces three system architecture of sr system and analyses the theory of radio frequency band - pass sampling . the third chapter - this chapter analyses and designs the dsp hardware platform with radio frequency band - pass sampling architecture 本论文分为六章：第一章在分析软件无线电的起源、概念、发展概况的基础上，阐述了软件无线电的关键技术及实现难点，提出了本论文研究的目的与意义；第二章射频直接带通采样软件无线电结构是接近理想化的软件无线电设计方案，本章对软件无线电系统的体系结构及射频直接带通采样原理进行了分析；第三章分析并设计了射频直接带通采样结构软件软件无线电系统的dsp硬件平台；第四章研究了调制解调及信号调制样式的识别算法并给出了dsp实现，这是在dsp平台上实现软件无线电功能的一种常规方法；第五章分析了应用快速原型技术开发软件无线电系统的必要性及可行性，完成了软件无线电系统的matlab仿真及结合ti公司的tms320c6711dsk板的快速原型实现，这也是本论文提出的软件无线电的一种新的研究方法。
Secondly , the paper researches blind estimation of signals parameters , including the carrier frequency , signal to noise ratio and symbol rate of digital modulations . thirdly , with the combination of parameters from early studies on the decision theory , a set of robust feature parameters are extracted from signal power spectrum and the power spectrum of the second and fourth power of signal . based on these parameters , the proposed scheme is able to recognize 12 types of common used modulations , namely ask 、 2fsk 、 msk 、 4fsk 、 psk 、 qpsk 、 / 4qpsk 、 8psk 、 am 、 dsb 、 ssb 、 fm 接着,对信号功率谱、平方谱及四次方谱进行研究,针对通信中常用的调制方式,结合前人提出的基于决策理论中的特征参数,设计了一组对信噪比和信号调制参数不敏感的分类特征参数,利用上述参数完成了一种基于信号频域的识别方法,可以对ask 、 2fsk 、 msk 、 4fsk 、 psk 、 qpsk 、 / 4qpsk 、 8psk 、 am 、 dsb 、 ssb和fm这12种常用调制方式进行识别。
With multi - modulation , the disadvantages of single - modulation ( such as fsk , psk and ppm ) can be eliminated . by taking the advantages of different modulations , the performance of range resolving , doppler resolving and low probability of intercept ( lpi ) of the signal can be improved 复合调制信号可以克服单一信号调制形式(如fsk 、 psk 、 ppm等)的缺点,实现信号之间的取长补短,提高距离、速度分辨力,提高信号的低截获概率( lpi )性能,是雷达理论与技术的发展方向。
Secondly the detection precision is only related to the synchronization phase but not to the amplitude of the mainline voltage because that it uses the optimized pulses synchronous with the mainline voltage as modulation signals . thirdly it decreases the requirement of the input low pass filter and eliminates the error resulting from the direct component and even harmonics of load current . the most significant merit is that it can eliminate the effect of a few low order odd harmonics and the detecting circuit is easy to be implemented 仿真和实验结果表明该方法的主要优点有：不需使用乘法器进行信号调制，调制信号采用与电网电压同步的优化特定脉冲，其检测精度只与同步相位有关，而与电网电压幅值无关；降低了对输入低通滤波器的通频带要求，直流和偶次谐波分量对检测精度没有影响；突出的优点是可以消除有限个低奇次谐波对检测结果的影响。
The automatic identification of the modulation types has been applied to many fields such as source identification , interference identification , radio interception , - electronic countermeasures , etc . the modulation recognizer based on the decision - theoretic approach and the constellation diagram is proposed and the signal ' s kurtosis is used as the indicator to differentiate the analogue modulation from the digital modulation 通信信号调制类型的自动识别广泛应用于信号确认、干扰辨识、无线电侦听、电子对抗和信号监测等领域。本文提出基于决策论与星座图的综合调制识别器，使用信号的峰度区分调制类型是模拟调制还是数字调制。
In order to construct a system to sense and recognize the enemy transceivers , we proposed many algorithms to emulate signal extraction , signal modulation recognition , blind spread spectrum signal detection and parameter estimation , and the fingerprint identification of the transceiver 以构建对敌方电台进行侦收和指纹识别的系统为目的，本文提出了多种算法，仿真实现了复杂电磁环境中的电台信号提取、信号调制模式识别、扩频信号检测、扩频参数估计，并实现了电台的指纹识别。
