【作者】 张哲；

【导师】 张晓林；

【作者基本信息】 哈尔滨工程大学 ， 信息与通信工程， 2017， 硕士

【摘要】 随着无线通信技术的发展,空间的电磁环境愈加复杂,调制类型成为了通信信号的首要特征。这使得数字通信信号调制方式的识别在军事电子对抗及民用电磁频谱监管等领域都起到非常重要的作用。尤其是在军事对抗中,通信信号检测需要在复杂的电磁环境下对待识别信号进行处理和判断,得到非合作方通信信号的调制方式、载波频率、信号带宽等参数,从而达到获取信息、搜索信号源及干扰通信的目的。调制方式识别技术在近几十年来被不断的探索和挖掘出了许多新算法,本文在前人研究的基础上,针对非合作通信中的2ASK、2PSK、QPSK、2FSK、MSK信号的检测理论进行了深入研究学习,并设计了一套完整的能够对信号进行存在性检测、调制方式识别和参数估计的系统,主要内容总结如下:首先,对循环谱密度函数进行了推导,并计算了常用通信信号的循环谱密度函数表达式,包括2ASK、2PSK、QPSK、2FSK、MSK;分析了通信信号的循环平稳特性和高斯白噪声的非循环平稳特性之间的差异,结合各个非零循环频率截面的特征对待识别信号进行了存在性检测。其次,分析了2ASK、2PSK、QPSK、2FSK、MSK信号的时域特性及谱相关特性,完成了对这五种调制信号的调制方式识别。针对以往算法中对单峰2FSK信号和MSK信号识别存在的不足,提出了一种基于差分相位峰均比的特征参数来识别单峰2FSK信号和MSK信号。仿真结果表明,在信噪比大于等于10dB的情况下,对这两种信号的平均正确识别概率达到99%;算法整体识别概率达92%以上。再次,研究了基于循环谱密度函数零频率归一化截面的谱峰与调制信号的载波频率及信号带宽间的数学关系,并且通过循环谱截面对调制信号进行了载波频率估计及带宽估计。仿真结果表明,在信噪比大于等于10dB的情况下,可以对五种信号的两个参数进行相对准确的估计,其中对载频估计的相对误差小于0.500%,对信号带宽估计的相对误差小于3.252%。最后,根据本文设计的算法,采用基于FPGA+DSP结构的硬件系统平台解决方案来实现调制方式识别算法,使用所设计的硬件系统对信号发生器产生的三种信号进行了实时检测,通过串行接口反馈回的数据表明,硬件系统平台达到了预期要求。更多还原

【Abstract】 With the development of wireless communication technologies,the electromagnetic environment of space becomes more and more complex,and the modulation types becomes the primary characteristic of communication signals.Digital communication signals modulation mode identification,in the military electronic confrontation and civil electromagnetic spectrum monitoring and other fields have played a very important role.The communication signals detection needs to process and judge the identification signals in the complicated electromagnetic environment,and obtains the parameters such as modulation mode,carrier frequency and signals bandwidth of the non-cooperative communication so as to obtain the information,search the signals source and interfere with the communication.Based on the previous research,the detection theory of 2ASK,2PSK,QPSK,2FSK and MSK signals in non-cooperative communication is studied.The detection methods of 2ASK,2PSK,2FSK and MSK are studied.A complete set of system which can detect the existence of the signals,the modulation mode identification and the parameter estimation is designed.The main contents are summarized as follows:Firstly,the cyclic spectral density function is deduced and the cyclic spectrum density functions of the commonly used communication signals are calculated,including 2ASK,2PSK,QPSK,2FSK and MSK.The cyclostationary characteristics of the communication signals and the acyclic of Gaussian white noise are analyzed.And the existence of the discriminant signals is detected in each non-zero cyclic frequency cross section.Secondly,the time-domain characteristics and spectral correlation characteristics of 2ASK,2PSK,QPSK,2FSK,MSK signals are analyzed,and modulation recognition of these five modulation signals is completed.Aiming at the deficiency of single-peak-2FSK signals and MSK signals recognition in the past algorithms,a characteristic parameter based on peak to average ratio of differential phase is proposed to identify single-peak-2FSK signals and MSK signals.The simulation results show that the average correct recognition probability of these two signals is more than 99% when the signals to noise ratio is more than 10 dB,and the whole recognition probability is more than 92%.Thirdly,the relationship between the carrier frequency and the signals bandwidth of the modulation signals based on the zero-frequency normalized cross-section of the cyclic spectral density function is studied,and the carrier frequency estimation and the bandwidth estimation of the modulated signals are carried out by the cyclic spectrum cross-section.The simulation results show that the relative error of carrier frequency estimation is less than 0.500% and the relative error of signals bandwidth estimation is less than 3.525% when the SNR is more than 10 dB.Finally,according to the design of the algorithm,the hardware platform based on the structure of FPGA+DSP solution to implement the algorithm,three kinds of signal hardware system designed by the use of the signal generator for real-time detection,through the serial interface feedback data show that the hardware platform to achieve the desired requirements.更多还原