【作者】 张翔；

【导师】 吕明；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2019， 硕士

【摘要】 短波通信是一种使用电离层来完成通信的技术,因其具有成本低,抗破坏性强,组网灵活等特点,并且随着短波通信技术中自适应技术、差错控制技术、时频调制技术等的发展,使得短波通信的通信质量得到了很大的提高,在不同领域发挥了重要的作用。时频调制技术是短波通信技术中的一种,它的本质是一种编码调制,根据不同组合的二进制符号来选择不同频率的载波,在其持续时间内完成信号的发送。由于在不同时隙采用不同的频率发送相同的信号,因此时频调制技术具有分集的特点,具有良好的抗衰落、抗干扰能力。本文针对时频调制技术进行深入的研究,主要研究了时频调制的调制、解调以及抗干扰方法。首先是调制,针对时频调制的调制技术,从传统的调制原理入手,分析了不同进制的时频调制信号产生原理。进一步,研究了在不同调制体制下的时频调制技术,重点研究了调相下的时频调制技术和空时编码下的时频调制技术。接着是解调,针对不同的时频调制解调技术研究当前解调方案下的抗干扰方法。首先对影响通信质量的干扰和衰落进行了说明,分析了不同干扰与衰落的特点,之后从现有的解调方法出发研究了基于能量的解调方法和基于边带相关算法的解调方法。在这两种解调方法下,分析其解调原理,并对现有解调方法进行改进使其具备更好的抗干扰性能。之后,提出了一种新的解调方案,即基于瞬时频率的解调方案。该方案能在信噪比较低的情况下对信号进行解调。最后,通过试验得到了三种解调方案的性能与各自的适用场景。最后是抗干扰方法,主要研究了基于循环码、卷积码、Turbo码的抗干扰方法、基于分集接收的抗干扰方法、基于跳频的抗干扰方法以及基于盲源分离技术的抗干扰方法。通过在不同干扰环境下进行试验,得到了不同抗干扰方法对时频调制系统性能改善情况。更多还原

【Abstract】 Short-wave communication is a technology that uses ionosphere to complete communication,because it has the characteristics of low cost,strong anti-destructiveness and flexible networking,and with adaptive technology,error control technology and time-frequency modulation technology in short-wave communication technology.The development of the communication has greatly improved the communication quality of short-wave communication and played an important role in different fields.The time-frequency modulation technology is one of the short-wave communication technologies.Its essence is a code modulation.The carriers of different frequencies are selected according to different combinations of binary symbols,and the signal transmission is completed within the duration thereof.Since the same signal is transmitted with different frequencies in different time slots,the time-frequency modulation technology has the characteristics of diversity and has good anti-fading and antiinterference ability.In this thesis,the in-depth study of time-frequency modulation technology is carried out,and the modulation,demodulation and anti-interference methods of time-frequency modulation are mainly studied.The first is modulation,for the modulation technology of time-frequency modulation,starting from the traditional modulation principle,the principle of generating different time-frequency modulation signals is analyzed.Furthermore,the time-frequency modulation technique under different modulation systems is studied,and the timefrequency modulation technique under phase modulation and the time-frequency modulation technique under space-time coding are mainly studied.Followed by demodulation,the anti-interference method under the demodulation method is studied for different time-frequency modulation and demodulation techniques.Firstly,the interference and fading that affect the communication quality are described.The characteristics of different interference and fading are analyzed.Then the energybased demodulation method and the demodulation method based on the sideband correlation algorithm are studied from the existing demodulation methods.Under these two demodulation methods,the demodulation principle is analyzed,and the existing demodulation method is made to make the existing demodulation method have better anti-interference performance.After that,a new demodulation scheme,ie,an instantaneous frequency based demodulation scheme,is proposed.This scheme can demodulate the signal at a lower signal to noise ratio.Finally,the performance of the three demodulation schemes and their respective application scenarios are obtained through experiments.Finally,the anti-interference method mainly studies the anti-interference method based on cyclic code,convolutional code,Turbo code,anti-interference method based on diversity reception,anti-interference method based on frequency hopping and antiinterference method based on blind source separation technology.Through the experiments under different interference environments,the anti-interference performance improvement of the time-frequency modulation technology by different anti-interference methods is obtained.更多还原