QDPSK全数字调制解调技术研究

发布时间：2018-05-17 08:17

本文选题：调制解调 + QDPSK　；参考：《南京理工大学》2014年硕士论文

【摘要】：数字调制解调技术是数字通信系统的关键技术之一,也是制约数字通信系统研究的瓶颈。数字调制解调技术的研究,不仅对于进一步提高数字通信系统能力有着非常重要的意义,而且在未来的通信系统中将有非常广阔的应用前景。因此,开展全数字QDPSK调制解调技术的研究具有重要的意义。本文介绍了调制解调系统所用到的基本理论知识,对QDPSK全数字调制解调技术的原理进行了深入的研究,并给出系统的设计框图。QDPSK调制部分主要包括数据加扰、卷积编码、差分编码、基带成型滤波、内插滤波和正交调制,解调部分则主要有数字下变频、匹配滤波、差分译码、维特比译码、数据解扰及同步技术,论文在分析各个模块原理的基础上进行了MATLAB仿真,给出了仿真结果并对其进行分析。其中,重点研究了同步技术,对载波频偏估计、载波恢复环路及符号同步环路进行了详细的介绍,通过对多种同步算法的分析和比较,选取了基于FFT的频偏估计算法对载波进行大频偏校正,Costas交叉环进行载波相位跟踪和基于Gardner算法的全数字反馈值插值符号同步,并对算法进行了理论分析和基于MATLAB的仿真。最后,还对整个系统进行了性能仿真,给出了系统的误码率特性。
[Abstract]:Digital modulation and demodulation technology is one of the key technologies of digital communication system, and it is also the bottleneck of digital communication system research. The research of digital modulation and demodulation technology is not only of great significance for further improving the capability of digital communication system, but also has a very broad application prospect in the future communication system. Therefore, it is of great significance to develop the full-digital QDPSK modulation and demodulation technology. In this paper, the basic theory of modulation and demodulation system is introduced, and the principle of QDPSK full digital modulation and demodulation technology is deeply studied, and the design block diagram of the system is given. The QDPSK modulation part mainly includes data scrambling and convolution coding. Differential coding, baseband shaping filtering, interpolation filtering and quadrature modulation, and demodulation mainly include digital downconversion, matched filtering, differential decoding, Viterbi decoding, data descrambling and synchronization techniques. On the basis of analyzing the principle of each module, the MATLAB simulation is carried out, and the simulation results are given and analyzed. Among them, the synchronization technology is studied in detail. The carrier frequency offset estimation, carrier recovery loop and symbol synchronization loop are introduced in detail. Through the analysis and comparison of various synchronization algorithms, The frequency offset estimation algorithm based on FFT is selected to track the carrier phase of the large frequency offset correction Costas crossover loop and the full digital feedback value interpolation symbol synchronization based on the Gardner algorithm. The algorithm is analyzed theoretically and simulated based on MATLAB. Finally, the performance of the whole system is simulated, and the BER characteristic of the system is given.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.3

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