扩频信号的BPSK调制仿真.doc

《控制系统CAD与数字仿真》 2014～20学年 第学期 学院（部） 学院 学 号 姓 名 扩频pread spectrum signal with BPSK digital modulation Abstract：With digital signal processing technology continues to evolve, digital software radio receiver has become a trend, modulation/demodulation technology is the core technology in digital communication system。The rapid development of modern computer science and technology, makes the communications system simulation design and analysis process become relatively intuitive and convenient, which also makes the communication system simulation technology has been faster development. Communication system simulation with wide adaptability and excellent flexibility, helps to better study the communication system performance. This paper introduces the digital modem technology situation and development.Then introduced digital modulation and demodulation of BPSK theoretical foundation, including analysis of the BPSK digital modulation and demodulation principle. In this paper, based on the powerful simulation using MATLAB function in its environment designed the spread spectrum signal system and the BPSK modulation demodulation system simulation model, and through the constellation confirmed that the demodulation algorithm. Finally, this paper made a summary of the research work, and proposed future work and research directions. Key words: BPSK, Modem, MATLAB, Spread spectrum signal system 目录 一、引言 5 1.1 研究背景及其意义 5 1.2 数字化调制解调技术的现状发展及其应用 5 1.3 MATLAB的简介 6 二、BPSK调制解调原理 7 2.1 BPSK信号调制原理 7 2.2 BPSK 信号解调原理 9 三、扩频信号的BPSK调制系统设计仿真 10 3.1基本扩频系统仿真流程图 10 3.2 生成m序列及m序列性质 11 3.3 生成50位随机待发送二进制比特序列及进行扩频编码 12 3.4 对扩频前后信号进行BPSK调制并观察其时域波形 13 3.5 计算并观察扩频前后BPSK调制信号的频谱 13 四、总结与展望 14 4.1 总结 14 4.2 展望 15 参考文献 16 附录 17 一、引言 1.1 研究背景及其意义 随着数字信号处理技术的不断发展，数字化软件无线电接收机已经成为趋势。在卫星通信、移动通信、微波通信、光纤通信等现代通信系统中，信道中传输的都是数字已调信号，称它们为数字调制系统。数字调制技术是数字通信系统中的核心技术，随着数字调制技术的出现，在有限的带宽内传输高速的数据已经成为可能，并且与过去使用的模拟调制相比，如调幅(AM)和调频(FM)、频移键控(FSK)、开关键控(OOK)、脉宽调制(PWM)、脉位调制(PPM)、脉幅调制(PAM)等技术相比有更高的可靠性和抗干扰