π/4 QPSK调制解调的MATLAB仿真及性能分析

摘要

阐明了QPSK和π/4 QPSK之间的联系和区别。概述了π/4 QPSK的调制与解调的原理及其所实现的功能,并通过MATLAB编程对系统在高斯噪声信道条件下的抗噪声性能和频谱做了详细分析。在相同信道条件下分析比较了QPSK和π/4 QPSK的频谱及抗噪声性能。仿真结果表明,π/4 QPSK的频谱扩展现象优于QPSK,且更易消除信号的旁瓣分量而不影响信号码元稳定区内的波形。%This article describes the links and distinctions between QPSK and π/4 QPSK,summarizes the principle as well as the achievement on the modulation and demodulation of π/4QPSK,and addresses a method for programming with MATLAB to analyze signal spectrum and performance against noise under the condition of Gauss noise channel.The comparison is made on the spectrum and anti-noise performance between π/4QPSK and QPSK under the same channel.The result of simulation shows that the spectrum expanding of π/4QPSK is superior to that of the QPSK and it is easy to get rid of side beam power effectively but not to change the waveform in steady section.