介绍了数字通信中的QPSK调制解调的原理，通过用Matlab编写脚本程序对QPSK通信系统的发射和接收过程的具体实现进行模拟仿真，绘出信号在理想信道和加噪信道中模拟传输时的时域图，并对各模块进行了频谱分析，所得到的结果与

理论基本相符，对于理解QPSK系统的性能并在系统的实际应用上作进一步的设计，提供了有效的参考依据。

-The introduction was done with the principle of the QPSK modulation and demodulation in digital communications，a scr ipt was written by using Matlab program to CalTy out a simulation of the QPSK communication

system．which contains the concrete realization of transmit and receive process．The time-domain diagram is drew

separately when the signal transmits in the ideal channel and in the channel with noise，spectral analysis of each

module is also done，the results obtained with theoretical results in the main，which provides an effective fr a me of

reference for understanding the performance of QPSK systems，and the practical application in the system to make

further designed．