中文摘要：

使用MATLAB软件对QPSK（正交相移键控）信号经过移动信道时的解调特性进行了建模仿真,分析结果表明传输过程中多径衰落、多普勒频移效应对接收端QPSK信号的影响。在此基础上,从理论上提出通过在移动信号接收端增加适当的信号延迟电路,可以使解调后的信号抵消多径衰落与多普勒频移引起的衰落影响,增强信号传输的可靠性及有效性。

英文摘要：

Performance Improvement and Simulation were performed for the demodulation characteristics of QPSK signal after mobile channel.The analysis results show that during the transmission,multipath fading and doppler shift had effect on the attenuation of the receiving end of a QPSK signal.Based on this,it was theoretically proposed that at the signal receiving end in the mobile increasing appropriate signal delay circuit,would offset the fading effects in demodulated signal caused by multipath fading and Doppler frequency shift,and enhance the reliability and effectiveness of signal transmission.