基于DFT的QPSK数字化解调算法研究

对软件无线电中的数字化解调算法进行研究,并提出一种基于离散傅立叶变换(DFT)的四进制相移键控信号(QPSK)数字化解调算法.该算法考虑到实际中接收到的信号波形有过渡区和稳定区之分,通过对稳定区内载波周期的采样值进行离散傅立叶变换(DFT)提取相位信息来恢复原始调制信号.文中给出了软件仿真实现,其结果表明:采用该方法可以正确地实现QPSK信号的解调,与传统的解调方法相比,不仅解调过程简单易于实现,计算量小,而且抗干扰性能也得到了明显改善.若将该方法应用于采用QPSK信号方式的数字化接收机设计中将具有实际的意义.

DFT-based Digital Demodulation for QPSK

This paper studies the digital demodulation algorithm in software radio and presents a DFT-based digital demodulation scheme for QPSK signals.Since the yard wave of signal can be divided into transitional section and steady section,the idea is to do DFT on samples of every one(or several) carrier circle in steady section to get the phase of the QPSK signal and resume the modulated signal.The simulation with software is also given out and the result indicates: QPSK signal can be demodulated accurately with DFT algorithm.Comparing with traditional methods,not only the process is simple and easy to realize with less computation,but also noise-resisting property is improved obviously.This method is of practical significance for designing QPSK signal digital receiver.