【摘要】 在实际的四相绝对相移键控(QPSK)数字解调系统中,多普勒频移和接收机本振的中心频率偏移及相位噪声都会引起载波频率和相位的误差.针对这一误差,介绍了开环系统中频差校正原理,然后通过滑动窗口求均值的方法实现平均相位误差校正,并利用Matlab仿真证实,在同样信噪比下,采用平均相差法得到的误码率比直接相差提取的方法低很多.目前,平均相位误差校正方法已应用到实际的QPSK解调系统中,并获得理想的通信效果.更多还原

【Abstract】 In the QPSK demodulation′s system,many factors can cause the carrier′s frequency offset and phase error,such as Doppler frequency offset,the central frequency offset of the receiver′s local oscillator and the phase noise.In this paper,the theory of the correction of frequency offset in the open-loop system was introduced,and the method of averaging the phase error was also presented.Moreover,averaging the phase error was implemented by the method of getting the average in the sliding window.The simulation showed that,in the same SNR,the bit error rate (BER) of using the method of averaging phase error was much smaller than that of the method of direct getting.Now,the method of averaging the phase error is applied in actual system,and better performance is obtained.更多还原