CARRIER EXTRACTION OF QPSK BASEBAND DIGITAL DEMODULATION
QPSK基带数字相干解调的载波提取

The principle and structure of the carrier recovery PLL of baseband digl-tal coherent demodulation are presented, and the performance of this PLL is analysed. Comparing with the "four times frequency" method under the same conditions, the signal to noise ratio of this PLL is 5-10dB higher. The experimenta! results show that the recovered carrier is stable.