可变速率QPSK Modem中码元定时恢复电路的研制

本文介绍了一种利用混合数字锁相环(HDPLL)实现码元定时恢复的新方法。HDPLL中定时误差检测器、环路滤波器是全数字的,而VCXO使用了模拟器件。定时误差检测器从基带眼图中提取定时相位误差。此信号与载波相位信息无关,因而容许码元定时和载波相位恢复操作同时进行。

Development of Symbol Timing Recovery Circuit for Variable Rate QPSK Modem

Anovel approach to implement symbol timing recovery is presented which uses a hybrid digital phase locked loop (HDPLL).The timing error detector and loop filter of HDPLL are all digitized, whereas the VCXO employs analog components. The baseband eye diagram drives a timing error detector to provide the timing error. This signal is independent of carrier phase information, thus permitting parallel symbol timing and carrier phase recovery operations.