基于晶振频率补偿的高精度数字时钟设计

Design of high precision digital clock based on crystal oscillator compensation

为解决普通晶振频率长期漂移量较大的问题,提出了一种用GPS秒脉冲对晶振脉冲在线自动测量及修正,从而产生本地高精度时钟的方法,据此设计了一种基于单片机和CPLD的智能自校准数字时钟系统。介绍了时钟产生及校准模块、鉴相及相差测量模块等硬件电路组成和数据采集、晶振误差补偿算法实现等软件设计。该系统在需要较高精度时间显示的场所具有实际应用价值。

To resolve the long term existing problem of long drift distance of crystal oscillator frequency,a method of pro-ducing local high-accuracy clock by automatically detecting and correcting the crystal oscillator pulse by means of GPS second pulse on line is put forward. According to this means,a CPLD and MCU based digital clock system with intelligent auto-calibra-tion was designed. The composition of the hardware circuits of clock production and emendation module,and phase discrimina-tion and phase difference measurement module,as well as design realization of the software for data acquisition and the crystal oscillator error compensation are introduced. The system has the actual application value in the site of needing high-accuracy time display.