中文摘要：

时钟源的稳定性在授时系统中扮演着重要角色,而晶振随着时间的推移会有不同程度的稳定度误差和累积误差,这给整个授时系统的授时精度带来了很大的误差。基于FPGA设计了一种压控晶振校频系统。通过分析影响晶振输出的几个重要因素,综合考虑后,对输出的码NCO值做加权求平均处理,使得输出更加稳定可靠。系统可以实现两块晶振同步的误差在短时间内达到基本同步的水平,为提高非同源条件下时间同步系统的授时精度提供了一种很好的方法。

英文摘要：

The stability of clock source plays an important role in the time service system, but the different stability error and cumulative error of the crystal oscillator may occur as time goes on, which brings a big error for the time service accuracy of the whole time service system. A voltage controlled oscillator frequency calibration system was designed based on FPGA. Several important factors affecting on the output of the crystal oscillator are analyzed, and considered comprehensively to perform a weighted average for the value of the code NCO, so as to make the output stable and reliable. The system can realize the basic synchronization of the two crystal oscillators＇ errors in a short time, which provides a better method to improve the time service accuracy of the time synchronization system under the non-homologous condition.