高精度GPS同步时钟的研究与实现

Research and Realization of the High Accuracy GPS Synchronization Clock

根据全球定位系统(GPS)时钟信号和晶振时钟信号精度互补的特点,提出了一种利用GPS时钟同步晶振信号实现高精度时钟的新方法。该方法利用GPS秒脉冲精确测量晶振时钟实际频率,对晶振信号误差进行在线修正,并用IRIG-B码校正绝对时标,在GPS正常工作时能够保证其精度稳定在0.1μs,且不受GPS信号短时失效的影响。采用现场可编程门阵列(FPGA)对其进行硬件实现并应用于电力系统的相角测量,在保证系统测量精度时,GPS信号失效情况下的稳定工作时间长达6h。

This paper presents a new method of implementing the highly accurate clock by the synchronization of crystal oscillator clock with the GPS clock, which is based on the complementation of the accuracy of the GPS and crystal oscillator. The method accurately measures the actual frequency of the crystal oscillator clock by the one pulse per second of GPS, then corrects the crystal oscillator clock on-line and corrects the absolute timestamp by the IRIG--B code. The synchronous timer can keep its precision at 0.1 μs and is not affected by the possible transient invalidation of GPS. The synchronous clock based on FPGA has been applied in phasor measurement of a power system. It not only features high precision and high integrity, but also works stably as long as 6 hours when the GPS signal becomes ineffective.