GPS同步时钟的高精度守时方案

A High Accuracy Time Keeping Scheme Based on GPS

基于全球定位系统(GPS)的高精度同步时钟信号在电网广域测量系统(WAMS)等很多领域具有广泛用途,但在实际应用中存在因卫星失锁等原因导致同步时钟信号失步的问题。文中提出了一种预设时间差补偿值实现高精度守时的方案。研制了基于GPS接收器和复杂可编程逻辑器件(CPLD)的高精度守时GPS授时系统样机,并在实验室与上升沿同步及时间差反馈调整2种守时方案进行了对比验证。实测结果表明,采用文中提出的方案,GPS授时系统样机输出的秒脉冲(PPS)信号在正常情况下的精度可达±300ns,并能保证在卫星失锁24h内的误差不超过20μs,守时精度明显优于另外2种方案。

The high accuracy time synchronization signal based on global positioning system（GPS）is widely used in many fields like wide area measurement system（WAMS）,but in actual applications some problems such as losing satellite lock will lead to synchronous clock signals getting out of sync.A high accuracy time keeping scheme by presetting time difference compensation is proposed.A high accuracy time keeping GPS timing system prototype based on GPS receiver and complex programmable logic device（CPLD）is developed.Comparative tests are made between the time keeping scheme proposed and the other two time keeping schemes,i.e.rising-edge time synchronization scheme and time difference feedback adjusting scheme.Test results show that when using the time keeping scheme proposed,the PPS（pulse per second）signal reaches an accuracy of ±300 ns under normal conditions and will ensure an accuracy of ±20 μs when losing satellite lock within 24 hours,which is obviously better than the other two schemes.