The Research of Traceability of CAPS System Time

摘要

Chinese Area Positioning System (abbreviated as CAPS) has its own special system time called CAPST (China Area Positioning System time). To realize the function of time service, CAPST must be precisely traceable to UTC(NTSC). The very important process when CAPS is to be traced to UTC (NTSC) is that the transmission delay of one pulse per second (lpps) though phase stable cable from the UTC (NTSC) to CAPS time system must be determined. According to the characteristic that rubidium clock is good in shortterm stability but bad in long-term drift rate, the method moving clock out and home is researched and adopted to precisely measure the clock difference between CAPST and UTC (NTSC). According to this clock difference data and the realtime clock difference comparison data acquired from the running CAPS time comparison system, the transmission delay is calculated and it is the crucial data for the traceability of CAPST to UTC (NTSC). Then, the transmission delay subtracted from the real-time clock difference comparison data gives the real-time clock difference between CAPST and UTC (NTSC). That is, CAPST is precisely traced to UTC (NTSC). This campaign is vital to realize CAPS time service function.