Remote time and frequency calibration system for telecommunication synchronization applications

A new remote time and frequency calibration system using Global Positioning System (GPS) common-view or all-in-view method for the purpose of time synchronization and frequency syntonization is presented. The system integrates GPS timing receiver with measurement hardware and software. It can be used as Primary Reference Clock (PRC), remote time and frequency calibration, and monitoring the characteristic of the primary reference clocks for wireless and power system applications. A series of experiments were executed to evaluate the performance of the system. The common view common clock test using hydrogen maser as reference was studied for the evaluation of the system noise level. The short-baseline test between Chunhwa Telecommunication Laboratories (TL) and HsinChu within 18.6 km, and mid-baseline test within 200 km between TL and Yunlin were also performed. Experiment results show that the system works by making simultaneous all-in-view measurements at National Time and Frequency Standard Laboratory of TL and at under test sites in Taiwan with up to eight GPS satellites. The combined expand time uncertainty and frequency uncertainty of the designed system with a coverage factor of k=2 are equal to 94.52 ns and 1.0 × 10^-12 respectively, which can meet ITU-T G.811 standard and requirements for the dominant wireless and power systems applications.