Study On Remote Time Synchronization Technology Of Time And Frequency Subsystem

The high precise remote time synchronization is playing a more and more important role inmany fileds. And, the remote time comparison technique is a critical factor in the high preciseremote time synchronization.The global navigation satellite system common-view technique(GNSS CV) is one of the most widely used remote time comparison techniques. With therequirement of the project of the establishment of Time and Frequency Subsystem, in order toimprove the performance of GNSS CV in real-time, automatic, comparison precision andcontinuity, on the basis of studying the key techniques of real-time and automatic timecomparison based on GNSS CV, this paper introduces a design of GNSS CV real-time andautomatic time comparison system. Combined with computer networks communicationtechnology, this system realizes the observation, transmission, comparison, process and analysisof GNSS CV datum in real-time. And it provides an available method for high precision remotetime synchronization between remote atomic clocks and primary clock system, atomic clockperformance analysis and time-keeping, and calibration of time transfer receiver. The core ofthe paper includes:(1) According to the requirement of the project of the establishment of Time andFrequency Subsystem, deeply analsized the key techniques of real-time and automatic timecomparison based on GNSS CV, including the basic principle and characters of GNSS CV,computer networks communication technology.(2) The Kalman filter for removing noise in CV datum and RLS adaptive filter forpredicting the clock difference were analsized, to match the remote time synchronization of theTime and Frequency Subsystem.(3) Proposed the design of the GNSS CV real-time and automatic time comparison system.Designed the working procedures of the threes main functions of the syetem. Designed thesoftware of the system. Then the sofeware was developped with VC++, realising theobservation, transmission, comparison, process, analysis and display of GNSS CV datum inreal-time.(4) The system’s connection, installation and testing were completed. The functions of thesystem were fulfilled widely, the Kalman filter and Vondrak smoothing could match therequirements in noise reduction of GNSS CV datum and RLS adaptive prediction filter couldforecast the change of clock difference and reflect the tendency of clock fluctuation.