Recently, the national key research and development program NQI focused on "satellite navigation remote time frequency transmission and traceability application demonstration" technical exchange conference held in Shanghai. Each participating unit introduced the progress of their respective projects and the problems encountered in the implementation process, and discussed the solutions.

The Shanghai Institute of Metrology and testing has set up a high precision time and frequency standard device that can be tamed in real time to the national atomic time scale benchmark UTC (NIM). It also assists China Metrology Research to test, verify, perfect and perfect the related indicators of the remote time traceability platform.

Remote time real time traceability comparison platform

The independent research and development program of the Chinese Academy of metrology is aimed at supporting users who use NIMDO at home and abroad, and other users who have traced to the UTC (NIM), which is maintained by the Metrology Research Institute of China. The platform updates and releases real-time comparison information between user observation station and UTC (NIM) reference station and other users, as well as important technical indicators and statistical analysis results of the platform, enabling users to get timely information about their current remote time traceability and understand the operation of other related users.

The remote time real time traceability and comparison platform can get the measured data of each observation station in real time through the FTP, and use the common view comparison and the full view comparison method to carry out the remote comparison of the real-time data of the two observation stations, and get the time bias, frequency deviation and other changes and statistical analysis results, so as to provide users with remote real-time traceability, so that users can obtain the latest trends in a timely and effective manner. 。

Remote time frequency calibration system

With the operation of the Beidou satellite navigation system, the remote time frequency comparison based on the Beidou satellite is possible. Based on the Beidou satellite common view time comparison method, the national time service center set up a set of remote time frequency calibration system, which is composed of remote time comparison, reference terminal, remote time comparison calibration terminal and data analysis and processing center, and can recover the UTC (NTSC) time frequency signal remotely. The clock time difference between the UTC (NTSC) and the Beidou satellite clock is measured by the remote time comparison, and the clock difference between the local atomic clock and the Beidou satellite clock is measured by the remote time comparison calibration terminal, and the time frequency signal synchronizing with the UTC (NTSC) is controlled by the local terminal. The data processing center deals with the data from the remote time comparison between the reference terminal and the remote time comparison calibration terminal. The system abandons the traditional discontinuous observation method and takes 10 min as the 1 observation cycle to achieve a continuous time and frequency comparison.

High precision time and frequency standard device

The high precision time frequency source, which is tamed to the time and frequency standard in real time, can get the first time clock difference sequence generated by the reference terminal and the global navigation satellite system in a long distance and near real-time. It includes: tamed terminals, generating N time-frequency signals of the waiting clock, and generating second time frequency clock difference sequence based on the satellite signal. According to the first time frequency clock difference sequence and the second time frequency clock difference sequence, the third time-frequency clock difference sequence between the N time frequency signal of the reference time frequency source and the N time-frequency signal of the clock to be calibrated is obtained, and the relative frequency difference sequence is calculated based on the above. The clock is monitored and calibrated through the third time frequency clock difference sequence and the corresponding relative frequency difference sequence. The embodiment of the invention enables any laboratory to easily track the time and frequency performance of reference time frequency sources (usually time frequency standards, including national time and frequency references), and traceability of time and frequency to the international system of units, with high reliability, accuracy and stability.

Accurate and uniform frequency and time signals have been widely used in manned space engineering, missile launch and electronic countermeasures, because of their excellent accuracy and long-term stability. The main parameters of time and frequency standards are remote calibration and metrological verification, and a long distance calibration system with wide coverage and high accuracy is established.