The New Remote Time And Frequency Calibration System

With the rapid development of our country’s aerospace and defense, the precision demand of the time and frequency is higher and higher. More and more experts and scholars of scientific research institutions in our country want to have a more accurate time and frequency reference. National Institute of Metrology (NIM), which has fountain cesium atomic clocks that have not bad for a second in30million, several punctual hydrogen maser and cesium atomic clocks, sets up the national primary standards of time and frequency (UTC (NIM)). If NIM wants to better serve the country and society from considering the reliability, efficiency and cost. Traditional calibration method has many limitations. New remote time and frequency calibration system has broad space for development. The author in this paper participated in the research of a general class project topic of Beidou second generation major projects in NIM and participated in the establishment of a Web based time-frequency Comparison System, Combined the theory of atomic clocks time-frequency features, realized new remote time and frequency calibration system--UTC(NIM) disciplined oscillator(NIMDO).In this paper a new GNSS time-frequency transfer receiver NIMTFGNSS-1and the time and frequency comparison system based on Web are studied. On this basis, this paper builds NIMDO hardware and software platform, integrates the NIMDO and explains system operation environment. In order to achieve the data for the purpose of the preliminary processing of rubidium atomic oscillator readying for disciplining oscillator, depth study the time-frequency characteristic analysis of rubidium atomic clocks, data used in the system were converted, accuracy assessment, stability analysis, noise analysis and frequency drift is estimated; At the same time, this paper analysis the time difference of rubidium oscillator and UTC(NIM) in the NIMDO, masters all performance of rubidium oscillator, ready for next the work of remote time and frequency calibration.Based on two important performance indexes from frequency accuracy and stability, the GNSS receiver real-time data will be preprocessed, forecast time difference and step to tame rubidium atomic clocks. Then this paper finishes common clock difference experiment, zero baseline experiment with different references, long baseline experiment and NIMDO system performance verification experiment. These experiments test and verify key parts and NIMDO exports. After setting up the system1PPS and frequency signal accuracy of NIMDO output is better than9ns and1.0×10-13, stability is better than5ns and6.0×10-14; Finally this paper complete a new reporting system uncertainty, Synthetic standard uncertainty less than6.8ns, Expanded uncertainty less than13.6ns. These has reached the requirement of general laboratory frequency benchmark for fashion, can be used as general laboratory reference frequency standard. Simultaneously, NIMDO directly refer to the UTC(NIM), which makes the laboratory very easy to put the time and frequency traceability to the international system of units.