Improvement And Application Of Remote Time And Frequency Source Calibration Based On UTC

The rapid development of modern science and technology puts forward higher requirements to time and frequency standard. It is of great significance to obtain high accuracy timing and keep accurate time synchronization in order to provide high accuracy time and frequency reference. At present, the common-view comparison of navigation satellites can realize time and frequency transfer and tracing over long distances, and ultimately can achieve the purpose of calibration of time and frequency source, which has become the mainstream way for time and frequency transfer. Based on the national time and frequency reference UTC(NIM) which is located at NIM(National Institute of Metrology, NIM), combined with the GNSS common-view technique and the theory of time and frequency source calibration, the remote time and frequency calibration system (A UTC(NIM) Disciplined Oscillator, NIMDO) has been realized.This paper focuses on the improvement and application of remote time and frequency source calibration with the help of the GNSS common-view technique, the principle of the atom clock calibration and the evaluation methods of system performance. After analyzing the factors that affect earlier NIMDO system, the paper proposes the internal delay calibration of NIMDO, outliers time difference data processing, time difference data noise filtering and GPS backup tracing. The test is done to compare the performance of NIMDO under different discipline interval. Also the system initialization method is adopted to accelerate the calibration process. Based on all the theories and methods above, the software is designed and implemented.When the calibration of NIMDO interval delay is finished, the feasible discipline interval is obtained. The performance test is carried out using multiple NIMDOs to compare the difference among them simultaneously. The comparison with NISTDO (National Institute of Standards and Technology Disciplined Oscillator) made by NIST (National Institute of Standards and Technology) is also done, the result is analyzed.The GPS tracing backup experiment verify its feasibility. The results show that the time and frequency accuracy of the improved NIMDO is better than Ins and1E-14in one day respectively and that the time and frequency stability of the improved NIMDO is better than Ins and2e-14in one day respectively. Therefore, the proposed method is validated, and it improves the robustness, reliability, fast disciplinary and traceability of the system.