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The atomic H-masers are widely used in time keeping nowadays. BIPM has changed clock frequency prediction method since September 2011 based on weighting the clocks according to their predictability. An H-maser characterized by a very significant frequency drift can be used in time keeping because its behavior can be well predicted. The clock ensemble of UTC(NIM) consists 6 H-masers (5 at the new campus)...
In Global Navigation Satellite Systems (GNSS), atomic clocks are fundamental for their excellent stability. Being the distance measured from the time, any error on the measure of time leads to an error in the positioning: accurate and stable atomic clocks need to be employed on board satellites. Hence, the on board clock behaviour has to be continuously monitored and any malfunctioning has to be immediately...
A new algorithm for the clock frequency prediction used to calculate EAL is presented. The mathematical model adopted in the new prediction algorithm takes in account the effect of the frequency drift of the H-masers. We demonstrate that there is an improvement in long term stability of EAL by using the new prediction algorithm.
The advantage of a hydrogen maser is in its short-term stability, however, with the same hydrogen masers, their performance are different. In 2004, four hydrogen masers were bought to time keeping laboratory of NTSC, two of which were made in USA, and the other two in China. In order to make full use of the hydrogen masers, it is necessary to study their performance which includes the short-term stability,...
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