Relationship between time interval measurement and frequency sources comparison and its application

Comparison of 1pps signals has been applied in the relevant fields, such as time transferring, time keeping, and communication. Time comparison can be carried out in many methods with different precision and the time interval universal instrument is used usually. However, 1pps signals are generated from frequency standard sources so there is the relationship of multi-periods synchronization between 1pps signals comparison and frequency sources comparison, which restricts the improvement of the resolution of time comparison. The paper analyzes the relationship between 1pps signals comparison and frequency sources comparison. The precision of frequency sources comparison is far better than the direct comparison of 1pps signals, reaching ps. The indirect scheme of time comparison is proposed using frequency sources comparison. Utilizing the high precision of frequency sources comparison, the scheme has get round many disturbance factors from acquiring 1pps signals. Then, by the way of computation to get the comparison results, the better precision comparison can be obtained. The scheme has been tested by lots of experiments. The scheme has simpler construction and higher accuracy. The comparison of atomic clocks is similar with the comparison of 1pps signals and the scheme also applies to it. Furthermore in time transferring, due to the definite phase relations between the local time signal and the master clock in Astronomical Observatory, the user can also acquire high accurate time transferring utilizing indirect phase comparison. The comparison procedure should be done with determining the initial state and continuous measuring, or the error will be increased. The further research is required for the scheme because the experiment model has a bit idealization and simplicity.