Analysis of In-Orbit Data of Domestic Space-Borne Cesium Atomic Clock

Space-borne cesium clock is the load of space time keeping system of navigation system, which provides frequency information with high accuracy and high stability for positioning and timing. Satellite-borne cesium clock has the characteristics of low drift, high frequency accuracy and high environmental adaptability. The Beidou Navigation Satellite carried a cesium clock, which is the first time that China has sent a domestic cesium clock into space. The performance of the cesium clock can be characterized by frequency stability, accuracy and drift. Taking the passive hydrogen clock as a reference, the output frequency signal of the cesium clock was measured and transmitted down to the ground. Based on the phase comparison data of 29.17 million valid data points, Allan Deviation was used to calculate the frequency stability of the space-borne cesium clock, which was 1.91E−12 per second, 4.95E−14 per 100,000 s. And the frequency accuracy was 1.73E−12. The frequency drift rate was 1.12E−16/day.