Improvement of the frequency stability of the cesium fountain clock by data processing

Abstract

The cesium fountain clock is used as the primary frequency standard to improve the accuracy of the excitation source (active hydrogen maser) through cesium atomic transition frequency. The authors find that the frequency stability of cesium fountain clock is poorer than the active hydrogen maser according to the laws of the frequency stability evaluated by the Allan variance. The cesium fountain frequency stability can only reach 2 × 10−15 after 10 000 s. The traditional stability improvement methods are based on the Ramsey line-width optimization. The correction signal of fountain clock contains error, which can be removed partly by data correction. A new method to improve the frequency stability by modified error factor with statistical theory is presented in this paper. The results of frequency stability can reach 1.03 × 10−14/2 s and 2.78 × 10−16/16 400 s.