TANG Sheng1,2,3,4, LIU Ya1,2, LI Xiao-hui1,2
(1. National Time Service Center, Chinese Academy of Sciences, Xi′an 710600, China;
2.Key Laboratory of Time and Frequency Primary Standard, National Time Service Center,
Chinese Academy of Sciences, Xi′an 710600, China;
3. School of Information and Technology, Northwest University, Xi′an 710127, China;
4.Graduate University of Chinese Academy of Sciences, Beijing 100039, China)
Abstract: On the basis of analysis of the limitation of the traditional dual mixer time difference method, a digital method to achieve high precision of frequency standards measurement is proposed, and a new frequency standards comparison system towards such frequency standards as 5 MHz and 10 MHz is presented in this paper. The system is designed by adopting some new and original technologies, such as sinusoidal beat technology, synchronous sampling technology and digital signal processing technology. The experiment results verify that the noise floor of the system is about 1×10-12/s for 10 MHz frequency standard. Since the system has the characters of high precision, small volume and low cost, it is of great value of application and dissemination in the field of time/frequency measurement.
Key words: frequency standard comparison; sinusoidal beat; digital frequency measurement; noise floor; digital signal processing
