2ITU-R Recommendations.Time Signals and Frequency Standard Emissions,Volume 1997
3ITU-R.Handbook Selection and Use of Precise Frequency and Time Systems,1997
4ITU-T C.703.Physical/Electrical Characteristics of Hierarchical Digital Interfaces,1991
5ITU-T G.707.Network Node Interface for the Synchronous Digital Hierarchy (SDH),1996
6ITU-T G.810.Definitions and Terminology for Synchronization Networks,1996
7David L Mills.Network Time Protocol (Version 3) Specification,Implementation and Analysis.RFC 1305,1992
8USAF.Global Positioning System Standard Positioning Service Signal Specification,1995
9Predehl K,Grosche G,Raupach S M F,et al. A 920-kilo- meter optical fiber link for frequency metrology at the 19th decimal place[J]. Science,2012,336(27) :441-444.
10Lopez D,Amy-Klein A,Daussy C,et al. 86 km optical link with a resolution of 2 × 10^-18 for RF frequency transfer [J]. Eur. Phys. d. D,2008,48(1) :35-41.