Report From the ITU-R Working Party 7A on Time Signals and Frequency Standard Emissions

摘要

The Working Party 7A (WP-7A) on 'Time Signals and Frequency Standard Missions' is one of the four Working Parties of Study Group 7 'Science Services' (SG 7) of the Radiocommunication Sector of the International Telecommunication Union (ITU-R). The subjects which are addressed in the WP-7A meetings on the basis of input documents as answers to questions are: (worldwide) Standard frequency and time (T&F) dissemination from terrestrial transmitters and from satellites, including GPS, GLONASS, and Two-Way Satellite T&F transfer, time codes, requirements for high precision time, performance of T&F standards, time scale stability characterization, signal delays in antennas and other circuits, time delay measurements, compensation methods in SDH/SONET systems, etc. The results of the discussions during the meetings are presented, preferably in the form of ITU-R Recommendations to the ITU member states. Also, for the purpose of communication of the best use and selection of T&F systems to a wide group of users, the writing of handbooks in WP-7A has been started with contributions from internationally recognized specialists. The manuscript of the first handbook has been finished under Dr. R. Sydnor as main editor and D. W. Allan as co-editor. The English version has been prepared for press and is also being translated into French and Spanish. Several ITU-R Study Group and Working Party meetings were held in Geneva in October 1996. The results of the last WP-7A meeting, held 8 to 16 October 1996, are presented.