ITU-R QUESTION 152-27-1997 Standard frequencies and time signals from satellites《来自卫星的标准频率和时间信号》.pdf

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1、QUESTION ITU-R 152-2/7*Standard frequencies and time signals from satellites (1990-1993-1997) The ITU Radiocommunication Assembly, considering a) that continuing advances in science and technology have increased the requirements for accuracy and service range of standard-frequency and time-signal em

2、issions; b) that the work of several Radiocommunication Study Groups describes radiocommunication systems making use of satellites that give extensive coverage and satisfactory stability of signals over the Earths surface; c) that satellite techniques are important for standard-frequency and time-si

3、gnal comparison and dissemination systems; d) that a number of satellite services (e.g. for navigation, meteorology, geosciences, television and communication) may be used additionally for the comparison and dissemination of standard frequencies and time signals, decides that the following Question

4、should be studied 1 What are the technical factors and quantitative measures to be considered in recommending frequencies and in determining the transmitting, modulating, and receiving techniques which are important to the development of standard-frequency and time-signal emissions from satellites?

5、NOTE 1 See Recommendation ITU-R TF.1153 and Chapter 2 Part B and 6.3 of the ITU-R Handbook “Selection and use of precise frequency and time systems”. further decides 1 that the results of the above studies should be included in (a) Recommendation(s); 2 that the above studies should be completed by 2011. _ *In the year 2009, Radiocommunication Study Group 7 extended the completion date of studies for this Question.