1、QUESTION ITU-R 203-1/7*Characteristics and telecommunication requirements for space very long baseline interferometry (1993-1997) The ITU Radiocommunication Assembly, considering a) that the angular resolution of measurements made by very long baseline interferometry (VLBI) techniques is limited by
2、the distance between two observing stations; b) that, compared to the largest possible distance between two observing stations on Earth, this baseline distance may be substantially increased by locating one or more of the observing stations in space; c) that VLBI measurements made in space eliminate
3、 the limitations of ground-based observations caused by absorption, path length fluctuations and atmospheric noise contributions; d) that space VLBI will provide invaluable knowledge of physical parameters leading to highly accurate determination of: radiosources structure; deep-space navigation; ge
4、odynamics; astrometry; satellites orbit parameters; e) that the transmission of wideband space VLBI data from space-to-Earth is required; f) that space VLBI systems require the transmission of highly accurate time/phase reference signals from Earth-to-space and space-to-Earth, decides that the follo
5、wing Question should be studied 1 What are the technical telecommunication characteristics and operational requirements of space VLBI systems? 2 What are the orbital characteristics of spacecraft engaged in space VLBI? 3 What are the frequency bands most suitable for the precise time/phase transmiss
6、ion? 4 What are the frequency bands and bandwidths most suitable for the wideband data transmission space-to-Earth? _ *In the year 2009, Radiocommunication Study Group 7 extended the completion date of studies for this Question. - 2 - 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.
