1、 Rec. ITU-R SA.1344-1 1 RECOMMENDATION ITU-R SA.1344-1 Preferred frequency bands and bandwidths for the transmission of space VLBI data within existing space research service (SRS) allocations (Question ITU-R 203/7) (1998-2009) Scope This Recommendation provides the preferred frequency bands and ban
2、dwidths for the transmission of science data and time/phase reference signals. The ITU Radiocommunication Assembly, considering a) that the angular resolution of measurements made by very long baseline interferometry (VLBI) techniques improves as the distance between two observing stations increases
3、; 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 by conducting VLBI measurements which utilize spacecraft, it is possible to substant
4、ially reduce the errors of ground-based observations caused by the absorption, path length fluctuations and noise contributions by the atmosphere, or eliminate these errors if both VLBI stations are in space; d) that space VLBI can provide data for accurate determination of: radio source structure a
5、nd positions; geodynamic parameters; and deep-space spacecraft navigation; e) that the transmission of wideband space VLBI data from space-to-Earth is required; f) that contemporary space VLBI systems require the transmission of highly accurate time/phase reference signals from Earth-to-space and sp
6、ace-to-Earth; g) that space VLBI systems are an application of the space research service (SRS), 2 Rec. ITU-R SA.1344-1 recommends 1 that preferred frequency bands for transmission of telemetry data and time/phase reference signals in the space-to-Earth direction should be as follows: Frequency band
7、 (GHz) RF bandwidth (MHz) SRS allocation status Direction of transmission in SRS allocation 8.45-8.5(1), (2)0.1 Primary Space-to-Earth 14-14.3 300 Secondary All directions 14.5-15.35 300-500 Secondary All directions 25.5-27 1 000 Primary Space-to-Earth 37-38 1 000 Primary Space-to-Earth74-84 10 000
8、Secondary Space-to-Earth (1)Radioastron will continue to use the frequency 8 400 MHz for phase transfer under existing ITU-R publication API/A/3957. (2)Use for phase transfer only. 2 that preferred frequency bands for the transmission of telecommand data and time/phase reference signals in the Earth-to-space direction should be as follows: Frequency band (GHz) RF bandwidth (MHz) SRS allocation status Direction of transmission in SRS allocation 7.190-7.235 0.1-2 Primary Earth-to-space 15.20-15.35 0.1-2 Secondary All directions 40-40.5 0.1-2 Primary Earth-to-space
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