RECOMMENDATION ITU-R SA.1018-1 Hypothetical reference system for networks/systems comprising data satellites in the geostationary orbit and their user spacecraft in lowEarth orbits (Question ITU-R 117/7) (1994-2017) Scope This Recommendation provides architecture and characterization of a hypothetical reference system for network/systems comprising data relay satellites. Keywords DRS, Earth-to-space, space-to-space, forward feeder link, return feeder link Related ITU-R Recommendations and Reports Recommendations ITU-R SA.510, ITU-R SA.1019, ITU-R SA.1155, ITU-R SA.1274, ITU-R SA.1275, ITU-R SA.1276, ITU-R SA.1414. The ITU Radiocommunication Assembly, considering that communications between the ground and low-orbiting spacecraft and launch vehicles a) used for space research, Earth exploration and other purposes is essential; that such communications may be required to be continuous or near continuous; b) that such communications may be required while the spacecraft are passing over specific c) points on the Earthʼs surface; that a land-based station has only limited visibility of a low-orbiting spacecraft; d) that available land-based stations are only able to cover limited portions of any low orbit; e) that it is not economically or practically feasible to extend networks of stations to f) provide full or more complete coverage; that a data relay satellite (DRS) in geostationary orbit can provide communications between g) a single earth station and a low-orbiting spacecraft for more than one-half of its orbit (see description in Annex); that two such DRSs, suitably located in geostationary orbit, with a wide separation angle, h) can provide communications between two co-located earth stations and a low-orbiting spacecraft almost continuously, with the exception only of a zone of exclusion (ZOE), above the part of the Earth opposite to these earth stations; that two such DRSs, suitably placed in geostationary orbit, can provide fully-continuous i) coverage between two separate earth stations and a low-orbiting spacecraft; that a DRS system comprising two DRSs can serve several user spacecraft simultaneously, j) and many more user spacecraft by means of time-sharing; that a DRS system can also serve additional earth stations, either both transmitting and k) receiving or only receiving signals from user spacecraft;
RECOMMENDATION ITU-R SA.1018-1 Hypothetical reference system for networks/systems comprising data satellites in the geostationary orbit and their user spacecraft in lowEarth orbits (Question ITU-R 117/7) (1994-2017) Scope This Recommendation provides architecture and characterization of a hypothetical reference system for network/systems comprising data relay satellites. Keywords DRS, Earth-to-space, space-to-space, forward feeder link, return feeder link Related ITU-R Recommendations and Reports Recommendations ITU-R SA.510, ITU-R SA.1019, ITU-R SA.1155, ITU-R SA.1274, ITU-R SA.1275, ITU-R SA.1276, ITU-R SA.1414. The ITU Radiocommunication Assembly, considering a) that communications between the ground and low-orbiting spacecraft and launch vehicles used for space research, Earth exploration and other purposes is essential; b) that such communications may be required to be continuous or near continuous; c) that such communications may be required while the spacecraft are passing over specific points on the Earthʼs surface; d) that a land-based station has only limited visibility of a low-orbiting spacecraft; e) that available land-based stations are only able to cover limited portions of any low orbit; f) that it is not economically or practically feasible to extend networks of stations to provide full or more complete coverage; g) that a data relay satellite (DRS) in geostationary orbit can provide communications between a single earth station and a low-orbiting spacecraft for more than one-half of its orbit (see description in Annex); h) that two such DRSs, suitably located in geostationary orbit, with a wide separation angle, can provide communications between two co-located earth stations and a low-orbiting spacecraft almost continuously, with the exception only of a zone of exclusion (ZOE), above the part of the Earth opposite to these earth stations; i) that two such DRSs, suitably placed in geostationary orbit, can provide fully-continuous coverage between two separate earth stations and a low-orbiting spacecraft; j) that a DRS system comprising two DRSs can serve several user spacecraft simultaneously, and many more user spacecraft by means of time-sharing; k) that a DRS system can also serve additional earth stations, either both transmitting and receiving or only receiving signals from user spacecraft;
R-REC-SA.1018-1-201707-I!!MSW-E.docx