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Aviation History
1985
1985 - 0102.PDF
INTERNATIONAL SATELLITE DIRECTORY Commercial ACTS Nasa's Advanced Communications Tech nology Satellite (ACTS) programme will develop and test new techniques required for the 1990s, including Ka-band (30/20GHz) relay, onboard switching and processing, and multiple scanning spot beams. Adoption of Ka-band will open up a new part of the radio-frequency spec trum clear of the crowded C and Ku bands. With it will come wide bandwidths, allowing more transponders per satellite, and smaller Earth station antennas. ACTS will also feature onboard high speed digital switching of high-volume communication trunks, time division multiple access, and baseband processing—a form of high-speed digital switch-board for efficient message routing. Scanning spot beams, each with a 280km-diameter footprint, will require synchronised storage and routing of messages. RCA leads a team comprising TRW (payload), Hughes Aircraft (travel ling wave tube amplifiers), Motorola (baseband processor), Electromagnetic Sciences, and Comsat (ground segment). Nasa's Lewis Research Centre is project manager. Payload 3 30/20GHz transponders Owner Nasa Manufacturer RCA Astro-Electronics Orbit Geostationary—about 100°W Launch by Shuttle in September 1989 Stabilisation 3-axis Design life 2 years (payload) Cost $260m (1984)—design, develop ment, and fabrication of ACTS Remarks ACTS will generate three fixed or two scanning spot beams, or a combi nation. To compensate for rain fade, char acteristic of higher frequencies, ACTS will use forward error correction to recon struct messages, and a variable-gain amplifier (20 or 40W) to boost power momentarily to overcome fade. Anik Canada's domestic network of com munications satellites comprises four operational spacecraft. The last of three Anik As was retired in November 1984. The sole Anik B will be retired at the end of 1986 and will be replaced by Anik D2, placed in two-year in-orbit storage in November 1984. The three-satellite Anik C series was planned to expand Telesat capacity. Due to lower than expected traf fic growth, the third in the series, Anik Cl, will be sold or placed in orbital storage after launch in February 1985. Payload Anik B 12 6/4GHz transponders 6 14/12Ghz transponders Anik C 16 14/12GHz transponders RCA is to build Nasa's scanning beams ACTS advanced communications technology satellite featuring multiple Anik D 24 6/4GHz transponders Owner Telesat Canada Manufacturer Anik B RCA Astro-Electronics Anik C Hughes Aircraft Anik D Spar Aerospace Orbit Geostationary Launch/location/status B Dec 1978 Delta/109°W/ operational C3 Nov 1982 Shuttle 117 • 5"W/ operational C2 Jun 1983 Shuttle/112-5°W/ operational Cl Feb 1985 Shuttle Dl Aug 1982 Delta/104-5°W/ operational D2 Nov 1984 Shuttle/111-5°W/ in-orbit storage Stabilisation B 3-axis C+D spin Power B 0-6kw C+D 0-9kw Weight (at launch) B 920kg C 1,140kg D 1,220kg 30 Design life B 7 years C+D 10 years Cost B $19-lm (1975) C up to $67-3m (1978) D $78-6m (1979) Remarks Anik C and D use the Hughes HS 376 bus. Anik C covers southern Canada via four spot beams. Anik D covers all Canada. Arabsat Arabsat will provide point-to-point tele communications and community tele vision services to the 22-nation Arab League. The operational network will comprise two satellites in orbit with a ground-based spare. Arabsat is the first commercial satellite to be exported by France or any European company. Payload 25 6/4GHz transponders 1 4/2-5GHz transponder (TV) Owner Arab Satellite Communications Organisation (Arabsat) Manufacturer Aerospatiale FLIGHT International, 12 January 1985 r
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