Fixed-satellite service (short: FSS) is – in line to ITU Radio Regulations – a radio-communication service between earth stations at given positions, when one or more satellites are used; the given position may be a specified fixed point or any fixed point within specified areas; in some cases this service includes satellite-to-satellite links, which may also be operated in the inter-satellite service; the fixed-satellite service may also include feeder links for other space radiocommunication services.
The ITU Radio Regulations define this radiocommunication service as follows:
- Fixed service:
- Fixed-satellite service
FSS – is as well the official classification (used chiefly in North America) for geostationary communications satellites that provide broadcast feeds to television stations, radio stations and broadcast networks. FSSs also transmit information for telephony, telecommunications, and data communications.
FSSs have been used for Direct-To-Home (DTH) satellite television channels in North America since the late 1970s. This role has been largely supplanted by direct broadcast satellite (DBS) television systems, which began in 1994 with the launch of Primstar, the first DBS television system. FSSs in North America are used to relay channels of cable TV networks from their originating studios to local cable headends and to the operations centers of DBS services (such as DirecTV and Dish Network), to be re-broadcast over their DBS systems.
In North America
FSSs operate in either the C band (from 3.7 to 4.2 GHz) or the FSS Ku bands (from 11.45 to 11.7 and 12.5 to 12.75 GHz in Europe, and 11.7 to 12.2 GHz in North America). The higher-frequency bands tend to have more spectrum and orbital slots available, but more expensive technology and higher rain margin.
FSSs operate at lower power than DBSs, requiring a much larger receiving dish than a DBS system, usually 3 to 8 feet (0.91 to 2.44 m) for Ku band, and 12 feet (3.7 m) or larger for C band, compared to 18 to 24 inches (460 to 610 mm) for DBS dishes. Unlike DBSs, which use circular polarization on their transponders, FSS transponders use linear polarization.
Systems that receive television channels and other feeds from FSSs are usually referred to as TVRO (Television Receive Only) systems, or pejoratively "big ugly dish" (BUD) systems (due to the much larger dish size compared to systems for DBS reception).
The Canadian Shaw Direct satellite TV service relies on FSS technology in the Ku band. Primestar in the USA used Ku transponders on an FSS for its delivery to subscribing households until Primestar was acquired by DirecTV in 1999.
FSS outside of North America
"Fixed satellite service", is a commonly used term in North America but rare elsewhere. Most satellites used for direct-to-home television outside of North America have the same high power output as DBS-class satellites in North America, but use the same linear polarization as FSS-class satellites.
Dish Network and FSS
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The Dish Network satellite TV service also relies on FSS technology in the Ku band to provide the necessary additional capacity to handle local channels required by FCC must-carry rules and to make room for HDTV resolution. The old SuperDish system receives a circularly polarized DBS 12.7 GHz signal from both 110-degree (the Echostar 8 & 10 satellites) and 119-degree (the Echostar 7 satellite) orbital locations as well as linearly polarized FSS 11.7 GHz from either the 121-degree (Echostar 9) or 105-degree (AMC 15) orbital locations depending on consumer choice; Dish ceased manufacture of this system years ago.[when?] Those FSSs are no longer used for Dish Network home subscribers, and are now used exclusively for commercial or corporate services. Dish now uses the 118.7-degree Anik-F3 FSS to provide international channel services on their Dish 500+ and Dish 1000+ dishes. It has an oval low-noise block downconverter (LNB) called a DP DBS/FSS Dual Band. This LNB will receive both the 119-degree and 118.7-degree satellites.
The SuperDish has three LNBs to accommodate the three satellites and two different technologies. SuperDish came in two configurations: SuperDish 121 was for international programming (but is now used exclusively for commercial and corporate services) and SuperDish 105 (also used today exclusively for commercial and corporate services) was used for high definition and for those customers in areas where local channels are only available on the 105-degree satellite. As with other FSS technologies, these signals are much lower power and as a result the SuperDish is large and lopsided. However, since the SuperDish is under 1 meter in width, it cannot be banned by homeowners' associations.
- ITU, RR, article 1.21
- Chartrand, Mark R. (2003). Satellite communications for the nonspecialist. Bellingham, WA: SPIE Press. p. 31. ISBN 978-0-8194-5185-9.
- Barker, Keith; Barnes, Carl; Price, K. M. "Space-Based Communications Infrastructure for Developing Countries". NASA Contractor Report. NASA Technical Reports Server. Retrieved 6 October 2011.