Fixed Service Satellite
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Fixed Service Satellite (FSS) is 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.[1]
FSSs have also been used for Direct-To-Home (DTH) satellite television channels in North America since the late 1970s. This role has been mostly supplanted by direct broadcast satellite (DBS) television systems starting in 1994 when DirecTV the first DBS television system launched. However, FSSs in North America are also 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.
FSSs were the first geosynchronous communications satellites launched in space (such as Intelsat 1 (Early Bird), Syncom 3, Anik 1, Westar 1, Satcom 1 and Ekran) and new ones are still being launched and utilized to this day.
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 the United States). The higher frequency bands tend to have more spectrum and orbital slots available, but more expensive technology and higher rain margin.[2]
FSSs operate at a lower power than DBSs, requiring a much larger dish than a DBS system, usually 3 to 8 feet (0.91 to 2.4 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). Also, 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, as well as being referred to as big-dish systems (due to the much larger dish size compared to systems for DBS reception), or, more pejoratively, "big ugly dish" (BUD) systems.
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 as well for its delivery to subscribing households, until Primestar was acquired by DirecTV in 1999.
FSS and the rest of the world [edit]
The term Fixed Service Satellite is chiefly a North American one, and is seldom used elsewhere. This is because most satellites used for direct-to-home television in Europe, Asia, and elsewhere 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 [edit]
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 make room for HDTV resolution. The old SuperDish system that Dish ceased manufacture of years ago, receives circularly-polarized DBS 12.7 GHz 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. 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 LNB called a DP DBS/FSS Dual Band. This LNB will receive both the 119-degree and 118.7-degree satellites.
While the original Dish Network satellites use circular polarity at 12.7 GHz, the newer Intelsat 13/Echostar 9 satellite at 121-degrees uses the older FSS technology to broadcast commercial and corporate services. As a result, newer DiSH Network receivers are designed to receive both circular and linearly-polarized signals at two different intermediate frequencies from up to five different orbital locations.
The SuperDish has three low-noise block downconverters 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 whose 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 a very large and lopsided appendage. However, since the SuperDISH is under 1-meter in width it cannot be banned by homeowners' associations.
References [edit]
- ^ Chartrand, Mark R. (2003). Satellite communications for the nonspecialis. Belingham, 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.
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