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Satellite television is a system of delivering television programmes by the means of communications satellites. The signals are received by an outdoor antenna, usually a parabolic reflector generally referred to as a satellite dish, and as far as household usage is concerned, a satellite receiver is either in the form of an external set-top box or a satellite tuner module built into a television set. Satellite television tuners are also available as a card or a USB peripheral to be attached to a personal computer. In many areas of the world satellite television provides a wide range of channels and services, often to areas that are not served by terrestrial or cable providers.
Direct-broadcast satellite television comes to the general public in two distinct ways – analog and digital. This necessitates either having an analog satellite receiver or a digital satellite receiver. Analog satellite television is being replaced by digital satellite television and the latter is becoming available in a better quality known as high-definition television.
- 1 History
- 2 Technology
- 3 Standards
- 4 Categories of usage
- 5 See also
- 6 References
- 7 External links
In 1961 the United States' Relay satellite began transmitting television signals, and in the same year Syncom established itself as the first geosynchronous satellite capable of transmitting signals to one particular area on the earth's surface continuously. The first satellite television signals were relayed from Europe to the Telstar satellite over North America on 23 July 1962. The signals were received and broadcast in North American and European countries and watched by over 100 million. The first geosynchronous communication satellite, Syncom 2, was launched on 26 July 1963. The world's first commercial communications satellite, called Intelsat I (nicknamed "Early Bird"), was launched into synchronous orbit on April 6, 1965. The first national network of satellite television, called Orbita, was created in Soviet Union in 1967, and was based on the principle of using the highly elliptical Molniya satellite for rebroadcasting and delivering of television signals to ground downlink stations. The first commercial North American satellite to carry television transmissions was Canada's geostationary Anik 1, which was launched on 9 November 1972. ATS-6, the world's first experimental educational and Direct Broadcast Satellite (DBS), was launched on 30 May 1974. The first Soviet geostationary satellite to carry Direct-To-Home television, called Ekran 1, was launched on 26 October 1976.
Beginning of the satellite TV industry, 1976-1980
The years 1976 to 1980 saw the beginnings of the satellite TV industry, with signals broadcast from Home Box Office (HBO), Turner Broadcasting System (TBS), and Christian Broadcasting Network (CBN, later The Family Channel). Taylor Howard of San Andreas, California became the first person to receive C-band satellite signals with his home-built system in 1976. Howard's dish, which was placed into operation on 14 September 1976, was made of aluminum mesh and was about 16 feet (5 m) in diameter. The Society for Private and Commercial Earth Stations (SPACE) was established in 1977 by COMSAT/Satellite Television Corporation's request to construct and operate a Direct Broadcast Satellite (DBS) system. On October 18, 1979, the Federal Communications Commission (FCC) began allowing people to have home satellite earth stations without a federal government license. The front cover of the 1979 Neiman-Marcus Christmas catalogue featured the first home satellite TV stations on sale for $36,500. The dishes were nearly 20 feet (6.1 m) in diameter, were remote controlled, and could only pick up HBO signals from one of two satellites. The price went down by half soon after that, but there were only eight more channels. The FCC established the Direct-Broadcast Satellite (DBS) system in 1980. Japan and China were the first to be successful at launching satellites for the consumer market. These early systems were not very popular due to their expense and the large size of the receiver dishes. They were most commonly found in low-rise commercial buildings. The receivers of the systems in the late 1970s and early 1980s were 10 to 16 feet (3.0 to 4.9 m) in diameter and made of fibreglass or solid aluminum or steel and in the United States cost more than $5,000, sometimes as much as $10,000. Programming sent from ground stations was relayed from eighteen satellites in geostationary orbit located 22,300 miles (35,900 km) above the Earth.
TVRO/C-band satellite era, 1980-1986
By 1980, 5,000 satellite dishes had been purchased for home use. From 1981 to 1985, TVRO systems' sales rates increased as prices fell and the dishes became smaller, with 500,000 systems selling in 1984  and costing as little as $2,000 by that same year. Dishes pointing to one satellite were even cheaper. Once a user paid for a dish, it was possible to receive even premium movie channels, raw feeds of news broadcasts or television stations from other areas. People in areas without local broadcast stations or cable television service could obtain good-quality reception with no monthly fees. By the end of 1984, an estimated one million systems were in use, with over 120 channels available, some not available any other way. Some people who installed DBS systems were discontent with cable television. The large dishes were more popular in rural areas, and residents typically placed them prominently in front yards. People joked that Vermont, where 30% of the population did not have access to cable, should declare the satellite dish the official state flower. The large dishes were a subject of much consternation, as many people considered them eyesores, and in the US most condominiums, neighborhoods, and other homeowner associations tightly restricted their use, except in areas where such restrictions were illegal. These restrictions were altered in 1986 when the Federal Communications Commission ruled all of them illegal. A municipality could require a property owner to relocate the dish if it violated other zoning restrictions, such as a setback requirement, but could not outlaw their use. The necessity of these restrictions would slowly decline as the dishes got smaller.
Originally, all channels could be received in the clear (ITC) and free of charge. Scrambling systems were developed so people with satellite dishes could not receive signals without any payment to the program developers. In October 1984, the U.S. Congress passed the Cable Communications Policy Act of 1984, which gave those using TVRO systems the right to receive signals for free unless they were scrambled, and required those who did scramble to make their signals available for a reasonable fee. Since cable channels could prevent reception by big dishes, other companies had an incentive to offer competition. In Janurary 1986, HBO began using the now-obsolete VideoCipher system to encrypt their channels. This was met with much protest from owners of big-dish systems, most of which had no other option at the time for receiving such channels, claiming that clear signals from cable channels would be difficult to receive. Eventually HBO allowed dish owners to subscribe directly to their service for $12.95 per month, a price equal to or higher than what cable subscribers were paying, and required a descrambler to be purchased for $395. This led to the attack on HBO's transponder on Galaxy 1 by John R. MacDougall in April 1986. One by one, all commercial channels followed HBO's lead and began encrypting their channels. In December 1986, the Satellite Broadcasting and Communications Association (SBCA) was founded as a result of a merge between SPACE and the Direct Broadcast Satellite Association. Analogue encryption using VideoCipher and VideoCipher II could be defeated, and there was a black market for illegal descrambler devices.
Late 1980s and 1990s to present
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By 1987, nine channels were scrambled, but 99 others were available free-to-air. While HBO initially charged a monthly fee of $19.95, soon it became possible to unscramble all channels for $200 a year. Dish sales went down from 600,000 in 1985 to 350,000 in 1986, but pay television services were seeing dishes as something positive since some people would never have cable service, and the industry was starting to recover as a result. Scrambling would also lead to the development of pay-per-view. On November 1, 1988, NBC began scrambling its C-band signal but left its Ku band signal unencrypted in order for affiliates to not lose viewers who could not see their advertising. Most of the two million satellite dish users in the United States still used C-band. ABC and CBS were considering scrambling, though CBS was reluctant due to the number of people unable to receive local network affiliates.
In the early 1990s, four large cable companies launched PrimeStar, a direct broadcast satellite. The Cable Television Consumer Protection and Competition Act of 1992 increased the fines and imprisonment duration for anyone caught engaging in signal theft to $50,000 and a sentence of two years. A repeat offender can be fined up to $100,000 and be imprisoned for up two five years. In 1994, the Hughes DIRECTV satellite system was introduced, and on March 4, 1996 EchoStar introduced Digital Sky Highway (Dish Network) using the EchoStar 1 satellite. EchoStar launched a second satellite in September 1996 to increase the number of channels available on Dish Network to 170. These systems provided better pictures and stereo sound on 150-200 video and audio channels, and allowed small dishes to be used for the first time, greatly reducing the popularity of TVRO systems. In the mid-1990s, channels began moving their broadcasts to digital television transmission using DigiCipher scrambling and conditional access.
In addition to encryption, DBS services such as PrimeStar had been reducing the popularity for TVRO systems since the early 1990s. Signals from DBS satellites (operating in the more recent Ku band) are higher in both frequency and power (due to improvements in the solar panels and energy efficiency of modern satellites) and therefore require much smaller dishes than C-band, and the digital signals now used require far less signal strength at the receiver, resulting in a lower cost of entry. Each satellite also can carry up to 32 transponders in the Ku band, but only 24 in the C band, and several digital subchannels can be multiplexed (MCPC) or carried separately (SCPC) on a single transponder. General advancements in noise abatement have also had an effect. However, a consequence of the higher frequency used for DBS services is rain fade where viewers lose signal during a heavy downpour. C-band's immunity to rain fade is one of the major reasons the system is still used as the preferred method for television broadcasters to distribute their signal.
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Satellites used for television signals are generally in either naturally highly elliptical (with inclination of +/-63.4 degrees and orbital period of about twelve hours, also known as Molniya orbit) or geostationary orbit 37,000 km (23,000 mi) above the earth's equator.
Satellite television, like other communications relayed by satellite, starts with a transmitting antenna located at an uplink facility. Uplink satellite dishes are very large, as much as 9 to 12 meters (30 to 40 feet) in diameter. The increased diameter results in more accurate aiming and increased signal strength at the satellite. The uplink dish is pointed toward a specific satellite and the uplinked signals are transmitted within a specific frequency range, so as to be received by one of the transponders tuned to that frequency range aboard that satellite. The transponder 'retransmits' the signals back to Earth but at a different frequency band (a process known as translation, used to avoid interference with the uplink signal), typically in the C-band (4–8 GHz) or Ku-band (12–18 GHz) or both. The leg of the signal path from the satellite to the receiving Earth station is called the downlink.
A typical satellite has up to 32 transponders for Ku-band and up to 24 for a C-band only satellite, or more for hybrid satellites. Typical transponders each have a bandwidth between 27 and 50 MHz. Each geostationary C-band satellite needs to be spaced 2° from the next satellite to avoid interference; for Ku. the spacing can be 1°. This means that there is an upper limit of 360/2 = 180 geostationary C-band satellites and 360/1 = 360 geostationary Ku-band satellites. C-band transmission is susceptible to terrestrial interference while Ku-band transmission is affected by rain (as water is an excellent absorber of microwaves at this particular frequency). The latter is even more adversely affected by ice crystals in thunder clouds.
On occasion, sun outage will occur when the sun lines up directly behind the geostationary satellite the reception antenna is pointing to. This will happen twice a year at around midday for a two-week period in the spring and in the fall, and affects both the C-band and the Ku-band. The line-up swamps out all reception for a few minutes due to the sun emitting microwaves on the same frequencies used by the satellite's transponders.
The downlinked satellite signal, quite weak after traveling the great distance (see inverse-square law), can be collected by using a parabolic receiving dish, which reflects the weak signal to the dish's focal point. Mounted on brackets at the dish's focal point is a device called a feedhorn. This feedhorn is essentially the flared front-end of a section of waveguide that gathers the signals at or near the focal point and 'conducts' them to a probe or pickup connected to a low-noise block downconverter or LNB. The LNB amplifies the relatively weak signals, filters the block of frequencies in which the satellite television signals are transmitted, and converts the block of frequencies to a lower frequency range in the L-band range. The evolution of LNBs was one of necessity and invention.
The original C-Band satellite television systems used a low-noise amplifier connected to the feedhorn at the focal point of the dish. The amplified signal was then fed via very expensive and sometimes 50 ohm impedance gas filled hardline coaxial cable to an indoor receiver or, in other designs, fed to a downconverter (a mixer and a voltage tuned oscillator with some filter circuitry) for downconversion to an intermediate frequency. The channel selection was controlled, typically by a voltage tuned oscillator with the tuning voltage being fed via a separate cable to the headend. But this design evolved.
Designs for microstrip based converters for amateur radio frequencies were adapted for the 4 GHz C-Band. Central to these designs was concept of block downconversion of a range of frequencies to a lower, and technologically more easily handled block of frequencies (intermediate frequency).
The advantages of using an LNB are that cheaper cable could be used to connect the indoor receiver with the satellite television dish and LNB, and that the technology for handling the signal at L-Band and UHF was far cheaper than that for handling the signal at C-Band frequencies. The shift to cheaper technology from the 50 Ohm impedance cable and N-Connectors of the early C-Band systems to the cheaper 75 Ohm technology and F-Connectors allowed the early satellite television receivers to use, what were in reality, modified UHF television tuners which selected the satellite television channel for down conversion to another lower intermediate frequency centered on 70 MHz where it was demodulated. This shift allowed the satellite television DTH industry to change from being a largely hobbyist one where receivers were built in low numbers and complete systems were expensive (costing thousands of dollars) to a far more commercial one of mass production.
Direct broadcast satellite dishes are fitted with an LNBF, which integrates the feedhorn with the LNB.
In the United States, service providers use the intermediate frequency ranges of 950-2150 MHz to carry the signal to the receiver. This allows for transmission of UHF band signals along the same span of coaxial wire at the same time. In some applications (DirecTV AU9-S and AT-9), ranges the lower B-Band and upper 2250-3000 MHz, are used. Newer LNBFs in use by DirecTV referred to as SWM (Single Wire Multiswitch), See also Single Cable Distribution, use a less limited frequency range of 2-2150 MHz.
The satellite receiver or set-top box demodulates and converts the signals to the desired form (outputs for television, audio, data, etc.). Sometimes, the receiver includes the capability to unscramble or decrypt the received signal; the receiver is then called an integrated receiver/decoder or IRD. The cable connecting the receiver to the LNBF or LNB should be of the low loss type RG-6, quad shield RG-6 or RG-11, etc. RG-59 is not recommended for this application as it is not technically designed to carry frequencies above 950 MHz, but will work in many circumstances, depending on the quality of the coaxial wire.
A practical problem relating to satellite home reception is that basically an LNB can only handle a single receiver. This is due to the fact that the LNB is mapping two different circular polarizations – right hand and left hand – and in the case of the K-band two different reception bands – lower and upper – to one and the same frequency band on the cable. Depending on which frequency a transponder is transmitting at and on what polarization it is using, the satellite receiver has to switch the LNB into one of four different modes in order to receive a specific desired program on a specific transponder. This is handled by the receiver using the DiSEqC protocol to control the LNB mode. If several satellite receivers are to be attached to a single dish a so-called multiswitch will have to be used in conjunction with a special type of LNB. There are also LNBs available with a multiswitch already integrated. This problem becomes more complicated when several receivers are to use several dishes (or several LNBs mounted in a single dish) pointing to different satellites.
A common solution for consumers wanting to access multiple satellites is to deploy a single dish with a single LNB and to rotate the dish using an electric motor. The axis of rotation has to be set up in the north-south direction and, depending on the geographical location of the dish, have a specific vertical tilt. Set up properly the motorized dish when turned will sweep across all possible positions for satellites lined up along the geostationary orbit directly above the equator. The disk will then be capable of receiving any geostationary satellite that is visible at the specific location, i.e. that is above the horizon. The DiSEqC protocol has been extended to encompass commands for steering dish rotors.
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Analog television distributed via satellite is usually sent scrambled or unscrambled in NTSC, PAL, or SECAM television broadcast standards. The analog signal is frequency modulated and is converted from an FM signal to what is referred to as baseband. This baseband comprises the video signal and the audio subcarrier(s). The audio subcarrier is further demodulated to provide a raw audio signal.
If the signal is a digitized television signal or multiplex of signals, it is typically QPSK.
The conditional access encryption/scrambling methods include NDS, BISS, Conax, Digicipher, Irdeto, Cryptoworks, DG Crypt, Beta digital, SECA Mediaguard, Logiways, Nagravision, PowerVu, Viaccess, Videocipher, and VideoGuard. Many conditional access systems have been compromised.
Categories of usage
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There are three primary types of satellite television usage: reception direct by the viewer, reception by local television affiliates, or reception by headends for distribution across terrestrial cable systems.
Direct broadcast via satellite
Direct broadcast satellite, (DBS) also known as "Direct-To-Home" can either refer to the communications satellites themselves that deliver DBS service or the actual television service. DBS systems are commonly referred to as "mini-dish" systems. DBS uses the upper portion of the Ku band, as well as portions of the Ka band.
Modified DBS systems can also run on C-band satellites and have been used by some networks in the past to get around legislation by some countries against reception of Ku-band transmissions.
Most of the DBS systems use the DVB-S standard for transmission. With pay television services, the datastream is encrypted and requires proprietary reception equipment. While the underlying reception technology is similar, the pay television technology is proprietary, often consisting of a conditional-access module and smart card.
This measure assures satellite television providers that only authorised, paying subscribers have access to pay television content but at the same time can allow free-to-air (FTA) channels to be viewed even by the people with standard equipment (DBS receivers without the conditional-access modules) available in the market.
The term Television receive-only, or TVRO, arose during the early days of satellite television reception to differentiate it from commercial satellite television uplink and downlink operations (transmit and receive). This was before there was a DTH satellite television broadcast industry. Satellite television channels at that time were intended to be used by cable television networks rather than received by home viewers. Satellite television receiver systems were largely constructed by hobbyists and engineers. In 1978 Microcomm, a small company founded by radio amateur and microwave engineer H. Paul Shuch, introduced the first commercial home satellite television receiver. These early TVRO systems operated mainly on the C band frequencies and the dishes required were large; typically over 3 meters (10 ft) in diameter. Consequently TVRO is often referred to as "big dish" or "Big Ugly Dish" (BUD) satellite television.
TVRO systems are designed to receive analog and digital satellite feeds of both television or audio from both C-band and Ku-band transponders on FSS-type satellites. The higher frequency Ku-band systems tend to be Direct To Home systems and can use a smaller dish antenna because of the higher power transmissions and greater antenna gain.
TVRO systems tend to use larger rather than smaller satellite dish antennas, since it is more likely that the owner of a TVRO system would have a C-band-only setup rather than a Ku band-only setup. Additional receiver boxes allow for different types of digital satellite signal reception, such as DVB/MPEG-2 and 4DTV.
The narrow beam width of a normal parabolic satellite antenna means it can only receive signals from a single satellite at a time. Simulsat or the Vertex-RSI TORUS, is a quasi-parabolic satellite earthstation antenna that is capable of receiving satellite transmissions from 35 or more C- and Ku-band satellites simultaneously.
Direct to Home television
Many satellite television customers in developed television markets get their programming through a direct broadcast satellite (DBS) provider. The provider selects programs and broadcasts them to subscribers as a set package. Basically, the provider’s goal is to bring dozens or even hundreds of channels to the customer's television in a form that approximates the competition from cable television. Unlike earlier programming, the provider’s broadcast is completely digital, which means it has high picture and stereo sound quality. Early satellite television services were broadcast in C-band radio, in the 3.7 GigaHertz (GHz) to 4.2 GHz frequency range. Digital broadcast satellite transmits programming in the Ku frequency range (10 GHz to 14 GHz).
Programming sources are simply the channels that provide television programming for broadcast. The provider (the DTH platform) does not create original programming itself. The broadcast center is the central hub of the system. At the broadcast center, the television provider receives signals from various programming sources, compresses these signals using digital video compression (encryption if necessary), and sends a broadcast signal to the proper satellite.
- Dish Home (HD Panaroma)
- Commercialization of space
- FTA Receiver
- Microwave antenna
- Molniya orbit
- Satellite dish
- Satellite subcarrier audio
- Satellite television by region
- Smart TV: provides television via internet connection
- "How satellite dish is made". Retrieved 30 June 2014.
- Klein, Christopher (23 July 2012). "The Birth of Satellite TV, 50 Years Ago". History.com. History Channel. Retrieved 5 June 2014.
- Darcey, RJ (16 August 2013). "Syncom 2". NASA.gov. NASA. Retrieved 5 June 2014.
- "Encyclopedia Astronautica - Intesat I". Retrieved 5 April 2010.
- Robertson, Lloyd (1972-11-09). "Anik A1 launching: bridging the gap". CBC English TV. Retrieved 2007-01-25.
- Ezell, Linda N. (22 January 2010). "NASA - ATS". Nasa.gov. NASA. Retrieved 1 July 2014.
- "Ekran". Astronautix.com. Astronautix. 2007. Retrieved 1 July 2014.
- "TV Timeline". http://w2.parentstv.org. Parents Television Council. 2010. Retrieved 5 June 2014.
- "Industry History". sbca.com. Satellite Broadcasting and Communications Association. 2014. Retrieved 5 June 2014.
- The "Glory Days" of Satellite
- Browne, Ray (2001). The Guide to United States Popular Culture. Madison, Wisconsin: Popular Press. p. 706. ISBN 9780879728212. Retrieved 1 July 2014.
- Giarrusso, Michael (28 July 1996). "Tiny Satellite Dishes Sprout in Rural Areas". Los Angeles Times (Los Angeles: Los Angeles Times). Retrieved 1 July 2014.
- Keating, Stephen (1999). "Stealing Free TV, Part 2". The Denver Post (Denver, CO: The Denver Post). Retrieved 3 July 2014.
- Stein, Joe (1989-01-24). "Whatta dish : Home satellite reception a TV turn-on". Evening Tribune. p. C-8.
- History of Satellite TV
- Brooks, Andree (10 October 1993). "Old satellite dish restrictions under fire New laws urged for smaller models". The Baltimore Sun (Baltimore, MD: The Baltimore Sun). Retrieved 1 July 2014.
- Nye, Doug (14 Januray 1990). "SATELLITE DISHES SURVIVE GREAT SCRAMBLE OF 1980S". Deseret News (Salt Lake City: Deseret News). Retrieved 30 June 2014.
- Stecklow, Steve (1984-07-07). "America's Favorite Dish". The Miami Herald. Knight-Ridder News Service. p. 1C.
- Reibstein, Larry (1981-09-27). "Watching TV Via Satellite Is Their Dish". The Philadelphia Inquirer. p. E01.
- Dawidziak, Mark (1984-12-30). "Satellite TV Dishes Getting Good Reception". Akron Beacon-Journal. p. F-1.
- Stecklow, Steve (1984-10-25). "Research Needed in Buying Dish: High Cost Is Important Consideration for Consumer". Wichita Eagle. Knight-Ridder News Service. p. 6C.
- "Installing Consumer-Owned Antennas and Satellite Dishes". FCC. Retrieved 2008-11-21.
- Marples, Gareth (11 September 2008). "The History of Satellite TV – A Vision for the Future". TheHistoryOf.net. TheHistoryOf.net. Retrieved 30 June 2014.
- Takiff, Jonathan (1987-05-22). "Satellite TV Skies Brighten As War With Programmers Ends". Chicago Tribune. Knight-Ridder Newspapers. Retrieved 2014-04-10.
- Wolf, Ron (1985-01-20). "Direct-Broadcast TV Is Still Not Turned On". The Philadelphia Inquirer. p. C01.
- Lyman, Rick; Borowski, Neill (April 29, 1986). "On The Trail Of 'Captain Midnight'". Philly. Retrieved May 20, 2014.
- Paradise, Paul R. (1 January 1999). Trademark Counterfeiting, Product Piracy, and the Billion Dollar Threat to the U.S. Economy. Westport, Connecticut: Greenwood Publishing Group. p. 147. ISBN 1567202500. Retrieved 3 July 2014.
- "Scrambled NBC Bad News for Satellite Pirates". The San Francisco Chronicle. United Press International. 1988-11-03. p. E3.
- Article STATUTE-106-Pg1460.pdf, Cable Television Consumer Protection and Competition Act of 1992, Act No. 1460 of 8 October 1992 (in English). Retrieved on 3 July 2014.
- Grant, August E. Communication Technology Update, 10/e. Taylor & Francis. p. 87. ISBN 978-0-240-81475-9.
- "The C Band Myth". http://www.level421.com.
- "Frequency letter bands". http://www.microwaves101.com. 25 April 2008.
- Channels and satellite fleets
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