FTA Satellite TV

  • Satellite television

    Satellite television is television delivered by the means of communications satellite and received by a satellite dish and set-top box. In many areas of the world it provides a wide range of channels and services, often to areas that are not serviced by terrestrial or cable providers.

    The first satellite television signal was relayed from Europe to the Telstar satellite over North America in 1962. The first geosynchronous communication satellite, Syncom 2, was launched in 1963. The world's first commercial communication 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 re-broadcasting and delivering of TV signal to ground downlink stations. The first domestic North American satellite to carry television was Canada’s geostationary Anik 1, which was launched in 1972.[1] ATS-6, the world's first experimental educational and Direct Broadcast Satellite, was launched in 1974. The first Soviet geostationary satellite to carry Direct-To-Home television, called Ekran, was launched in 1976.

    Satellites used for television signals are generally in either naturally highly elliptical (with inclination of +/-63.4 degrees and orbital period of about 12 hours, also known as Molniya orbit) or geostationary orbit 37,000 km (22,300 miles) 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 MHz and 50 MHz. Each geo-stationary C-band satellite needs to be spaced 2 degrees from the next satellite (to avoid interference). For Ku the spacing can be 1 degree. 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 downlinked satellite signal, quite weak after traveling the great distance (see inverse-square law), is collected by 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 TV 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 TV 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 TV 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 TV receivers to use, what were in reality, modified UHF TV 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.

    The satellite receiver 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 receiver is then called an Integrated receiver/decoder or IRD. The cable connecting the receiver to the LNBF or LNB must be of the low loss type RG-6, quad shield RG-6 or RG-11, etc. It cannot be standard RG-59.

  • Satellite Television Providers

    Currently, there are two primary satellite television providers of subscription based service available to United States consumers: Dish Network and DirecTV.

    Over the past three decades, various U.S. satellite services have come and gone or combined to form the current primary services. In 1975 RCA created Satcom 1, the first satellite built especially for use by the then three national television networks (CBS, NBC, and ABC). Later that same year, HBO leased a transponder on Satcom 1 and began transmission of television programs via satellite to cable systems. Owners of cable systems paid $10,000 to install 3-meter dishes to receive TV signals in C-band. In 1976 Taylor Howard built an amateur system, which consisted of a converted military surplus radar dish and a satellite receiver designed and built by Howard, for home satellite reception. Taylor's system could be used for receiving TV programs both from American and Soviet communication satellites. In 1977 Pat Robertson launched the first satellite-delivered basic cable service called the CBN Cable Network. In 1979, the Satellite Home Viewers Act allowed homeowners in the US to own and operate their own home satellite system, consisting of C-band equipment from a multitude of manufacturers who were making parts for systems such as Taylor Howard's, and began a large controversy of which channels could be received by whom.

    USSB was a direct-to-home service founded in 1981. In the early 1990s they partnered with Hughes and continued operation until purchased in 1998 by DirecTV.

    In 1991 Primestar launched as the first North American DBS service. Hughes’s DirecTV, the first national high-powered upper Ku-band DBS system, went online in 1994. The DirecTV system became the new delivery vehicle for USSB. News Corporation currently holds a 38% stake, which it is in the process of selling to Liberty Media. In 1996, EchoStar’s Dish Network went online in the United States and has gone on to similar success as DirecTV’s primary competitor. The AlphaStar service launched in 1996 and went into bankruptcy in 1997. Dominion Video Satellite Inc's Sky Angel also went online in the United States in 1996 with its DBS service geared towards "faith and family". Primestar sold its assets to Hughes in 1999 and switched from DBS to an IPTV platform.

    In 2004, Cablevision’s Voom service went online, specifically catering to the emerging market of HDTV owners and aficionados, but folded in April 2005. The service’s “exclusive” high-definition channels were migrated to the Dish Network system. Commercial DBS services are the primary competition to cable television service, although the two types of service have significantly different regulatory requirements (for example, cable television has public access requirements, and the two types of distribution have different regulations regarding carriage of local stations).

    The majority of ethnic-language broadcasts in North America are carried on Ku band free-to-air. The largest concentration of ethnic programming is on Galaxy 25 at 97° W. Pittsburgh International Telecommunications and GlobeCast World TV offers a mix of free and pay-TV ethnic channels in the internationally-standard DVB-S format, as do others. Home2US Communications Inc. also offers several ethnic channels on AMC-4 at 101° W, as well as other free and pay-TV channels. Several U.S.-English language network affiliates (representing CBS, NBC, ABC, PBS, FOX, the CW (formerly the WB and UPN), ION Network and MyNetworkTV) are available as free-to-air broadcasts, as are the three U.S.-Spanish language networks (Univisión, Telefutura and Telemundo). The number of free-to-air specialty channels is otherwise rather limited. Specific FTA offerings tend to appear and disappear rather often and typically with little or no notice, although sites such as LyngSat do track the changing availability of both free and pay channels worldwide.[2]

    On October 7, 2009, NAB TV Board chair Paul Karpowicz planned to testify before the Senate Communications Subcommittee that broadcasters would be willing to allow subscribers of distant signals to continue to do so even if the digital transition resulted in those subscribers receiving stations that they could not before. The NAB did oppose offering new distant signals if a digital signal was available. The Satellite TV Modernization Act had to be passed by the end of 2009. The House bill also allowed Dish Network to offer distant signals.[3]

    The leading satellite television broadcaster in the United Kingdom is a subscription based service named Sky Digital, marketed by British Sky Broadcasting. Since May 2008, a subscription free alternative known as Freesat has been available as part of preparations to migrate the UK to exclusively digital TV broadcasting. The Freesat service is run jointly by the UK's two largest broadcasters, ITV and BBC and should not be confused with the similarly named freesat from sky, a subscription free version of the Sky platform.

FTA Satellite TV