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Terrestrial television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth-based) transmitter of a television station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in the United States it is called broadcast or over-the-air television (OTA). The term "terrestrial" is used to distinguish this type from the newer technologies of satellite television (direct broadcast satellite or DBS television), in which the television signal is transmitted to the receiver from an overhead satellite; cable television, in which the signal is carried to the receiver through a cable; and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is generally limited by the visual horizon to distances of 64–97 kilometres (40–60 mi), although under better conditions and with tropospheric ducting, signals can sometimes be received hundreds of kilometers distant.
Terrestrial television was the first technology used for television broadcasting. The BBC began broadcasting in 1929 and by 1930 many radio stations had a regular schedule of experimental television programmes. However, these early experimental systems had insufficient picture quality to attract the public, due to their mechanical scan technology, and television did not become widespread until after World War II with the advent of electronic scan television technology. The television broadcasting business followed the model of radio networks, with local television stations in cities and towns affiliated with television networks, either commercial (in the US) or government-controlled (in Europe), which provided content. Television broadcasts were in black and white until the transition to color television in the 1950s and 60s.
There was no other method of television delivery until the 1950s with the beginnings of cable television and community antenna television (CATV). CATV was, initially, only a re-broadcast of over-the-air signals. With the widespread adoption of cable across the United States in the 1970s and 1980s, viewing of terrestrial television broadcasts has been in decline; in 2018, it was estimated that about 14% of US households used an antenna.However, in certain other regions terrestrial television continue to be the preferred method of receiving television, and it is estimated by Deloitte as of 2020 that at least 1.6 billion people in the world receive at least some television using these means. The largest market is thought to be Indonesia, where 250 million people watch through terrestrial.
By 2019, over-the-top media service (OTT) which is streamed via the internet had become a common alternative.
Following the ST61 conference, UHF frequencies were first used in the UK in 1964 with the introduction of BBC2. In the UK, VHF channels were kept on the old 405-line system, while UHF was used solely for 625-line broadcasts (which later used PAL colour). Television broadcasting in the 405-line system continued after the introduction of four analogue programmes in the UHF bands until the last 405-line transmitters were switched off on January 6, 1985. VHF Band III was used in other countries around Europe for PAL broadcasts until planned phase-out and switch over to digital television.
The success of analogue terrestrial television across Europe varied from country to country. Although each country had rights to a certain number of frequencies by virtue of the ST61 plan, not all of them were brought into service.
In 1941, the first NTSC standard was introduced by the National Television System Committee. This standard defined a transmission scheme for a black and white picture with 525 lines of vertical resolution at 60 fields per second. In the early 1950s, this standard was superseded by a backwards-compatible standard for color television. The NTSC standard was exclusively being used in the Americas as well as Japan until the introduction of digital terrestrial television (DTT). While Mexico have ended all its analogue television broadcasts and the US and Canada have shut down nearly all of their analogue TV stations, the NTSC standard continues to be used in the rest of Latin American countries except for Argentina, Paraguay and Uruguay where PAL-N standard is used, while testing their DTT platform.
In the late 1990s and early 2000s, the Advanced Television Systems Committee developed the ATSC standard for digital high definition terrestrial transmission. This standard was eventually adopted by many American countries, including the United States, Canada, Dominican Republic, Mexico, El Salvador, Guatemala and Honduras; however, the three latter countries ditched it in favour of ISDB-Tb.
The Pan-American terrestrial television operates on analog channels 2 through 6 (VHF-low band, 54 to 88 MHz, known as band I in Europe), 7 through 13 (VHF-high band, 174 to 216 MHz, known as band III elsewhere), and 14 through 51 (UHF television band, 470 to 698 MHz, elsewhere bands IV and V). Unlike with analog transmission, ATSC channel numbers do not correspond to radio frequencies. Instead, a virtual channel is defined as part of the ATSC stream metadata so that a station can transmit on any frequency but still show the same channel number. Additionally, free-to-air television repeaters and signal boosters can be used to rebroadcast a terrestrial television signal using an otherwise unused channel to cover areas with marginal reception. (see Pan-American television frequencies for frequency allocation charts)
Analog television channels 2 through 6, 7 through 13, and 14 through 51 are only used for LPTV translator stations in the U.S. Channels 52 through 69 are still used by some existing stations, but these channels must be vacated if telecommunications companies notify the stations to vacate that signal spectrum. By convention, broadcast television signals are transmitted with horizontal polarization.
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Terrestrial television broadcast in Asia started as early as 1939 in Japan through a series of experiments done by NHK Broadcasting Institute of Technology. However, these experiments were interrupted by the beginning of the World War II in the Pacific. On February 1, 1953, NHK (Japan Broadcasting Corporation) began broadcasting. On August 28, 1953, Nippon TV (Nippon Television Network Corporation), the first commercial television broadcaster in Asia was launched. Meanwhile, in the Philippines, Alto Broadcasting System (now ABS-CBN Corporation), the first commercial television broadcaster in Southeast Asia, launched its first commercial terrestrial television station DZAQ-TV on October 23, 1953, with the help of Radio Corporation of America (RCA).
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By the mid-1990s, the interest in digital television across Europe was such the CEPT convened the "Chester '97" conference to agree on means by which digital television could be inserted into the ST61 frequency plan.
The introduction of digital terrestrial television in the late 1990s and early years of the 21st century led the ITU to call a Regional Radiocommunication Conference to abrogate the ST61 plan and to put a new plan for DTT broadcasting only in its place.
In December 2005, the European Union decided to cease all analogue audio and analogue video television transmissions by 2012 and switch all terrestrial television broadcasting to digital audio and digital video (all EU countries have agreed on using DVB-T). The Netherlands completed the transition in December 2006, and some EU member states decided to complete their switchover as early as 2008 (Sweden), and (Denmark) in 2009. While the UK began to switch off analog broadcasts, region by region, in late 2007, it was not completed until 24 October 2012. Norway ceased all analog television transmissions on 1 December 2009.Two member states (not specified in the announcement) have expressed concerns that they might not be able to proceed to the switchover by 2012 due to technical limitations; the rest of the EU member states had stopped analog television transmissions by the end 2012.
Many countries are developing and evaluating digital terrestrial television systems.
Australia has adopted the DVB-T standard and the government's industry regulator, the Australian Communications and Media Authority, has mandated that all analogue transmissions will cease by 2012. Mandated digital conversion started early in 2009 with a graduated program. The first centre to experience analog switch-off will be the remote Victorian regional town of Mildura, in 2010. The government will supply underprivileged houses across the nation with free digital set-top converter boxes in order to minimise any conversion disruption. Australia's major free-to-air television networks have all been granted digital transmission licences and are each required to broadcast at least one high-definition and one standard-definition channel into all of their markets.
In North America, a specification laid out by the ATSC has become the standard for digital terrestrial television. In the United States, the Federal Communications Commission (FCC) set the final deadline for the switch-off of analogue service for 12 June 2009. All television receivers must now include a DTT tuner using ATSC. In Canada, the Canadian Radio-television and Telecommunications Commission (CRTC) set 31 August 2011 as the date that terrestrial analogue transmission service ceased in metropolitan areas and provincial capitals.In Mexico, the Federal Telecommunications Institute (IFT) set the final deadline for the end of analogue terrestrial television for 31 December 2015.
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In late 2009, US competition for the limited available radio spectrum led to debate over the possible re-allocation of frequencies currently occupied by television, and the FCC began asking for comments on how to increase the bandwidth available for wireless broadband. Some have proposed mixing the two together, on different channels that are already open (like White Spaces) while others have proposed "repacking" some stations and forcing them off certain channels, just a few years after the same thing was done (without compensation to the broadcasters) in the DTV transition in the United States.
Some U.S. commentators[ who? ] have proposed the closing down of terrestrial TV broadcasting, on the grounds that available spectrum might be better used, and requiring viewers to shift to satellite or cable reception. This would eliminate mobile TV, which has been delayed several years by the FCC's decision to choose ATSC and its proprietary 8VSB modulation, instead of the worldwide COFDM standard used for all other digital terrestrial broadcasting around the world. Compared to Europe and Asia, this has hamstrung mobile TV in the US, because ATSC cannot be received while in motion (or often even while stationary) without ATSC-M/H as terrestrial DVB-T or ISDB-T can even without DVB-H or 1seg.
The National Association of Broadcasters has organized to fight such proposals, and public comments are also being taken by the FCC through mid-December 2009, in preparation for a plan to be released in mid-February 2010.
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A set-top box (STB), also colloquially known as a cable box, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that can then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems as well as other uses. A computer that connects to your television allows you to use a telephone line or cable connection for you to browse the Internet and exchange electronic mail on your television.
A television channel is a terrestrial frequency or virtual number over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the terrestrial or cable band of 54 to 60 MHz, with carrier frequencies of 55.25 MHz for NTSC analog video (VSB) and 59.75 MHz for analog audio (FM), or 55.31 MHz for digital ATSC (8VSB). Channels may be shared by many different television stations or cable-distributed channels depending on the location and service provider
Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).
The Integrated Services Digital Broadcasting is a Japanese standard for digital television (DTV) and digital radio used by the country's radio and television networks. ISDB supersedes both the NTSC-J analog television system and the previously used MUSE Hi-vision analog HDTV system in Japan as well as the NTSC, PAL-M, and PAL-N broadcast standards in South America and the Philippines. Digital Terrestrial Television Broadcasting (DTTB) services using ISDB-T started in Japan in December 2003 and Brazil in December 2007 as a trial. Since then, many countries have adopted ISDB over other digital broadcasting standards.
Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that standard, is used mostly in the United States, Mexico, Canada, and South Korea. Several former NTSC users, in particular Japan, have not used ATSC during their digital television transition, because they adopted their own system called ISDB.
Broadcast television systems are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analog television systems in use around the world until the late 2010s (expected): NTSC, PAL, and SECAM. Now in digital terrestrial television (DTT), there are four main systems in use around the world: ATSC, DVB, ISDB and DTMB.
Digital terrestrial television is a technology for terrestrial television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' residences in a digital format. DTTV is a major technological advance over the previous analog television, and has largely replaced analog which had been in common use since the middle of the 20th century. Test broadcasts began in 1998 with the changeover to DTTV beginning in 2006 and is now complete in many countries. The advantages of digital terrestrial television are similar to those obtained by digitising platforms such as cable TV, satellite, and telecommunications: more efficient use of limited radio spectrum bandwidth, provision of more television channels than analog, better quality images, and potentially lower operating costs for broadcasters.
A tuner is a subsystem that receives radio frequency (RF) transmissions and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually because a lower frequency is used on the output. Broadcast FM/AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that converts the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker.
The following tables show the frequencies assigned to broadcast television channels in various regions of the world, along with the ITU letter designator for the system used. The frequencies shown are for the analogue video and audio carriers. The channel itself occupies several megahertz of bandwidth. For example, North American channel 2 occupies the spectrum from 54 to 60 MHz. See Broadcast television systems for a table of signal characteristics, including bandwidth, by ITU letter designator.
Datacasting is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital terrestrial television, but may also be applied to digital signals on analog TV or radio. It generally does not apply to data which is inherent to the medium, such as PSIP data which defines virtual channels for DTT or direct broadcast satellite systems; or to things like cable modem or satellite modem, which use a completely separate channel for data.
Multiplexed analogue components (MAC) was a satellite television transmission standard, originally proposed for use on a Europe-wide terrestrial HDTV system, although it was never used terrestrially.
Channel 37 is an intentionally unused ultra-high frequency (UHF) television broadcasting channel in the United States, Canada and Mexico. The frequency range allocated to this channel is important for radio astronomy, so broadcasting is not licensed.
Band III is the name of the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 174 to 240 megahertz (MHz). It is primarily used for radio and television broadcasting. It is also called high-band VHF, in contrast to Bands I and II.
Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961". Band I ranges from 47 to 68 MHz for the European Broadcasting Area, and from 54 to 88 MHz for the Americas and it is primarily used for television broadcasting in compliance with ITU Radio Regulations. With the transition to digital TV, most Band I transmitters in Europe, Africa, Asia and Australia have already been switched off.
Television frequency allocation has evolved since the start of television in Australia in 1956, and later in New Zealand in 1960. There was no coordination between the national spectrum management authorities in either country to establish the frequency allocations. The management of the spectrum in both countries is largely the product of their economical and political situation. New Zealand didn't start to develop television service until 1965 due to World War 2 and its economic harm in the country's economy.
In the United States, digital television broadcasts, or DTV, can be received via cable, via internet, via satellite, or via digital terrestrial television — much like analog television broadcasts have been. Full-power analog television broadcasts, however, were required by U.S. federal law to cease by June 12, 2009. Low-power, Class A, and TV Translator stations are not currently required to cease analog broadcasts. Also by law, digital broadcasts — when transmitted as over-the-air signals — must conform to ATSC standards. it is unclear whether satellite operators are free to use their own proprietary standards; and many standards exist for Internet television.
Digital terrestrial television in the Philippines are in development by the Philippine major broadcasting companies.
The digital television transition, also called the digital switchover (DSO), the analog switch-off (ASO), the digital migration, or the analog shutdown, is the process in which older analog television broadcasting technology is converted to and replaced by digital television. Conducted by individual nations on different schedules, this primarily involves the conversion of analog terrestrial television broadcasting infrastructure to digital terrestrial (DTT), a major benefit being extra frequencies on the radio spectrum and lower broadcasting costs, as well as improved viewing qualities for consumers.
The Pan-American television frequencies are different for terrestrial and cable television systems. Terrestrial television channels are divided into two bands: the VHF band which comprises channels 2 through 13 and occupies frequencies between 54 through 216 MHz, and the UHF band, which comprises channels 14 through 51 and occupies frequencies between 470 and 700 MHz. These bands are different enough in frequency that they often require separate antennas to receive, and separate tuning controls on the television set. The VHF band is further divided into two frequency ranges: VHF low band between 54 and 88 MHz, containing channels 2 through 6, and VHF high band between 174 and 216 MHz, containing channels 7 through 13. The wide spacing between these frequency bands is responsible for the complicated design of rooftop TV antennas. The UHF band has higher noise and greater attenuation, so higher gain antennas are often required for UHF.
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