Over the air television
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Terrestrial television or over-the-air television (OTA) is a type of
television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
broadcasting Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio ...
in which the
signal transmission In telecommunications, transmission is the process of sending or propagating an analog or digital signal via a medium that is wired, wireless, or fiber-optic. Transmission technologies typically refer to physical layer protocol duties such ...
occurs via
radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...
s from the terrestrial (Earth-based)
transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which i ...
of a
TV station A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth ...
to a TV receiver having an
antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...
. The term ''terrestrial'' is more common in Europe and Latin America, while in Canada and the United States it is called ''over-the-air'' or simply ''broadcast''. This type of TV broadcast is distinguished from newer technologies, such as
satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...
(
direct broadcast satellite Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...
or DBS television), in which the 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 Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, ...
, 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 Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
between about 52 and 600 MHz in the
VHF Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF ...
and
UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...
bands. Since radio waves in these bands travel by line of sight, reception is generally limited by the visual horizon to distances of , 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 greyscale (called
black and white Black-and-white (B&W or B/W) images combine black and white in a continuous spectrum, producing a range of shades of grey. Media The history of various visual media began with black and white, and as technology improved, altered to color. ...
) until the transition to
color television Color television or Colour television is a television transmission technology that includes color information for the picture, so the video image can be displayed in color on the television set. It improves on the monochrome or black-and-white t ...
in the 1960s. 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 An over-the-top (OTT) media service is a media service offered directly to viewers via the Internet. OTT bypasses cable, broadcast, and satellite television platforms: the types of companies that traditionally act as controllers or distributors ...
(OTT) which is streamed via the internet had become a common alternative.


Analogue


Europe

Following the ST61 conference, UHF frequencies were first used in the UK in 1964 with the introduction of
BBC2 BBC Two is a British free-to-air public broadcast television network owned and operated by the BBC. It covers a wide range of subject matter, with a remit "to broadcast programmes of depth and substance" in contrast to the more mainstream an ...
. In the UK, VHF channels were kept on the old
405-line The 405-line monochrome analogue television broadcasting system was the first fully electronic television system to be used in regular broadcasting. The number of television lines influences the image resolution, or quality of the picture. It was ...
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 Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below 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.


Americas

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 Color television or Colour television is a television transmission technology that includes color information for the picture, so the video image can be displayed in color on the television set. It improves on the monochrome or black-and-white t ...
. 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, Argentina, El Salvador, Guatemala and Honduras; however, the four latter countries reversed their decision in favour of
ISDB-T Integrated Services Digital Broadcasting (ISDB; Japanese: , ''Tōgō dejitaru hōsō sābisu'') is a Japanese broadcasting standard for digital television (DTV) and digital radio. ISDB supersedes both the NTSC-J analog television system and th ...
b. The Pan-American terrestrial television operates on analog channels 2 through 6 (
VHF Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF ...
-low band, 54 to 88 MHz, known as
band I 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 U ...
in Europe), 7 through 13 (VHF-high band, 174 to 216 MHz, known as
band III 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-b ...
elsewhere), and 14 through 51 (
UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...
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.


Asia

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 DWWX-TV, Channel 2, was the flagship VHF station of Philippine television network ABS-CBN. The station was owned and operated by ABS-CBN Corporation with its studio and transmitter located at the ABS-CBN Broadcasting Center, Sgt. Esguerra Av ...
on October 23, 1953, with the help of Radio Corporation of America (RCA).


Digital

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 A frequency plan, bandplan, band plan or wavelength plan is a plan for using a particular band of radio frequencies, that are a portion of the electromagnetic spectrum. Each frequency plan defines the frequency range to be included, how channels a ...
. 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 A Regional Radiocommunication Conference (RRC) is a meeting held between members of the International Telecommunication Union from one or more ITU Regions, but from the whole world. Such a meeting is normally used to put in place an agreement on use ...
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 Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syste ...
television transmissions by 2012 and switch all terrestrial television broadcasting to
digital audio Digital audio is a representation of sound recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is typically encoded as numerical samples in a continuous sequence. For example, in CD audio, sa ...
and
digital video Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises ...
(all EU countries have agreed on using
DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Febr ...
). 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 The Australian Communications and Media Authority (ACMA) is an Australian government statutory authority within the Communications portfolio. ACMA was formed on 1 July 2005 with the merger of the Australian Broadcasting Authority and the Austr ...
, 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 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 ...
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 The Canadian Radio-television and Telecommunications Commission (CRTC; french: Conseil de la radiodiffusion et des télécommunications canadiennes, links=) is a public organization in Canada with mandate as a regulatory agency for broadcasti ...
(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.


See also

* List of United States over-the-air television networks * Pay television * Broadcast television systems * Lists of television channels for various lists * List of digital television deployments by country * Television channel frequencies *
DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Febr ...
* ATSC tuner * Television antenna


References


External links


TVRadioWorld TV stations directoryW9WI.com
(Terrestrial repeater and TV hobbyist information)
TV Coverage maps and Signal Analysis
{{DEFAULTSORT:Terrestrial Television Television technology Television terminology History of television