Terrestrial television

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Indoor "rabbit ears" antenna often used for terrestrial television reception. This model also has a loop antenna for UHF reception. Rabbit-ears dipole antenna with UHF loop 20090204.jpg
Indoor "rabbit ears" antenna often used for terrestrial television reception. This model also has a loop antenna for UHF reception.

Terrestrial television or over-the-air television (OTA) is a type of television broadcasting in which the content is transmitted via radio waves from the terrestrial (Earth-based) transmitter of a TV station to a TV receiver having an antenna. 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 (direct broadcast satellite 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, 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. [1]

Contents

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) until the transition to color television in the 1960s. [2]

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. [3] [4] 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. [5] 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. [6]

Analog

Rooftop television antennas like these are required to receive terrestrial television in fringe reception areas far from the television station. Antenna.jpg
Rooftop television antennas like these are required to receive terrestrial television in fringe reception areas far from the television station.

Europe

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 color). Television broadcasting in the 405-line system continued after the introduction of four analog programs 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 the planned phase-out and switch over to digital television.

The success of analog 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

The first National Television System Committee standard was introduced in 1941. 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 backward-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 has ended all its analog television broadcasts and the United States and Canada have shut down nearly all of their analog 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. [7]

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 favor of ISDB-Tb. [8] [9]

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. [10] 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) [11]

Analog television channels 2 through 6, 7 through 13, and 14 through 51 are only used for LPTV translator stations in the United States. 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 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.

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 analog audio and analog 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. [12] Two member states (not specified in the announcement) 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 analog transmissions will cease by 2012. Mandated digital conversion started early in 2009 with a graduated program. The first centre to experience analog switch-off was the remote Victorian regional town of Mildura, in 2010. The government supplied underprivileged houses across the nation with free digital set-top converter boxes in order to minimize conversion disruption. Australia's major free-to-air television networks were all granted digital transmission licenses 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 analog 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 analog transmission service ceased in metropolitan areas and provincial capitals. [13] [14] In Mexico, the Federal Telecommunications Institute (IFT) discontinued the use of analog terrestrial television on 31 December 2015.

See also

Related Research Articles

<span class="mw-page-title-main">Television channel</span> Frequency/channel over which a television station is distributed

A television channel, or TV 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

<span class="mw-page-title-main">DVB</span> Open standard for digital television broadcasting

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).

Integrated Services Digital Broadcasting is a Japanese broadcasting standard for digital television (DTV) and digital radio.

<span class="mw-page-title-main">ATSC standards</span> Standards for digital television in the US

Advanced Television Systems Committee (ATSC) standards are an International set of standards for broadcast and 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, South Korea and Trinidad & Tobago. Several former NTSC users, such as Japan, have not used ATSC during their digital television transition, because they adopted other systems such as ISDB developed by Japan, and DVB developed in Europe, for example.

Broadcasttelevision systems are the encoding or formatting systems for the transmission and reception of terrestrial television signals.

Digital terrestrial television is a technology for terrestrial television where television stations broadcast television content in a digital format. DTTV is a major technological advance over analog television, and has largely replaced analog television broadcast, which had been in common use since the middle of the 20th century. Test broadcasts began in 1998 with the changeover to DTTV, also known as the Analog Switchoff (ASO) or Digital Switchover (DSO), which began in 2006 and is now complete in many countries. The advantages of digital terrestrial television are similar to those obtained by digitizing platforms such as cable TV, satellite, and telecommunications: more efficient use of radio spectrum bandwidth, provision of more television channels than analog, better quality images, and potentially lower operating costs for broadcasters.

<span class="mw-page-title-main">All-Channel Receiver Act</span> United States legislation

The All-Channel Receiver Act of 1962 (ACRA), commonly known as the All-Channels Act, was passed by the United States Congress in 1961, to allow the Federal Communications Commission to require that all television set manufacturers must include UHF tuners, so that new UHF-band TV stations could be received by the public. This was a problem at the time since most affiliated stations of the Big Three television networks were well-established on VHF, while many local-only stations on UHF were struggling for survival.

<span class="mw-page-title-main">Tuner (radio)</span> Frequency selection subsystem for various receiver systems

A tuner is a subsystem that receives radio frequency (RF) transmissions, such as FM broadcasting, 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 1 occupies the spectrum from 44 to 50 MHz. See Broadcast television systems for a table of signal characteristics, including bandwidth, by ITU letter designator.

<span class="mw-page-title-main">Television antenna</span> Antenna used with a television to receive television programs

A television antenna is an antenna specifically designed for use with a television receiver (TV) to receive over-the-air broadcast television signals from a television station. Television reception is dependent upon the antenna as well as the transmitter. Terrestrial television is broadcast on frequencies from about 47 to 250 MHz in the very high frequency (VHF) band, and 470 to 960 MHz in the ultra high frequency (UHF) band in different countries. Television antennas are manufactured in two different types: "indoor" antennas, to be located on top of or next to the television set, and "outdoor" antennas, mounted on a mast on top of the owner's house. They can also be mounted in a loft or attic, where the dry conditions and increased elevation are advantageous for reception and antenna longevity. Outdoor antennas are more expensive and difficult to install but are necessary for adequate reception in fringe areas far from television stations. The most common types of indoor antennas are the dipole and loop antennas, and for outdoor antennas the Yagi, log periodic, and for UHF channels the multi-bay reflective array antenna.

<span class="mw-page-title-main">ATSC tuner</span> Tuner for digital television channels

An ATSCtuner, often called an ATSC receiver or HDTV tuner, is a type of television tuner that allows reception of digital television (DTV) television channels that use ATSC standards, as transmitted by television stations in North America, parts of Central America, and South Korea. Such tuners are usually integrated into a television set, VCR, digital video recorder (DVR), or set-top box which provides audio/video output connectors of various types.

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 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.

Digital television in the United States is available via digital terrestrial television (DTT), digital cable, satellite television, and IPTV providers.

Digital terrestrial television in the Philippines began in 2015 with the implementation of ISDB-T, currently coexisting with analog television that operates on the NTSC standard after the set analog switch-off (ASO) deadline encountered multiple postponements.

<span class="mw-page-title-main">Digital television transition</span> Global switchover to digital television

The digital television transition, also called the digital switchover (DSO), the analogue switch/sign-off (ASO), the digital migration, or the analogue shutdown, is the process in which older analogue television broadcasting technology is converted to and replaced by digital television. Conducted by individual nations on different schedules, this primarily involves the conversion of analogue 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 digital transition in the United States was the switchover from analog to exclusively digital broadcasting of terrestrial television programming. According to David Rehr, then president and CEO of the National Association of Broadcasters, this transition represented "the most significant advancement of television technology since color TV was introduced." For full-power TV stations, the transition went into effect on June 12, 2009, with stations ending regular programming on their analog signals no later than 11:59 p.m. local time that day.

<span class="mw-page-title-main">UHF television broadcasting</span> Ultra high frequency radio to transmit TV

UHF television broadcasting is the use of ultra high frequency (UHF) radio for over-the-air transmission of television signals. UHF frequencies are used for both analog and digital television broadcasts. UHF channels are typically given higher channel numbers, like the US arrangement with VHF channels (initially) 1 to 13, and UHF channels (initially) numbered 14 to 83. Compared with an equivalent VHF television transmitter, to cover the same geographic area with a UHF transmitter requires a higher effective radiated power, implying a more powerful transmitter or a more complex antenna. However, the additional channels allow more broadcasters in a given region without causing objectionable mutual interference.

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 and 216 MHz, and the UHF band, which comprises channels 14 through 36 and occupies frequencies between 470 and 608 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.

References

  1. ↑ BBC. "Help receiving TV and radio" . Retrieved September 28, 2020.
  2. ↑ "The Color Revolution: Television In The Sixties". TVObscurities. 2005-02-15. Retrieved 2017-09-04.
  3. ↑ "OTA Homes Cross 16M Mark, Per Nielsen", TVTechnology, 13 February 2019, Michael Balderston
  4. ↑ McAdams, Deborah D (14 January 2013). "Nielsen: Broadcast Reliance Grew in 2012". TVTechnology. Archived from the original on Feb 21, 2014.
  5. ↑ "Deloitte: Terrestrial TV has surprising staying power". Broadband TV News. 11 December 2019. Archived from the original on Jun 16, 2023.
  6. ↑ Jacobson, Adam (2019-04-25). "Is OTT Eating Into OTA, While Killing Cable TV?" . Radio & Television Business Report. Archived from the original on Dec 6, 2020. Retrieved 2020-07-25.
  7. ↑ Mick Hurbis-Cherrier (2007). "NTSC Broadcast Standards" (PDF). Voice & Vision ed. 1. Archived from the original (PDF) on 2017-09-05. Retrieved 2017-09-04.
  8. ↑ "About ATSC". Advanced Television Systems Committee. Retrieved 2017-09-04.
  9. ↑ "ATSC Standards". Advanced Television Systems Committee. Retrieved 2017-09-04.
  10. ↑ ATSC Standard: Program and System Information Protocol for Terrestrial Broadcast and Cable (PDF). Advanced Television Systems Committee. Archived (PDF) from the original on 2015-04-14. Retrieved 2017-09-04.
  11. ↑ "FCC regulations CFR 47 Part 74 Subpart L: FM Broadcast Translator Stations and FM Broadcast Booster Stations". Edocket.access.gpo.gov. Retrieved 2017-09-04.
  12. ↑ "DVB – Digital Video Broadcasting – Norway". Digital Video Broadcasting Project.
  13. ↑ "The Commission establishes a new approach for Canadian conventional television" (Press release). Canadian Radio-television and Telecommunications Commission. 2007-05-17. Archived from the original on 2007-05-19. Retrieved 2007-05-17.
  14. ↑ "Broadcasting Public Notice CRTC 2007–53". Sections 50 to 80. Canadian Radio-television and Telecommunications Commission. 2007-05-17. Retrieved 2007-05-17.
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