Citizendia

"UHF" redirects here. For other uses, see UHF (disambiguation).

Ultra high frequency (UHF) designates a range (band) of electromagnetic waves with frequencies between 300 MHz and 3 GHz (3,000 MHz). A band is a small section of the spectrum of Radio communication frequencies, in which channels are usually used or set aside for the same Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. Frequency is a measure of the number of occurrences of a repeating event per unit Time. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Also known as the decimeter band or decimeter wave as the wavelengths range from ten to one decimeters. A decimetre ( American spelling: decimeter, symbol dm) is a unit of Length in the Metric system, equal to one tenth Radio waves with frequencies above the UHF band fall into the SHF (Super high frequency) and EHF (Extremely high frequency) bands; all of which fall into the Microwave frequency range. Super high frequency (or SHF) refers to radio frequencies (RF in the range of 3  GHz and 30 GHz Extremely high frequency is the highest Radio frequency band. Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 Lower frequency signals fall into the VHF (Very high frequency) or lower bands. Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. See electromagnetic spectrum for a full listing of frequency bands. The electromagnetic (EM spectrum is the range of all possible Electromagnetic radiation frequencies

Contents

Uses

UHF and VHF are the most commonly used frequency bands for transmission of television signals. Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic Modern mobile phones also transmit and receive within the UHF spectrum. In Telecommunications transmission is the process of sending propagating and receiving an analogue or digital information signal over a physical point-to-point or UHF is widely used by public service agencies for two-way radio communication, usually using narrowband frequency modulation, but digital services are on the rise. There has traditionally been very little radio broadcasting in this band until recently; see digital audio broadcasting for details. Digital Audio Broadcasting ( DAB) also known as Eureka 147, is a Digital radio technology for Broadcasting Radio stations used in The Global Positioning System also uses UHF. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth

One uncommon use of UHF waves is for the detection of partial discharges. In Electrical engineering, a partial discharge (PD is a localised Dielectric breakdown of a small portion of a solid or liquid Electrical insulation system Partial discharges occur because of the sharp geometries created in high voltage insulated equipment. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical The advantage of UHF detection is that this method can be used to localize the source of the discharge. A drawback to UHF detection is the extreme sensitivity to external noise. UHF detection methods are used in the field, especially for large distribution transformers. A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors

2. 45 GHz, now mainly used for WiFi, Bluetooth and US cordless phones has been proposed for Wireless energy transfer. Wi-Fi (ˈwaɪfaɪ is the trade name for the popular wireless technology used Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmission over short distances from fixed and/or mobile devices creating wireless Wireless energy transfer or wireless power transmission is the process that takes place in any system where Electrical energy is transmitted from a power Some pilot experiments have been performed, but it is not used on a large scale.

Amateur radio operators also operate in several UHF bands. See also Amateur radio An amateur radio operator is an individual who typically uses equipment at an Amateur radio station to engage in two-way

Some radio frequency identification (RFID) tags utilize UHF. Radio-frequency identification ( RFID) is an automatic identification method relying on storing and remotely retrieving data using devices called RFID tags or These tags are commonly known as UHFID's or Ultra-HighFID's (Ultra-High Frequency Identification).

Characteristics and advantages

Main article: radio propagation

The point to point transmission of radio waves is affected by many variables. Radio propagation is a term used to explain how Radio waves behave when they are Transmitted, or are propagated from one point on the Earth Atmospheric moisture, the stream of particles from the sun called solar wind, and time of day will all have an effect on the signal transmission. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. All radio waves are partially absorbed by atmospheric moisture. Atmospheric absorption reduces, or attenuates, the strength of radio signals over long distances. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium The effects of attenuation increases according to the frequency. UHF signals are generally more degraded by moisture than lower bands such as VHF. The layer of the Earth's atmosphere called the ionosphere is filled with charged particles that can reflect radio waves. The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation The reflection of radio waves can be helpful in transmitting a radio signal over long distances as the wave repeatedly bounces from the sky to the ground. UHF benefits less from the effects of reflection than lower (VHF, etc. ) frequencies. UHF transmissions may be enhanced by tropospheric ducting as the atmosphere warms and cools throughout the day. TV DX and FM DX are two terms customarily grouped together that refer to long-distance reception of TV and FM Radio stations respectively

The main advantage of UHF transmission is the physically short wave that is produced by the high frequency. The size of transmission and reception equipment, (particularly antennas), is related to the size of the radio wave. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into Smaller and less conspicuous antennas can be used with higher frequency bands.

UHF is widely used in two-way radio systems and cordless telephones. A cordless telephone or portable telephone is a Telephone with a Wireless handset that communicates via Radio waves with a Base station UHF signals travel over line-of-sight distances. Transmissions generated by two-way radios and cordless telephones do not travel far enough to interfere with local transmissions. A number of public safety and business communications are handled on UHF. Civilian applications such as GMRS, PMR446, UHF CB, and 802.11b ("WiFi") are popular uses of UHF frequencies. The General Mobile Radio Service (GMRS is a licensed land-mobile FM UHF Radio service in the United States available for short-distance two-way PMR446 (Personal Mobile Radio 446 MHz is a Radio frequency part of the UHF range that is open without licensing for personal usage in most countries of the UHF CB is a class licensed (meaning Licence -free use for most users Citizen's band Radio service authorised by the IEEE 80211 is a set of standards for wireless local area network (WLAN computer communication developed by the IEEE LAN/MAN Standards Committee ( IEEE 802 A repeater is used to propagate UHF signals when a distance that is greater than the line-of-sight is required. A repeater is an electronic device that receives a signal and Retransmits it at a higher level and/or higher power or onto the other side of an obstruction

History

Australia

In Australia, UHF was first anticipated in the mid 1970s with TV channels 28 to 69. In Telecommunication, radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the Earth For a topic outline on this subject see List of basic Australia topics. This article is about the Decade 1970-1979 For the Year 1970 see 1970. The first UHF TV broadcasts in Australia were operated by Special Broadcasting Service (SBS) on channel 28 in Sydney and Melbourne starting in 1980, and translator stations for the Australian Broadcasting Corporation (ABC). The Special Broadcasting Service (SBS is one of two government-funded Australian Public broadcasting radio and television networks, the other being the Sydney (ˈsɪdniː is the most populous city in Australia, with a Metropolitan area population of approximately 4 Melbourne ( is the second most populous city in Australia, with a Metropolitan area population of approximately 3 The Australian Broadcasting Corporation, commonly abbreviated to the 'ABC' is Australia's national public broadcaster. The UHF band is now used extensively as ABC, SBS, commercial and community (public access) television services have expanded particularly through regional areas. The Australian Broadcasting Corporation, commonly abbreviated to the 'ABC' is Australia's national public broadcaster. Public-access television in the United States is a form of Citizen media, similar to Canada's community channels Australia's community television

Australia also provides the UHF CB service for general-purpose two-way communications. UHF CB is a class licensed (meaning Licence -free use for most users Citizen's band Radio service authorised by the

Ireland

In the Republic of Ireland, UHF was introduced in 1978 to augment the existing RTÉ One VHF 625-line transmissions and to provide extra frequencies for the new RTÉ Two channel. Ireland ( Irish: Éire, ˈeːrʲə is a country in north-western Europe. RTÉ One (Irish RTÉ a hAon) is the Republic of Ireland 's oldest and most popular Television channel operated by Irish state broadcaster Radio Telefís RTÉ Two (Irish RTÉ a Dó) (known from 1988 to 2004 as Network 2, RTÉ Network Two, RTÉ2 or N2) is the Republic of Ireland The first UHF transmitter site was Cairn Hill in Co. Longford, followed by Three Rock Mountain in South Co. Dublin. County Longford (Contae an Longfoirt is a county situated in the Irish Midlands, in northwest Leinster. Three Rock is a 450 metre mountain located in the Dublin Mountains, in the east of Ireland. County Dublin (Contae Bhaile Átha Cliath or more correctly today the Dublin Region ( Réigiúin Átha Cliath) is the area that contains the city of Dublin These sites were followed by Clermont Carn in Co. Louth and Holywell Hill in Co. Donegal in 1981. Clermont Carn, variously spelt as "Clermont Cairn" "Clairmont Carn/Cairn" or other variations is a 510 Metre high mountain in County Louth which County Louth (Contae Lú is a County on the East coast of Ireland, on the border with Northern Ireland. County Donegal (ˌdʌnəˈgɔːl Irish: Contae Dhún na nGall. Elsewhere in Ireland, both the RTÉ channels are available on VHF. Since then RTÉ have migrated nearly all their low-power relay sites to UHF. TV3 and TG4 are transmitted entirely in UHF only. When Digital Terrestrial TV is introduced, it is intended to broadcast this on UHF only initially, although VHF allocations exist. VHF TV is likely to cease whenever the existing analogue broadcasts are switched off. Analog (or analogue) television encodes Television picture and sound information and transmits it as an Analog signal: one in which the The UHF band is also used in parts of Ireland for Television deflector systems bringing British television signals to towns and rural areas which cannot receive these signals directly

Malaysia

UHF broadcasting was used outside Kuala Lumpur and the Klang Valley by private TV station TV3 in the late 80s, with the government stations only transmitting in VHF (Bands 1 and 3) and the 450 MHz range being occupied by the ATUR cellular phone service operated by Telekom Malaysia. Kuala Lumpur (ˈkwɑːləlʊmˈpʊər Malay /kwɑlɑlʊmpʊ/ and locally /kwɑləlʊmpɔ/ or even /kɔlɔmpɔ/ or often abbreviated as K Klang Valley (Lembah Klang is an area in Malaysia comprising Kuala Lumpur and its suburbs and adjoining cities and towns in the state of Selangor Sistem Televisyen Malaysia Berhad (STMB or TV3 was incorporated in 1983 as Malaysia ’s first commercial Television station. Telekom Malaysia Berhad (TM) is the largest telecommunication company in Malaysia and also Southeast Asia 's second-largest telecommunication company The ATUR service ceased operation in the late 90s, freeing up the frequency for other uses. UHF was not commonly used in the Klang Valley until 1994 (despite TV3's signal also being available over UHF Channel 29, as TV3 transmitted over VHF Channel 12 in the Klang Valley). 1994 saw the introduction of the channel MetroVision (which ceased transmission in 1999, got bought over by TV3's parent company - System Televisyen Malaysia Berhad - and relaunched as 8TV in 2004). 8TV (; literal 8th dimension is a private Malaysian Television station previously known as Metrovision This was followed by Ntv7 in 1998 (also acquired by TV3's parent company in 2005) and recently Channel 9 (which started in 2003, ceased transmission in 2005, was also acquired by TV3's parent company shortly after, and came back as TV9 in early 2006). Natseven TV Sdn Bhd or better known as ntv7 is a Terrestrial television channel in Malaysia. TV9 is a Malaysian private-owned Television station which started transmission on April 22, 2006. At current count, there are 4 distinct UHF signals receivable by an analog TV set in the Klang Valley: Channel 25 (8TV), Channel 29 (TV3 UHF transmission), Channel 37 (NTV7) and Channel 39 (TV9). Channel 35 is usually allocated for VCRs, decoder units (i. e. the ASTRO and MiTV set top boxes) and other devices that have an RF signal generator (i. A set-top box (STB or set-top unit (STU is a device that connects to a Television and an external source of signal, turning the signal into e. game consoles).

United Kingdom

In the UK, UHF television began in 1964 following a plan by the GPO to allocate sets of frequencies for 625-lined television to regions across the country, so as to accommodate four national networks with regional variations (the VHF allocations only allowed for only two such networks using 405 lines). The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The UK UHF channels would range from 21 to 68 (later extended to 69) and regional allocations were generally grouped close together to allow for the use of aerials designed to receive a specific sub-band with greater efficiency than wider-band aerials could. Aerial manufacturers would therefore divide the band into over-lapping groups; A (channels 21-34), B (39-53), C/D (48-68) and E (39-68). The first service to use UHF was BBC2 in 1964 followed by BBC1 and ITV (already broadcast on VHF) in 1969 and Channel 4/S4C in 1982. Year 1964 ( MCMLXIV) was a Leap year starting on Wednesday (link will display full calendar of the 1964 Gregorian calendar. Independent Television (generally known as ITV) is a public service network of British commercial television broadcasters set up under the Independent Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. Channel 4 is a public-service Television and Radio broadcaster in the United Kingdom centred around a television channel of the same name which began S4C (Sianel Pedwar Cymru meaning Channel Four Wales) is a television channel in Wales PAL colour was introduced on UHF only in 1967 (for BBC2) and 1969 (for BBC1 & ITV). PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar. Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar.

As a consequence of achieving maximum national coverage, signals from one region would typically over-lap with that of another, which was accommodated for by allocating a different set of channels in each adjacent area, often resulting in greater choice for viewers when a network in one region aired different programmes to the neighbouring region.

Initial uptake of UHF television was very slow: Differing propagation characteristics between VHF and UHF meant new additional transmitters needed to be built, often at different locations to the then-established VHF sites, and generally with a larger number of relay stations to fill the greater number of gaps in coverage that came with the new band. This led to poor picture quality in bad coverage areas, and many years before the service achieved full national coverage. In addition to this, the only exclusively UHF service, BBC2, would run for only a few hours a day and comprised of alternative programming for minority audiences in contrast to the more popularist schedules of BBC1 and ITV. Popularism ( Popolarismo) is a political doctrine conceived by Don Luigi Sturzo, which was the ideological basis for the Italian People's Party However the 1970s saw a large increase in UHF TV viewing, and VHF take a significant decline: The appeal of colour, which was never introduced to VHF (despite preliminary plans to do so in the late 1950s and early 1960s) and the fall in television prices saw most households use a UHF set by the end of that decade. With the second and last VHF television service having launched in 1955, VHF TV was finally decommissioned for good in 1985 with no plans for it to return to use. Year 1955 ( MCMLV) was a Common year starting on Saturday (link displays the 1955 Gregorian calendar) Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar)

The launch of Channel 5 in 1997 added a fifth national television network to UHF, requiring deviation from the original frequency allocation plan of the early 1960s and the allocation of UHF frequencies previously not used for television (such as UK Channels 35 and 37 which was previously reserved for domestic VCRs requiring an expensive VCR re-tuning programme funded by the new network). Year 1997 ( MCMXCVII) was a Common year starting on Wednesday (link will display full 1997 Gregorian calendar PLEASE BEAR IN MIND THAT THIS IS A GENERAL ARTICLE ABOUT VCRs/VIDEOCASSETTE RECORDERS A lack of capacity within the band to accommodate a fifth service with the complex over-lapping led to the fifth and final network having a significantly reduced national coverage compared to the other networks, with reduced picture quality in many areas and the use of wide-band aerials often required.

The launch of digital terrestrial television in 1998 saw the continued use of UHF for television, with six multiplexes allocated for the service, all within the UHF band. Digital terrestrial television in the United Kingdom is made up of over fifty primarily free-to-air television channels (including all the national analogue stations A multiplex or mux (called virtual sub-channel in the United States and Canada) is a group of Digital TV channels that are mixed together However analogue transmissions have been planned to cease completely by 2012 after which time it is uncertain as to whether the vacated capacity will be used for additional digital television services or put into alternative use, such as mobile telecommunications or internet services. Analogue terrestrial television in the United Kingdom is traditionally the method most people in the UK, Channel Islands and the Isle of Man used to receive 2012 ( MMXII) will be a Leap year starting on Sunday of the Gregorian calendar.

United States

On December 29, 1949, KC2XAK of Bridgeport, Connecticut, became the first UHF television station to operate on a regular daily schedule. Events 1170 - Thomas Becket: Thomas Becket Archbishop of Canterbury is assassinated inside Canterbury Cathedral by followers of King Henry II Year 1949 ( MCMXLIX) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar. KC2XAK was the world's first UHF television station It was simply a rebroadcast / Broadcast translator Transmitter of New York City's The first commercially licensed UHF television station on the air was KPTV/Channel 27 (now VHF Channel 12) in Portland, Oregon, on September 18, 1952. KPTV is the Fox television affiliate serving the Portland Oregon metropolitan area Portland is a city located in the Northwestern United States, near the Confluence of the Willamette and Columbia rivers Events 96 - Nerva is proclaimed Roman Emperor after Domitian is assassinated Year 1952 ( MCMLII) was a Leap year starting on Tuesday (link will display full calendar of the Gregorian calendar. The station even used much of the equipment, including the transmitter, from KC2XAK, which was delivered by high-speed freight train.

Hopes that UHF would allow dozens of television stations in every media market were thwarted by poor image frequency rejection in superheterodyne tuners with 45. A media market, broadcast market, media region, designated market area, DMA or simply market is a region where the Population Image frequency: In Radio reception using Heterodyning in the tuning process an undesired Input Frequency that is capable of producing In Electronics, the superheterodyne receiver (also known by its full name the supersonic heterodyne receiver, or by the abbreviated form superhet) is a 75 MHz intermediate frequency. In communications and Electronic engineering, an intermediate frequency ( IF) is a Frequency to which a carrier frequency is shifted as an This shortcoming led to "UHF taboos," which limited each area to only modestly more UHF than VHF stations, despite the much larger number of channels. See [1]

In the United States, UHF stations (broadcast channels above 13) originally gained a reputation for being locally owned, less polished and professional, not as popular, and having weaker signal propagation than their VHF counterparts (channels 2 through 13). The movie UHF, starring "Weird Al" Yankovic and Michael Richards, parodied the phenomenon. UHF (also known as The Vidiot from UHF in Australia, New Zealand and parts of Europe, Los Telelocos Alfred Matthew "Weird Al" Yankovic (ˈjæŋkəvɪk born October 23 1959 is a Grammy Award winning American singer Musician, actor satirist Michael Anthony Richards (born July 24, 1949) is an American Comedian and Actor best known for his portrayal of the eccentric In the late 1940s/early 1950s, affiliates of the four major US television networks (NBC, CBS, ABC and DuMont) transmitted their programs primarily through VHF. A television network is a distribution network for Television content whereby a central operation provides programming for many Television stations The National Broadcasting Company ( NBC) is an American Television network headquartered in the GE Building in New York City's CBS Broadcasting Inc ( CBS) is an American radio and Television network. The American Broadcasting Company ( ABC) is an American Television network. The DuMont Television Network was the world's first commercial Television network, beginning operation in the United States in 1946 Most UHF stations that operated in major population centers of the USA were unable to obtain network affiliation and thus were independent stations. ABC and DuMont, being smaller and less prosperous networks, did have a number of UHF affiliates, and the later PBS had even more. The Public Broadcasting Service ( PBS) is a Non-profit Public broadcasting Television service with 354 member TV stations in the Conversely, many mid-sized and small television markets within the United States were too close to the outer fringe of the broadcast range of VHF stations from major population centers to qualify for their own VHF licenses from the FCC, because of interference from would-be overlapping broadcast ranges. Instead, the FCC granted many mid- and small-sized cities only UHF licenses (even for the big three networks), because of the vastly greater number of available channels (56 total UHF channels vs. only 12 total VHF).

A minority of UHF TV transmitters have no programming or commercial identity of their own, and merely retransmit the signal of a VHF station that owns it, to a smaller area poorly covered by the VHF signal. Such transmitters are called "translators" rather than “stations”.

The distinction between UHF and VHF characteristics has declined in importance with the emergence of additional broadcast television networks (Fox, The CW, MyNetworkTV, Univision, Telemundo and ION), and the decline of direct OTA reception. The CW Television Network ( The CW) is a Television network in the United States launched at the beginning of the 2006-2007 television season. MyNetworkTV (unofficially abbreviated MyNet or MNT) is a Television network in the United States, owned by the Fox Broadcasting Company Univision is a Spanish-language television network in the United States and Puerto Rico. Telemundo is an American television network based in Hialeah Florida a suburb of Miami Florida. Ion Television is a broadcast television network first broadcast on August 31 1998 Terrestrial television is a term which refers to modes of television broadcasting which do not involve satellite transmission The concentration of media ownership, the proliferation of cable television, digital television and DBS have contributed to the quality equalization of VHF and UHF broadcasts. Concentration of media ownership (also known as media consolidation) is a commonly used term that refers to the majority of the media outlets being owned by a small number of Digital television (DTV is the sending and receiving of moving images and sound by discrete ( digital) signals in contrast to the analog signals used by Direct broadcast satellite (DBS is a term used to refer to Satellite television broadcasts intended for home reception also referred to more broadly as direct-to-home Most HDTV stations broadcast over-the-air signals in the UHF band. High-definition television (HDTV is a Digital television Broadcasting system with higher resolution than traditional television systems (standard-definition

The Family Radio Service and General Mobile Radio Service use the 462 and 467 MHz areas of the UHF spectrum. The Family Radio Service (FRS is an improved Walkie talkie radio system authorized in the United States since 1996 The General Mobile Radio Service (GMRS is a licensed land-mobile FM UHF Radio service in the United States available for short-distance two-way There is a considerable amount of (legal) unlicensed activity (cordless phones, wireless networking) clustered around 900 MHz and 2. 4 GHz.

In February 2009, as part of the transition from analog to digital over-the-air broadcast of television, the spectrum from 698 MHz to 806 MHz (UHF channels 52-69) will no longer be used for TV broadcasting. Digital television (DTV is the sending and receiving of moving images and sound by discrete ( digital) signals in contrast to the analog signals used by The FCC's scheduled auction for this newly-available spectrum was completed in March 2008. The United States 700 MHz FCC wireless Spectrum auction was started by the FCC on January 24, 2008 for the rights to operate the 700 [2]

Frequency allocation

Australia

United Kingdom

United States

A brief summary of some UHF frequency use:

See also

External links

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic