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Band I

From Wikipedia, the free encyclopedia

Band Iis a range ofradio frequencieswithin thevery high frequency(VHF) part of theelectromagnetic 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".[1]Band I ranges from 47 to 68MHzfor the European Broadcasting Area,[2]and from 54 to 88 MHz for the Americas[3]and it is primarily used fortelevision broadcastingin compliance withITU Radio Regulations(article 1.38). With the transition to digital TV, most Band I transmitters have already been switched off.

Television broadcasting usage

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Channel spacings vary from country to country, with spacings of 6, 7 and 8MHzbeing common.

In the UK, Band I was originally used by theBBCformonochrome405-linetelevision;[4]likewise, the French former 455-line (1937-1939) then 441-line (1943-1956) transmitter on theEiffel TowerinParis,and some stations of the French monochrome819-linesystem used Band I. Both 405-line and 819-line systems were discontinued in the mid-1980s. Other European countries used Band I for625-lineanalogue television, first in monochrome and later in colour.

This was being gradually phased out with the introduction ofdigital televisionin theDVB-Tstandard, which is not defined for VHF Band I, though some older receivers and some modulators do support it.

In the United States, use of this band is for analogNTSC(ended June 12, 2009) and digitalATSC(current). Digital television has problems with impulse noise interference, particularly in this band.

Europe

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In European countries that usedSystem Bfor television broadcasting, the band was subdivided into three channels, each being 7 MHz wide:

Channel Frequency range
E2 47-54 MHz
E2A 48.5-55.5 MHz
E3 54-61 MHz
E4 61-68 MHz
C 82.25-87.75 MHz

Italy also used a "outband" "channel C" (video: 82.25 MHz - audio: 87.75 MHz). It was used by the first transmitter brought in service by theRAIinTorinoin the 1950s which was previously used in WW2 by the US to broadcastNTSCTV on channel A6 for military purposes, later donated to Italy, it had its video carrier shifted 1 MHz lower to accommodate theSystem Bstandard. This channel was also widely used by private local stations until the switch over toDVB-T.

Some countries used slightly different frequencies or don't use Band 1 at all for terrestrial broadcast television. The fast growing of digital television as well as the susceptibility of this band to interference duringE skipevents in all European countries was accompanied by the progressive closedown of band I analog transmitters from 2006 to 2020.

Russia and other former members ofOIRT

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In the countries that useSystem Dtelevision broadcast system, the channel allocation in the VHF-I band is as follows:

Channel Frequency range
1 48.5-56.5 MHz
2 58-66 MHz

Russia, Ukraine, Kazakhstan and a few other countries still broadcast analog TV on Band I in 2023.

North America

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The band is subdivided into five channels for television broadcasting, each occupying 6 MHz (System M). Channel 1 is not being used for broadcasting.

Channel Frequency range
1* 44-50 MHz
A2 54-60 MHz
A3 60-66 MHz
A4 66-72 MHz
A5 76-82 MHz
A6 82-88 MHz
A6A 81.5-87.5 MHz

FM radio usage

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The upper end of this band, 87.5 to 88 MHz, is the lower end of theFM radioband. In the United States, theFCCwill occasionally issue a license for 87.9 MHz (though it only does so on rare occurrences and special circumstances;KSFHwas the most recent standalone station to use 87.9); 87.7, which is approximately the same frequency as the audio feed of channel 6, is used by some television licenses to broadcast primarily to radio, such asPulse 87's stations. In Japan and some former Soviet republics frequencies lower than 87 MHz are still used for theFM broadcast band.

In Brazil, with the phasing out of thePAL-Manalog broadcasts,AM radiostations have been migrated to a newFM radioband between the frequencies from former analog TV channels A5 and A6 (76.1Mhz to 87.5Mhz) calledExtended FMor e-FM.[5]

Amateur radio and TV DX

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The6-meter band(50 MHz) and the4-meter band(70 MHz) are used byradio amateurs.Short wave-like propagation is only possible under special circumstances, including frequentE skipevents in the summer season. This leads to strong signals in the 800–2,000 km range allowing thereception of distant TV stations (TV DX).World wide connections are possible but remain a challenge on these frequencies.

See also

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References

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  1. ^"Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961".ero.dk.Retrieved2019-01-09.
  2. ^"FM / TV Regional Frequency Assignment Plans".ITU.Retrieved20 February2017.
  3. ^"Frequency Bands allocated to Terrestrial Broadcasting Services".ITU.Retrieved20 February2017.
  4. ^Paulu, Burton (1981-10-01).Television and Radio in the United Kingdom.U of Minnesota Press. p.91.ISBN9780816609413.Retrieved11 April2012.
  5. ^"ABERT - Associação Brasileira de Emissoras de Rádio e Tv".ABERT - Associação Brasileira de Emissoras de Rádio e Televisão(in Brazilian Portuguese).Retrieved2022-11-12.