View source for Band I

{{short description|Radio wave frequency range}}
{{refimprove|date=April 2012}}
'''Band I''' is a range of [[radio frequency|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".<ref>{{Cite web|url=http://www.ero.dk/46D34362-434B-45DF-A7C1-64A3F85F4FFD?frames=no&|title=Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961|website=www.ero.dk|access-date=2019-01-09}}</ref> Band I ranges from 47 to 68 [[MHz]] for the European Broadcasting Area,<ref name="freqplans">{{cite web|title=FM / TV Regional Frequency Assignment Plans|url=http://www.itu.int/en/ITU-R/terrestrial/broadcast/Pages/FMTV.aspx|access-date=20 February 2017|publisher=ITU}}</ref> and from 54 to 88 MHz for the Americas<ref name="freqbands">{{cite web|title=Frequency Bands allocated to Terrestrial Broadcasting Services|url=http://www.itu.int/en/ITU-R/terrestrial/broadcast/Pages/Bands.aspx|access-date=20 February 2017|publisher=ITU}}</ref> and it is primarily used for [[television broadcasting]] in compliance with [[ITU Radio Regulations]] (article 1.38). With the transition to digital TV, most Band I transmitters have already been switched off.
==Television broadcasting usage==
Channel spacings vary from country to country, with spacings of 6, 7 and 8 [[MHz]] being common.
In the UK, Band I was originally used by the [[BBC]] for [[monochrome]] [[405-line television system|405-line]] [[television]];<ref name="Paulu1981">{{cite book|last=Paulu|first=Burton|title=Television and Radio in the United Kingdom|url=https://archive.org/details/televisionradioi0000paul|url-access=registration|access-date=11 April 2012|date=1981-10-01|publisher=U of Minnesota Press|isbn=9780816609413|page=[https://archive.org/details/televisionradioi0000paul/page/91 91]}}</ref> likewise, the French former 455-line (1937-1939) then 441-line (1943-1956) transmitter on the [[Eiffel Tower]] in [[Paris]], and some stations of the French monochrome [[Analog high-definition television system#French 819-line system|819-line]] system used Band I. Both 405-line and 819-line systems were discontinued in the mid-1980s.  Other European countries used Band I for [[576i|625-line]] analogue television, first in monochrome and later in colour.
This was being gradually phased out with the introduction of [[digital television]] in the [[DVB-T]] standard, 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 analog [[NTSC]] (ended June 12, 2009 for high power stations) and digital [[ATSC standards|ATSC]] (current).  Digital television has problems with impulse noise interference, particularly in this band.
===Europe===
In European countries that used [[CCIR System B|System B]] for television broadcasting, the band was subdivided into three channels, each being 7&nbsp;MHz wide:
{| class="wikitable"
|-
! Channel
! Frequency range
|-
|E2||47-54&nbsp;MHz
|-
|E2A||48.5-55.5&nbsp;MHz
|-
|E3||54-61&nbsp;MHz
|-
|E4||61-68&nbsp;MHz
|-
|C||82.25-87.75&nbsp;MHz
|}
Italy also used a "outband" "channel C" (video : 82.25&nbsp;MHz - audio : 87.75&nbsp;MHz). It was used by the first transmitter brought in service by the [[RAI]] in [[Torino]] in the 1950s which was previously used in WW2 by the US to broadcast [[NTSC]] TV on channel A6 for military purposes, later donated to Italy, it had its video carrier shifted 1 MHz lower to accommodate the [[CCIR System B|System B]] standard. This channel was also widely used by private local stations until the switch over to [[DVB-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 during [[Sporadic E propagation|E skip]] events in all European countries was accompanied by the progressive closedown of band I analog transmitters from 2006 to 2020.
=== Russia and other former members of [[International Radio and Television Organisation|OIRT]] ===
In the countries that use [[CCIR System D|System D]] television broadcast system, the channel allocation in the VHF-I band is as follows:
{| class="wikitable"
|-
! Channel
! Frequency range
|-
|1||48.5-56.5&nbsp;MHz
|-
|2||58-66&nbsp;MHz
|}
Russia, Ukraine, Kazakhstan and a few other countries still broadcast analog TV on Band I in 2023.
===North America===
The band is subdivided into five channels for television broadcasting, each occupying 6&nbsp;MHz ([[CCIR System M|System M]]). Channel 1 is not being used for broadcasting.
{| class="wikitable"
|-
! Channel
! Frequency range
|-
|[[Channel 1 (NTSC-M)|1]]*||44-50&nbsp;MHz
|-
||| <!-- indicates break in bandplan -->
|-
|A2||54-60&nbsp;MHz
|-
|A3||60-66&nbsp;MHz
|-
|A4||66-72&nbsp;MHz
|-
||| <!-- indicates break in bandplan -->
|-
|A5||76-82&nbsp;MHz
|-
|A6||82-88&nbsp;MHz
|}
==FM radio usage==
The upper end of this band, 87.5 to 88&nbsp;MHz, is the lower end of the [[FM radio]] band. In the United States, the [[Federal Communications Commission|FCC]] will occasionally issue a license for 87.9&nbsp;MHz (though it only does so on rare occurrences and special circumstances; [[KSFH]] was 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 as [[Pulse 87]]'s stations.
In Japan and some former Soviet republics frequencies lower than 87&nbsp;MHz are still used for the [[FM broadcast band]].
In Brazil, with the phasing out of the [[PAL-M]] analog broadcasts, [[Am radio|AM radio]] stations have been migrated to a new [[FM radio]] band between the frequencies from former analog TV channels A5 and A6 (76.1Mhz to 87.5Mhz) called [[FM extended band in Brazil|Extended FM]] or e-FM.<ref>{{Cite web |title=ABERT - Associação Brasileira de Emissoras de Rádio e Tv |url=https://www.abert.org.br/web/migracao-am.html |access-date=2022-11-12 |website=ABERT - Associação Brasileira de Emissoras de Rádio e Televisão |language=pt-br}}</ref>
==Amateur radio and TV DX==
The [[6-meter band]] (50 MHz) and the [[4-meter band]] (70 MHz) are used by [[Amateur radio|radio amateurs]]. [[Short wave]]-like propagation is only possible under special circumstances, including frequent [[Sporadic E propagation|E skip]] events in the summer season. This leads to strong signals in the 800&ndash;2,000 km range allowing the [[TV DX|reception of distant TV stations (TV DX)]]. World wide connections are possible but remain a challenge on these frequencies.
==See also==
*[[Television channel frequencies]]
==References==
{{reflist}}
{{TVRband}}
{{Audio broadcasting}}
[[Category:Broadcast engineering]]
[[Category:Radio spectrum]]