View source for Channel 37

'''Channel 37''' is an intentionally unused [[UHF television broadcasting|ultra-high frequency (UHF) television broadcasting]] channel by countries in most of ITU region 2 such as the United States, Canada, Mexico and Brazil. The frequency range allocated to this channel is important for [[radio astronomy]], so all broadcasting is prohibited within a window of frequencies centered typically on {{val|611|ul= MHz}}. Similar reservations exist in portions of the Eurasian and Asian regions, although the channel numbering varies.

==History==
Channel 37 in [[CCIR System M|System M]] and N countries occupied a [[band (radio)|band]] of [[UHF]] frequencies from {{Val|608|to|614|u=MHz}}. This band is particularly important to [[radio astronomy]] because it allows observation in a region of the spectrum in between the dedicated frequency allocations near 410&nbsp;MHz and 1.4&nbsp;GHz. The area reserved or unused differs from nation to nation and region to region (as for example the EU and British Isles have slightly different reserved frequency areas).

One radio astronomy application in this band is for [[very-long-baseline interferometry]].<ref>{{cite web|url=http://sites.nationalacademies.org/xpedio/groups/bpasite/documents/webpage/bpa_048869.pdf |title=Archived copy |access-date=2010-08-12 |url-status=live |archive-url=https://web.archive.org/web/20120310090720/http://sites.nationalacademies.org/xpedio/groups/bpasite/documents/webpage/bpa_048869.pdf |archive-date=2012-03-10 }}</ref>

When UHF channels were being allocated in the United States in 1952, channel 37 was assigned to 18 communities across the country. One of them, [[Valdosta, Georgia]], featured the only [[construction permit]] ever issued for channel 37: WGOV-TV, owned by Eurith Dickenson "Dee" Rivers Jr., son of the [[Eurith D. Rivers|former governor of Georgia]] (hence the call letters). Rivers received the CP on February 26, 1953, but WGOV-TV never made it to the air; on October 28, 1955, they requested an allocation on channel 8, but the petition was denied.<ref>[http://www.uhfhistory.com/articles/channel37.html History of UHF television: Why Is There No Channel 37?]</ref>

In 1963, the [[Federal Communications Commission]] (FCC) adopted a 10-year moratorium on any allocation of stations to Channel 37. A new ban on such stations took effect at the beginning of 1974, and was made permanent by a number of later FCC actions. As a result of this, and similar actions by the [[Canadian Radio-television and Telecommunications Commission]], Channel 37 has never been used by any [[terrestrial television|over-the-air]] [[television station]] in Canada or the United States.

The [[2016 United States wireless spectrum auction#Repacking|2016-2021 repack]] left no North American stations above UHF 36.

The low-power [[WNWT-LD]] in [[New York City|New York]] was given [[virtual channel]] 37 in August 2019, thus becoming the first American station to be so assigned via the digital television [[Program and System Information Protocol|PSIP]] standard. While the channel is displayed as "37.1" or "37-1" on a digital television set, WNWT-LD's physical signal remains on [[VHF]] channel 3, causing no interference.

== Allocation issues ==
Reservations and use outside the US have a non-exclusive legal status
* The [[Canadian Radio-television and Telecommunications Commission]] (CRTC) enacted such a ban on Channel 37, but radio astronomy has no exclusive status on this channel.
* [[Mexico]] observes a similar ban on the use of this TV channel, but the allocation, like Canada's, is not exclusive. 
* [[Guatemala]] has a ban on Channel 37.
* [[The Bahamas]] has a similar ban to Canada's on Channel 37.
* [[Belize]] has an absolute ban on Channel 37.<ref>[https://barc.bz/wp-content/uploads/2015/08/BELIZE_ITU.pdf Belize National Frequency Spectrum Band Allocation Plan; retrieved February 20, 2019.]</ref>
* Most [[NTSC]] System-M countries have an informal ban on Channel 37 as well but give radio astronomy no exclusive use of the channel.

The [[2016 United States wireless spectrum auction#Repacking|2016-2021 repack]] left no US, Canadian, and Mexican OTA TV broadcasters [[Pan-American television frequencies#600 MHz band|above UHF 36]]. Many small-market [[rebroadcaster]]s were taken [[dark (broadcasting)|dark]] by their corporate owners. This left former UHF 38–83 in the hands of cellular telephone and land-mobile operators, with UHF 14-36 as the main OTA TV broadcast band and UHF 37 as a vacant guardband.

Since July 2000, Channel 37 may be used in the US for medical [[telemetry]] equipment on a co-primary basis.{{clarify|date=September 2018}} The equipment must emit no more than one [[watt]] of [[effective radiated power]] and is for use in hospitals and other such facilities.
* The power level permitted by the FCC is many times more than the amount allowed for [[Title 47 CFR Part 15|Part 15]] [[low-power broadcasting|unlicensed broadcasting]].
* In US areas set aside for radio-frequency silence, the equipment is banned by statute and regulation. 
* The seemingly-low power level can be troublesome for radio astronomy equipment, which depends on detecting extraordinarily low [[signal strength]]s. Any use of the same frequencies raises the [[noise floor]], thereby decreasing the [[signal-to-noise ratio]] and making the work more difficult.

[[Channel 1 (NTSC-M)|Channel 1]] was also removed from the TV [[bandplan]] in the late 1940s, [[channel 70|channels 70]] to [[channel 83|83]] (800&nbsp;MHz band) by the 1980s mainly for cellular telephone and trunked two-way land mobile radio systems and, in June 2009, channels 52 to 69 (700&nbsp;MHz band) for [[mobile phone]]s, [[emergency service]]s and [[mobile TV]] services such as [[Qualcomm]]'s now-defunct [[MediaFLO]] (channel 55).  Additional channels from 38 to 51 (600&nbsp;MHz band) were auctioned in early 2017, leaving channel 37 as a [[guard band]] between repacked TV stations and more mobile networks, for which [[T-Mobile US]] won most of the licenses.

Certain channels, 14 through 20, are used for land mobile communications in some large metropolitan areas in the U.S.  However, facilities using this decades-old co-allocation are treated as just another station to avoid interference to in their local area.

The channels displayed by [[cable converter box]]es under these numbers are not on the same frequencies as their over-the-air counterparts; there are also [[virtual channel]] numbering schemes in use in [[digital television]] which do not map directly to fixed frequency channel assignments. As such, a "cable 37" channel may (and most often does) exist, but on a much lower frequency.

== Outside North America ==

===In NTSC-M countries===
Outside North America, channel 37 is actively used in these countries where NTSC-M is used:
* In the [[Philippines]], [[DXMJ-TV|GMA TV-5]] in Davao uses UHF 37 as [[GMA Network]]'s digital channel (ISDB-T) with analog broadcasts on Channel 5.  Channel 37 was also used by [[DWAO-TV|UNTV-37]] in Metro Manila as [[Progressive Broadcasting Corporation]]'s analog channel, with digital broadcasts assigned to Channel 38 (ISDB-T). <!-- [[ABS-CBN_Corporation#2020_order_to_cease_broadcasting|ABS-CBN]] also held UHF 37 spectrum before its OTA TV stations were [[ABS-CBN franchise renewal controversy|knocked off the air]] by the Duterte régime in 2020. UHF 37 was used by [[DYCB-TV|ABS-CBN TV-3]] in Cebu City, Cebu as [[ABS-CBN Corporation|ABS-CBN]]'s digital channel (ISDB-T) with analog broadcasts on Channel 3. It was used by [[DYAF-TV|ABS-CBN TV-10]] in Iloilo City, Iloilo as [[ABS-CBN Corporation|ABS-CBN]]'s digital channel (ISDB-T) with analog broadcasts primarily on Channel 10. These assignments are currently [[dark (broadcasting)|silent]]. -->
* In the [[Dominican Republic]] channel 37 is also used for the ''CDN'' news channel
* In [[South Korea]] [[KBS2|KBS 2TV]]'s analog channel on gwanak-san Transmission station.

===In other countries===
In these other countries, the [[frequency allocation]] for these TV channels is different:
* in the UK (many [[transmitter]]s used by the [[Five (TV channel)|Five]] network actually broadcast in the past on PAL channel 37; as mentioned below, it was previously used as a local device output channel before Five's launch, and the network had to provide service regarding re-tunes of those devices to a new channel at no cost to the viewer).
* in Western Europe, Channel 37 is used fairly widely as a relay transmitter frequency.
* In Malaysia, NTV7 broadcast in PAL on CCIR Channel 37 (599.25&nbsp;MHz) prior to analogue shutdown. Currently the frequency is not in use. 
* In Indonesia, Channel 37 UHF has been used by many analog terrestrial networks depending on its location, such as [[MNCTV]] for the [[Jakarta metropolitan area]], [[TvOne (Indonesian TV network)|tvOne]] for [[Medan]], [[GTV (Indonesian TV network)|GTV]] for [[Semarang]], [[TVRI (TV channel)|TVRI]] for [[Makassar]], and [[Metro TV (Indonesian TV network)|Metro TV]] for [[Denpasar]], while in [[Digital terrestrial television|digital]], the frequency now used as [[multiplexing]] by [[Emtek]] in [[Samarinda]] and [[Media Nusantara Citra|MNC Group]] in [[Mamuju (city)|Mamuju]].

Channel 37 is not the same frequency as it is in the countries using the System-M/N standard. At least in the UK, 606–614&nbsp;MHz is reserved for radio astronomy.

The UK's namesake "Channel 37", while different in frequency, was formerly part of a small group of channels reserved for non-broadcast purposes such as [[RF modulator]]s for output devices such as [[game console]]s and [[videocassette recorder]]s.<ref>[http://www.tinsleyviaduct.com/phil/channel5.html five analogue reception issues] {{webarchive |url=https://web.archive.org/web/20080406124750/http://www.tinsleyviaduct.com/phil/channel5.html |date=April 6, 2008 }}, tinsleyviaduct.com</ref> The UK-named 34-37 channel range is no longer reserved in this manner.

In Japan, [[Television channel frequencies#Japan 2|UHF television channel frequencies]] are offset by one channel compared to North American channel naming convention. Japan's channel 36 is in use by [[TV Asahi]] in some regions.

== Global UHF TV allocation table (605–615 MHz) ==
This Radio Astronomy Allocation is between the following wavelengths:
* 605&nbsp;MHz = 0.49552 m = 49.55&nbsp;cm
* 615&nbsp;MHz = 0.48747 m = 48.75&nbsp;cm
* Assume either a 100&nbsp;kHz or a 250&nbsp;kHz guardband with respect to this allocation.
{{clear}}

{{col-begin}}

{{col-5}}
{| class="wikitable" width="25%" 
|+ [[Western Europe]]
! Ch !! DVB Video (MHz) !! Audio (MHz) 
|-
|align=center| 36 || 594 || 596.75 
|-
|align=center| 37 || 602 || 604.75 
|-
|align=center| 38 || 610 || 612.75 
|-
|align=center| 39 || 618 || 620.75 
|-
|align=center| 40 || 626 || 628.75
|}

{{col-5}}
{| class="wikitable" width="25%" 
|+ [[Eastern Europe]]
! Ch !! DVB Video (MHz) !! Audio (MHz) 
|-
|align=center| 35 || 586 || 589.75 
|-
|align=center| 36 || 594 || 597.75 
|-
|align=center| 37 || 602 || 605.75 
|-
|align=center| 38 || 610 || 613.75 
|-
|align=center| 39 || 618 || 621.75 
|}

{{col-5}}
{| class="wikitable" width="25%" 
|+ [[China]]
! Ch !! DTMB Video (MHz) !! Audio (MHz) 
|-
|align=center| 24 || 562 || 565.75 
|-
|align=center| 25 || 610 || 611.75 
|-
|align=center| 26 || 618 || 619.75 
|-
|align=center| 27 || 626 || 627.75 
|-
|align=center| 28 || 634 || 635.75 
|}

{{col-5}}
{| class="wikitable" width="25%" 
|+ [[Australia]]
! Ch !! DVB Video (MHz) !! Audio (MHz) 
|-
|align=center| 37 || 590.25 || 595.75 
|-
|align=center| 38 || 597.25 || 602.75 
|-
|align=center| 39 || 604.25 || 609.75 
|-
|align=center| 40 || 611.25 || 616.75 
|-
|align=center| 41 || 618.25 || 623.75 
|}

{{col-5}}
{| class="wikitable" width="25%"
|+[[New Zealand]]
! align="right" |Ch
!DVB Video (MHz)!!Audio (MHz)
|-
|-
|36||591.25||596.75
|-
|37||599.25||602.75
|-
|38||607.25||612.75
|-
|39||615.25||620.75
|-
|40||623.25||628.75
|-
|}

{{col-end}}

DVB-T adoption note : The tables above are not accurate for nations that have adopted [[DVB-T]]. The frequencies for audio and video are merged with DVB terrestrial television. The new DVB frequencies are rounded off to an even number in MHz as a general rule.

== National arrangements for radio astronomy different from ITU-R ==

National arrangements for radio astronomy different from ITU-R Radio Regulations

Central & Western Europe 
* Austria: no allocation - only mention of No. 5.149
* Bulgaria: no allocation
* Belgium: assignment to radio astronomy (shared with active services)
* Finland: no allocation
* Estonia: no allocation
* Iceland: no allocation
* Liechtenstein: no allocation
* Luxembourg: no allocation
* Netherlands: primary status
* Portugal: no allocation
* Spain: no allocation
* Sweden: no allocation
* United Kingdom: no reference to No. 5.149

Rest of World
* Armenia: no allocation
* Russian Federation: no allocation
* Turkey: no allocation<ref>Both channel 37 and channel 38, which covers the relevant frequency range in Turkey, are being used by TV stations. {{cite web|url=https://www.turkiye.gov.tr/rvtk-karasal-yayin-frekans-kanal-sorgulama|access-date=1 April 2021| title=Karasal Yayın Frekans / Kanal Sorgulama | language=tr}}</ref>
* New Zealand, Maori TV and others (not allocated to Radio Astronomy at all)

==References==
<references/>

==External links==
North America
* [http://www.fcc.gov/fcc-bin/tvq?chan=37&cha2=37&serv=&type=0&list=1&slon2=&size=9 FCC database for Channel 37], had shown possible usage conflict with Mexico but now has the channel entirely clear in Canada, the U.S.A. & Mexico.
* [https://web.archive.org/web/20160531020618/http://www.cedmagazine.com/article/2012/11/capital-currents-fccs-attack-channel-37 US FCC's attack on Channel 37]
* [http://www.ae5d.com/37/ AE5D.com]: Channel 37 - The last Empty Channel
* [https://web.archive.org/web/20080516084337/http://www.w9wi.com/tvdb/tvdbweir.htm W9WI.com]: An article about channel 37 and channels above 69
* [https://web.archive.org/web/20070707114927/http://www.craf.eu/608m.htm#4 craf.eu]: Astrophysical importance of the band 608 - 614&nbsp;MHz
* [https://web.archive.org/web/20080308041939/http://www.time.com/time/magazine/article/0,9171,830284,00.html Spare That Channel], [[Time (magazine)|''Time'']], 10 May 1963
* [https://web.archive.org/web/20120115165047/http://dsnra.jpl.nasa.gov/freq_man/ra_freqs.html FREQUENCIES ALLOCATED TO RADIO ASTRONOMY USED BY THE DSN ]
* [https://web.archive.org/web/20121030203344/http://www.tvtechnology.com/mcadams-on/0117/mcadams-on-channel-/216031 McAdams On: Channel 37]

Rest of World
* [http://www.rsm.govt.nz/cms/pdf-library/policy-and-planning/digital-futures-planning-for-digital-tv-and-new-uses/Long_Term_Digital_TV_Frequency_Plan.pdf NZ Long Term Digital TV Plan]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}

[[Category:Broadcast engineering]]
[[Category:TV stations by channel number|37]]
[[Category:History of television]]
[[Category:Fictional television stations]]