Channel 37
Encyclopedia
Channel 37 is an unused television channel
in countries using the M and N broadcast television system standards. Channel 37 occupies a band of UHF frequencies from 608 to 614 MHz
, frequencies that are particularly important to radio astronomy
. In 1963, when there were very few stations in the UHF band, the US 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 over-the-air television station
in Canada or the United States.
Since July 2000, channel 37 may also be used in the U.S. for medical telemetry
equipment on a co-primary basis. This equipment must emit no more than one watt
of effective radiated power
, and is for use in hospitals and other such facilities.
Even this seemingly low power level can be troublesome for radio astronomy, 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 was also removed from the TV bandplan
in the late 1940s, channels 70
to 83
by the 1980s mainly for AMPS
mobile phone
s and, in June 2009, channels 52 to 69 for mobile phone
s, emergency service
s and mobile TV
services such as Qualcomm
's MediaFLO
(channel 55). Certain channels, 14 through 20, are used for land mobile communications in some large metropolitan areas in the U.S.
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.
s with the "555" telephone exchange
prefix
are used.
Channel 37 has been used as a hypothetical example in instruction manuals, where it serves a role analogous to the fictitious example.org
and example.net
Internet domains. The "Channel 37" newsroom also occasionally has made a fictional appearance on sites such as YouTube
and MySpace
.
for these TV channels is different:
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 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 in video players. The UK-named 34-37 channel range is no longer reserved in this manner.
In Japan, 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.
No Allocation and Primary Status could be considered equivalent legal status. Very often the lack of allocation implies an internal regulatory coherence with ITU-R regulations freeing up this band for Astronomy. Assignment and Primary Status could be considered equivalent legal statuses as well.
Television channel
A television channel is a physical or virtual channel over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the broadcast or cable band of 54 to 60 MHz, with carrier frequencies of 55.25 MHz for NTSC analog video and...
in countries using the M and N broadcast television system standards. Channel 37 occupies a band of UHF frequencies from 608 to 614 MHz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
, frequencies that are particularly important to radio astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...
. In 1963, when there were very few stations in the UHF band, the US Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(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 over-the-air television station
Television station
A television station is a business, organisation or other such as an amateur television operator that transmits content over terrestrial television. A television transmission can be by analog television signals or, more recently, by digital television. Broadcast television systems standards are...
in Canada or the United States.
Allocation issues
Reservations non-exclusive- The Canadian Radio-television and Telecommunications Commission (CRTC) also enacted such a ban on channel 37.
- It appears that MexicoMexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
may also observe a similar ban on the use of this TV channel, if only informally. - Most NTSCNTSCNTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
System-M countries have an informal ban on channel 37 as well.
Since July 2000, channel 37 may also be used in the U.S. for medical telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...
equipment on a co-primary basis. This equipment must emit no more than one watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
of effective radiated power
Effective radiated power
In radio telecommunications, effective radiated power or equivalent radiated power is a standardized theoretical measurement of radio frequency energy using the SI unit watts, and is determined by subtracting system losses and adding system gains...
, 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 Part 15 unlicensed broadcastingLow-power broadcastingLow-power broadcasting is electronic broadcasting at very low power and low cost, to a small community area.The terms "low-power broadcasting" and "micropower broadcasting" should not be used interchangeably, because the markets are not the same...
.
Even this seemingly low power level can be troublesome for radio astronomy, which depends on detecting extraordinarily low signal strength
Signal strength
In telecommunications, particularly in radio, signal strength refers to the magnitude of the electric field at a reference point that is a significant distance from the transmitting antenna. It may also be referred to as received signal level or field strength. Typically, it is expressed in...
s. Any use of the same frequencies raises the noise floor
Noise floor
In signal theory, the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system, where the noise is defined as any signal other than the one being monitored....
, thereby decreasing the signal-to-noise ratio
Signal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...
, and making the work more difficult.
Channel 1 was also removed from the TV bandplan
Bandplan
A bandplan or band plan is a plan for using a particular band of radio frequencies, that are a portion of the electromagnetic spectrum . Each bandplan defines the frequency range to be included, how channels are to be defined, and what will be carried on those channels...
in the late 1940s, channels 70
Channel 70
Channel 70 has been removed from television use in 1983, but was formerly used by television stations in North America which broadcast on 806-812 MHz. In the United States, channels 70-83 served primarily as a "translator band" containing repeater transmitters to fill gaps in coverage for existing...
to 83
Channel 83
Channel 83 was removed from television use in 1983. The highest frequency to have been used for NTSC-M terrestrial TV broadcasting, it was formerly used by a handful of television stations in North America which broadcast on 884-890 MHz...
by the 1980s mainly for AMPS
Advanced Mobile Phone System
Advanced Mobile Phone System was an analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1983, Israel in 1986, and Australia in 1987. It was the primary analog mobile phone system in North America through the 1980s and into the 2000s...
mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s and, in June 2009, channels 52 to 69 for mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s, emergency service
Emergency service
Emergency services are organizations which ensure public safety and health by addressing different emergencies. Some agencies exist solely for addressing certain types of emergencies whilst others deal with ad hoc emergencies as part of their normal responsibilities...
s and mobile TV
Mobile TV
Mobile television usually means television watched on a small handheld device. It may be a pay TV service broadcast on mobile phone networks or received free-to-air via terrestrial television stations from either regular broadcast or a special mobile TV transmission format...
services such as Qualcomm
Qualcomm
Qualcomm is an American global telecommunication corporation that designs, manufactures and markets digital wireless telecommunications products and services based on its code division multiple access technology and other technologies. Headquartered in San Diego, CA, USA...
's MediaFLO
MediaFLO
MediaFLO is a technology developed by Qualcomm for transmitting audio, video and data to portable devices such as mobile phones and personal televisions, used for mobile television...
(channel 55). Certain channels, 14 through 20, are used for land mobile communications in some large metropolitan areas in the U.S.
The channels displayed by cable converter box
Cable converter box
A cable converter box or television converter box is an electronic tuning device that transposes/converts any of the available channels from a cable television service to an analog RF signal on a single channel, usually VHF channel 3 or 4. The device allows a television set that is not “cable...
es under these numbers are not on the same frequencies as their over-the-air counterparts; there are also virtual channel
Virtual channel
In telecommunications, a logical channel number , also known as virtual channel, is a channel designation which differs from that of the actual radio channel on which the signal travels....
numbering schemes in use in digital television
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
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.
Fictional usage
Channel 37 is sometimes seen in fiction, the same way telephone numberTelephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
s with the "555" telephone exchange
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
prefix
Telephone prefix
A telephone prefix is the first set of digits of a telephone number; in the North American Numbering Plan countries , it is the first three digits out of a seven-digit phone number...
are used.
Channel 37 has been used as a hypothetical example in instruction manuals, where it serves a role analogous to the fictitious example.org
Example.com
Example.com, example.net, example.org, and example.edu are second-level domain names reserved for documentation purposes and examples of the use of domain names....
and example.net
Example.com
Example.com, example.net, example.org, and example.edu are second-level domain names reserved for documentation purposes and examples of the use of domain names....
Internet domains. The "Channel 37" newsroom also occasionally has made a fictional appearance on sites such as YouTube
YouTube
YouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....
and MySpace
MySpace
Myspace is a social networking service owned by Specific Media LLC and pop star Justin Timberlake. Myspace launched in August 2003 and is headquartered in Beverly Hills, California. In August 2011, Myspace had 33.1 million unique U.S. visitors....
.
In NTSC-M countries
Outside North America, channel 37 is actively used in these countries where NTSC-M is used:- in the Philippines (UNTV Channel 37DWAO-TVUNTV is a UHF television station in the Philippines operated by the Progressive Broadcasting Corporation, the same company that operates the 107.5 Win Radio and 91.5 Big Radio network of FM stations. DWAO is one of very few NTSC-System M stations in the world that broadcast on channel 37...
) - in Trinidad and TobagoTrinidad and TobagoTrinidad and Tobago officially the Republic of Trinidad and Tobago is an archipelagic state in the southern Caribbean, lying just off the coast of northeastern Venezuela and south of Grenada in the Lesser Antilles...
, WIN-TV is broadcast on Channels 37 and 39, using NTSCNTSCNTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as... - In Dominican Republic channel 37 is also used for the CDN news channel
In other countries
In these other countries, the frequency allocationFrequency allocation
Use of radio frequency bands of the electromagnetic spectrum is regulated by governments in most countries, in a Spectrum management process known as frequency allocation or spectrum allocation. Radio propagation does not stop at national boundaries...
for these TV channels is different:
- in the UK (many transmitterTransmitterIn electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
s used by the Five network actually broadcast on channel 37) - in Western Europe, Channel 37 is used fairly widely as a relay transmitter frequency.
- In Malaysia, NTV7 broadcasts in PAL on CCIR Channel 37 (599.25 MHz)
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 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
RF modulator
An RF modulator is a device that takes a baseband input signal and outputs a radio frequency-modulated signal....
s in video players. The UK-named 34-37 channel range is no longer reserved in this manner.
In Japan, 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
TV Asahi
, also known as EX and , is a Japanese television network headquartered in Roppongi, Minato, Tokyo, Japan. The company writes its name in lower-case letters, tv asahi, in its logo and public-image materials. The company also owns All-Nippon News Network....
in some regions.
Global UHF TV allocation table (605–615 MHz)
This Radio Astronomy Allocation is between the following wavelengths:- 605 MHz = 0.49552 m = 49.55 cm
- 615 MHz = 0.48747 m = 48.75 cm
- Assume either a 100 kHz or a 250 kHz guardband with respect to this allocation.
| Ch | DVB Video (MHz) | Audio (MHz) |
|---|---|---|
| 36 | 591.25 | 596.75 |
| 37 | 599.25 | 604.75 |
| 38 | 607.25 | 612.75 |
| 39 | 615.25 | 620.75 |
| 40 | 623.25 | 628.75 |
| Ch | DVB Video (MHz) | Audio (MHz) |
|---|---|---|
| 35 | 583.25 | 589.75 |
| 36 | 591.25 | 597.75 |
| 37 | 599.25 | 605.75 |
| 38 | 607.25 | 613.75 |
| 39 | 615.25 | 621.75 |
| Ch | DVB Video (MHz) | Audio (MHz) |
|---|---|---|
| 24 | 559.25 | 565.75 |
| 25 | 605.25 | 611.75 |
| 26 | 613.25 | 619.75 |
| 27 | 621.25 | 627.75 |
| 28 | 629.25 | 635.75 |
| Ch | DVB Video (MHz) | Audio (MHz) |
|---|---|---|
| 37 | 590.25 | 595.75 |
| 38 | 597.25 | 602.75 |
| 39 | 604.25 | 609.75 |
| 40 | 611.25 | 616.75 |
| 41 | 618.25 | 623.75 |
| 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 |
National Arrangements for Radio Astronomy different from ITU-R
National Arrangements for Radio Astronomy different from ITU-R Radio Regulations- Armenia: no allocation
- 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
- Russian Federation: no allocation
- Spain: no allocation
- Sweden: no allocation
- Turkey: no allocation
- United Kingdom: no reference to No. 5.149
No Allocation and Primary Status could be considered equivalent legal status. Very often the lack of allocation implies an internal regulatory coherence with ITU-R regulations freeing up this band for Astronomy. Assignment and Primary Status could be considered equivalent legal statuses as well.
External links
- FCC database for Channel 37, showing possible usage conflict with Mexico
- W9Wi.com: An article about channel 37 and channels above 69
- craf.eu: Astrophysical importance of the band 608 - 614 MHz
- Spare That Channel, TimeTime (magazine)Time is an American news magazine. A European edition is published from London. Time Europe covers the Middle East, Africa and, since 2003, Latin America. An Asian edition is based in Hong Kong...
, 10 May 1963 - FREQUENCIES ALLOCATED TO RADIO ASTRONOMY USED BY THE DSN