List of North American broadcast station classes

This is a list of broadcast station classes applicable in much of North America under international agreements between the United States, Canada and Mexico. Effective radiated power (ERP) and height above average terrain (HAAT) are listed unless otherwise noted.

All radio and television stations within 320 kilometers (about 200 miles) of the U.S.-Canada or U.S.-Mexico border must get approval by both the domestic and foreign agency. These are Industry Canada/Canadian Radio-television and Telecommunications Commission (CRTC) in Canada, the Federal Communications Commission (FCC) in the U.S., and the Secretaría de Comunicaciones y Transportes (SCT) in Mexico.

AM

* A (former I): clear channels, 10 kW to 50 kW day and night
* B (former II and III): 250 W to 50 kW (to 10 kW on 1620 kHz to 1710 kHz)
** D (former II-D, II-S, III-S): daytime 250 W to 50 kW, nighttime under 250 W or off-air, field strength up to 140 mV/m² at 1 km, no new stations except downgraded B
* C (former IV): 250 W to 1 kW (also grandfathered 100 W)
* TIS/HAR: Travelers' Information Stations up to 10 W transmitter output power
* Unlicensed broadcasting (see low-power broadcasting): 100 mW, no license needed (US only?), may be measured at edge of campus for school stations

Notes
* In the Western Hemisphere (ITU region 2), medium wave AM broadcasts are on channels spaced 10 kHz apart from 530 kHz to 1710 kHz, with certain classes restricted to subsets of the available frequencies.
* Class A stations can be found only on the frequencies of 540 kHz, 640 to 780 kHz, 800 to 900 kHz, 940 kHz, 990 to 1140 kHz, 1160 to 1220 kHz, and 1500 to 1580 kHz.
* While Class A stations can only operate at a maximum of 50,000 watts day and night, from 1934 to 1939, Cincinnati's class A station 700 WLW broadcast at 500,000 watts under an experimental license. The signal was able to cover the entire continent and reach overseas, but was soon shut down due to complaints from competitors and stations in far away cities where the 700 kHz frequency was bleeding into nearby stations on the dial.
* Class B and D stations can be found on any frequencies from 540 kHz to 1700 kHz except where frequencies have been reserved for Class C stations.
* Class C stations can be found in the lower 48 US states on the frequencies of 1230 kHz, 1240 kHz, 1340 kHz, 1400 kHz, 1450 kHz, and 1490 kHz. Other countries may use other frequencies for their Class C stations.
* TIS stations can be found on any frequency from 530 kHz to 1700 kHz in the US, but may only carry non-commercial messages without music.
* Low-power AM stations located on a school campus are allowed to be more powerful, so long as their signal strength does not exceed roughly 14 to 45 µV/m² (depending on frequency) at a distance of 30 meters (98.4 ft) from campus.
* AM classes were previously assigned Roman numerals from I to IV in the US, with subclasses indicated by a letter suffix. Current class A is equivalent to the old class I; class B is the old classes II and III, with class D being the II-D, II-S, and III-S subclasses; and class C is the old class IV.

See also: North American Radio Broadcasting Agreement (NARBA)

FM

* C: 100 kW, 300 m to 600 m, 91.8 km
* C0: 100 kW, 300 m to 450 m, 83.4 km
* C1: up to 100 kW, under 300 m, 72.3 km
* C2: up to 50 kW, up to 150 m, 52.2 km
* C3: up to 25 kW, up to 100 m, 39.1 km
* B: up to 50 kW, up to 150 m, 65.1 km
* B1: up to 25 kW, up to 100 m, 44.7 km
* A: 100 W to 6 kW, up to 100 m, 28.3 km
** AA (Mexico): up to 3 kW, the former limit for A
* D: up to 250 W ERP, except U.S. non-translators to 10 W TPO
** L1 (U.S., also LP100): 50 W to 100 W ERP, up to 30 m, 5.6 km
** L2 (U.S., also LP10): 1W to 10 W ERP, up to 30 m, 3.2 km
* Unlicensed: 250 µV/m² at 3 m in U.S., 100µV/m² at 30 m in Canada

Notes:
* Canada protects all radio stations out to a signal strength of 0.5 mV/m², whereas only commercial B stations in the U.S. are. Commercial B1 in the U.S. is 0.7 mV/m², and all other stations are 1.0 mV/m². Noncommercial-band stations (88.1 to 91.9) are not afforded this protection, and are treated as C3 and C2 even when they are B1 or B. C3 and C2 may also be reported internationally as B1 and B, respectively.
* Class C0 is for former C stations, demoted at request of another station which needs the downgrade to accommodate its own facilities.
* In practice, many stations are above the maximum HAAT for a particular class, and correspondingly must downgrade their power to remain below the reference distance. Conversely, they may "not" increase power if they are "below" maximum HAAT.
* All class D (including L1 and L2 LPFM and translator) stations are secondary in the U.S., and can be bumped or forced off-air completely, even if they are not just a repeater and are the only station a licensee has.
* The United States is divided into separate regions that have different restrictions for FM stations. Zone I (much of the U.S. Northeast and Midwest) and I-A (most of California, plus Puerto Rico) is limited to classes B and B1, while Zone II (everything else) has only the C classes. All areas have the same classes for A and D.
* Power and height restrictions were put in place in 1962. A number of previously-existing stations were grandfathered in, such as KRUZ in Santa Barbara, California and WMC-FM in Memphis, Tennessee.

FM zones

Zone I in the U.S. includes all of Connecticut, the District of Columbia, Delaware, Illinois, Indiana, Massachusetts, Maryland, New Jersey, Ohio, Pennsylvania, Rhode Island, and West Virginia. It also includes the areas south of latitude 43.5°N in Michigan, New Hampshire, New York, and Vermont; as well as coastal Maine, southeastern Wisconsin, and northern and eastern Virginia.

Zone I-A includes California south of 40°N, as well as Puerto Rico and the U.S. Virgin Islands.

TV

Full-Service Stations

Full-Service Stations Suffix: -TV or -DT, -DS for temporary Digital permits ("special temporary authority"):

* VHF low (2-6): 100 kW video, 10 kW audio; 20 kW digital
* VHF high (7-13): 316 kW video, 31.6 kW audio; 63.2 kW digital
* UHF all (14-69): 5 MW video, 500 kW audio; 1MW digital

Notes:
* Power level limitations are not firmly enforced in Canada, and Industry Canada has been known to license stations for power levels much higher than the generally-accepted limits. For example, CFRN-TV in Edmonton, Alberta operates on Channel 3 at over 600 kW but is not subject to international co-ordination due to its location 500km north of the border.
* Digital television stations have the suffix of -DT (though some early on in the adaptation to digital television had the suffix of -HD. This has since been discontinued).

Class A

Class-A stations (U.S.) (suffix: -CA or -DC for Digital Class-A):
* VHF all (2-13): 3 kW video; 300 W digital
* UHF all (14-69): 150 kW video; 15 kW digital

The Class-A Television Station service Category was created in 2000 by the FCC to allocate and protect some low-power affiliates. Class-A stations are still low-power, but are protected from interference and from having to move should a full-service station request that channel. [http://www.fcc.gov/Bureaus/Mass_Media/Orders/2001/fcc01123.txt]

Low-Power TV

LPTV (secondary) (suffix: -LP, -TX, for translators, or -DL / -LD, for low-power digital stations):
* VHF all (2-13): 3 kW video; 300 W digital
* UHF all (14-69): 150 kW video; 15 kW digital
* Experimental
* Unlicensed: not allowed except for medical telemetry, and certain wireless microphones

The LPTV (Low-Power Television) service Category was created in 1982 by the FCC to allocate channels for smaller, local stations, and community channels, such as public access stations. LPTV stations that meet additional requirements such as Children's "E/I" core programming and Emergency Alert System broadcasting capabilities can qualify for a Class A (-CA) license. [http://www.fcc.gov/cgb/consumerfacts/lptv.html]

Broadcast translators, boosters, and other LPTV stations are secondary, unless they have upgraded to class A. Class A is still considered LPTV with respect to stations in Canada and Mexico.

The United States Federal Communications Commission lists the following services on their website for television broadcasting:

See also

* North American call sign - How call signs and classes are used in North America
* ITU prefix - How callsigns and classes are used worldwide
* Low-power broadcasting
* Class A television service

References

External links

* [http://www.fcc.gov/mb/audio/amclasses.html FCC AM classes]
* [http://www.fcc.gov/mb/audio/fmclasses.html FCC FM classes]
* [http://www.fcc.gov/cgb/consumerfacts/lptv.html FCC LPTV Facts]
* [http://www.fcc.gov/mb/video/lptv.html FCC LPTV classes]
* [http://www.fcc.gov/Bureaus/Mass_Media/Orders/2001/fcc01123.txt FCC Class-A TV Information]
* [http://www.apsalin.com/fm-zone-lookup.aspx FCC FM Broadcast Zone Lookup by Coordinate]