List of North American broadcast station classes

This diagram illustrates how the AM radio spectrum is classified in North America.

  Clear-channel; classes A, B and D

  Regional; classes B and D

  Local; classes B and C

Station class descriptions

All domestic (United States) AM stations are classified as A, B, C, or D. ^[1]

• A (formerly I) — clear-channel stations — 10 kW to 50 kW, 24 hours.
  • Class A stations are only protected within a 750-mile (1,207-kilometer) radius of the transmitter site.
  • The old Class I was divided into three: Class I-A, I-B and I-N. NARBA distinguished between Class I-A, which were true clear-channel stations that did not share their channel with another Class I station, and Class I-B, in which a station operated with 50 kW at night but shared its channel with at least one other I-B station, requiring directional operation. This distinction was superseded by the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 (Rio Agreement), which instituted the current class system.
  • The former Class I-As are omnidirectional, with the exception of 870 WWL New Orleans and 1030 WBZ Boston, which use directional antennas to put a better signal over their largest population areas.
  • Most former Class I-Bs are directional at night, although a few are also directional during days. (A handful of I-Bs did not have to use directional antennas: 680 KNBR San Francisco, 810 WGY Schenectady, 850 KOA Denver, 940 XEQ Mexico City, 1070 KNX Los Angeles and 1070 CBA Moncton. KNX and CBA were far enough apart that both could operate without using a directional antenna. XEQ is far enough from Montreal that it did not need a directional antenna. KNBR and KOA are the only Class Is on their frequency but share those frequencies with several Class II-Bs.)
  • Former Class I-N stations exist only in Alaska, where they are too remote to interfere with other clear-channel stations in the contiguous 48 states. They are only held to Class B efficiency standards (although higher efficiency is acceptable).
  • No new Class A stations are licensed in the conterminous United States, although the FCC states it may be possible to license additional Class A stations in Alaska.
• B (formerly II and III) — regional stations — 250 W to 50 kW, 24 hours.
  • Stations on the AM expanded band, 1610 kHz to 1700 kHz, are limited to 10 kW days and 1 kW nights, non-directionally.
  • Several expanded band stations operate DA-N or even DA-2 with up to 10 kW during all hours, after providing proof that such operations will not cause co- or adjacent-channel interference.
  • If under 250 W at night, the antenna must be efficient enough to radiate more than 140.82 mV/m at 1 km.
• C (formerly IV) — local unlimited-time stations — 250 W to 1 kW, 24 hours.
  • Class C stations that were licensed at 100 W are grandfathered.
  • Rare Class Cs operate with directional arrays, such as KYPA and KHCB.
• D (formerly II-D, II-S, III-S) — current and former daytimers — Daytime 250 W to 50 kW, nighttime under 250 W or off-air.
  • Field strength is limited to 140 mV/m (millivolts per meter) at 1 km.
  • No new class D stations are licensed, with the exception of Class B stations that are downgrading their nighttime operations to Class D (i.e., less than 250 W). The station's daytime operation is then also reclassified as Class D.
  • If a Class D station is on the air at night, it is not protected from any co-channel interference.
• TIS/HAR — travelers' information stations / highway advisory radio stations — Up to 10 W transmitter output power. Stations within US national parks are licensed by NTIA and not the FCC.
• Unlicensed broadcasting — (see low-power broadcasting) — 100 mW DC input to final amplifier with a 3-meter (10-foot) maximum length radiator, no license needed, 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 1700 kHz, with certain classes restricted to subsets of the available frequencies.
• With few exceptions, 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. The exceptions are cited in relevant international treaties.
• While US and Canadian Class A stations are authorized to operate at a maximum of 50,000 watts day and night (and a minimum of 10,000 watts at night, if grandfathered), certain existing Mexican Class A stations, and certain new Cuban Class A stations are authorized to operate at a higher power. Certain Mexican Class A stations are authorized to operate at less than 50,000 watts at night, if grandfathered, but may operate at up to 100,000 watts during the day.
• 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 (commonly known as "graveyard" frequencies). Other countries may use other frequencies for their Class C stations.
• American territories in ITU region 3 with AM broadcasting stations (Guam and the Northern Mariana Islands) use the 9 kHz spacing customary to the rest of the world. All stations are class B or lower.
• Canada also defines Class CC (Carrier Current, restricted to the premises) and LP. (less than 100 watts)^[2]
• 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. There is a network of TISs on 1710 in New Jersey.
• 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/m (microvolts per meter) (depending on frequency) at a distance of 30 meters (98.4 ft) from campus.

Former system

AM station 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.

The following conversion table compares the old AM station classes with the new AM station classes:

Old Domestic Station Class	New Domestic Station Class
I	A
II	B
III	B
IV	C
II-S	D
III-S	D
II-D (Daytime Only)	D

AM station classes and clear channels listed by frequency

The following chart lists frequencies on the broadcast company band, and which classes broadcast on these frequencies; Class A and Class B, 10,000 watt and higher (full-time) stations in North America which broadcast on clear-channel station frequencies are also shown.

By international agreement, Class A stations must be 10,000 watts and above, with a 50,000 watt maximum for the US and Canada, but no maximum for other governments in the region. Mexico, for example, typically runs 150,000 to 500,000 watts, but some stations are grandfathered at 10,000 to 20,000 watts at night; by treaty, these sub-50,000 watt Mexican stations may operate with a maximum of 100,000 watts during the daytime.^[3]

Because the AM broadcast band developed before technology suitable for directional antennas, there are numerous exceptions, such as the US use of 800 (kHz) and 900 non-directionally in Alaska, limited to 5 kW at night; and 1050 and 1220, directionally, in the continental US, and without time limits; each of these being assigned to specific cities (and each of these being Mexican Class I-A clear channels). In return for these limits on US stations, Mexico accepted limits on 830 and 1030 in Mexico City, non-directionally, restricted to 5 kW at night (both of these being US Class I-A clear channels).

Discover more about AM related topics

Clear-channel station

Clear-channel station

A clear-channel station is an AM radio station in North America that has the highest protection from interference from other stations, particularly concerning nighttime skywave propagation. The system exists to ensure the viability of cross-country or cross-continent radio service enforced through a series of treaties and statutory laws. Known as Class A stations since the 1983 adoption of the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2, they are occasionally still referred to by their former classifications of Class I-A, Class I-B, or Class I-N. The term "clear-channel" is used most often in the context of North America and the Caribbean, where the concept originated.

AM expanded band

AM expanded band

The extended mediumwave broadcast band, commonly known as the AM expanded band, refers to the broadcast station frequency assignments immediately above the earlier upper limits of 1600 kHz in International Telecommunication Union (ITU) Region 2, and 1602 kHz in ITU Regions 1 and 3.

Grandfather clause

Grandfather clause

A grandfather clause, also known as grandfather policy, grandfathering, or grandfathered in, is a provision in which an old rule continues to apply to some existing situations while a new rule will apply to all future cases. Those exempt from the new rule are said to have grandfather rights or acquired rights, or to have been grandfathered in. Frequently, the exemption is limited, as it may extend for a set time, or it may be lost under certain circumstances; for example, a grandfathered power plant might be exempt from new, more restrictive pollution laws, but the exception may be revoked and the new rules would apply if the plant were expanded. Often, such a provision is used as a compromise or out of practicality, to allow new rules to be enacted without upsetting a well-established logistical or political situation. This extends the idea of a rule not being retroactively applied.

KYPA

KYPA

KYPA is a Korean-language radio station in Los Angeles, California. It is owned by Woori Media Group, LLC.

KHCB (AM)

KHCB (AM)

KHCB is a commercial AM radio station owned by Houston Christian Broadcasters, Inc. It is licensed to League City, Texas, and serves Greater Houston. KHCB airs a Spanish-language Christian radio format. The studios and offices are on South Boulevard in Houston.

Field strength

Field strength

In physics, field strength is the magnitude of a vector-valued field. For example, an electromagnetic field results in both electric field strength and magnetic field strength. As an application, in radio frequency telecommunications, the signal strength excites a receiving antenna and thereby induces a voltage at a specific frequency and polarization in order to provide an input signal to a radio receiver. Field strength meters are used for such applications as cellular, broadcasting, wi-fi and a wide variety of other radio-related applications.

National Park Service

National Park Service

The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational properties with various title designations. The U.S. Congress created the agency on August 25, 1916, through the National Park Service Organic Act. It is headquartered in Washington, D.C., within the main headquarters of the Department of the Interior.

National Telecommunications and Information Administration

National Telecommunications and Information Administration

The National Telecommunications and Information Administration (NTIA) is an agency of the United States Department of Commerce that serves as the President's principal adviser on telecommunications policies pertaining to the United States' economic and technological advancement and to regulation of the telecommunications industry.

Low-power broadcasting

Low-power broadcasting

Low-power broadcasting is broadcasting by a broadcast station at a low transmitter power output to a smaller service area than "full power" stations within the same region. It is often distinguished from "micropower broadcasting" and broadcast translators. LPAM, LPFM and LPTV are in various levels of use across the world, varying widely based on the laws and their enforcement.

ITU Region

ITU Region

The International Telecommunication Union (ITU), in its International Radio Regulations, divides the world into three ITU regions for the purposes of managing the global radio spectrum. Each region has its own set of frequency allocations, the main reason for defining the regions.

Medium wave

Medium wave

Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the daytime, reception is usually limited to more local stations, though this is dependent on the signal conditions and quality of radio receiver used. Improved signal propagation at night allows the reception of much longer distance signals. This can cause increased interference because on most channels multiple transmitters operate simultaneously worldwide. In addition, amplitude modulation (AM) is often more prone to interference by various electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on the FM broadcast band but require more energy and longer antennas. Digital modes are possible but have not reached momentum yet.

Guam

Guam

Guam is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. Guam's capital is Hagåtña, and the most populous village is Dededo. It is the westernmost point and territory of the United States, reckoned from the geographic center of the U.S.. In Oceania, Guam is the largest and southernmost of the Mariana Islands and the largest island in Micronesia.

^[4]

Station class description

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Notes:

• Canada protects all radio stations out to a signal strength of 0.5mV/m (54dBu), whereas only commercial B stations in the US are. Commercial B1 in the US is 0.7mV/m (57dBu), and all other stations are 1.0mV/m (60dBu). 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 US, 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 regions that have different restrictions for FM stations. Zone I (much of the US 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 KVYB in Santa Barbara, California and WMC-FM in Memphis, Tennessee.

The following table lists the various classes of FM stations, the reference facilities for each station class, and the protected and city grade contours for each station class:^[6]

Historically, there were local "Class A" frequencies (like AM radio's class C stations) to which only class A stations would be allocated & the other frequencies could not have a class A. According to the 1982 FCC rules & regulations, those frequencies were: 92.1, 92.7, 93.5, 94.3, 95.3, 95.9, 96.7, 97.7, 98.3, 99.3, 100.1, 100.9, 101.7, 102.3, 103.1, 103.9, 104.9, 105.5, 106.3 & 107.1. Stations on those twenty frequencies were limited to having equivalent signals no greater that 3KW at 300 feet (91 meters) above average terrain.

FM zones

FM broadcast zones in the US

The US is divided into three zones for FM broadcasting: I, I-A and II. The zone where a station is located may limit the choices of broadcast class available to a given FM station.

Zone I in the US 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 US Virgin Islands.

Zone II includes the remainder of the continental US, plus Alaska and Hawaii.

In Zones I and I-A, there are no Class C, C0, or C1 stations. However, there are a few Class B stations with grandfathered power limits in excess of 50 KW, such as WETA (licensed for Washington DC in zone I, at a power of 75 kW ERP), WNCI (Columbus, Ohio in zone I, at 175 kW ERP), KPFK (Los Angeles in zone I-A, at 110 KW ERP), and the most extreme example being WBCT (Grand Rapids, Michigan, in zone I, at 320  kW ERP).

Discover more about FM related topics

Transmitter power output

Transmitter power output

In radio transmission, transmitter power output (TPO) is the actual amount of power of radio frequency (RF) energy that a transmitter produces at its output.

California

California

California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2 million residents across a total area of approximately 163,696 square miles (423,970 km2), it is the most populous U.S. state and the third-largest by area. It is also the most populated subnational entity in North America and the 34th most populous in the world. The Greater Los Angeles and San Francisco Bay areas are the nation's second and fifth most populous urban regions respectively, with the former having more than 18.7 million residents and the latter having over 9.6 million. Sacramento is the state's capital, while Los Angeles is the most populous city in the state and the second most populous city in the country. San Francisco is the second most densely populated major city in the country. Los Angeles County is the country's most populous, while San Bernardino County is the largest county by area in the country. California borders Oregon to the north, Nevada and Arizona to the east, the Mexican state of Baja California to the south; and it has a coastline along the Pacific Ocean to the west.

Puerto Rico

Puerto Rico

Puerto Rico, officially the Commonwealth of Puerto Rico, is a Caribbean island and unincorporated territory of the United States with official Commonwealth status. It is located in the northeast Caribbean Sea, approximately 1,000 miles (1,600 km) southeast of Miami, Florida, between the Dominican Republic and the U.S. Virgin Islands, and includes the eponymous main island and several smaller islands, such as Mona, Culebra, and Vieques. It has roughly 3.2 million residents, and its capital and most populous city is San Juan. Spanish and English are the official languages of the executive branch of government, though Spanish predominates.

Grandfather clause

Grandfather clause

A grandfather clause, also known as grandfather policy, grandfathering, or grandfathered in, is a provision in which an old rule continues to apply to some existing situations while a new rule will apply to all future cases. Those exempt from the new rule are said to have grandfather rights or acquired rights, or to have been grandfathered in. Frequently, the exemption is limited, as it may extend for a set time, or it may be lost under certain circumstances; for example, a grandfathered power plant might be exempt from new, more restrictive pollution laws, but the exception may be revoked and the new rules would apply if the plant were expanded. Often, such a provision is used as a compromise or out of practicality, to allow new rules to be enacted without upsetting a well-established logistical or political situation. This extends the idea of a rule not being retroactively applied.

KRUZ (FM)

KRUZ (FM)

KRUZ is a commercial radio station that is licensed to Santa Barbara, California and broadcasts a classic hits radio format throughout Santa Barbara, Ventura, and San Luis Obispo counties. The station is owned by Cumulus Media and has its studios in Ventura.

Santa Barbara, California

Santa Barbara, California

Santa Barbara is a coastal city in Santa Barbara County, California, of which it is also the county seat. Situated on a south-facing section of coastline, the longest such section on the West Coast of the United States, the city lies between the steeply rising Santa Ynez Mountains and the Pacific Ocean. Santa Barbara's climate is often described as Mediterranean, and the city has been dubbed "The American Riviera". According to the 2020 U.S. Census, the city's population was 88,665.

Memphis, Tennessee

Memphis, Tennessee

Memphis is a city in the U.S. state of Tennessee. It is the seat of Shelby County in the southwest part of the state; it is situated along the Mississippi River. With a population of 633,104 at the 2020 U.S. census, Memphis is the second-most populous city in Tennessee, after Nashville.

Effective radiated power

Effective radiated power

Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power in watts that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity as the actual source antenna at a distant receiver located in the direction of the antenna's strongest beam. ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. It is equal to the input power to the antenna multiplied by the gain of the antenna. It is used in electronics and telecommunications, particularly in broadcasting to quantify the apparent power of a broadcasting station experienced by listeners in its reception area.

Height above average terrain

Height above average terrain

Height above average terrain (HAAT), or effective height above average terrain (EHAAT), is the vertical position of an antenna site is above the surrounding landscape. HAAT is used extensively in FM radio and television, as it is more important than effective radiated power (ERP) in determining the range of broadcasts. For international coordination, it is officially measured in meters, even by the Federal Communications Commission in the United States, as Canada and Mexico have extensive border zones where stations can be received on either side of the international boundaries. Stations that want to increase above a certain HAAT must reduce their power accordingly, based on the maximum distance their station class is allowed to cover.

Connecticut

Connecticut

Connecticut is the southernmost state in the New England region of the Northeastern United States. As of the 2020 United States census, Connecticut was home to over 3.6 million residents, its highest decennial count count ever, growing every decade since 1790. The state is bordered by Rhode Island to its east, Massachusetts to its north, New York to its west, and Long Island Sound to its south. Its capital is Hartford, and its most populous city is Bridgeport. Historically, the state is part of New England as well as the tri-state area with New York and New Jersey. The state is named for the Connecticut River which approximately bisects the state. The word "Connecticut" is derived from various anglicized spellings of "Quinnetuket”, a Mohegan-Pequot word for "long tidal river".

Delaware

Delaware

Delaware is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent Delaware Bay, in turn named after Thomas West, 3rd Baron De La Warr, an English nobleman and Virginia's first colonial governor.

Illinois

Illinois

Illinois is a state in the Midwestern United States. It shares borders with Wisconsin to its north, Iowa to its northwest, Missouri to its southwest, Kentucky to its south, and Indiana to its east. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other metropolitan areas include Peoria and Rockford, as well as Springfield, its capital. Of the fifty U.S. states, Illinois has the fifth-largest gross domestic product (GDP), the sixth-largest population, and the 25th-largest land area.

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Full-power stations in the US

• VHF low (2-6): 100 kW video analog at 1,000 feet (305 meters) in Zone I and 2,000 feet (610 meters) in Zone II and Zone III above average terrain; 10 kW in Zone I and 45 kW in Zone II and Zone III digital at 1,000 feet (305 meters) above average terrain
• VHF high (7-13): 316 kW video analog at 1,000 feet (305 meters) in Zone I and 2,000 feet (610 meters) in Zone II and Zone III above average terrain; 30 kW in Zone I and 160 kW in Zone II and Zone III digital at 1,000 feet (305 meters) above average terrain
• UHF (14-36): 5 MW (5,000 kW) video analog at 2,000 feet (610 meters) above average terrain; 1 MW (1,000 kW) digital at 2,000 feet (610 meters) above average terrain

Notes:

All full-power analog television station transmissions in the US were terminated at midnight Eastern Daylight Time on June 12, 2009.^[7][8] Many broadcasters replaced their analog signal with their digital ATSC signal on the same transmission channel at that time.

• All US digital stations received a -DT suffix during the analog-to-digital transition. At analog shutdown, the FCC assigned to each digital station the call sign its associated analog station had used. (with a -TV suffix if the analog station had this suffix, without the -TV suffix if the analog station didn't have it). Stations could optionally choose to keep the -DT suffix.^[9] Most stations did not keep the -DT suffix.^[10]
• For US analog stations, the -TV suffix was required if there was a radio station with the same three- or four-letter callsign. Stations not required to use the -TV suffix may optionally request it if desired.
• Analog audio power was limited to 22% of video.^[11]

Full-power stations in Canada

• Class A: UHF, 10 kW video/100 m (328 ft) EHAAT
• Class B: UHF, 100 kW video/150 m (492 ft) EHAAT
• Class C: UHF, 1 MW (1,000 kW) video/300 m (984 ft) EHAAT (?)
• Class D: UHF, more than 1 MW (1,000 kW)/300 m (984 ft) EHAAT
• Class R: VHF, 100 kW low-band (channels 2–6), 325 kW high-band. (channels 7-13)
• Class S: VHF, more than 100 kW low-band/325 kW high-band.

Notes:

• Official definitions of these classes are difficult to locate. The values above are inferred from the Industry Canada database. There is some ambiguity about the difference between Classes C and D.
• 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 operated on Channel 3 at over 600 kW but was not subject to international co-ordination due to its location 500 km (311 mi) north of the border.
• In Canada, the callsigns of all private TV stations have the -TV suffix. Most CBC Television and Ici Radio-Canada Télé TV callsigns end in the letter T and have no suffix. A few Radio-Canada stations, purchased by the CBC from private owners, retain the old -TV callsigns.
• Canadian digital stations all receive the -DT suffix. (this includes CBC and Radio-Canada stations) The Industry Canada database shows -PT suffixes for the channel allotments for permanent post-transition digital operation but when licences are issued for these permanent digital stations, -DT callsigns are used.

Low-power TV (US)

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LPTV (secondary) (suffix: -LP, or a sequential-numbered callsign in format W##XX with no suffix for analog or with -D suffix for digital, or -LD for low-power digital stations):

• VHF: 3 kW analog video; 3 kW digital
• UHF: 150 kW analog video; 15 kW digital
• Experimental
• Unlicensed: not allowed except for medical telemetry, and certain wireless microphones

The LPTV (low-power television) service 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.^[12]

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

Class A television (US)

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Class-A stations (US) (suffix: -CA or -CD for digital class A):

• VHF: 3 kW analog video; 3 kW digital
• UHF: 150 kW analog video; 15 kW digital

The class-A television class is a variant of LPTV 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 RF interference and from having to change channel should a full-service station request that channel.^[13]

Additionally, class-A stations, LPTV stations, and translators are the only stations currently authorized to broadcast both analog and digital signals, unlike full-power stations which must broadcast a digital signal only.

Low-power TV (Canada)

In Canada, there is no formal transmission power below which, a television transmitter is considered broadcasting at low power. Industry Canada considers that a low power digital television undertaking "shall not normally extend a distance of 20 km in any direction from the antenna site," based on the determined noise-limited bounding contour.^[14]

Mexico

All digital television stations in Mexico have -TDT callsign suffixes. Analog stations, which existed until December 31, 2016, had -TV callsign suffixes.

The equivalent of low power or translator service in Mexico is the equipo complementario de zona de sombra, which is intended only to fill in gaps between a station's expected and actual service area caused by terrain; a station of this type shares the callsign of another station. In analog, these services often were broadcast on the same or adjacent channels to their parent station, except in certain areas with tight packing of television stations (such as central Mexico). In digital, these services usually operate on the same RF channel as their parent station, except for those with conflicting full-power applications (XHBS-TDT Cd. Obregón, Son., channel 30 instead of 25), in certain other cases where it is technically not feasible (XHAW-TDT Guadalupe, NL, channel 26 instead of 25) or to make way for eventual repacking on upper UHF (XHPNW-TDT has four shadows on 33, its post-repacking channel, instead of 39).

Equipos complementarios can relay their parent station, or a station that carries 75% or more of the same programming as its parent station.^[15]

Stations of either type may have unusually low or high effective radiated powers. XHSMI-TDT in Oaxaca is licensed for two watts in digital. The highest-powered shadows are XEQ-TDT Toluca and XHBS-TDT Ciudad Obregón, both at 200 kW.

FCC service table

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

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Alberta

Alberta

Alberta is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Territories (NWT) to the north, and the U.S. state of Montana to the south. It is one of the only two landlocked provinces in Canada. The eastern part of the province is occupied by the Great Plains, while the western part borders the Rocky Mountains. The province has a predominantly continental climate but experiences quick temperature changes due to air aridity. Seasonal temperature swings are less pronounced in western Alberta due to occasional Chinook winds.

CBC Television

CBC Television

CBC Television is a Canadian English-language broadcast television network owned by the Canadian Broadcasting Corporation, the national public broadcaster. The network began operations on September 6, 1952. Its French-language counterpart is Ici Radio-Canada Télé.

Ici Radio-Canada Télé

Ici Radio-Canada Télé

Ici Radio-Canada Télé is a Canadian French-language free-to-air television network owned by the Canadian Broadcasting Corporation, the national public broadcaster. It is the French-language counterpart of CBC Television, the broadcaster's English-language television network.

Telemetry

Telemetry

Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots tele, 'remote', and metron, 'measure'. Systems that need external instructions and data to operate require the counterpart of telemetry: telecommand.

Wireless microphone

Wireless microphone

A wireless microphone, or cordless microphone, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Also known as a radio microphone, it has a small, battery-powered radio transmitter in the microphone body, which transmits the audio signal from the microphone by radio waves to a nearby receiver unit, which recovers the audio. The other audio equipment is connected to the receiver unit by cable. In one type the transmitter is contained within the handheld microphone body. In another type the transmitter is contained within a separate unit called a "bodypack", usually clipped to the user's belt or concealed under their clothes. The bodypack is connected by wire to a "lavalier microphone" or "lav", a headset or earset microphone, or another wired microphone. Most bodypack designs also support a wired instrument connection. Wireless microphones are widely used in the entertainment industry, television broadcasting, and public speaking to allow public speakers, interviewers, performers, and entertainers to move about freely while using a microphone without requiring a cable attached to the microphone.

Public-access television

Public-access television

Public-access television is traditionally a form of non-commercial mass media where the general public can create content television programming which is narrowcast through cable television specialty channels. Public-access television was created in the United States between 1969 and 1971 by the Federal Communications Commission (FCC), under Chairman Dean Burch, based on pioneering work and advocacy of George Stoney, Red Burns, and Sidney Dean.

Emergency Alert System

Emergency Alert System

The Emergency Alert System (EAS) is a national warning system in the United States designed to allow authorized officials to broadcast emergency alerts and warning messages to the public via cable, satellite, or broadcast television, and both AM/FM and satellite radio.

Class A television service

Class A television service

The class A television service is a system for regulating some low-power television (LPTV) stations in the United States. Class A stations are denoted by the broadcast callsign suffix "-CA" (analog) or "-CD" (digital), although very many analog -CA stations have a digital companion channel that was assigned the -LD suffix used by regular (non-class-A) digital LPTV stations.