List of North American broadcast station classes

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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 agencies are Industry Canada/Canadian Radio-television and Telecommunications Commission (CRTC) in Canada, the Federal Communications Commission (FCC) in the U.S., and the Federal Telecommunications Institute (IFT) in Mexico.

AM[edit]

Station Class Descriptions[edit]

  • A (formerly I) — clear-channel stations — 10 kW to 50 kW day and night (Class I-N stations are only assigned to the non-conterminous United States, and then with a minimum power of 10 kW (and a maximum power of 50 kW) and Class B efficiency (although higher efficiency is acceptable). Class A stations are only protected within 750 miles radius of the transmitter site. Most former Class I-As are omni-directional, though some do operate (or have operated) directional arrays; additionally, most former Class I-Bs are directional at night, although a few are also directional during days, and a very few operate omni-directionally during all hours (these last cases being former Class I-As which were subsequently reduced to Class I-Bs but retained their Class I-A facilities).
  • B (formerly II and III) — 250 W to 50 kW (to 10 kW/daytime/1kW night on 1610 kHz to 1700 kHz)
  • D (formerly 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/m (millivolts per meter) at 1 km, no new stations except downgraded B. A Class D station is not protected from any co-channel interference at nighttime (if it has any night power authorized).
  • C (formerly IV) — Usually 1 kW 24 hours (also grandfathered 100 W). Rare Class Cs operate with directional arrays, such as KYPA and KHCB-AM.
  • TIS/HARtravelers' information stations / highway advisory radio stations — Up to 10 W transmitter output power (TISs at Dallas Fort Worth airport are authorized to 50 watts transmitter power). Stations within U.S. national parks are licensed by NTIA and not the FCC.
  • Unlicensed broadcasting — (see low-power broadcasting) — 100 mW DC input to final amplifier, 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 U.S. 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.
  • Canada also defines Class CC (Carrier Current, restricted to the premises) and LP. (less than 100 watts)[1]
  • 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/m (microvolts per meter) (depending on frequency) at a distance of 30 meters (98.4 ft) from campus.

Former system[edit]

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[edit]

The following chart is a list of frequencies on the AM band and which classes broadcast on these frequencies; Class A and Class B, 10,000 watt and higher (fulltime) 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 U.S. and Canada, but no maximum for other signatories to the relevant treaties. Mexico, for example, typically runs 150,000 to 500,000 watts, but some are grandfathered at 10,000 to 20,000 watts at night and by treaty, these sub-50,000 watt Mexican stations may operate with a maximum of 100,000 watts days.[2]

Because the AM broadcast band "emerged" before there existed technology suitable for operating directionally, there are numerous apparent anomalies, such as the U.S. use of 800 and 900, non-directionally, in Alaska, and limited to 5 kW at night, and 1050 and 1220, directionally, in the "lower 48", and without limit, each of these being assigned to specific cities (and each of these being Mexican Class I-A clear channels), in return for which Mexico received use of 830 and 1030 in Mexico City, non-directionally, and limited to 5 kW at night (and both of these being U.S. Class I-A clear channels).

See also: North American Radio Broadcasting Agreement (NARBA).
Channel
Type
Frequency
(kHz)
Available
Classes
Assignment
Old class designation in ()
530 In the USA, reserved for low power
AM Travelers' Information Stations
Clear 540 A,B,D CBK Watrous, Saskatchewan: Class A (I-A)
CBT Grand Falls-Windsor, Newfoundland and Labrador: Class A (I-B)
XEWA San Luis Potosí, San Luis Potosí: Class A (I-A)
WFLF Pine Hills, Florida: Class B (II-B)
Regional 550 (A),B,D CMBV Wajay, Cuba: Class A ("Rio" grant: 500 kW all hours; special grant of a Cuban Class A on a regional channel)
Regional 560 B,D
Regional 570 (A),B,D CMEA Santa Clara, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a regional channel)
Regional 580 (A),B,D CMAA Pinar del Rio, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a regional channel
KMJ Fresno, California Class B (III-A) (50 kW all hours; directional all hours)
Regional 590 (A),B,D CMCA San Antonio Vegas, Cuba: Class A ("Rio" grant: 150 kW all hours; special grant of a Cuban Class A on a regional channel)
Regional 600 (A),B,D CMKA San German, Cuba: Class A ("Rio" grant: 150 kW all hours; special grant of a Cuban Class A on a regional channel)
Regional 610 B,D
Regional 620 (A),B,D CMDA Colon, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a regional channel)
Regional 630 (A),B,D CMHA Camaguey, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a regional channel)
Clear 640 A,B,D KFI Los Angeles, California: Class A (I-A)
KYUK Bethel, Alaska: Class A (I-N)
CBN St. John's, Newfoundland and Labrador: Class A (I-B) (NARBA grant: 10 kW non-directional all hours)
Clear 650 A,B,D WSM Nashville, Tennessee: Class A (I-A)
KENI Anchorage, Alaska: Class A (I-N)
Clear 660 A,B,D WFAN New York City: Class A (I-A)
KFAR Fairbanks, Alaska: Class A (I-N)
KTNN Window Rock, Arizona: Class B (II-B)
CMDC Colon, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a U.S. clear channel)
Clear 670 A,B,D WSCR Chicago, Illinois: Class A (I-A)
KDLG Dillingham, Alaska: Class A (I-N)
KBOI Boise, Idaho: Class B (II-A)
CMBC Arroyo Arena, Cuba: Class A ("Rio" grant: 50 kW all hours; special grant of a Cuban Class A on a U.S. clear channel)
Clear 680 A,B,D KNBR San Francisco, California: Class A (I-B) ND-U
KBRW Barrow, Alaska: Class A (I-N)
WRKO Boston, Massachusetts: Class B (II-B)
WCBM Baltimore, Maryland: Class B (II-B)
WPTF Raleigh, North Carolina: Class B (II-B)
Clear 690 A,B,D CKGM Montreal, Quebec: Class A (I-A)
XEWW Tijuana, Baja California: Class A (I-B) (NARBA grant: 50 kW, directional all hours; currently 77kW days, 50 kW nights, directional all hours)
WOKV Jacksonville, Florida: Class B (II-B)
CMEC Santa Clara, Cuba: Class A ("Rio" grant: 50 kW all hours; special grant of a Cuban Class A on a Canadian clear channel)
Clear 700 A,B,D WLW Cincinnati, Ohio: Class A (I-A)
KBYR Anchorage, Alaska: Class A (I-N)
Clear 710 A,B,D WOR New York City: Class A (I-B)
KIRO Seattle, Washington: Class A (I-B)
KSPN Los Angeles, California: Class B (II-B)
WAQI Miami, Florida: Class B (II-B)
Clear 720 A,B,D WGN Chicago, Illinois: Class A (I-A)
KOTZ Kotzebue, Alaska: Class A (I-N)
KDWN Las Vegas, Nevada: Class B (II-A)
Clear 730 A,B,D CKAC Montreal, Quebec: Class A (II-B) ("Rio" grant: promotion to Class A)
XEX Mexico City: Class A (I-A)
CMHC Camaguey, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a Mexican clear channel)
Clear 740 A,B,D CFZM Toronto, Ontario: Class A (I-A)
KCBS San Francisco, California: Class B (II-B) (Formerly KQW San Jose, California)
WYGM Orlando, Florida: Class B (II-B)
KRMG Tulsa, Oklahoma: Class B (II-B)
KTRH Houston, Texas: Class B (II-B)
CMAC Pinar del Rio, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a Canadian clear channel)
Clear 750 A,B,D WSB Atlanta, Georgia: Class A (I-A)
KFQD Anchorage, Alaska: Class A (I-N)
CBGY Bonavista, Newfoundland and Labrador: Class A (I-B) (New station; Grandfathered at 10 kW)
KMMJ Grand Island, Nebraska: Class B (II-B)
KXTG Portland, Oregon: Class B (II-B)
Clear 760 A,B,D WJR Detroit, Michigan: Class A (I-A)
KFMB San Diego, California: Class B (II-B)
CMKC Cacocun, Cuba: Class A ("Rio" grant: 75 kW all hours; special grant of a Cuban Class A on a U.S. clear channel)
Clear 770 A,B,D WABC New York City: Class A (I-A)
KKOB Albuquerque, New Mexico: Class B (II-A)
KCHU Valdez, Alaska: Class A (I-N)
KTTH Seattle, Washington: Class B (II-B)
Clear 780 A,B,D WBBM Chicago, Illinois: Class A (I-A)
KNOM Nome, Alaska: Class A (I-N)
KKOH Reno, Nevada: Class B (II-A)
Regional 790 (A),B,D CMAC Guanabacoba, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a regional channel)
Clear 800 A,B,D XEROK Ciudad Juárez, Chihuahua: Class A (I-A)
CKLW Windsor, Ontario: Class B (II-B)
CMEB Santa Clara, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a Mexican clear channel)
Clear 810 A,B,D KGO San Francisco, California: Class A (I-B)
WGY Schenectady, New York: Class A (I-B) ND-U, but KGO was the originally assigned dominant station
WHB Kansas City, Missouri: Class B (II-B)
WKVM San Juan, Puerto Rico: Class B (II-B)
Clear 820 A,B,D WBAP Fort Worth, Texas: Class A (I-A)
KCBF Fairbanks, Alaska: Class A (I-N)
Clear 830 A,B,D WCCO Minneapolis, Minnesota: Class A (I-A)
KLAA Orange, California: Class B (II-B)
XELA Mexico City, Mexico: Class B (II-B) (NARBA grant: 5 kW all hours; present operation 10 kW days, 5 kW nights)
Clear 840 A,B,D WHAS Louisville, Kentucky: Class A (I-A)
KXNT North Las Vegas, Nevada: Class B (II-B)
Clear 850 A,B,D KOA Denver, Colorado: Class A (I-B) ND-U
KICY Nome, Alaska: Class A (I-N)
WEEI Boston, Massachusetts: Class B (II-B)
WTAR Norfolk, Virginia: Class B (II-B)
Clear 860 A,B,D CJBC Toronto, Ontario: Class A (I-A)
KTRB San Francisco, California: Class B (II-B) Presently operating at 7.5 kW nights
CMDB Colon, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a Canadian clear channel)
Clear 870 A,B,D WWL New Orleans, Louisiana: Class A (I-A)
KSKO McGrath, Alaska: Class A (I-N)
Clear 880 A,B,D WCBS New York City: Class A (I-A)
KRVN Lexington, Nebraska: Class B (II-A)
CMAB Pinar del Rio, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a U.S. clear channel)
Clear 890 A,B,D WLS Chicago, Illinois: Class A (I-A)
KBBI Homer, Alaska: Class A (I-N)
KDXU St. George, Utah: Class B (II-A)
CMHB Camaguey, Cuba: Class A ("Rio" grant: 30 kW all hours; special grant of a Cuban Class A on a U.S. clear channel)
Clear 900 A,B,D XEW Mexico City: Class A (I-A)
CKBI Prince Albert, Saskatchewan: Class A (II-B)
CMKB Cacocun, Cuba: Class A ("Rio" grant: 200 kW days, 50 kW nights; special grant of a Cuban Class A on a Mexican clear channel)
Regional 910 (A),B,D CMAC Guanabacoba, Cuba: Class A ("Rio" grant: 75 kW all hours; special grant of a Cuban Class A on a regional channel)
Regional 920 B,D
Regional 930 B,D
Clear 940 A,B,D CINW Montreal, Quebec: Class A (I-B)
XEQ Mexico City: Class A (I-B)
KFIG Fresno, California: Class B (II-B)
Regional 950 B,D KJR Seattle, Washington Class B (III-A) (50 kW all hours; directional all hours)
Regional 960 B,D
Regional 970 B,D
Regional 980 B,D
Clear 990 A,B,D CBW Winnipeg, Manitoba: Class A (I-A)
CBY Corner Brook, Newfoundland and Labrador: Class A (I-B)
WDYZ Orlando, Florida: Class B (II-B)
Clear 1000 A,B,D WMVP Chicago, Illinois: Class A (I-B)
KOMO Seattle, Washington: Class A (I-B)
XEOY Mexico City, Mexico: Class A (I-B) (NARBA grant: 10 kW all hours; present operation 50 kW days, 10 kW nights)
Clear 1010 A,B,D CBR Calgary, Alberta: Class A (I-A)
CFRB Toronto, Ontario: Class A (II-B) (Class II-B promoted to Class A)
WINS New York City: Class B (II-B)
CMBX Wajay, Cuba: Class A ("Rio" grant: 500 kW all hours; special grant of a Cuban Class A on a Canadian clear channel)
Clear 1020 A,B,D KDKA Pittsburgh, Pennsylvania: Class A (I-A)
KVNT Eagle River, Alaska: Class A (I-N)
KCKN Roswell, New Mexico: Class B (II-A)
KTNQ Los Angeles, California: Class B (II-B)
Clear 1030 A,B,D WBZ Boston, Massachusetts: Class A (I-A)
KTWO Casper, Wyoming: Class B (II-A)
XEQR Mexico City, Mexico: Class B (II-B) (NARBA grant: 5 kW all hours; present operation 50 kW days, 5 kW nights)
Clear 1040 A,B,D WHO Des Moines, Iowa: Class A (I-A)
Clear 1050 A,B,D CHUM Toronto, Ontario: Class B (II-B)
XEG Guadalupe, Nuevo León: Class A (I-A)
WEPN New York City: Class B (II-B) (NARBA grant: 50 kW all hours, directional all hours; present operation: same)
Clear 1060 A,B,D KYW Philadelphia, Pennsylvania: Class A (I-B)
XEEP Mexico City: Class A (I-B) (NARBA grant: 20 kW all hours; present operation 50 kW days, 20 kW nights)
Clear 1070 A,B,D KNX Los Angeles, California: Class A (I-B) ND-U
CBA Moncton, New Brunswick: Class A (I-B) ND-U (Silent)
Clear 1080 A,B,D WTIC Hartford, Connecticut: Class A (I-B)
KRLD Dallas, Texas: Class A (I-B)
KOAN Anchorage, Alaska: Class A (I-N)
KFXX Portland, Oregon: Class B (II-B)
Clear 1090 A,B,D KAAY Little Rock, Arkansas: Class A (I-B)
WBAL Baltimore, Maryland: Class A (I-B)
XEPRS Rosarito Beach, Baja California: Class A (I-B)
KFNQ Seattle, Washington: Class B (II-B)
Clear 1100 A,B,D WTAM Cleveland, Ohio: Class A (I-A)
KNZZ Grand Junction, Colorado: Class B (II-A)
KFAX San Francisco, California: Class B (II-B)
Clear 1110 A,B,D WBT Charlotte, North Carolina: Class A (I-B)
KFAB Omaha, Nebraska: Class A (I-B)
KDIS Pasadena, California: Class B (II-B)
Clear 1120 A,B,D KMOX St. Louis, Missouri: Class A (I-A)
KPNW Eugene, Oregon: Class B (II-A)
Clear 1130 A,B,D KWKH Shreveport, Louisiana: Class A (I-B)
WBBR New York City: Class A (I-B)
CKWX Vancouver, British Columbia: Class A (I-B)
KTLK Minneapolis, Minnesota: Class B (II-B)
Clear 1140 A,B,D WRVA Richmond, Virginia: Class A (I-B)
XEMR Apodaca, Nuevo León: Class A (I-B)
KHTK Sacramento, California: Class B (II-B)
Regional 1150 B,D
Clear 1160 A,B,D KSL Salt Lake City, Utah: Class A (I-A)
WYLL Chicago, Illinois: Class B (II-B)
Clear 1170 A,B,D KFAQ Tulsa, Oklahoma: Class A (I-B)
WWVA Wheeling, West Virginia: Class A (I-B)
KJNP North Pole, Alaska: Class A (I-N)
Clear 1180 A,B,D WHAM Rochester, New York: Class A (I-A)
KOFI Kalispell, Montana: Class B (II-A)
Clear 1190 A,B,D KEX Portland, Oregon: Class A (I-B)
WOWO Fort Wayne, Indiana: Class B (I-B) (Former I-B downgraded to Class B by licensee's request; 9.8 kW nights)
WLIB New York City: Class B (II-B) (10 kW days, 30 kW nights)
XEWK-AM Guadalajara, Jalisco, Mexico: Class A (I-B) (NARBA grant: 10 kW all hours; present operation 50 kW days, 10 kW nights)
Clear 1200 A,B,D WOAI San Antonio, Texas: Class A (I-A)
WCHB Taylor, Michigan: Class B (II-B)
Clear 1210 A,B,D WPHT Philadelphia, Pennsylvania: Class A (I-A)
KGYN Guymon, Oklahoma: Class B (II-A)
Clear 1220 A,B,D XEB Mexico City: Class A (I-A)
WHKW Cleveland, Ohio: Class B (II-B) (NARBA grant: 50 kW all hours, directional all hours; present operation: same)
Regional 1230 B Stations in Alaska, Hawaii, Puerto Rico, and the United States Virgin Islands
Local 1230 C Stations in coterminous 48 states
Regional 1240 B Stations in Alaska, Hawaii, Puerto Rico, and the United States Virgin Islands
Local 1240 C Stations in coterminous 48 states
Regional 1250 B,D
Regional 1260 B,D CFRN Edmonton, Alberta: Class A (III-B) (Class III-B promoted to Class A, but operating on a Class III frequency)
Regional 1270 B,D
Regional 1280 B,D
Regional 1290 B,D
Regional 1300 B,D
Regional 1310 B,D
Regional 1320 B,D
Regional 1330 B,D
Regional 1340 B Stations in Alaska, Hawaii, Puerto Rico, and the United States Virgin Islands
Local 1340 C Stations in coterminous 48 states
Regional 1350 B,D
Regional 1360 B,D
Regional 1370 B,D
Regional 1380 B,D KRKO Everett, Washington Class B (III-A) (50 kW all hours; directional nights)
Regional 1390 B,D
Regional 1400 B Stations in Alaska, Hawaii, Puerto Rico, and the United States Virgin Islands
Local 1400 C Stations in coterminous 48 states
Regional 1410 B,D
Regional 1420 B,D
Regional 1430 B,D
Regional 1440 B,D
Regional 1450 B Stations in Alaska, Hawaii, Puerto Rico, and the United States Virgin Islands
Local 1450 C Stations in coterminous 48 states
Regional 1460 B,D
Regional 1470 B,D
Regional 1480 B,D
Regional 1490 B Stations in Alaska, Hawaii, Puerto Rico, and the United States Virgin Islands
Local 1490 C Stations in coterminous 48 states
Clear 1500 A,B,D WFED Washington, D.C.: Class A (I-B)
KSTP Saint Paul, Minnesota: Class A (I-B)
Clear 1510 A,B,D WLAC Nashville, Tennessee: Class A (I-B)
WUFC Boston, Massachusetts: Class B (II-B)
KGA Spokane, Washington: Class B (I-B) (Former I-B downgraded to Class B by licensee's request; 15 kW nights)
Clear 1520 A,B,D WWKB Buffalo, New York: Class A (I-B)
KOKC Oklahoma City, Oklahoma: Class A (I-B)
KGDD Oregon City, Oregon: Class B (II-B)
KKXA Snohomish, Washington Class B (II-B) (50 kW all hours; directional all hours)
Clear 1530 A,B,D KFBK Sacramento, California: Class A (I-B)
WCKY Cincinnati, Ohio: Class A (I-B)
Clear 1540 A,B,D KXEL Waterloo, Iowa: Class A (I-B)
ZNS-1 Nassau, Bahamas: Class A (I-A)
KMPC Los Angeles, California: Class B (II-B)
WDCD Albany, New York: Class B (II-B)
Clear 1550 A,B,D XERUV Xalapa, Veracruz: Class A (I-B) (NARBA grant: 10 kW non-directional)
CBEF Windsor, Ontario: Class A (I-B) (NARBA grant: 10 kW directional all hours)
KKOV Vancouver, Washington: Class B (II-B)
Clear 1560 A,B,D KNZR Bakersfield, California: Class A (I-B) Only U.S. Class A grandfathered at 10 kW nights
WQEW New York City: Class A (I-B)
Clear 1570 A,B,D XERF Ciudad Acuña, Coahuila: Class A (I-A) (NARBA grant: 250 kW; believed to be operating at 50 kW, but operated at 10 kW for many years)
Clear 1580 A,B,D CKDO Oshawa, Ontario: Class A (I-A)
KMIK Tempe, Arizona: Class B (II-B)
KBLA Santa Monica, California: Class B (II-B)
Regional 1590 B,D
Regional 1600 B,D
Regional (Expanded) 1610 B
Regional (Expanded) 1620 B
Regional (Expanded) 1630 B
Regional (Expanded) 1640 B
Regional (Expanded) 1650 B
Regional (Expanded) 1660 B
Regional (Expanded) 1670 B
Regional (Expanded) 1680 B
Regional (Expanded) 1690 B
Regional (Expanded) 1700 B

FM[edit]

Station class description[edit]

Class ERP HAAT Reference distance
C 100 kW (or higher for grandfathered stations) 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
C4 (US rulemaking) up to 12 kW up to 100 m 33.3 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 10W TPO unlimited unspecified
L1 (U.S., also LP100) 50 W to 100 W up to 30 m 5.6 km
L2 (U.S., also LP10) 1 W to 10 W up to 30 m 3.2 km
LP (Canada) 10-50 W
VLP (Canada) up to 10 W
unlicensed signal strength of 250 µV/m (US), 100 µV/m (Canada) unspecified measured at 3 m (US), 30 m (Canada)

Notes:

  • Canada protects all radio stations out to a signal strength of 0.5mV/m (54dBu), whereas only commercial B stations in the U.S. are. Commercial B1 in the U.S. 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 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 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:[3]

FM station
class
Reference
(maximum)
facilities for
station class
(ERP / HAAT)
FM
protected
or primary
service
contour
Distance to
protected or
primary
service
contour
Distance to 70
dBu city-grade
or principal
community
coverage
contour
Class A 6 kW
100 m (328 ft)
60 dBu (1.0mV/m) 28.3 km (17.6 mi) 16.2 km (10.1 mi)
Class B1 25 kW
100 m (328 ft)
57 dBu (0.7mV/m) 44.7 km (27.8 mi) 23.2 km (14.4 mi)
Class B 50 kW
150 m (492 ft)
54 dBu (0.5mV/m) 65.1 km (40.5 mi) 32.6 km (20.3 mi)
Class C3 25 kW
100 m (328 ft)
60 dBu (1.0mV/m) 39.1 km (24.3 mi) 23.2 km (14.4 mi)
Class C2 50 kW
150 m (492 ft)
60 dBu (1.0mV/m) 52.2 km (32.4 mi) 32.6 km (20.3 mi)
Class C1 100 kW
299 m (981 ft)
60 dBu (1.0mV/m) 72.3 km (44.9 mi) 50.0 km (31.1 mi)
Class C0 100 kW
450 m (1,476 ft)
60 dBu (1.0mV/m) 83.4 km (51.8 mi) 59.0 km (36.7 mi)
Class C 100 kW
600 m (1,969 ft)
60 dBu (1.0mV/m) 91.8 km (57.0 mi) 67.7 km (42.1 mi)

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.

FM zones[edit]

FM broadcast zones in the U.S.

The U.S. is divided into three zones for FM broadcasting, (I, I-A and II). Depending on which zone a station is located determines what class a FM station may elect to be.

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.

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 in excess of 50 KW, such as WETA-FM licensed to Washington, DC (zone I), which has a power of 75 kW ERP, and KPFK in Los Angeles (zone I-A) at 110 KW ERP.

TV[edit]

Full-power stations in the USA[edit]

  • VHF low (2-6): 100 kW video analog; 45 kW digital (sliding scale varying with height)
  • VHF high (7-13): 316 kW video analog; 160 kW digital (sliding scale varying with height)
  • UHF all (14-69): 5 MW video analog; 1 MW digital

Notes:

All Full power analogue television station transmissions in the USA were terminated at midnight Eastern Daylight Time on June 12, 2009.[4][5] Many broadcasters replaced their analogue signal with their digital ATSC signal on the same transmission channel at that time.

  • All U.S. digital stations received a -DT suffix during the analog-to-digital transition. At analog shutdown, the FCC assigned each digital station the callsign its associated analog station had used. (with a -TV suffix if the analog station had one, without the -TV suffix if the analog station didn't have it) Stations could optionally choose to keep the -DT suffix.[6] Most stations did not keep the -DT suffix.[7]
  • For U.S. 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 could optionally request it if desired.
  • Analog audio power was limited to 22% of video.[8]

Full-power stations in Canada[edit]

  • Class A: UHF, 10 kW video/100m EHAAT
  • Class B: UHF, 100 kW video/150m EHAAT
  • Class C: UHF, 1000 kW video/300m EHAAT (?)
  • Class D: UHF, more than 1000 kW/300m 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 north of the border.
  • In Canada, the callsigns of all private TV stations have the -TV suffix. Most CBC Television and Télévision de Radio-Canada 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 (USA)[edit]

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

  • VHF (2-13): 3 kW analog video; 3 kW digital
  • UHF (14-69): 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. [9]

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 (USA)[edit]

Class-A stations (U.S.) (suffix: -CA or -CD for digital class A):

  • VHF (2-13): 3 kW analog video; 3 kW digital
  • UHF (14-69): 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. [10]

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

Low-power TV (Canada)[edit]

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.[11]

FCC service table[edit]

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

Broadcast class Service Suffixes used or call sign examples
Television allotment (analog) TA An allocation of a frequency to a city of license for which no corresponding call sign or license has been assigned. FCC placeholder for possible future construction permits or frequencies allocated to non-US broadcast use. No call sign, identifier is a date (yymmdd) followed by a sequential two-letter value in the US FCC database.
Full-service TV (analog) TV -TV or none (such as "WABC-TV" and "WMYD") Since the shutdown of all full power analog stations in June 2009, used only for historical records.
Class A (analog) CA -CA, -LP, or a translator-style call sign (such as "WDNN-CA", "WKGK-LP", and "W33BY")
Low-power station (analog) or translator TX -LP, none (rare), or a translator-style call sign (such as "WLPC-LP", [example needed], and "W47DL-D")
Low-power TV (analog LPTV) TL Usually placed under TX class; these use the -LP suffix or translator-style call signs.
TV boosters TB Rare. These use the parent station's call sign plus a sequential number, such as WSTE1, WSTE2, WSTE3. Nameplates for on-channel repeaters bear the parent station's call sign, followed by "booster".[12] See distributed transmission. If the station is digital, and has on-channel boosters, they would typically be named WSTE-DT1, WSTE-DT2, WSTE-DT3 and so on.
TV auxiliary (analog backup) service TS no specific suffix (uses same call sign as main transmitter)
NTSC (analog) petition for a channel change NN no specific suffix; uses same call sign as the station which made a request for a number/channel change (for NTSC/analog stations, and low-power repeaters, such as those registered as TX).
Digital Television
(full power)
DT -DT, -TV or none (such as KGLA-DT, WSKY-TV or KJWP) Some stations formerly used -HD but this has become obsolete (though it may sometimes still be seen identifying the station's main subchannel in a PSIP listing). The -DT suffix, optional for digital-only stations, was used primarily to distinguish a DTV transmission from an analog signal of the same broadcast (or is seen identifying the main subchannel of a station on a PSIP display); likewise, -TV is optional except if the eponymous radio stations exist.
Digital Class-A DC -CD or -LD (such as "WDNI-CD" and "WYYW-CD") Some stations briefly used -DC as well (this has since become obsolete). A scant few still use translator-style call signs with the -D suffix (such as "W23BV-D").
Digital Low-power LD -LD or translator-style calls with -D suffix (such as "WBND-LD" and "W38EA-D"), occasionally no suffix (uses same call sign as main transmitter). Some stations briefly used -DL as well (this has since become obsolete). Some full-powered stations (such as WOIO, WXMI and WLS-TV) have been granted approval for fill-in translators within their broadcast market to better cover outlying towns or heavily-urbanied areas, particularly by stations with a VHF digital signal. These are technically -LD stations, but have the same call-sign as their parent station (such as WLS-TV or WOIO, and not as WLS-LD or WOIO-LD, though they could be considered as such for ease of differentiating the low-power repeater from its parent), similar to a Distributed Transmission System (but on different frequencies).
Digital special temporary authority (STA) DS no specific suffix; uses same call sign as station making a request for permission from the FCC to use a channel, power level or transmitter location not permanently allocated for one particular station. Temporary assignments retain, unmodified, the call sign of the corresponding permanent allocation; this includes translator-style calls (a format, such as W55ZZ-D, based on RF channel number plus a sequential identifier) even on those temporarily moving to another frequency.
Digital Television distributed transmission system (multiple transmitter sites) DD no specific suffix (uses same call sign as main transmitter); this is usually requested for a single-frequency network and to tailor coverage area to the needs of the viewers in the station's service area (such as covering towns and farmland, and not mountainous terrain or the ocean)
Digital auxiliary (backup) service DX
(not to be confused with DXing)
no specific suffix (uses same call sign as main transmitter)
Digital rulemaking petition DR no specific suffix; uses same call sign as station making this request to add or modify a digital channel allocation
Land mobile use of a TV channel LM As "LM" is used in the FCC database to indicate reallocation of an entire channel, but not to identify individual users transmitting in that spectrum, a 6 MHz LM allocation does not itself carry a TV-style call sign.[13]

See also[edit]

References[edit]

  1. ^ Industry Canada Broadcasting Database
  2. ^ Clear Channel Stations
  3. ^ FM Station Classes and Contours
  4. ^ A New Era in Television Broadcasting - DTVTransition.org
  5. ^ Congress delays DTV switch
  6. ^ [1] - FCC DA-09-1253
  7. ^ [2] Searching for the -DT suffix returns only 91 stations; -TV returns 903, searching for TV stations with no suffix at all returns 1,827. Searches conducted 29 Jan 2011.
  8. ^ [3] - FCC regulation 73.1560(c)(2)
  9. ^ [4]
  10. ^ [5]
  11. ^ Part 10: Application and Procedures and Rules for Digital Television (DTV) Undertakings
  12. ^ U.S. CFR 47 Part 74G - 74.733 UHF translator signal boosters.
  13. ^ FCC TV query for -LM allocations

External links[edit]