Clear channel

:This article is about the class of AM radio stations that are called clear channel stations based on their technical parameters, not their owner. For the company named Clear Channel, which owns radio stations most of which are not in this class, please see Clear Channel Communications.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Clear channel stations are AM radio stations that are designated as such so that only one or two 50,000 watt powerhouses operate at night on each designated frequency, covering a wide area via sky wave propagation. Non-clear channel stations transmitting on these frequencies are (or were) required to shut down at night, leading them to be known as daytimers. In North America, some frequencies were designated by the North American Radio Broadcasting Agreement (NARBA) (to which the U.S., Canada, and Mexico are signatory) as clear channels. These are considered by the FCC and CRTC to be class A (formerly class 1-A or I-A) stations. Daytimers are in class D.

Related Topics:
AM - Radio station - Watt - Frequency - Sky wave - Propagation - North America - North American Radio Broadcasting Agreement - U.S. - Canada - Mexico - Signatory - FCC - CRTC - Class A

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

For the U.S., clear channels first appeared in 1922 when the Commerce Department moved stations which had all used two frequencies (one for entertainment stations, one for news) onto 52 frequencies. Two were used for all low-power stations and the large stations each got their own frequency. A few frequencies were used on both the East and West Coast, which were considered far enough apart to limit interference. At this time large stations were limited to 1000 watts. Later in 1928, the AM band was reorganized with local, regional and clear channels (and a few reserved for Canada) by the new Federal Radio Commission. Gradually maximum power was increased to 50,000 watts. This system was continued in the 1941 NARBA system although almost all stations shifted broadcast frequencies.

Related Topics:
1922 - Commerce Department - 1928 - Federal Radio Commission - 1941

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Recently however, the FCC has authorized nighttime operation by lower-powered stations on these frequencies, thus limiting the non-interference range of the primary licensees. Stations are still required to reduce power or reconfigure their transmitters at night. Regional class stations have been allowed to increase their power to the same 50,000 watts as clear channel stations. In 1987 the rules were changed so that no new stations would have daytime-only licenses.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Clear Channel Communications, a San Antonio, Texas-based company which owns a large number of U.S. radio stations, was originally formed to purchase one of these stations, WOAI; the company now owns more than a dozen.

Related Topics:
Clear Channel Communications - San Antonio, Texas - U.S. - WOAI

~ ~ ~ ~ ~ ~ ~ ~ ~ ~