This is the Broadcast History section of
The Broadcast Archive
Maintained by:
Barry Mishkind - The Eclectic Engineer
Last updated 8/8/02
It would be a kindness if you'd just send a short note to let
me know who you are, and what your interests are. Thanks.
AM:
In 1922, all stations were assigned by the Secretary of Commerce to 360
meters (833 kHz) for the transmission of "important news items,
entertainment, lectures, sermons, and similar matter."
Later that year, 400 meters (750 kHz) was added, with power limits raised to
1,000 watts. One frequency was set aside for music broadcasts, the other for
news and other voice transmissions.
In 1923 and 1924, additional changes were made, opening up 550 to 1500 kHz
for broadcasting (in 10 kHz increments) with powers up to 5,000 watts. (The
band from 810-850 kHz was "left" for the stations on 833 to continue
for a while).
In 1938, an administrative conference designated 1500-1600 kHz to be opened
in May, 1941.
In 1979, the WARC expanded the band again, this time to 1700 kHz. The first
station on the new band was WJDM, Elizabeth, NJ, which went on in 1995.
FM:
The original FM band was 43.0 to 50.0 MHz, but unlike the
present, the assigned channels were on the even frequencies (43.6) instead of
the odd (98.3).
The band was originally to be used for experimental
"high-frequency AM stations," where the channels would be spaced
farther apart (200 kHz) and permitted to broadcast the full frequency spectrum.
The idea was to relieve the congestion and skywave problems which would lead to
the severe bandwidth limiting which would eventually doom the AM band to talk
radio and poor quality radios.
The FM band was moved higher up in frequency (88-108 MHz) for
several reasons:
David Sarnoff and Major Armstrong had become bitter adversaries. Sarnoff
wanted to delay or "kill" FM, in favor of the new television service
he was promoting.
RCA also wanted to protect the coverage areas of its clear
channel AMs, which might be threatened by the ability of low-band FMs to use
skywave to send crystal clear audio free from the interference that was starting
to affect AM.
TV:
The original TV band ran from 50 MHz to 108 MHz and was designated channels 1
to 7. In June 1945, as part of his campaign against FM, David Sarnoff had it
moved down to 44 MHz.
The low TV channels soon proved to be woefully inadequate for the expressed
interest in TV broadcasting, so the FCC decided to go back and allocate more
spectrum. They also decided to deal with some of the problems being seen with
severe skywave on channel 1. Therefore, in 1948, channel 1 was officially
dropped, with channel 2 starting at 54 MHz. (Channel 2 still has the skywave
problem - or "benefit," if you are a TV DXer - of the early years, but
since FM was moved up to the high-band no broadcast service was affected by the
interference from TV.)
With FM moved to 88-108, the VHF TV band came to be "wrapped"
around FM. That is why you can usually hear the sound of a local Channel 6 at
the bottom of your FM dial.
The band was expanded further in 1953 with the lifting of the license freeze
that had been in effect since 1947, and the requirement of many of the new
licensees to start transmitting in the UHF band (channels from 14-83 running
well up into the 800 MHZ range). It was only with the passage of the 1962
All-channel Act mandating TV manufacturers to produce TVs with both VHF and UHF
step tuners that UHF stations finally were put on an even footing with the VHF
stations.
Later UHF channels from 70-83 were dropped when the land mobile industry
lobbied the FCC for more space. Ironically, today, the "trunking"
services are languishing due to the widespread use of cellular telephones.
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