Editing FM broadcast band (section)

==Historic U.S. bandplan==

In the 1930s investigations were begun into establishing radio stations transmitting on "Very High Frequency" (VHF) assignments above 30&nbsp;MHz. In October 1937, the [[Federal Communications Commission]] (FCC) announced new frequency allocations, which included a band of experimental and educational "[[Apex (radio band)|Apex]]" stations, that consisted of 75 channels spanning from 41.02 to 43.98&nbsp;MHz.<ref name="upper">[https://archive.org/stream/broadcasting13unse_0#page/n749/mode/1up "Upper Bands Set Aside for Television"], ''Broadcasting'', November 1, 1937, pages 60-61.</ref> Like the existing AM band these stations employed amplitude modulation, however the 40&nbsp;kHz spacing between adjacent frequencies was four times as much as the 10&nbsp;kHz spacing on the standard AM broadcast band, which reduced adjacent-frequency interference, and provided more bandwidth for high-fidelity programming.

Also during the 1930s [[Edwin Howard Armstrong]] developed a competing transmission technology, "wide-band frequency modulation", which was promoted as being superior to AM transmissions, in particular due to its high-fidelity and near immunity to static interference. In May 1940, largely as the result of Armstrong's efforts, the FCC decided to eliminate the Apex band, and authorized an FM band effective January 1, 1941, operating on 40 channels spanning 42–50&nbsp;MHz,<ref>[https://babel.hathitrust.org/cgi/pt?id=uiug.30112059131711&view=1up&seq=767 "FCC Order No. 67"], ''Federal Register'', May 25, 1940, page 2011.</ref> with the first five channels reserved for educational stations. There was significant interest in the new FM band by station owners, however, construction restrictions that went into place during World War II limited the growth of the new service.

Following the end of the war, the FCC moved to standardize its frequency allocations. One area of concern was the effects of [[Tropospheric propagation|tropospheric]] and [[Sporadic E propagation]], which at times reflected station signals over great distances, causing mutual interference. A particularly controversial proposal, spearheaded by the [[RCA|Radio Corporation of America]] (RCA), which was headed by [[David Sarnoff]], was that the FM band needed to be shifted to higher frequencies in order to avoid this potential problem. Armstrong charged that this reassignment had the covert goal of disrupting FM radio development,<ref name="Lessing">{{cite book|title=Man Of High Fidelity|author=Lawrence Lessing|publisher=J. B. Lippincott|year=1956}}</ref> however RCA's proposal prevailed, and on June 27, 1945 the FCC announced the reassignment of the FM band to 90 channels from 88–106&nbsp;MHz,<ref>[https://archive.org/details/broadcasting291unse/page/n16/mode/1up "FCC Allocates 88-106 mc Band to FM"] by Bill Bailey, ''Broadcasting'', July 2, 1945, pages 13-14.</ref><ref>[https://archive.org/details/broadcasting291unse/page/n67/mode/1up "FCC Allocations Order Text"], ''Broadcasting'', July 2, 1945, pages 64-68.</ref> which was soon expanded to 100 channels from 88–108&nbsp;MHz, with the first 20 channels reserved for educational stations. A period of allowing existing FM stations to broadcast on both the original "low" and new "high" FM bands followed, which ended at midnight on January 8, 1949, at which time all low band transmissions had to end.<ref>{{Cite news|url=https://www.newspapers.com/image/93688720|title=395,000 FM Radio Sets Must Be Replaced|last=INS|date=June 27, 1945|work=Journal Gazette|access-date=2017-08-14|page=6|language=en|via=Newspapers.com}}</ref>

In 1978 one additional frequency reserved for educational stations, 87.9 MHz, was allocated.<ref>[https://worldradiohistory.com/Archive-BC/BC-1978/1978-06-12-BC.pdf#page=50 "FCC moves to overhaul rules for noncommercial radio and TV"], ''Broadcasting'', June 12, 1978, page 50.</ref> In March 2008, the FCC requested public comment on turning the bandwidth currently occupied by analog television channels 5 and 6 (76–88&nbsp;MHz) over to extending the FM broadcast band when the digital television transition was to be completed in February 2009 (ultimately delayed to June 2009).<ref>{{cite web|url=http://www.regulations.gov/fdmspublic/component/main?main=DocumentDetail&o=090000648064a653|title=In the Matter of Promoting Diversification of Ownership in the Broadcasting Services|author=Federal Communications Commission|date=2008-05-16|access-date=2008-08-26|quote=Certain commenters have urged the Commission to give a "hard look" to a proposal that the Commission re-allocate TV Channels 5 and 6 for FM broadcasting|archive-url=https://web.archive.org/web/20081227021445/http://www.regulations.gov/fdmspublic/component/main?main=DocumentDetail&o=090000648064a653|archive-date=2008-12-27|url-status=dead}}  {{USFR|73|28400}}, 28403</ref> This proposed allocation would have effectively assigned frequencies corresponding to the existing Japanese FM radio service (which begins at 76&nbsp;MHz) for use as an extension to the existing North American FM broadcast band.<ref>[http://www.radioworld.com/article/67266 Could EXB Band Be Your New Home?] {{Webarchive|url=https://web.archive.org/web/20090506025738/http://radioworld.com/article/67266 |date=2009-05-06 }}''Radio World'' September 10, 2008</ref> Several low-power television stations colloquially known as "[[Channel 6 radio stations in the United States|Franken-FM]]s" operated primarily as radio stations on channel 6, using the 87.7&nbsp;MHz audio carrier of that channel as a radio station receivable on most FM receivers configured to cover the whole of [[Band II]], from 2009 to 2021; since then, a reduced number have received special temporary authority to carry a special audio carrier on their [[ATSC 3.0]] signals to continue the status quo.<ref name=estimated>[https://www.insideradio.com/free/franken-fms-have-a-week-left-to-live-two-will-remain-in-test-of-new/article_f1d52bcc-def6-11eb-b3d3-0b70f11a6f0a.html "Franken FMs Have A Week Left To Live; Two Will Remain In Test Of New Technology"], July 7, 2021 (insideradio.com)</ref>