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- Q4779411 subject Q449969.
- Q4779411 subject Q7019172.
- Q4779411 subject Q7468934.
- Q4779411 subject Q7469389.
- Q4779411 subject Q8134779.
- Q4779411 subject Q8136403.
- Q4779411 subject Q8621151.
- Q4779411 abstract "Apex was an experimental radio broadcasting system introduced in the United States in 1934 that used high frequencies between roughly 25 and 42 MHz and wideband AM modulation (as opposed to traditional AM broadcasting's narrowband modulation) to achieve high fidelity sound with less static and distortion than medium wave AM stations in the so-called standard broadcast band (then, 545-1505 kHz) experience. They were called "apex", "skyscraper" or "pinnacle" stations because of the height of the broadcast antennas used.The Federal Communications Commission thought initially that very high frequency (VHF) radio waves would have a small, discrete range, and would allow two or more stations to broadcast on duplicate frequencies without interfering with each other. But later it was realized that during peaks in the 11-year sunspot cycle even VHF radio waves could reflect from the ionosphere, and Apex station signals could sometimes be heard on the other side of the planet. In October 1937, the FCC made public its allocation plan for VHF radio broadcasting: 75 channels with 40 kHz separation on 41.02 to 43.98 MHz for Apex stations and 16 channels in 30-40 MHz for relay stations. Twenty-five of the 75 channels were reallocated for educational use in 1938.Until the late 1930s, commercially made radio receivers did not operate within that band of frequencies, so early listeners to Apex stations used self-built receivers, or built converters for existing models.Most Apex stations operated under experimental licenses, and were affiliated with and subsidized by commercially licensed stations. In 1934, Buffalo, New York's W8XH, WBEN's ultra short wave station, became the first 5-meter station to air a regular schedule. It is a direct predecessor of current Buffalo FM adult contemporary station WTSS. In 1936, Milwaukee's W9XAZ (a service of The Milwaukee Journal's WTMJ (AM), which eventually became current day FM station WKTI-FM at 94.5) became the first Apex station to originate its own programming on a regular basis. By 1939, Apex stations were operating in 34 cities in 22 states. Apex radio broadcasting's goal of high fidelity sound was later realized by frequency modulation (FM), which operated at 42–50 MHz (later 88–106 MHz, 88–108 MHz later still, and currently 87.8–108 MHz), immediately above the Apex band of frequencies. The FCC in 1939 began encouraging Apex stations broadcasting in AM to consider the change to the technically superior FM system.The former Apex band is, as of 2012, allocated to land mobile communications.".
- Q4779411 wikiPageExternalLink 1939apex.html.
- Q4779411 wikiPageExternalLink 1942fmra.html.
- Q4779411 wikiPageExternalLink chronofm.html.
- Q4779411 wikiPageExternalLink fm1.html.
- Q4779411 wikiPageExternalLink prehist.pdf.
- Q4779411 wikiPageWikiLink Q11652.
- Q4779411 wikiPageWikiLink Q128831.
- Q4779411 wikiPageWikiLink Q131214.
- Q4779411 wikiPageWikiLink Q1368380.
- Q4779411 wikiPageWikiLink Q1377707.
- Q4779411 wikiPageWikiLink Q152466.
- Q4779411 wikiPageWikiLink Q162219.
- Q4779411 wikiPageWikiLink Q1765623.
- Q4779411 wikiPageWikiLink Q181417.
- Q4779411 wikiPageWikiLink Q183755.
- Q4779411 wikiPageWikiLink Q37836.
- Q4779411 wikiPageWikiLink Q39369.
- Q4779411 wikiPageWikiLink Q40435.
- Q4779411 wikiPageWikiLink Q449969.
- Q4779411 wikiPageWikiLink Q49385.
- Q4779411 wikiPageWikiLink Q7019172.
- Q4779411 wikiPageWikiLink Q7468934.
- Q4779411 wikiPageWikiLink Q7469389.
- Q4779411 wikiPageWikiLink Q747066.
- Q4779411 wikiPageWikiLink Q7947088.
- Q4779411 wikiPageWikiLink Q7952569.
- Q4779411 wikiPageWikiLink Q7956282.
- Q4779411 wikiPageWikiLink Q7956419.
- Q4779411 wikiPageWikiLink Q8134779.
- Q4779411 wikiPageWikiLink Q8136403.
- Q4779411 wikiPageWikiLink Q8621151.
- Q4779411 wikiPageWikiLink Q872.
- Q4779411 comment "Apex was an experimental radio broadcasting system introduced in the United States in 1934 that used high frequencies between roughly 25 and 42 MHz and wideband AM modulation (as opposed to traditional AM broadcasting's narrowband modulation) to achieve high fidelity sound with less static and distortion than medium wave AM stations in the so-called standard broadcast band (then, 545-1505 kHz) experience.".
- Q4779411 label "Apex (radio band)".