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In North American broadcast television frequencies, channel 1 is a former broadcast (over-the-air) television channel. During the experimental era of TV operation, Channel 1 was moved around the lower VHF spectrum repeatedly, with the entire band displaced upward at one point due to an early 40MHz allocation for the FM broadcast band. FM was moved to its current frequencies in 1946. TV Channel 1's last location was 44 Mhz to 50 MHz. Land Mobile Radio and television broadcasters shared the same frequencies until 1948. This shared allocation was eventually found to be unworkable, so the FCC reallocated the Channel 1 frequencies for public safety and land mobile use and assigned TV channels 2-13 exclusively to broadcasters. Aside from the shared frequency issue, this part of the VHF band was (and to a some extent still is) prone to higher levels of radio-frequency interference (RFI) than even VHF 2 (System M). Neither Canada nor Mexico was able to get around to the issues of TV Frequency allocation until 1946, so the historical Channel 1 (System M) is exclusively a US allocation artefact. == History == Channel 1 was allocated at 44–50 MHz between 1937 and 1940. Visual and aural carrier frequencies within the channel fluctuated with changes in overall TV broadcast standards prior to the establishment of permanent standards by the National Television Systems Committee. In 1940, the FCC reassigned 44–50 MHz to the FM broadcast band. Television's channel 1 frequency range was moved to 50–56 MHz (see table below). Experimental television stations in New York, Chicago, and Los Angeles were affected.〔"Threat to Television Is Feared in Frequency Modulation Order", ''New York Times'', May 21, 1940, p. 23. "Gives Du Mont Right to Television Here", ''New York Times, July 21, 1940, p. 28.〕 Commercial TV allocations were made by the Federal Communications Commission (FCC) under the NTSC system on July 1, 1941. Channel 1 was located at 50–56 MHz, with visual carrier at 51.25 MHz and aural carrier at 55.75 MHz. At the same time, the spectrum from 42 to 50 MHz was allocated to FM radio. Several commercial and experimental television stations operated on the 50–56 MHz Channel 1 between 1941 and 1946, including one station, WNBT in New York, which had a full commercial operating license. In the first postwar allocation in the spring of 1946, Channel 1 was moved back to 44–50 MHz, with visual at 45.25 MHz and aural at 49.75 MHz. FM was moved to its current 88–108 MHz band. But WNBT and all other existing stations were moved to other channels, because the final Channel 1 was reserved for low power community stations covering a limited area. While a handful of construction permits were issued for this final version of Channel 1, no station ever actually broadcast on it before it was removed from use in 1948. When the FCC initially allocated broadcast television frequencies, channel 1 was logically the first channel. These U.S. TV stations originally broadcast on the 50–56 MHz channel 1 * W2XBS/WNBT (today's WNBC), New York City (1941–1946), reassigned in 1946 to channel 4; * W6XAO/KTSL (today's KCBS-TV), Los Angeles, reassigned post-war to channel 2; * W9XZV Chicago, Zenith's experimental station, billed as the first all-electric TV station in 1939.〔http://www.fundinguniverse.com/company-histories/Zenith-Electronics-Corporation-Company-History.html〕 Reassigned post-war to Channel 2,〔"(Zenith Enters FM and TV Broadcasting )", ''The Zenith Story'' (1954).〕 it broadcast an early form of monochrome pay-TV in 1951 as K2XBS Phonevision and conducted early color television experiments before ultimately going dark in 1953.〔http://www.chicagotelevision.com/timeline.htm〕 Its transmitters were donated to WTTW (PBS 11 Chicago)〔(CompassRose.org: WBKB Chicago )〕 and its channel 2 assignment was taken by CBS O&O WBBM-TV. * KARO, Riverside, California; never began broadcasting, no current VHF allocation; * WSBE, South Bend, Indiana; never began broadcasting on channel 1, but was reallocated to UHF channel 34 in the 1952 revised channel allocation table, where it went on the air as WSBT-TV that year. As part of a consolidation of the Elkhart and South Bend communities into a single television market, WSBT-TV was moved in 1958 to UHF channel 22, where it remains as a digital CBS affiliate today; channel 34 became the home of PBS member station WNIT. No full-service VHF TV allocations were made available to South Bend due to its proximity to Chicago, making the city a UHF island. By September 1945, additional stations temporarily granted construction permits to operate on channel 1 included: * W8XCT (WLW) Cincinnati, Ohio ultimately built on channel 4 as commercial station WLWT, later moved to channel 5. * W9RUI Iowa City, Iowa held an unbuilt construction permit, and additionally given a channel 12 assignment. * W8XGZ Charleston, West Virginia, licensed to a chemical company, also held a channel one construction permit; there is no indication the stations ever got on the air.〔http://www.anarc.org/wtfda/channel1.htm〕 ''See also list of experimental television stations for additional channel one pioneers.'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Channel 1 (North American TV)」の詳細全文を読む スポンサード リンク
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