Channel 1 (NTSC-M): Wikis

Advertisements
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

In North America, channel 1 is a former broadcast (over-the-air) television channel. During the experimental era of TV operation Channel 1 moved all over the shortwave and lower VHF spectrum, settling at 44-50 MHz between 1937 and 1941 although 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 the very first post-experimental commercial TV allocations made by the 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 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 which took effect 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, and 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 lower 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 taken out of service in the late 1940s and the frequency band re-assigned to public safety communications.

Contents

History

When the U.S. Federal Communications Commission 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, 1939–1945?; Zenith's experimental station, billed as the first all-electric TV station in 1939.[1] Later moved to Channel 2,[2] 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.[3] Its transmitters were donated to WTTW (PBS 11 Chicago)[4] 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, later relicensed as WSBT-TV in 1952 and began broadcasting on UHF channel 22.

In 1940, the FCC reassigned the 44–50 MHz area of the frequency range from television to the FM broadcast band, where it remained until being moved to its current location in 1946. 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.[5]

By September 1945, additional stations temporarily granted construction permits to operate on channel one included:

  • W8XCT (WLW) Cincinnati, ultimately built on channel 4 as commercial station WLWT, later moved to channel 5.
  • W9RUI Iowa City, Iowa held an unbuilt construction permit,
  • 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.[6]

See also list of experimental television stations for additional channel one pioneers.

Advertisements

Community television

The first post-World War II telecommunications conferences formally allocated TV frequencies in 1945–1946. In 1946, the FCC decided to reserve channel 1 for lower-power community television stations, and moved existing channel 1 stations to higher frequencies. Community stations covered smaller cities and were allowed less radiated power. Channel 1 location assignments, intended for community stations, included:

None of these stations were built before the FCC imposed a freeze on all television station construction permits in mid-1948, and removed the channel one allocations.

A shared (non-primary) allocation

From 1945 to 1948 TV stations in the U.S. shared Channel 1 and other channels with fixed and mobile services. The FCC decided in 1948 that a primary (non-shared) allocation of the VHF radio spectrum was needed for television broadcasting. Except for select VHF frequencies in Alaska and Hawaii (and some overseas territories) the FCC-administered VHF band is primarily allocated for television broadcasting to this day.

The FCC in May 1948 formally changed the rules on TV band allocations based on propagation knowledge gained during the era of shared-user allocations. The 44-50MHz band used by Channel 1 was replaced by lower-power narrowband users.

Channel 1 was reassigned to fixed and mobile services (44-50 MHz) in order to end their former shared use of other VHF TV frequencies. Rather than renumber the TV channel table, it was decided to merely remove Channel 1 from the table.

As of Sept. 2000, the Federal Spectrum Use of the band [7] was as follows:

  • 43.69-46.6 Non-Military Land Mobile Radio (LMR). Primarily used by Federal agencies for mutual aid response with local communities.
    Military LMR. Used by the military services for tactical and training operations on a non-interference basis. (Band is otherwise non-government exclusive).
  • 46.6- 47 Govt. FIXED MOBILE Allocation:
    Non-Military LMR. Extensive use of this band is for contingency response to various national disasters. Others uses are for national resources management, law enforcement, tornado tracking, and various meteorological research support.
    Military LMR. This band is used primarily for tactical and training operations by U.S. military units for combat net radio operations that provide command and control for combat, combat support, and combat service support units. Frequencies also used for air-to-ground communications for military close air support requirements as well as some other tactical air-ground and air-air communications.
  • 47- 49.6 Experimental: Used for experimental research to observe and measure currents in harbor areas in support of vessel safety.

    Military LMR. Used by the military services for tactical and training operations on a non-interference basis. (Band is otherwise non-government exclusive).

  • 49.6- 50 Govt. FIXED MOBILE Allocation:
    Non-Military LMR. This band is used extensively to support contingencies or naturalecological emergencies, some public safety requirements, MARS system, and air-quality measurements.

    Experimental. Research is performed in various regions of the atmosphere as well as experimental development of portable space orbital debris ground radars.

    Military LMR. This band is used primarily for tactical and training operations by U.S. military units for combat net radio operations that provide command and control for combat, combat support, and combat service support units. Frequencies also used for air-to-ground communications for military close air support requirements as well as some other tactical air-ground and air-air communications.

Canada did not start regular television broadcasts until after the US had decommissioned Channel 1 (44-50 MHz) for television use; CBFT and CBLT signed on in 1952. This TV channel was never used in Latin America, South Korea and the Philippines as TV broadcasting did not start in these areas until the 1950s.

Historic US FCC allocation of VHF band

Channel 1938-1940 1940-1946 1946-1948 since 1948
  Lower edge Upper edge Lower edge Upper edge Lower edge Upper edge Lower edge Upper edge
1 44 50 50 56 44 50    
2 50 56 60 66 54 60 54 60
3 66 72 66 72 60 66 60 66
4 78 84 78 84 66 72 66 72
5 84 90 84 90 76 82 76 82
6 96 102 96 102 82 88 82 88
7 102 108 102 108 174 180 174 180
8 156 162 162 168 180 186 180 186
9 162 168 180 186 186 192 186 192
10 180 186 186 192 192 198 192 198
11 186 192 204 210 198 204 198 204
12 204 210 210 216 204 210 204 210
13 210 216 230 236 210 216 210 216
14 234 240 236 242        
15 240 246 258 264        
16 258 264 264 270        
17 264 270 282 288        
18 282 288 288 294        
19 288 294            

Cable TV allocation issues

Legacy issues with System M cable TV

  • North American cable television frequencies (analog System M) include a formally defined and allocated Channel 1.
  • Cable TV's use of Channel 1 is rare and its frequency assignment (HRC, IRC, ICC, STD, EIA, etc) is sometimes inconsistent.
  • The On Demand services of providers such as Comcast are allocated on EPG's on Channel 1, and are marketed as such.

System M cable TV in North America uses frequencies

for additional standard 6 MHz channels. This normally places cable converter channels 14-22 (midband) directly below VHF channel 7 in frequency and sequentially places the remaining converter channels (except 95-99) directly above VHF channel 13 (superband). Where 95-99 are used as cable channels, their standard location is 90-120 MHz, directly below the other midband channels.

Interference issues

  • These cable channels overlap assorted other over-the-air uses, including marine, weather, aeronautical, police and amateur radio bands.
  • North American cable systems must avoid interference to (and from) these other services.
  • The range from 88 - 120MHz is avoided for cable television channels on most systems, as many are carrying FM stereo radio signals to their subscribers using the standard 88-108 MHz FM broadcast band.
  • The use of 45.75 MHz as an intermediate frequency within most modern television receivers became commonplace after UHF reception became an option in 1953. With this as the internal output frequency from standard UHF and VHF tuners, its use as Channel 1's input frequency (terrestrially or on analogue cable) could create interference internally within TV's.
  • Most cable systems use frequencies below 54MHz (VHF TV 2) for communication back to the cable provider from cable modems and digital apparatus, so any "Cable 1" channel needs to avoid operation on the original VHF Channel 1 frequencies from the pre-1948 bandplans. As such, "cable 1" is not related to the original 44-50MHz VHF channel one except in name. It operates always at some higher frequency - often with channels 00 and 01 merely aliased to 98/99 or 100/101.
  • HRC and IRC systems increase the spacing between channels 4 and 5 to a non-standard 6 MHz, inserting "cable 1" between channels four and five. This non-standard spacing is rarely-used, is not compatible with all television receivers and has the effect of pushing channel six partially into the FM broadcast band.

Other reassigned channels

Channel 1 is also not the only "missing" channel. No stations are assigned to UHF Channel 37 (608 to 614 MHz), which is reserved for radio astronomy. It remains on TV sets and tuners.

Other channels have been removed and reassigned as well, but only from the higher UHF bands. Channels 14 to 83 (sans 37), from 470 to 890 MHz, were originally added by the FCC in 1952 for the rapidly-expanding TV service in the United States.[8] In the 1980s, channels 70 to 83 (806 to 890 MHz) were removed for AMPS mobile phone services (leading to one side of some conversations being heard on older TV sets on those channels). On June 12, 2009, channels 52 to 69 (698 to 806 MHz) were removed and will be reallocated for other uses. In Canada, Channels 64 to 68 are no longer in use. In South Korea and the Philippines, Channels 60 to 69 are no longer used. In Brazil, these channels are used only for linking (it will be phased out in the future [1] or government-based networks pt:Anexo:Lista de canais da televisão digital brasileira#São Paulo 2.

In Europe, other recently abandoned TV channels are being used for DAB digital radio, in VHF band III.

Current uses

In the 1990s, it was decided that digital television would be limited to the current channels Channel 2 through Channel 51, so that another 18 channels (Channel 52 to Channel 69, 698 to 806 MHz) could be auctioned for private use by mobile phone and wireless network providers; four of the channels were to be reserved for emergency services such as police radios. Renumbering in this case is not relevant, as virtual channels can maintain the original analog TV station brand number, despite the fact that the station actually transmits on another channel.

Digital TV

Technically, the ATSC standard allows for a major virtual channel number from 1 - 99, followed by a separator ('.' or '-') and a digital subchannel number from 1 - 99 (for broadcast TV) or 1 - 999 (datacasting or cable TV). As such, it does not preclude the creation of a virtual channel 1.1 or a virtual channel 37.1:

"The major_channel_number shall be between 1 and 99. The value of major_channel_number shall be set such that in no case is a major_channel_number / minor_channel_number pair duplicated within the TVCT."[9]

However, the specification does not define any criteria to determine whom (if anyone) could ultimately be assigned the 1.1 virtual channel series for over-the-air broadcast in a local community; it merely defines a procedure to allocate virtual channels 02-69 based on holders of the corresponding (former) analogue NTSC licenses and designates virtual channels 70-99 for possible use to carry additional, unrelated programming via the facilities of these same broadcasters. (99 was used briefly by the now-defunct USDTV, for instance, although such applications are rare.)

Cable TV

The situation for cable television differs in that channel numbering is at the discretion of the cable system operator.

Digital cable subscribers in many areas, such as those serviced by Comcast and Charter Communications, can find video on demand content at Channel 1. The TV Guide Network is also often found on a cable system's Channel 1.

Cable subscribers in the New York area receive local news channel NY1 on channel one (actually 101), served by Time Warner Cable and Cablevision. The physical channel number is 10, but converter boxes convert to channel one.

Satellite TV

The situation for satellite television depends on the receiver; most FTA receivers will by default assign the first channel located during an initial signal scan as "Channel 0001" while package receivers sold by individual pay-TV providers will often use the SID, a virtual identifier sent as part of the satellite signal, as a channel number.

The original Dish Network DishPlayer PVR (model 7100/7200) displayed a PTV Services menu listing recorded videos and upcoming scheduled recordings if tuned to channel 1. This menu is internal to the personal video recorder and does not correspond to a broadcast signal.[10]

NTSC-J

Japanese public broadcaster NHK General TV broadcasts on Channel 1 in Tokyo and other cities. The Japanese Channel 1 is assigned to the frequency 90 to 96 MHz, just above the Japanese FM band which is 76 to 90 MHz. Frequencies corresponding to Japan's channel 1 through 3 (90-108MHz) are used primarily for FM radio broadcasting (88-108 MHz) outside Japan and correspond to cable 95-97 in North America.

References

  1. ^ http://www.fundinguniverse.com/company-histories/Zenith-Electronics-Corporation-Company-History.html
  2. ^ "Zenith Enters FM and TV Broadcasting", The Zenith Story (1954).
  3. ^ http://www.chicagotelevision.com/timeline.htm
  4. ^ CompassRose.org: WBKB Chicago
  5. ^ "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.
  6. ^ http://www.anarc.org/wtfda/channel1.htm
  7. ^ http://www.ntia.doc.gov/osmhome/LRSP/LRSP5a.htm
  8. ^ "TV Thaw", Time, April 21, 1952.
  9. ^ ATSC standard A/65C, page 32, Advanced Television Systems Committee, May 2006.
  10. ^ http://www.iwantptv.com/dishplayer/dishplayerguide.htm

External links


Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message