CCIR System M

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Analog TV systems global map, with System M in red.

CCIR System M,[1][2][3] sometimes called 525–line, monochrome NTSC, NTSC-M, or CCIR-M,[4][5] is the analog broadcast television system approved by the FCC (upon recommendation by the National Television Systems Committee - NTSC)[6] for use in the United States since July 1, 1941,[7][8] replacing the 441-line TV system introduced in 1938.[8] System M comprises a total of 525 interlaced lines of video, of which 486 contain the image information, at 30 frames per second. Video is amplitude modulated and audio is frequency modulated, with a total bandwidth of 6 MHz for each channel, including a guard band.[9]

It was also adopted in the Americas and Caribbean; Myanmar, Philippines, South Korea, Taiwan and Japan (here with minor differences, informally referred to as System J). System M doesn't specify a color system, but NTSC (NTSC-M) was normally used, with some exceptions: NTSC-J in Japan, PAL-M in Brazil and SECAM-M in Cambodia, Laos and Vietnam (see Color standards section below).

The letter M designation was attributed by the ITU at the 1961 Stockholm meeting (see ITU identification scheme).[10]

In 1965, Thailand decided to replace System M with 625-line CCIR System B, which started in 1967, adopting PAL at the same time.[11]

Since 2015, System M is being replaced by digital broadcasting, in countries such as the Americas, Japan, South Korea, Taiwan and the Philippines.

Specifications

Further information: Broadcast television systems § ITU identification scheme

Some of the important specifications for System M are listed below:[12]

  • Radio spectrum of a System M television channel with NTSC color
    Radio spectrum of a System M television channel with NTSC color
  • Plan showing VHF frequency ranges for ITU Systems
    Plan showing VHF frequency ranges for ITU Systems

Color standards

Television color encoding by nation; Brazil (PAL-M) and all green countries (NTSC) are based on monochrome System M.

NTSC-M and NTSC-J

Main articles: NTSC and NTSC-J

Strictly speaking, System M does not designate how color is transmitted. However, in nearly every System M country NTSC is used for color television. This combination is called NTSC-M, but usually simply referred to as "NTSC", because of the relative lack of importance of black-and-white television. In NTSC-M and Japan's NTSC-J, the frame rate is offset slightly, becoming 30⁄1.001 frames per second, usually labeled as the rounded number 29.97.

PAL-M

Main article: PAL-M

The main exception to System M's being paired with NTSC color is Brazil, where PAL color is used instead, resulting in the PAL-M combination unique to that country. It is monochrome-compatible with other System M countries, but not compatible with other PAL countries, which use 625-line based systems.

SECAM-M

Main article: SECAM

Between 1970 and 1991 a variation of the SECAM color system, known as SECAM-M, was used in Cambodia,[13] Laos, and Vietnam (Hanoi and other northern cities).

References

  1. ^ Korea Electronics Association (1991). Journal of Korean Electronics (PDF).
  2. S2CID 11038252
    – via IEEE Xplore.
  3. ^ "C.C.I.R - Documents of the Xlth Plenary Assembly Oslo, 1966" (PDF).
  4. S2CID 232373635
    – via IEEE Xplore.
  5. S2CID 11567258
    – via IEEE Xplore.
  6. ISBN 9780470695333
    – via Google Books.
  7. ISBN 9780415326681
    – via Google Books.
  8. ^
    ISBN 9781461706915
    – via Google Books.
  9. ^ Rova, Andy (February 22, 2005). NTSC: Nice Technology, Super Color.
  10. ^ Final acts of the European Broadcasting Conference in the VHF and UHF bands. Stockholm, 1961.
  11. ^ "The Project of Nationwide Television Broadcasting Network in Thailand" (PDF). Overseas Technical Cooperation Agency, Government of Japan. January 1967. p. 234. Retrieved 4 March 2024.
  12. ^ "World Analogue Television Standards and Waveforms". 2007-05-15. Archived from the original on 2007-05-15. Retrieved 2023-04-13.
  13. ^ Broadband Data Book (PDF). Cisco. August 2019. p. 31.

See also

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