Jump to content

CCIR System M

Edit links
From Wikipedia, the free encyclopedia
Analog TV systems global map, with System M in red.

CCIR System M,[1][2][3] sometimes called 525–line, NTSC, NTSC-M, or CCIR-M,[4][5] is the analog broadcast television system approved by the FCC (upon recommendation by the National Television System 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] It is also known as EIA standard 170.[9] 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.[10]

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 color encoding 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).[11]

In 1965, Thailand decided to replace System M with 625-line CCIR System B, which started in 1967, adopting PAL at the same time.[12]

Circa 2003, the transition from analog System M to digital television broadcasting began, and in 2009 the United States ended high power analog transmissions. Other nations such as Japan, South Korea, and Taiwan also transitioned to digital while the Philippines remain on analog transmissions with digital simulcasts.

Specifications

[edit]
Further information: Broadcast television systems § ITU identification scheme

Some of the important specifications for System M are listed below:[13]

  • 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

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

NTSC-M and NTSC-J

[edit]
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 color encoding 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

[edit]
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

[edit]
Main article: SECAM

Between 1970 and 1991 a variation of the SECAM color system, known as SECAM-M, was used in Cambodia,[14] Laos, and Vietnam (Hanoi and other northern cities).

Clear-Vision

[edit]
Main article: Clear-Vision

Clear-Vision is a Japanese EDTV (Extended Definition TV)[15][16] television system introduced in the 1990s, that improves audio and video quality while remaining compatible with the existing System M broadcast standard.[15][17] Developed to improve analog NTSC,[18] it adds features like progressive scan, ghost cancellation and widescreen image format.[19]

See also

[edit]

References

[edit]
  1. ^ Korea Electronics Association (1991). Journal of Korean Electronics (PDF).
  2. ^ Alonso, Rodney Martínez; Pupo, Ernesto Fontes; Pan, Changyong (June 10, 2015). "Co-channel and adjacent channel interference in DTMB with 6MHz channel bandwidth". 2015 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting. pp. 1–5. doi:10.1109/BMSB.2015.7177274. ISBN 978-1-4799-5865-8. S2CID 11038252 – via IEEE Xplore.
  3. ^ "C.C.I.R - Documents of the Xlth Plenary Assembly Oslo, 1966" (PDF).
  4. ^ Pupo, Ernesto Fontes; Alvarez, Rufino Cabrera; García, Alejandro González; Hernández, Reinier Díaz (October 10, 2020). "Protection ratios and overload thresholds between 700 MHz FDD-LTE and analog/digital terrestrial television". 2020 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB). pp. 1–5. doi:10.1109/BMSB49480.2020.9379925. ISBN 978-1-7281-5784-9. S2CID 232373635 – via IEEE Xplore.
  5. ^ Odiaga, Martínez; Joussef, Hansel; Medina, Yarlequé; Augusto, Manuel (November 10, 2016). "Interference between UHF analog/digital television and LTE APT 700 MHz band: A field evaluation". 2016 8th IEEE Latin-American Conference on Communications (LATINCOM). pp. 1–5. doi:10.1109/LATINCOM.2016.7811615. ISBN 978-1-5090-5137-3. S2CID 11567258 – via IEEE Xplore.
  6. ^ Pursell, Carroll (April 30, 2008). A Companion to American Technology. John Wiley & Sons. ISBN 9780470695333 – via Google Books.
  7. ^ Herbert, Stephen (June 21, 2004). A History of Early Television. Taylor & Francis. ISBN 9780415326681 – via Google Books.
  8. ^ a b Meadow, Charles T. (February 11, 2002). Making Connections: Communication through the Ages. Scarecrow Press. ISBN 9781461706915 – via Google Books.
  9. ^ Canon ES8400V Instruction Manual, Canon, p. 72
  10. ^ Rova, Andy (February 22, 2005). NTSC: Nice Technology, Super Color.
  11. ^ Final acts of the European Broadcasting Conference in the VHF and UHF bands. Stockholm, 1961.
  12. ^ "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.
  13. ^ "World Analogue Television Standards and Waveforms". 2007-05-15. Archived from the original on 2007-05-15. Retrieved 2023-04-13.
  14. ^ Broadband Data Book (PDF). Cisco. August 2019. p. 31.
  15. ^ a b Fukinuki, Takahiko (March 1991). "EDTV".
  16. ^ "HI-Vision TV is given a low survival rating". Australian Financial Review. February 5, 1992.
  17. ^ Pollack, Andrew (September 15, 1994). "Japanese Taking to Wide-Screen TV". The New York Times – via NYTimes.com.
  18. ^ Recommendation ITU-R BT.1118-1 - Enhanced compatible widescreen television based on conventional television systems (PDF). ITU. 1997.
  19. ^ "Digital Television in Europe and Japan" (PDF).
Retrieved from "https://en.wikipedia.org/w/index.php?title=CCIR_System_M&oldid=1254869860"