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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, 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]

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

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Some of the important specifications for System M are listed below:[11]

Color standards

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


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 301.001 frames per second, usually labeled as the rounded number 29.97.


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.


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


  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.
  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. ^ 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. ^ "World Analogue Television Standards and Waveforms". 2007-05-15. Archived from the original on 2007-05-15. Retrieved 2023-04-13.

See also

This page was last edited on 26 October 2023, at 08:36
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