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Television line count by nation; countries that are using System M or J currently or have used them prior to digital switchover, are in green.
Television line count by nation; countries that are using System M or J currently or have used them prior to digital switchover, are in green.

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 displays a total of 525 lines of video (with 480 carrying visible image information) at 30 frames per second using 6 MHz spacing between channel numbers, and is used for both VHF and UHF channels. Video is amplitude modulated.[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 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.


Further information: Broadcast television systems § ITU identification scheme

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

World television systems
System(CCIR) Lines (total) Lines (visible) Frame rate (fps) Channel bandwidth (MHz) Visual bandwidth (MHz) Sound offset (MHz) Vestigial sideband (MHz) Vision modulation Preemphasis Sound modulation Color Standards
M 525 480 29.97 (NTSC color) 6 4.2 +4.5 0.75 Negative 75 μs FM NTSC-M
30 (original/PAL color)

Color standards

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


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 called 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.


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.


Main article: SECAM

Between 1970 and 1991 a variation of the SECAM color system, known as SECAM-M, was used in Cambodia 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". 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