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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, sometimes called 525 line or monochrome NTSC, is the analog broadcast television system approved by the FCC (upon recommendation by the National Television Systems Committee - NTSC)[1] for use in the United States since July 1, 1941,[2][3] replacing the 441-line TV system introduced in 1938.[3] 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.

It was also adopted in most of the Americas and Caribbean, 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 on Cambodia and Vietnam (see Color standards section below).

The letter M designation was attributed by the ITU on the 1961 Stockholm meeting (see ITU identification scheme).[4]

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

Specifications

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

Further information: Broadcast television systems § ITU identification scheme

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 Sound modulation Notes
M 525 480 29.97 (NTSC color) 6 4.2 +4.5 0.75 Negative FM Most of the Americas and Caribbean; Myanmar, Philippines, South Korea, Taiwan (all NTSC-M)
Japan (NTSC-J)
Brazil (PAL-M)
Cambodia, Vietnam (SECAM-M).
30 (original)

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.

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 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.

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 and Vietnam (Hanoi and other northern cities).

References

  1. ^ Pursell, Carroll (April 30, 2008). A Companion to American Technology. John Wiley & Sons. ISBN 9780470695333 – via Google Books.
  2. ^ Herbert, Stephen (June 21, 2004). A History of Early Television. Taylor & Francis. ISBN 9780415326681 – via Google Books.
  3. ^ a b Meadow, Charles T. (February 11, 2002). Making Connections: Communication through the Ages. Scarecrow Press. ISBN 9781461706915 – via Google Books.
  4. ^ Final acts of the European Broadcasting Conference in the VHF and UHF bands. Stockholm, 1961.

See also