{{Short description|Analog broadcast television system}} {{More citations needed|date=July 2022}} thumb|500px|Analog TV systems global map, with System M in red. '''CCIR System M''',<ref>{{cite book |last=Korea Electronics Association |url=https://koreascience.kr/article/JAKO199173871470038.pdf |title=Journal of Korean Electronics |year=1991}}</ref><ref>{{cite book |first1=Rodney Martínez |last1=Alonso |first2=Ernesto Fontes |last2=Pupo |first3=Changyong |last3=Pan |title=2015 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting |chapter=Co-channel and adjacent channel interference in DTMB with 6MHz channel bandwidth |date=June 10, 2015 |pages=1–5 |doi=10.1109/BMSB.2015.7177274 |isbn=978-1-4799-5865-8 |s2cid=11038252}}</ref><ref name="auto2">{{cite web |title=C.C.I.R - Documents of the Xlth Plenary Assembly Oslo, 1966 |url=https://search.itu.int/history/HistoryDigitalCollectionDocLibrary/4.277.43.en.1006.pdf}}</ref> sometimes called '''525–line''', '''NTSC''', '''NTSC-M''', or '''CCIR-M''',<ref>{{cite book |chapter=Protection ratios and overload thresholds between 700 MHz FDD-LTE and analog/digital terrestrial television |first1=Ernesto Fontes |last1=Pupo |first2=Rufino Cabrera |last2=Alvarez |first3=Alejandro González |last3=García |first4=Reinier Díaz |last4=Hernández |title=2020 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB) |date=October 10, 2020 |pages=1–5 |via=IEEE Xplore |doi=10.1109/BMSB49480.2020.9379925 |isbn=978-1-7281-5784-9 |s2cid=232373635}}</ref><ref>{{cite book |chapter=Interference between UHF analog/digital television and LTE APT 700 MHz band: A field evaluation |first1=Martínez |last1=Odiaga |first2=Hansel |last2=Joussef |first3=Yarlequé |last3=Medina |first4=Manuel |last4=Augusto |title=2016 8th IEEE Latin-American Conference on Communications (LATINCOM) |date=November 10, 2016 |pages=1–5 |via=IEEE Xplore |doi=10.1109/LATINCOM.2016.7811615 |isbn=978-1-5090-5137-3 |s2cid=11567258}}</ref> is the analog broadcast television system standardized by CCIR and approved by the FCC (upon recommendation by the National Television System Committee - NTSC)<ref>{{cite book |url=https://books.google.com/books?id=48YOVXgkq8QC&dq=525-line+standard+July+1%2C+1941.&pg=PA323 |title=A Companion to American Technology |first=Carroll |last=Pursell |date=April 30, 2008 |publisher=John Wiley & Sons |isbn=9780470695333 |via=Google Books}}</ref> for use in the United States since July 1, 1941,<ref>{{cite book |url=https://books.google.com/books?id=i_MndBVwJL8C&dq=525-line+standard+July+1%2C+1941.&pg=PA263 |title=A History of Early Television |first=Stephen |last=Herbert |date=June 21, 2004 |publisher=Taylor & Francis |isbn=9780415326681 |via=Google Books}}</ref><ref name="auto">{{cite book |url=https://books.google.com/books?id=iDEuQ_l__i0C&dq=525-line+standard+July+1%2C+1941.&pg=PA240 |title=Making Connections: Communication through the Ages |first=Charles T. |last=Meadow |date=February 11, 2002 |publisher=Scarecrow Press |isbn=9781461706915 |via=Google Books}}</ref> replacing the 441-line TV system introduced in 1938.<ref name="auto"/> It is also known as EIA standard 170.<ref>{{Citation |title=Canon ES8400V Instruction Manual |publisher=Canon |page=72}}</ref> 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.<ref>{{cite book |last=Rova |first=Andy |url=https://www2.cs.sfu.ca/CourseCentral/820/mark/material/postscript/Presentations/arova_NTSC.ppt |title=NTSC: Nice Technology, Super Color |date=February 22, 2005}}</ref>
It was also adopted in the Americas and Caribbean; Myanmar, Philippines, South Korea, Taiwan, Thailand, 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).<ref>[http://www.itu.int/dms_pub/itu-r/opb/act/R-ACT-RRC.1-1961-PDF-E.pdf Final acts of the European Broadcasting Conference in the VHF and UHF bands. Stockholm, 1961.]</ref>
In 1965, Thailand decided to replace System M with the 625-line CCIR System B, which began implementation in 1967 and eventually adopted the PAL color standard.<ref>{{cite web |title=The Project of Nationwide Television Broadcasting Network in Thailand |url=https://openjicareport.jica.go.jp/pdf/10502987_01.pdf |publisher=Overseas Technical Cooperation Agency, Government of Japan |access-date=4 March 2024 |pages=234 |date=January 1967}}</ref>
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 == {{More|Broadcast television systems#ITU identification scheme}} Some of the important specifications for System M are listed below:<ref>{{cite web |date=2007-05-15 |title=World Analogue Television Standards and Waveforms |url=http://www.pembers.freeserve.co.uk/World-TV-Standards/Transmission-Systems.html#CCIR |access-date=2023-04-13 |archive-url=https://web.archive.org/web/20070515044128/http://www.pembers.freeserve.co.uk/World-TV-Standards/Transmission-Systems.html#CCIR |archive-date=2007-05-15}}</ref> * Frame rate: 29.97 Hz (color), 30 Hz (monochrome) * Field rate: 59.94 Hz (color), 60 Hz (monochrome) * Lines (total): 525 * Lines (visible): 480 * Line rate: 15.734 kHz (color), 15.750 kHz (monochrome) * Visual bandwidth: 4.2 MHz * Vision modulation: Negative * Preemphasis: 75 μs * Sound modulation: FM * Sound offset: +4.5 MHz * Channel bandwidth: 6 MHz * Vestigial sideband: 0.75 MHz * Color standards: NTSC-M, NTSC-J, PAL-M, SECAM-M, Clear-Vision
<gallery mode="packed"> File:Ntsc channel.svg|Radio spectrum of a System M television channel with NTSC color File:VHF Usage.svg|Plan showing VHF frequency ranges for ITU Systems </gallery>
== Color standards == [[File:PAL-NTSC-SECAM.svg|thumb|500px|Television color encoding by nation: Brazil (PAL-M) and all green countries (NTSC) - except Japan - are based on monochrome System M.]]
=== NTSC-M and NTSC-J === {{Main|NTSC|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 {{frac|30|1.001}} frames per second, usually labeled as the rounded number 29.97.
=== PAL-M === {{Main|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|SECAM}} Between 1970 and 1991 a variation of the SECAM color system, known as SECAM-M, was used in Cambodia,<ref>{{Cite book |url=https://www.cisco.com/c/dam/en/us/solutions/service-provider/industry/cable/pdfs/broadband-data-book.pdf |title=Broadband Data Book |publisher=Cisco |date=August 2019 |pages=31}}</ref> Laos, and Vietnam (Hanoi and other northern cities).
=== Clear-Vision === {{Main|Clear-Vision}} Clear-Vision is a Japanese EDTV (Extended Definition TV)<ref name=":8">{{cite web |last=Fukinuki |first=Takahiko |date=March 1991 |title=EDTV |url=https://search.ieice.org/bin/summary.php?id=e74-b_3_540}}</ref><ref name=":9">{{cite web |date=February 5, 1992 |title=HI-Vision TV is given a low survival rating |url=https://www.afr.com/politics/hi-vision-tv-is-given-a-low-survival-rating-19920205-k4t0m |website=Australian Financial Review}}</ref> television system introduced in the 1990s, that improves audio and video quality while remaining compatible with the existing System M broadcast standard.<ref name=":8" /><ref name=":13">{{cite news |last=Pollack |first=Andrew |date=September 15, 1994 |title=Japanese Taking to Wide-Screen TV |url=https://www.nytimes.com/1994/09/15/business/japanese-taking-to-wide-screen-tv.html |work=The New York Times |via=NYTimes.com}}</ref> Developed to improve analog NTSC,<ref>{{cite book |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1118-1-199710-W!!PDF-E.pdf |title=Recommendation ITU-R BT.1118-1 - Enhanced compatible widescreen television based on conventional television systems |publisher=ITU |year=1997}}</ref> it adds features like progressive scan, ghost cancellation and widescreen image format.<ref name=":10">{{cite web |title=Digital Television in Europe and Japan |url=https://hartj.pages.iu.edu/documents/dtveurjpn_000.pdf}}</ref>
== See also == * NTSC — dominant color system used with System M, so much so that System M is often referred to as "NTSC". Much of the information in the NTSC article is actually about System M. * Broadcast television systems — explains other types of television system standards * Multichannel Television Sound — usual method for adding stereo to System M and System N audio carriers * Pan-American television frequencies
== References == {{reflist}}
{{Video formats}} {{Analogue TV transmitter topics}}
Category:Telecommunications-related introductions in 1941 Category:ITU-R recommendations Category:Television technology Category:Video formats Category:CCIR System