CCIR System M#SECAM-M

{{Short description|Analog broadcast television system}}

{{More citations needed|date=July 2022}}

File:Analog-TV-Systems.jpg

CCIR System M,{{cite book |last=Korea Electronics Association |url=https://koreascience.kr/article/JAKO199173871470038.pdf |title=Journal of Korean Electronics |year=1991}}{{cite book |url=https://ieeexplore.ieee.org/document/7177274 |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 |via=IEEE Xplore |doi=10.1109/BMSB.2015.7177274 |isbn=978-1-4799-5865-8 |s2cid=11038252}}{{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}} sometimes called 525–line, NTSC, NTSC-M, or CCIR-M,{{cite book |chapter-url=https://ieeexplore.ieee.org/document/9379925 |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}}{{cite book |chapter-url=https://ieeexplore.ieee.org/document/7811615|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}} is the analog broadcast television system approved by the FCC (upon recommendation by the National Television System Committee - NTSC){{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}} for use in the United States since July 1, 1941,{{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}}{{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}} replacing the 441-line TV system introduced in 1938. It is also known as EIA standard 170.{{Citation |title=Canon ES8400V Instruction Manual |publisher=Canon |page=72}} 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.{{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}}

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).[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.]

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

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.