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625 lines

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This article is about the analog standard-definition resolution. For the equivalent digital SD resolution, see 576i.

625-line (or CCIR 625/50) is a late 1940s European analog standard-definition television resolution standard.[1][2] It consists of a 625-line raster, with 576 lines carrying the visible image at 25 interlaced frames per second. It was eventually adopted by countries using 50 Hz utility frequency as regular TV broadcasts resumed after World War II.[3] With the introduction of color television in the 1960s,[4] it became associated with the PAL and SECAM analog color systems.

Analog TV standard by nation: countries using 625-line are in blue.
Image showing the full 625 line raster containing the visible 576 line image area

A similar 525-line system was adopted by countries using 60 Hz utility frequency (like the US). Other systems, like 375-line, 405-line, 441-line, 455-line and 819-line existed, but became outdated or had limited adoption.

The modern standard-definition digital video resolution 576i is equivalent and can be used to digitize an analogue 625-line TV signal, or to generate a 625-line compatible analog signal.[5]

History

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At the CCIR Stockholm Conference in July 1948 a first 625-line system with an 8 MHz channel bandwidth was proposed by the Soviet Union, based on 1946-48 studies[3] by Mark Krivosheev.[6][7][8][9][10][11][12][13] This was initially known as the I.B.T.O. 625-line system.

At a CCIR Geneva meeting in July 1950, Dr. Gerber (a Swiss engineer), proposed a modified 625-line system using a 7 MHz channel bandwidth - informally known as the "Gerber Standard". The system was based on work by Telefunken and Walter Bruch, and was supported by Belgium, Denmark, Italy, Netherlands, Sweden and Switzerland.[3]

At a CCIR Geneva meeting in May 1951, the existing VHF broadcast standards were standardized.[3] The older 405-line system was designated CCIR System A, the Gerber Standard was designated System B, the Belgian variant System C and the I.B.T.O. standard System D.

In the 1960s, with the introduction of UHF broadcasts, new 625-line standards were adopted, again with slightly different broadcast parameters, leading to the creation of Systems G, H, I, K and L.

Analog broadcast 625-line television standards

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The following International Telecommunication Union standards use 625-lines:

World analog 625-line television systems[14]
ITU System Letter Designation B
[15][16][17][18] 		C
[19][20][21] 		D
[22][21][23][24] 		G
[25] 		H
[25] 		I
[26] 		K
[22][27] 		K1 L
[28][21] 		N
[29][30]
Previous designation Gerber Standard
[15][16][17][18] 		Belgian 625-line system
[19][20][21] 		I.B.T.O. 625-line system
[22][21][23][24]
Band VHF UHF VHF/UHF UHF VHF/UHF
Introduced 1950 1953 1948 1961 1961 1962 1961 1964 1961 1951
Channel bandwidth (MHz) 7 8 6
Video bandwidth (MHz) 5 6 5 5.5 6 4.2
Vision sound carrier separation (MHz) +5.5 +6.5 +5.5 +5.9996 +6.5 -6.5 +4.5
Vestigial sideband (MHz) 0.75 1.25 0.75 1.25 0.75
Vision modulation (+, -) - + - + -
Sound modulation (AM, FM) FM AM FM AM FM
Frequency of chrominance subcarrier (MHz) 4.43 none 4.43 3.58
Vision/sound power ratio 5:1 8:1
Usual color PAL/SECAM none SECAM/PAL PAL/SECAM PAL SECAM/PAL SECAM PAL
Assumed display device gamma[31][14] 2.8 2.0 2.8

Analog color 625-line television systems

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The following analog television color systems were used in conjunction with the previous standards (identified by a letter after the colour system indication):

  • PAL analog color television system (ex: PAL-B, PAL-D, etc.)
  • SECAM analog color television system (ex: SECAM-D, SECAM-L, etc.)

Digital video

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625-lines is sometimes mentioned when digitizing analog video, or when outputting digital video in a standard-definition analog compatible format.

See also

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References

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  1. ^ Observer, Reflective (December 23, 2021). "Where did 625-line TV come from?".
  2. ^ "Televisionen - Das Fernsehen in der UdSSR  / TV in the USSR Die Geschichte des Fernsehens in Russland". www.scheida.at.
  3. ^ a b c d "Piet's Home-built Television". Maximus R&D.
  4. ^ "Television broadcasting 1960-70: BBC 625-line services and the introduction of colour" (PDF).
  5. ^ "What means 576i?". Afterdawn.com.
  6. ^ ""M.I. Krivosheev: participation in the development of mass TV broadcasting" - an exhibition at Ostankino TV Center". eng.rscc.ru.
  7. ^ "Mark Iosifovich Krivosheev (1922-2018)". ITU.
  8. ^ On the beginning of broadcast in 625-lines 60 year s ago, 625 magazine (in Russian). Archived 2016-03-04 at the Wayback Machine
  9. ^ "M.I. Krivocheev - an engineer's engineer" (PDF). EBU Technical Review. Spring 1993. pp. 27–28. Archived from the original (PDF) on 2004-12-30.
  10. ^ "In the vanguard of television broadcasting - Professor Mark Krivocheev" (PDF). cra.ir. Archived from the original (PDF) on 2007-02-21.
  11. ^ Observer, Reflective (2021-12-23). "Where did 625-line TV come from?". Medium. Retrieved 2021-12-31.
  12. ^ "625-Line Television System Origins - UK Vintage Radio Repair and Restoration Discussion Forum". www.vintage-radio.net. Retrieved 2021-12-31.
  13. ^ "Leader Electronics Corporation". Leader Electronics Corporation.
  14. ^ a b Suzuki, N.; Fukinuki, T.; Kageyama, M.; Ishikura, K.; Yoshigi, H. (January 1, 1994). "Multiplexing scheme of helper signals on bars in EDTV-II". International Broadcasting Convention - IBC '94. Vol. 1994. pp. 32–36. doi:10.1049/cp:19940723 – via digital-library.theiet.org.
  15. ^ a b "625-Line Television Broadcast Standards - UK Vintage Radio Repair and Restoration Discussion Forum". www.vintage-radio.net.
  16. ^ a b "405 Alive - FAQ - 405-Line Television in History". www.bvws.org.uk.
  17. ^ a b "The CCIR, the standards and the TV sets' market in France (1948-1985)" (PDF).
  18. ^ a b Magnetic Recording Handbook. Springer Science & Business Media. December 6, 2012. ISBN 9789401094689 – via Google Books.
  19. ^ a b "Documents of the XIth Plenary Assembly - Oslo, 1966" (PDF). International Telecommunication Union. Volume V.
  20. ^ a b "World Analogue Television Standards and Waveforms". August 30, 2012. Archived from the original on 30 August 2012.
  21. ^ a b c d e "World Analogue Television Standards and Waveforms". August 30, 2012. Archived from the original on 30 August 2012.
  22. ^ a b c "Section 11A: Characteristics of systems for monochrome and colour television" (PDF). itu.int. Reportt 624-4.
  23. ^ a b ""M.I. Krivosheev: Participation in the development of mass TV broadcasting" - an exhibition at Ostankino TV Center".
  24. ^ a b "Mark Iosifovich Krivosheev (1922-2018)".
  25. ^ a b Reference Data for Radio Engineers, ITT Howard W.Sams Co., New York, 1977, section 30
  26. ^ "Specification of Television Standards for 625-Line System I Transmissions in the United Kingdom" (PDF).
  27. ^ "World Analogue Television Standards and Waveforms". www.pembers.freeserve.co.uk. Archived from the original on 30 August 2012. Retrieved 12 January 2022.
  28. ^ Documents of the Xlth Plenary Assembly - Oslo, 1966 - Volume V - Sound Broadcasting Television (PDF). International Telecommunication Union. 1967.
  29. ^ "Help Guide | On TV color systems". www.sony-asia.com.
  30. ^ Tecnologica, Centro de Informacion (January 19, 1999). "Informacion Tecnologica". Centro de Informacion Tecnologica – via Google Books.
  31. ^ "C.C.I.R. Report 624-4 Characteristics of television systems, 1990" (PDF).
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