625 lines
This articleneeds additional citations forverification.(May 2023) |
625-line(orCCIR625/50) is a late 1940sEuropeananalogstandard-definition televisionresolution standard.[1][2]It consists of a 625-lineraster,with 576 lines carrying the visible image at 25interlacedframesper second. It was eventually adopted by countries using 50 Hzutility frequencyas regular TV broadcasts resumed after World War II.[3]With the introduction of color television in the 1960s,[4]it became associated with thePALandSECAManalog color systems.
A similar525-linesystem was adopted by countries using 60 Hz utility frequency (like theUS). Other systems, like375-line,405-line,441-line,455-lineand819-lineexisted, but became outdated or had limited adoption.
The modern standard-definitiondigital videoresolution576iis equivalent and can be used todigitizean analogue 625-line TV signal, or to generate a 625-line compatible analog signal.[5]
History
[edit]At the CCIRStockholmConference in July 1948 a first 625-line system with an 8 MHzchannel bandwidthwas proposed by theSoviet Union,based on 1946-48 studies[3]byMark Krivosheev.[6][7][8][9][10][11][12][13]This was initially known as theI.B.T.O.625-line system.
At a CCIRGenevameeting 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 byTelefunkenandWalter Bruch,and was supported byBelgium,Denmark,Italy,Netherlands,SwedenandSwitzerland.[3]
At a CCIR Geneva meeting in May 1951, the existingVHFbroadcast standards were standardized.[3]The older 405-line system was designatedCCIR System A,the Gerber Standard was designatedSystem B,the Belgian variantSystem Cand the I.B.T.O. standardSystem D.
In the 1960s, with the introduction ofUHFbroadcasts, new 625-line standards were adopted, again with slightly different broadcast parameters, leading to the creation of SystemsG,H,I,KandL.
Analog broadcast 625-line television standards
[edit]The followingInternational Telecommunication Unionstandardsuse 625-lines:
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 | |||||||
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
[edit]The followinganalog televisioncolor systems were used in conjunction with the previous standards (identified by a letter after the colour system indication):
- PALanalog color television system (ex: PAL-B, PAL-D, etc.)
- SECAManalog color television system (ex: SECAM-D, SECAM-L, etc.)
Digital video
[edit]625-lines is sometimes mentioned when digitizing analog video, or when outputting digital video in a standard-definition analog compatible format.
- 576i,astandard-definition televisiondigital video mode.
- PAL region,a common term regarding video games, meaning regions where the 625-lines PAL standard was traditionally used.
- PAL/SECAM DVD
- PAL/SECAM Video CD
- Rec. 601,a 1982 standard for encoding interlaced analog video signals in digital video form.
- D-1,a 1986 SMPTE component digital recording video standard.
- D-2,a 1988 SMPTE composite digital recording video standard.
See also
[edit]References
[edit]- ^Observer, Reflective (December 23, 2021)."Where did 625-line TV come from?".
- ^"Televisionen - Das Fernsehen in der UdSSR / TV in the USSR Die Geschichte des Fernsehens in Russland".www.scheida.at.
- ^abcd"Piet's Home-built Television".Maximus R&D.
- ^"Television broadcasting 1960-70: BBC 625-line services and the introduction of colour"(PDF).
- ^"What means 576i?".Afterdawn.com.
- ^""M.I. Krivosheev: participation in the development of mass TV broadcasting" - an exhibition at Ostankino TV Center ".eng.rscc.ru.
- ^"Mark Iosifovich Krivosheev (1922-2018)".ITU.
- ^On the beginning of broadcast in 625-lines 60 year s ago,625magazine (in Russian).Archived2016-03-04 at theWayback Machine
- ^"M.I. Krivocheev - an engineer's engineer"(PDF).EBU Technical Review.Spring 1993. pp. 27–28. Archived fromthe original(PDF)on 2004-12-30.
- ^"In the vanguard of television broadcasting - Professor Mark Krivocheev"(PDF).cra.ir.Archived fromthe original(PDF)on 2007-02-21.
- ^Observer, Reflective (2021-12-23)."Where did 625-line TV come from?".Medium.Retrieved2021-12-31.
- ^"625-Line Television System Origins - UK Vintage Radio Repair and Restoration Discussion Forum".www.vintage-radio.net.Retrieved2021-12-31.
- ^"Leader Electronics Corporation".Leader Electronics Corporation.
- ^abSuzuki, 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.
- ^ab"625-Line Television Broadcast Standards - UK Vintage Radio Repair and Restoration Discussion Forum".www.vintage-radio.net.
- ^ab"405 Alive - FAQ - 405-Line Television in History".www.bvws.org.uk.
- ^ab"The CCIR, the standards and the TV sets' market in France (1948-1985)"(PDF).
- ^abMagnetic Recording Handbook.Springer Science & Business Media. December 6, 2012.ISBN9789401094689– via Google Books.
- ^ab"Documents of the XIth Plenary Assembly - Oslo, 1966"(PDF).International Telecommunication Union. Volume V.
- ^ab"World Analogue Television Standards and Waveforms".August 30, 2012. Archived fromthe originalon 30 August 2012.
- ^abcde"World Analogue Television Standards and Waveforms".August 30, 2012. Archived fromthe originalon 30 August 2012.
- ^abc"Section 11A: Characteristics of systems for monochrome and colour television"(PDF).itu.int.Reportt 624-4.
- ^ab""M.I. Krivosheev: Participation in the development of mass TV broadcasting" - an exhibition at Ostankino TV Center ".
- ^ab"Mark Iosifovich Krivosheev (1922-2018)".
- ^abReference Data for Radio Engineers, ITT Howard W.Sams Co., New York, 1977, section 30
- ^"Specification of Television Standards for 625-Line System I Transmissions in the United Kingdom"(PDF).
- ^"World Analogue Television Standards and Waveforms".www.pembers.freeserve.co.uk.Archived fromthe originalon 30 August 2012.Retrieved12 January2022.
- ^Documents of the Xlth Plenary Assembly - Oslo, 1966 - Volume V - Sound Broadcasting Television(PDF).International Telecommunication Union. 1967.
- ^"Help Guide | On TV color systems".www.sony-asia.com.
- ^Tecnologica, Centro de Informacion (January 19, 1999)."Informacion Tecnologica".Centro de Informacion Tecnologica – via Google Books.
- ^"C.C.I.R. Report 624-4 Characteristics of television systems, 1990"(PDF).