819 line

819-line was an analog monochrome TV system developed and used in France[1][2] as television broadcast resumed after World War II. Transmissions started in 1949 and were active up to 1985, although limited to France, Belgium and Luxembourg.[3] It is associated with CCIR System E and F.[3]

"Marly Horses" test card from RTF Alger (predecessor of TV1 Algeria) from 1956, originally in 819 lines.

History

When Europe resumed TV transmissions after World War II (i.e. in the late 1940s and early 1950s) most countries standardized on 625-line television systems. The two exceptions were the British 405-line system, which had already been introduced in 1936, and the French 819-line system. During the 1940s René Barthélemy had already reached 1,015 lines[1] and even 1,042 lines.

On November 20, 1948, François Mitterrand, the then Secretary of State for Information, decreed a broadcast standard of 819 lines developed by Henri de France;[1][4] broadcasting began at the end of 1949 in this higher definition format. It was used in France by TF1, and in Monaco by Tele Monte Carlo.[5][6]

Some 819-line TV sets were available, like the Grammont 504-A-31 from 1951[7] and the Philips 14TX100 multi-standard 625/819-line TV from 1952[8][9]

The system was also adopted (with limited bandwidth, affecting image resolution) in 1953 in Belgium[1][4] by RTB and in 1955 in Luxembourg by Télé-Luxembourg.[10]

Broadcasts were discontinued in Belgium in February 1968, and in Luxembourg in September 1971. Despite some attempts to create a color SECAM version of the 819-line system,[1] France gradually abandoned the system in favor of the Europe-wide standard of 625-lines with the final 819-line transmissions taking place in Paris from the Eiffel Tower on 19 July 1983.[11]

Tele Monte Carlo in Monaco were the last broadcasters to transmit 819-line television, closing down their transmitter in 1985.

Technical details

This was arguably the world's first high-definition television system, and, by today's standards, it could be called 736i (as it had 737 lines active, but one of the lines was composed of 2 halves)[12] with a maximum theoretical resolution of 408×368 line pairs (which in digital terms can be expressed as broadly equivalent to 816×736 pixels) with a 4:3 aspect ratio. By comparison with modern digital standards, 720p is 1,280×720 pixels, of which the 4:3 portion would be 960×720 pixels, while PAL DVDs have a resolution of 720×576 pixels.

The testcards used with the system had resolution gratings that went up to 900 TV lines.[13][14] However, the theoretical picture quality far exceeded the capabilities of the analogue equipment of its time, and each 819-line channel occupied a wide 14 MHz of VHF bandwidth.

General technical specifications of the broadcast television systems used with 819-lines.[15][16]
Field frequency Active picture Field blanking No. of broad pulses Broad pulse width Line frequency Front porch Line sync Back porch Active line time Video/syncs ratio
50 Hz 737 lines 41 lines 1 per field 20.0 μs 20475 Hz 0.5 μs 2.5 μs 5.0 μs 40.8 μs 70/30

819-lines were broadcast using two CCIR systems, System E and System F.

System E and F specifications
CCIR System Lines Frame rate Channel bandwidth

(MHz)

 Visual bandwidth (MHz) Sound carrier offset Vestigial sideband Vision mod. Sound mod.
E 819 25 14 10 ±11.15 (+ on odd numbered channels; − on even numbered channels) 2.00 Pos. AM
F 819 25 7 5 +5.5 0.75 Pos. AM

System E

System E implementation provided very good (near HDTV) picture quality but with an uneconomical use of bandwidth; a 625/50 signal providing the same clarity as an 819-line image, but matted down 4:3 with the same number of lines, would still need nearly 6 MHz for the vision carrier alone (vs typical 5 to 6 MHz in actual use), and 5 MHz for 525/60 (vs typical 4.2 MHz), although a 405/50 transmission could get away with only 2.5 MHz (typical 3 MHz, as System A made no allowance for the Kell factor and thus had a "narrow pixel"/"tall line" appearance). Thus even an unusually crisp "standard" definition (or slightly soft 405-line) image only needed half, or even one-quarter the vision bandwidth of the 819-line system to give a "balanced" appearance, despite their lower overall resolution still seeming perfectly clear on the more affordable small-screen receivers often used in the pre-color era. With the usual additions of sound carrier and vestigial sideband the result was a combined signal that demanded approximately two to three times the bandwidth of more moderately specified standards, even when colour was added to them (as the color subcarrier resides within the luma signal space).

System E television channels were arranged as follows:

Ch picture (MHz) sound (MHz)
F2 52.40 41.25
F4 65.55 54.40
F5 164.00 175.15
F6 173.40 162.25
F7 177.15 188.30
F8 186.55 175.40
F8a 185.25 174.10
F9 190.30 201.45
F10 199.70 188.55
F11 203.45 214.60
F12 212.85 201.70

System F

System F was an adapted 819-line system used in Belgium and Luxembourg as an answer to the bandwidth problem, using only half the original vision bandwidth and approximately half the sound carrier offset. It allowed French 819-line programming to squeeze into the 7 MHz VHF broadcast channels used in those neighboring countries,[3] albeit with a substantial loss of horizontal resolution (408×737 effective); although this still offered approximately twice the actual clarity of 405-line System A (twice the lines, roughly the same horizontal definition), the contrast between vertical and horizontal resolution would have made it seem perceptually softer than a 625 line signal with the same bandwidth. Use of System F was discontinued in Belgium in February 1968, and in Luxembourg in September 1971.

Between 1976 and 1981 when French channel TF1 was switching area by area to the new analog 625-lines UHF network with SECAM colour, some transmitters and gapfillers broadcast the 819-line signal in UHF.[17] When switching to 625-lines, most gapfillers did not change UHF channel (e.g. many gapfillers using this transmission located in French Alps near Grenoble, Mont Salève and Geneva began broadcasting on UHF channel 42, and continue to use this frequency to this day). They were switched to 625-lines in June 1981.

Countries and territories that used the 819-line system

This is a list of nations that used the 819-line system for television broadcasting:

References
  1. Stout, Andy (2020). "France had a national HD TV system as far back as 1949". RedShark.
  2. Worswick, T. (March 11, 1959). "The B.B.C. Television Standards Converter". Journal of the SMPTE. 68 (3): 130–135. doi:10.5594/J14437 – via IEEE Xplore.
  3. BIRKINSHAW, DOUGLAS C (February 19, 2021). "New television standards: effect on British television". Transdiffusion.
  4. "Chronologie: Télévision". KronoBase la chronologie universelle.
  5. "Une bénédiction et une visite princière inaugurent Télé Monte-Carlo". Les radios au temps de la TSF. October 28, 2019.
  6. Parrot, Jacques (January 1, 1987). La Guerre des ondes: De Goebbels à Kadhafi. Plon (réédition numérique FeniXX). ISBN 9782259238137 – via Google Books.
  7. "Postwar British/European Grammont 504-A-31". Early Television Museum.
  8. "Postwar British/European Philips 14TX100". Early Television Museum.
  9. Philips 14TX100A Service Manual (PDF). Philips.
  10. MICHEL-DROIT (May 17, 1955). "Télé-Luxembourg a fait du nord-est de la France la région-témoin de la concurrence en matière de télévision". Le Monde.
  11. Rozat, Pascal (October 14, 2022). "Histoire de la télévision : une exception française ?". La Revue des Médias.
  12. Report 308-2 of the XIIth Pleniary Assembly of the CCIR – Characteristics of Monochrome Television Systems
  13. "Test card of the RTF with the horses of Marly". Getty Images.
  14. "Rétrospective : la mire à la télévision (1953 – 2002)". VivelaPub. January 5, 2012.
  15. "Vertical Blanking Interval of French and Belgian 819-Line Standards" (PDF). www.pembers.freeserve.co.uk. Archived from the original (PDF) on 24 September 2006. Retrieved 12 January 2022.
  16. Russell, Richard (2005). "Colour Test Card Generator - Introduction and specification". R. T. RUSSELL The home of BBC BASIC.
  17. TDF:situation des émetteurs au 31 December 1980

See also
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.