Talk:441-line television system

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Text and/or other creative content from History of television was copied or moved into 441-line television system. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists.

Some thoughts on Cleanup/clarification

Latest comment: 16 years ago1 comment1 person in discussion

Has the potential to be an interesting article but needs a lot of work/research/clarification.

A few areas need to be clarified particularly involving paramaters (perhaps a table layout would be better)

First off there seems to be confusion/incosistency over the meaning pf the terms "field rate" and "frame rate" too add to the confusion some of the transmissions used what we now call progressive scanning (i.e. no interlacing)

Secondly some of the paramaters such as: Field frequency 50 Hz Active picture 383 lines Field blanking 29 lines No. of broad pulses 8 per field Broad pulse width 36.3 µs Line frequency 11025 Hz Front porch 1.0 µs Line sync 9.0 µs Back porch 6.3 µs Active line time 74.3 µs Video/syncs ratio 70/30 image aspect ratio was close to 1.15:1 Frame rate 25Hz interlaced Are clearly only applicable to one/some of the variants of the system.

I believe some countries DID experiment with negative video modulation (possibly FM sound as well although this is less likely) but Vestigal sideband was probably only used in North America (And even there only in later years) The field/frame rate was not always synchronus with the mains frequency either (21 fps for example).

Incidently Ive always wondered why the BBC didnt move up to 441 lines after the initial Baird/EMI trials. While concerns about international programme exchange and reciever manufacturing economy may not have been paramount at the time surely it didnt take much foresight to anticipate that someday it would be. As for the Americans I cant help thinking a version of the 441 line system with 5 MHz channels. 0.75 MHz Vestigal sideband and negative modulation/FM sound could have been a contender even if the point is now moot. 213.40.217.126 (talk) 13:29, 5 December 2008 (UTC)Reply

383 i (or what happened 30 of the extra lines) ?

Latest comment: 13 years ago2 comments2 people in discussion

How came the 441 line system only produced 383 active lines when the 405-line television system managed 377 ? 86.112.91.158 (talk) 15:47, 26 August 2010 (UTC)Reply

Purely a matter of specification. In general early TV systems had long blanking intervals. The French 819 line system had very long intervals of 41 lines (in both fields) giving 737 active lines. 86.166.66.41 (talk) 17:59, 6 February 2011 (UTC)Reply

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