18 Mar
2015
18 Mar
'15
6:25 a.m.
A discussion about sync rates on a TV signal.
Christian Corti <cc at informatik.uni-stuttgart.de> Wrote:
This has absolutely *nothing* to do with NTSC or PAL
(or SECAM or
whatever). NTSC etc. are colour encoding standards and don't describe in
any way how a image signal is generated (fields, syncs, timing). They only
describe how to put colour information into the signal.
Christian
Sorry, but this is UNTRUE.? There have
been several NTSC standards. The first one defined the signals for standard Black/White
TV, it dates from the 1940s.? It defined such things as horizontal sync, vertical sync,
field definitions,? and equalizing pulses (among other things).? This version used a
horizontal sync rate of 15750Hz, and a vertical sync of 60Hz (field rate).? The later NTSC
standard (from the 1950's) added the color definitions (color burst, re-definition of
horizontal sync, color phase signals, color sub-carrier, etc.).? This version reduced the
sync rates by 0.1%, yielding a horizontal rate of 15734Hz, and a vertical rate of
59.94Hz.? This was needed to make things proper multiples of the color burst rate.? A
later definition added stereo audio (related to horizontal sync).
If you know things about the signal, you know that there are 4 field types in NTSC color
that differ with phase start of color burst, and odd/even field.? I believe that PAL has
8, but I'm not exactly sure.
Yes, PAL and SECAM are color definitions.? They are encoded over various underlying TV
sync systems.? One can make a SECAM receiver work a PAL signal.
Many of the broadcast standards have been dictated by governments.? I believe that the
625/50 standard is "CCIR"? What devices generate is anybodys guess.? What TV
sets accept is a crap shoot if it isn't "standard".
18 Mar
18 Mar
9:53 a.m.
On Mar 18, 2015, at 6:25 AM, Tom Watson <tsw-cc at
johana.com> wrote:
A discussion about sync rates on a TV signal.
...
Many of the broadcast standards have been dictated by governments. I believe that the
625/50 standard is "CCIR?
At one time there were at least four B&W video transmission standards in Europe (we
had a tube TV with a 4-position selection knob to support them). 625/50 regular, 625/50
inverted in some way (?) used by the Dutch speaking Belgian stations, 819/50 for France,
and a different 819/50 for French speaking Belgian stations.
paul
10:25 a.m.
"Apparently in the early days of colour TV (I do not know which system)
they were doing closed-
circuit tests. The camera was pointed at a known test subject, the image on
the monitor was
inspected and things were tweaked so it looked OK. One of the test subjects
was a still life of
a bowl of fruit. One day they just could not get a reasonable colour image
no matter how much
they fiddled with the phase shift controls, etc. And then somebody had the
sense to look at the
subject. Some joker had painted the banana blue..."
That story IS true, it happened at NBC while RCA was testing the
preproduction TK-40 cameras at the colonial theater in NYC.
It was a late night test and there had been problems all day with the
equipment.
On Wed, Mar 18, 2015 at 9:53 AM, Paul Koning <paulkoning at comcast.net> wrote:
--
Matt Patoray
Owner, MSP Productions
(330)542-3698
mspproductions at gmail.com
KD8AMG Amateur Radio Call Sign
On Mar 18, 2015, at 6:25 AM, Tom Watson
<tsw-cc at johana.com> wrote:
A discussion about sync rates on a TV signal.
...
Many of the broadcast standards have been dictated by governments. I
believe that
the 625/50 standard is "CCIR?
At one time there were at least four B&W video transmission standards in
Europe (we had a tube TV with a 4-position selection knob to support
them). 625/50 regular, 625/50 inverted in some way (?) used by the Dutch
speaking Belgian stations, 819/50 for France, and a different 819/50 for
French speaking Belgian stations.
paul
2:18 p.m.
At one time there were at least four B&W video transmission standards in Europe (we
had a tube TV with a
4-position selection knob to support them). 625/50 regular, 625/50 inverted in some way
(?) used by the Dutch
speaking Belgian stations, 819/50 for France, and a different 819/50 for French speaking
Belgian stations.
Not part of the _video_ signal, but part of the overall signal : IIRC continental Europe
(mostly?) put the sound
carrier 5.5 MHz way from the video carrier, but the UK had a 6MHz offset.
-tony
20 Mar
20 Mar
1:40 p.m.
On 2015-03-18 14:53, Paul Koning wrote:
There are a number of CCIR 625/50 standards, as well as other CCIR/ITU-R
standards for other broadcast systems. CCIR was a precursor to ITU-R,
which is a UN agency, in common with the FAO, the ICAO, the ILO, the
IMO, the IMF, etc etc.
On Mar 18,
2015, at 6:25 AM, Tom Watson <tsw-cc at johana.com> wrote:
A discussion about sync rates on a TV signal.
...
Many of the broadcast standards have been dictated by governments. I believe that the
625/50 standard is "CCIR?
At one time there were at least four B&W video
transmission standards in Europe (we had a tube TV with a 4-position selection knob to
support them). 625/50 regular, 625/50 inverted in some way (?) used by the Dutch speaking
Belgian stations, 819/50 for France, and a different 819/50 for French speaking Belgian
stations.
paul
3412
days inactive
3414
days old
4 comments
5 participants
participants (5)
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ard＠p850ug1.demon.co.uk -
jonas＠otter.se -
mspproductions＠gmail.com -
paulkoning＠comcast.net -
tsw-cc＠johana.com