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  #76  
Old 04-06-2015, 08:43 PM
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dtvmcdonald dtvmcdonald is offline
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As to efficient use of spectrum, COFDM and QAM are identical, **IF**
COFDM uses no guard interval, in which case multipath removal has
to be done using the same methods as ATSC. ATSC is less efficient by a
bit because of the useless lower sideband (using the same coding
for COFDM and QAM as NTSC, of course, which can be done using plain
4-VSB for NTSC and 16QAM for the others including the COFDM carriers.)
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  #77  
Old 01-13-2018, 06:16 PM
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  #78  
Old 05-05-2020, 06:03 AM
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Quote:
Originally Posted by NewVista View Post
So the sneaky Sony TV would store the 'NTSC' lines and repeat them in place if the sequential 'PAL' lines

A standard PAL-D TV would store the 'NTSC' line and process it with subsequent 'PAL' line. This would halve the chroma vertical resolution.

But it gets worse because of interlaced scanning: now sampled detail from two lines above is added to 'PAL' line
creating more degradation than unprocessed pure 'PAL' & 'NTSC' lines (as in a PAL-S receiver)?
And if there is picture motion even more blur.
Remember reading somewhere that the Sony idea of repeating a dropped line of chroma with a delay line wouldn't work very well in theory, but in practice it worked brilliantly, I remember how good & bright the pictures were, I was looking for the reduced vertical definition but couldn't see it. Some clever people at Sony me thinks...
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  #79  
Old 05-06-2020, 01:09 AM
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All colour TV systems have reduced horizontal resolution for the chroma signals. Legacy analogue PAL/NTSC/SECAM, SD-SDI, HD-SDI and 4K. Some digital transmission methods, sometimes known as 4:2:0 as against the usual 4:2:2, reduce vertical resolution likewise. All of this takes advantage of the fact that the eye cannot resolve fine detail in colour the way it can in monochrome.

If the H colour resolution is already halved (even more reduction in analogue) then halving vertical resolution really doesn't matter.

Incidentally, a standard PAL-D decoder moves the chroma half a line down the screen compared to the luma. Again this doesn't show. It matters if you're recovering old PAL material where you would normally be using much better decoders that don't have this effect.
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  #80  
Old 05-07-2020, 12:52 PM
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Quote:
Originally Posted by Colly0410 View Post
& probably 819 lines then convert to 625 lines, both with positive modulation & AM sound..
With Pierre Trudeau citing the need for SECAM towards allegiance with France and its two islands St. Pierre and Miquelon. He'd also want to ensure that Canadians wouldn't have full access to US programming in a way not unlike East Germany and West Berlin.
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  #81  
Old 06-19-2020, 01:26 AM
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With Pierre Trudeau citing the need for SECAM towards allegiance with France and its two islands St. Pierre and Miquelon.
What has Trudeau to do with the choice of the Canadian colour standard? The CBC began NTSC colour more than two years before Trudeau became PM.
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  #82  
Old 06-25-2020, 10:25 PM
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Quote:
Originally Posted by Penthode View Post
What has Trudeau to do with the choice of the Canadian colour standard? The CBC began NTSC colour more than two years before Trudeau became PM.
"...his close ties with Co-operative Commonwealth Federation (CCF) intellectuals (including F. R. Scott, Eugene Forsey, Michael Kelway Oliver and Charles Taylor) led to his support of and membership in that federal democratic socialist party throughout the 1950s."

"His decision to join the Liberal Party of Canada rather than the CCF's successor, the New Democratic Party (NDP) was partly based on his belief that the federal NDP could not achieve power. He also doubted the feasibility of the centralizing policies of the party."

He was in government in the late 60's and his propensity to intervene across portfolios in government was legendary. He later waged a personal campaign for example against what he figured was the Americanizing of Canadian media... the story of CKLW was a perfect example. Given the chance and if technology existed, he would have had no issue closing off Canadians' access to US media. What we have now through regulation of the CRTC (and previously via the CBC) was a direct result of his mandate.
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  #83  
Old 06-28-2020, 09:51 AM
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Well Brazil had a PAL 525/60 system, so maybe Canada should have had a SECAM 525/60 system to keep things equal, but common sense prevailed & they chose NTSC. England tried experiments with NTSC, SECAM & PAL on both 405/50 & 625/50 in the 1950's/60's. A few experts wanted wanted to go for NTSC, but eventually they went for PAL, we could have been the only NTSC 625/50 country in the world, wonder how that would have panned out?
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  #84  
Old 07-02-2020, 10:32 AM
BRC2000 BRC2000 is offline
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Hi All
R.C.A sold CTC11 / 15 / 16,s which had been converted by them to UK system I 625/50 4.43Mhz NTSC 240v 50Hz power in the early 1960s and some still exist.
I have ctc11 / 15/ 16 TVs the 15 and 16 are working well with good pictures.
If you go to :- https://www.vintage-radio.net/forum/...ighlight=ctc16 you can see the ctc16 coming back to life.
Keith
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  #85  
Old 07-02-2020, 12:03 PM
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Hi to all,

On the topic of NTSC experimentation outside the US, Switzerland had a go at testing it also in 1957 with a modified RCA set; see the info on the ETF site :

http://www.earlytelevision.org/rca_21ct55_swiss.html

Best Regards
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Paris/France
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  #86  
Old 07-04-2020, 01:53 AM
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Quote:
Originally Posted by Colly0410 View Post
Well Brazil had a PAL 525/60 system, so maybe Canada should have had a SECAM 525/60 system to keep things equal, but common sense prevailed & they chose NTSC. England tried experiments with NTSC, SECAM & PAL on both 405/50 & 625/50 in the 1950's/60's. A few experts wanted wanted to go for NTSC, but eventually they went for PAL, we could have been the only NTSC 625/50 country in the world, wonder how that would have panned out?
PAL-M was chosen to allow in part for Brazil to develop it's own domestic industrial base.
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  #87  
Old 06-01-2022, 02:42 PM
Colly0410 Colly0410 is offline
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Quote:
Originally Posted by ceebee23 View Post

What does 405 line NTSC /PAL look like? Anyone ever seen that? The BBC seems to have not wanted to migrate to 405 line colour using NTSC because it was too good and might have reduced the demand for the 625 line service.

.
Read somewhere that 405 NTSC looked superb, presume this was under lab conditions though. What it would have been like on sets out in the wild with interference, ghosting, low signal level that many 405 line viewers used to put up with can only be speculated on. I'm wondering if it would have coped fairly well with it having a lower definition/bandwidth?
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  #88  
Old 06-01-2022, 07:14 PM
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Quote:
Originally Posted by Colly0410 View Post
Read somewhere that 405 NTSC looked superb, presume this was under lab conditions though. What it would have been like on sets out in the wild with interference, ghosting, low signal level that many 405 line viewers used to put up with can only be speculated on. I'm wondering if it would have coped fairly well with it having a lower definition/bandwidth?
There is a rule in video media: "Content is king." People were happy to watch terrible-quality bootleg VHS copies of Star Wars. That is not to say that improved quality has no value, but it is ancillary to the programs. So, if 625 lines was never a thing, people would have watched 405 color contentedly, I think; but having 625 available at the same time as color definitely pushed things in that direction.
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  #89  
Old 06-02-2022, 04:05 AM
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Quote:
Originally Posted by Colly0410 View Post
Read somewhere that 405 NTSC looked superb, presume this was under lab conditions though. What it would have been like on sets out in the wild with interference, ghosting, low signal level that many 405 line viewers used to put up with can only be speculated on. I'm wondering if it would have coped fairly well with it having a lower definition/bandwidth?
There's a lot of info here on the BBC R&D site, just put NTSC in as a search term.
https://www.bbc.co.uk/rd/search?query=NTSC&submit=
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  #90  
Old 06-02-2022, 11:07 AM
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Quote:
Originally Posted by Mr Hoover View Post
There's a lot of info here on the BBC R&D site, just put NTSC in as a search term.
https://www.bbc.co.uk/rd/search?query=NTSC&submit=
Thanks for posting that. I didn't know they studied the effects on multiple existing B&W receivers. You may know that the U.S. NTSC did similar studies before adopting the standard, although there was more emphasis on the theoretical problems. Those resulted in the infamous change from 60.00 Hz scanning to (60)(1000/1001) Hz.

There were similar studies of the ATSC digital TV system effects on existing analog receivers during the transition period, mainly focussed on adjacent channel interference effects. These resulted in requiring precision offset frequencies between NTSC stations and lower adjacent ATSC stations.
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