#76
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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.) |
#77
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#78
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#79
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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. |
#80
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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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Audiokarma |
#81
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#82
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"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. |
#83
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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
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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 |
#85
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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 jhalphen Paris/France |
Audiokarma |
#86
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#87
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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
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#89
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https://www.bbc.co.uk/rd/search?query=NTSC&submit= |
#90
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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. |
Audiokarma |
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