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  #31  
Old 09-03-2014, 10:51 AM
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Quote:
Originally Posted by ceebee23 View Post
(somehow red never looked right in NTSC) .... .
NTSC has wider red depth, so incompatible with PAL TVs

I'd forgotten that one - another reason PAL sucks.
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  #32  
Old 09-03-2014, 11:54 AM
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Quote:
Originally Posted by ceebee23 View Post
Having seen PAL and NTSC in their real world forms OTA and on analogue cable...let's not over state the problems of either.

Far greater difference in quality with the two systems lies in the 525/60 625/50 standards.

From a viewer perspective .. 625 line (ie 576i) makes for a noticeably sharper image.
.

Did you guys in the NTSC world with tube sets suffer phase errors when you still had analog broadcasts? Real world test ... not lab stuff.
The main difference I saw in NTSC/PAL (50HZ) in old sets
(pre LCD or plasma non-sweep, light always on) was the horrendous
flicker at 50Hz, making it virtually unwatchable at respectable brightness.

I never noticed color problems with NTSC on live material. I saw
it only on material from very cheapie film chains. This dates
all the way back to 1954. I got my own set (actually a college
TV room set, but I ran it) in 1962. It never suffered color
problems after I put a locking pot on the hue control.

I have an RCA CT-100 from 1954, restored this summer. I have it actually
"calibrated" to match my modern calibrated flat screen. Colors
are not absolutely identical on all material, but are on most.
The difference could be corrected by adding two more color
adjustment pots, as it depends on 10% resistors in the color matrix,
and its so close I have not bothered. 10% error is easily visible,
my errors are in the 5-10% range
This, of course, is with modern source material. Looking at
very old prerecorded VHS tapes it looks ... excellent,
without adjustment. Just not absolutely perfect. I looked
at two 40 minute long slide shows I made of two recent vacations
I took on the CT-100 and they had perfect color.

PAL was a solution to a non-problem. The solution to the REAL
problem (50 Hz flicker) was the light-always-on LCD or plasma set.
Incidentally, phase alternation was not invented by the Germans,
but was developed in about 1951 by RCA and Hazeltine. I have
seen the "CPA" (color phase alternation) prototype (which is
PAF, phase alternating field, though RCA also tried PAL) working and
it does work OK. Nobody noticed interfield flicker.
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  #33  
Old 09-03-2014, 07:10 PM
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Fascinating you find the 50hz flicker an issue.... I never notice it.

I do notice the problem of 100 less lines though with 480i.

Have you watched 625/50 in a 50hz environment? I am wondering if your problem is the mix of 50hz flicker and 60hz lighting?

The CT100 of course had true phosphors.
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  #34  
Old 09-03-2014, 08:06 PM
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The 50Hz I have seen has all been in 50Hz South American countries, Malaysia,
and England.

I was in Malaysia at the height of the CRT to flat screen "always on"
transition and the flicker difference between
CRT and LCD was amazing. In the US one could see flicker (at 60 HZ)
on CRTs only on the brightest computer monitors with a full-white
screen. It seemed to go away about 72 or 75 Hz

Of course, given the terrible 50HZ flicker problem, perhaps
European producers avoided white screens even more
than ours did (because of blooming in tube sets
on white screens).

I never noticed a resolution difference between 525 and 625 lines,
vertical resolution. But I never compared side to side.
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  #35  
Old 09-04-2014, 02:27 AM
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People from 60hz countries often see flicker in 50hz countries for first day, then it goes away for rest of vacation!

By 1980s Tint control hidden in menu and best not messed with as solid state TVs had very accurate burst-Φ lock. To assess ⌂Φ over cable or network one would need a reference signal, chroma stairstep or color bars, on a vertical interval (VI) line and a vectorscope at receiving end. A cheap way would be to have a signal at burst phase in VI at 50% picture level & micro trim Φ with this?
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  #36  
Old 09-04-2014, 02:50 AM
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Quote:
Originally Posted by NewVista View Post
NTSC has wider red depth, so incompatible with PAL TVs

I'd forgotten that one - another reason PAL sucks.
The original NTSC red phosphor was indeed more red than current red phosphors. The problem was that it was also dim, something that was answered by rare earth phosphors, at the expense of colour gamut. All CRTs used since rare earth phosphors were invented (early 1960s?) don't go so far into the red.

There are no practical differences between the colour gamuts in PAL and NTSC. The colour gamut and rendering are largely down to how the cameras are set up and to a lesser extent the CRT. I've seen some really horrible CRTs but that's not a fault of the colour coding system.

As for colour gamut on LCD etc displays, this varies a lot. Sometimes good, sometimes horrible.

I agree about the difference in flicker between 50Hz and 60Hz. This is exacerbated by larger screens. Peripheral vision is much more sensitive to flicker than central vision. Overall, PAL has slightly better resolution than NTSC but in practice this is usually compromised by receiver design and CRT dot pitch. Comb filter decoders came much earlier to NTSC than PAL. A good PAL comb is more difficult. They certainly improve resolution and reduce artefacts.

Many years ago I spent a fair bit of time staring at the input and output monitors connected to a BBC "ACE" standards converter. High quality monitors, everything properly set up. It was hard to distinguish which was PAL and which was NTSC. Unless you caught the monitors out of the corner of your eye in which case the flicker gave it away.
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  #37  
Old 09-04-2014, 02:52 AM
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405/525 line systems benefit from improved vert sync design for interlace, reduction of overscan to <1%, progressive scan with upscaling interpolation to 1080 & vertical aperture correction. For horizontal, analog or digital comb filtering, picture peaking and deactivation of scan-velocity-modulation. Results can look like good 35mm film.
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  #38  
Old 09-04-2014, 05:33 PM
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My Wife has got epilepsy & was always affected (she'd get a headache & had to limit her viewing) by the 50hz flicker on CRT TV's in England, France, Spain & Malta. When we went to America (60hz flicker) she was hardly affected at all, she could watch a TV film all the way through with no ill effects. So what did she watch the most ? Eastenders that she'd already seen on WPBT (PBS) channel 2 Miami. Girls. (sigh)

We've now got an LCD TV that doesn't flicker at all, had it 6 years. Went to a friends house the other day & they'd got an old CRT TV connected to a digital converter box & boy did it flicker, I found it really annoying, but years ago it never bothered me at all, I think my brains flicker filter has stopped working through non use..
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  #39  
Old 09-04-2014, 10:35 PM
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Quote:
Originally Posted by dtvmcdonald View Post
The 50Hz I have seen has all been in 50Hz South American countries, Malaysia,
and England.
...
Back in the 80's there was talk of using frame stores to store the image and play it twice, to get the refresh rate to 100Hz. This was when CRTs were the only game in town.
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  #40  
Old 09-05-2014, 12:54 AM
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Originally Posted by wa2ise View Post
Back in the 80's there was talk of using frame stores to store the image and play it twice, to get the refresh rate to 100Hz. This was when CRTs were the only game in town.
I first saw this in a lab in the mid 1980s, before commercially available 100Hz sets. At first I could hardly see flicker even at 50Hz but after a while I became attuned to it. Watching 100Hz pictures felt very relaxed compared to 50Hz.

LCD sets inherently don't flicker, regardless of frame rate. The LCD cells have a zero order hold function by their nature. Motion portrayal is a different problem. LCDs have a laggy response, almost inevitably worse than CRTs, despite the whole arsenal of tricks employed by panel and set makers.
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  #41  
Old 09-05-2014, 01:52 AM
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BUT how would 525/60 PAL look compared to 525/60 NTSC? How bad was phase error in broadcast tv?

And the reverse what would 625/50 NTSC be like?

Ironically I think in good broadcast conditions ..hardly any difference ...but what happens in less than ideal reception conditions with multipath etc issues?

And afterall the 50hz/60hz issue is related to power supply... and in 1950s not really a matter of choice for the television system.
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  #42  
Old 09-05-2014, 10:40 AM
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Quote:
Originally Posted by ceebee23 View Post
525/60 PAL look compared to 525/60 NTSC? .
Look at a PAL-S TV and you are looking at NTSC. Good project: Convert a PAL set to Simple decoder for evaluation.

I've seen very rare instances of gross phase shift causing purple or green flesh tone but only on a local religious channel that used U-matic tapes to air and it wasn't the fault of the U-matic but the old program that had faulty production/equipment - all semi-professional junk and no quality control techs.
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  #43  
Old 09-05-2014, 11:28 AM
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If you want to see 525/60 PAL for yourself check the options menu in your DVD player. Some have an option to output 525/60 PAL when playing back NTSC encoded DVDs. This mode is compatible with most PAL only TVs while avoiding some of artifacting caused when then player converts an NTSC encoded disc to 625/50 PAL.

525/60 PAL is also output by most modified PAL Playstations and earlier consoles when playing NTSC games. I found I noticed the differences between PAL and NTSC far more when gaming. The artifacting, color bleed and dot crawl all seemed far worse in NTSC than PAL (same console, same TV, just switching between PAL and NTSC modes). I'm not suggesting that PAL is completely immune to any of these defects, just that they aren't as severe. Ultimately for gaming go with direct RGB wherever possible.

I've had several 100Hz line doubled TVs. Some are better than others. Generally it's a softer smoother image, but the line doubler itself causes artifacts that are painfully obvious. Perhaps only painfully obvious when sitting too close and gaming, but at the time it was enough to downgrade from a 34" 100Hz set to a 29" 50Hz set.
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  #44  
Old 09-05-2014, 10:11 PM
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Quote:
Originally Posted by dr.ido View Post
..color bleed and dot crawl all seemed far worse in NTSC than PAL ..
Actually PAL has hideous dot crawl, it's one of its worst aspects. Research it, it's an amazing stuffup. Also DVDs don't have NTSC encoding so no NTSC to see.

Edit: Your multistandard PAL/COFDM optimized TV probably didn't have an NTSC comb filter - or even a notch filter - in analog mode.

I'm thinking of the Simple-PAL set again as a detector for difΦ in the broadcast chain: just look for the Hanover Bars. Anyone done this, comparing different broadcast conditions? If it happened a lot, it would vindicate the need for PAL or SECAM systems.

Last edited by NewVista; 09-05-2014 at 10:22 PM.
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  #45  
Old 09-06-2014, 01:03 AM
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Here in NTSC-land I can see 60Hz flicker on CRT sets. It varies from unnoticeable to easy to see for me depending on the set and how fast my brain is clocking on a given day...I'm also more sensitive to it if I don't look straight at the screen. There have been times where I think I could actually just barely perceive the individual lines being scanned...

In the early 90's-DTV (the part of NTSC I've been alive for) color phase (tint/hue adjustment) tended to be fairly constant from station to station, and program to program, with some channels being slightly off from others occasionally (usually not not bad enough for anyone but knowledgeable videophiles/techs to notice enough to perhaps adjust the tint to compensate for).
However anecdotal evidence I've read/heard suggests that back in the tube era this was a more significant issue, and it was likely common in some places to have to tweak your tint knob on channel changes and some program source transitions. Tube equipment tended to suffer from adjustment drift, and it took many years for a vast majority of station techs to all learn how to keep their equipment calibrated properly...
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