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From: tomb@hplsla.HP.COM (Tom Bruhns)
Newsgroups: comp.sys.amiga
Subject: Re: Interlace-Flicker
Message-ID: <5160079@hplsla.HP.COM>
Date: 2 Feb 90 17:10:16 GMT
References: <6721@mentor.cc.purdue.edu>
Organization: HP Lake Stevens, WA
Lines: 25

navas@cory.Berkeley.EDU (David C. Navas) writes:
>In article <26360@cup.portal.com> phorgan@cup.portal.com (Patrick John Horgan) writes:
>>Of course it doesn't!  Your television is interlaced, and that looks quite
>>nice doesn't it?...Slow scan rate means flicker:)
>
>Eh, my TV looks *good*?  We talking about the same piece of NTSC garbage we're all
>familiar with?  :) :)  Of course our TV has flicker -- that's why overlaid text on
>Newscasts always seems to have ants in their pants... :)
...

Yep.  And the NTSC color standard has yet another level of interlace most
folk miss:  the color subcarrier is interlaced with the horizontal scan.
The result is that you don't refresh the screen the same way for a whole
1/15 (nom.) of a second!  So strong color borders (vertical ones) show
a very obvious wave motion.  At least on RGB you don't have that problem.

BTW, I have seldom seen such misinformation as is woven into this thread!
Megahertz vertical _or_ horizontal scan frequencies??!! C'mon.  Yes, NTSC
and the standard Amy screens both scan vertically at about 60 times a
second.  But both are interlaced, so alternate scans are slightly
vertically displaced (by 1/2 the scan line spacing of a single vertical
sweep, though monitors seldom put the alternate fields excatly where they
belong relative to eachother).  The result is that the screen is full-
refreshed only 30 times a second (and as noted, NTSC color screws this 
up one step further :-).  Can we get this right and kill the thread?