Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!snorkelwacker!spdcc!lexicon!fc From: fc@lexicon.com (Frank Cunningham) Newsgroups: comp.sys.amiga Subject: Re: Interlace-Flicker Message-ID: <554@lexicon.com> Date: 1 Feb 90 15:51:20 GMT References: <6721@mentor.cc.purdue.edu> <2016@ultb.isc.rit.edu> <3000@d75.UUCP> <3018@d75.UUCP> Organization: Lexicon, Inc., Waltham, MA Lines: 22 In-reply-to: robin@sabre.uucp's message of 31 Jan 90 15:02:25 GMT > >scan rate is 15.75 MHz. Doubling that will give you 31.5 MHz which is > the AMI are 60 Hz. That means that the entire screen is refreshed 60 times > 15.75 [M]hz (M = Mega/Millon). If the entire screen were redrawn 15.75 million Just to get a few things straight: American NTSC TV refreshes the entire screen 29.97 times per second. Color is not exactly 30 due to some interference problem with the broadcast color subcarrier frequencies. The two interlaced fields are refreshed at 59.94 Hz. They flicker because, being interlaced, they are slightly different and are alternately refreshed at 30 Hz. A 60Hz full screen refresh does not flicker on a reasonable phosphor. The horizontal scan rate of TV is 15.75 kHz (that's kilo = 1000) or 59.94 fields / second * (~=)260 lines / field. -- -Frank Cunningham smart: fc@lexicon.com phone: (617) 891-6790 dumb: {husc6,linus,harvard,bbn}!spdcc!lexicon!fc snail: Lexicon Inc. 100 Beaver St. Waltham MA 02174 Why are viola jokes so short ? So violinists can remember them.