Xref: utzoo sci.electronics:7251 rec.video:7416
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!stout!cook
From: cook@stout.ucar.edu (Forrest Cook)
Newsgroups: sci.electronics,rec.video
Subject: Re: sync signal generator
Summary: VSYNC on Green
Message-ID: <3881@ncar.ucar.edu>
Date: 4 Aug 89 22:24:53 GMT
References: <89216.120136BHB3@PSUVM>
Sender: news@ncar.ucar.edu
Reply-To: cook@stout.UCAR.EDU (Forrest Cook)
Organization: Field Observing Facility, NCAR, Boulder, CO
Lines: 22

In article <89216.120136BHB3@PSUVM> BHB3@PSUVM.BITNET writes:
>Does anybody know hwat the loewst cost device that would generate a 60Hz
>video sync signal would be.
...
>The specific application is an Ardent Workstation computer.
>The RS-170(NTSC) output from it requires that you put in a external
     ????????????
>sync signal.

RS-170 and NTSC are very different color signals, RS-170 uses separate
R G and B lines and NTSC puts it all on the same signal.
In 3 wire RS-170 setups, the sync signals (negative pulses) are often
sent along the same line as the green video signal (positive waveform)
during retrace.  A fairly simple comparator circuit set to trigger on the
Vsync level should work as a Vertical Sync Separator.  It is best to look
up some kind of RS-170 spec (preferably from Ardent in your case) to get
the exact specs on the signal.

 ^   ^  Forrest Cook - Beware of programmers who carry screwdrivers - LB
/|\ /|\ cook@stout.ucar.edu (The preceeding was all my OPINION)
/|\ /|\ {husc6|rutgers|ames|gatech}!ncar!stout!cook
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