Article View: sci.electronics
Article #1123Re: sync signal generator
From: Vidiot
Date: Tue, 08 Aug 1989 20:18
Date: Tue, 08 Aug 1989 20:18
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2213 bytes
In article <26659@amdcad.AMD.COM> rpw3@amdcad.UUCP (Rob Warnock) writes: < <Otherwise, it [MM5320] works o.k., I guess... Yep, the part works just fine. I use it to drive the sync inputs on the 3/4" Umatic decks that I use for editing (through a TTL buffer). I also have a sync separator part that I use to set off a one-shot to resync the sync generator every frame. The one shot is used because the timing of the signals available do not exactly match what the generator needs, but since one of them is early enough, I put it through a one-shot. The problem with the 3/4" Sony decks (older ones) is that when the input video is used for sync, a very minor glitch will cause the recorder to lose gen-lock. It is worse when editing and the source tape is used as the sync source. So, by feeding external sync into both decks, there isn't a sync separator problem in the 3/4" deck. I looked at the internals of the 3/4" and noticed that the composite video signal used as sync was about 1/5th of the size of external TTL sync. This extra level internally provided enough to keep glitches from screwing things up. I use the sync separator to take in video signals from the TV and provide re-sync for the sync generator. This keeps minor glitches from screwing up the 3/4" deck when recording off-the-air stuff. Also, the one-shot is such that it finishes a short while before the next frame starts, keeping random glitches between frames was causing random re-syncs. Of course, massive changes in original sync timing will still cause glitches. If only I had a frame-store unit :-) -- harvard\ att!nicmad\ Vidiot ucbvax!uwvax..........!astroatc!brown rutgers/ decvax!nicmad/ ARPA/INTERNET: brown%astroatc.UUCP@spool.cs.wisc.edu
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!watmath!iuvax!rutgers!uwvax!astroatc!brown From: brown@astroatc.UUCP (Vidiot) Newsgroups: sci.electronics,rec.video Subject: Re: sync signal generator Message-ID: <2548@astroatc.UUCP> Date: 8 Aug 89 20:18:24 GMT References: <89216.120136BHB3@PSUVM> <21056@cup.portal.com> <26659@amdcad.AMD.COM> Reply-To: brown@astroatc.UUCP (Vidiot) Organization: Vidiot's Hangout Lines: 32