Conference hydra::amiga_v1

1564.0. "Genlock stability problems." by SNDCSL::SMITH (Fezzik, tear his arms off.) Thu Jul 28 1988 16:30

    I'm using an Amiga 1000 with Genlock as a Head-Up-Display for a
    lunar teleoperations modelling project, and am having some rather
    serious problems with the genlock.  I've looked at the input and
    output signals with a scope, and it looks like when the signal starts
    to approach the black level on any scan line, the Genlock will decide
    that it's seen another sync pulse, which makes the entire picture
    tear and shake.
    
    Does the Amiga Genlock need DC level restoration, or should I look
    into trying to clean up the signal with a sync enhancer or something?
    it's a great idea, but I'm about to toss the whole package in favor
    of an Advanced Micro Systems cross-hair (etc) overlay card.  Has
    anyone had any experience getting the Genlock to work on 'marginal'
    signals?
    
    FWIW:  The signal from the camera on the vehicle goes thru a CH.
    14 UHF transmitter, a Sony ST-7TV tuner, the Genlock, and a 27 inch
    Sony monitor.  Works just fine without the genlock in the path,
    but with the Genlock in, it's hard to tell where you are driving!
                                                                    
    Also, when we were making a demo tape for our sponsors, we found
    that sometimes the Genlock would pass color information and sometimes
    it would just pass black-and-white pictures.  Not terribly important,
    as the vehicle camera is B/W, but it would be nice to know just
    what's going on.
    
    Is there any way to get schematics and such for the Genlock?  I
    really don't look forward to pulling the covers, prying it out of
    it's little faraday cage, and poking around at random.....
    
    Willie
    

>    I've looked at the input and
>    output signals with a scope, and it looks like when the signal starts
>    to approach the black level on any scan line, the Genlock will decide
>    that it's seen another sync pulse, which makes the entire picture
>    tear and shake.
    
    Seems to me you could check this out with an inexpensive video
    processor box (maybe not the right name) from Radio Shack.  You
    should be able to tweak the black level with the video processor
    and see if this is really a problem.
    
    Another possibility is that the source of sync in your video chain
    (the vehicle camera?) is not stable enough.  Or, is it possible
    that Genlock doesn't like non-interlaced signals?  This should be
    easy to check out with broadcast video off the air.  Just guessing.
    
    Schematics (and possibly assistance) should be available from
    Commodore-Amiga Technical Support in West Chester, PA.
    
    Wes