jdc@naucse.UUCP (John Campbell) (02/06/88)
We may soon acquire an IVAS (ok, a nice 1K frame buffer that generates RGB and sync output signals). We also have some cable TV bandwidth left. Is there a way to put a monitor a long distance away from the box? Can it be done over a TV channel? Speak simply since I don't know much about what I'm talking about. I'm not even sure I know the difference between composite video and RGBsynch. Anyone that can take a little time to educate me will be rewarded in heaven. Thanks! -- John Campbell ...!arizona!naucse!jdc unix? Sure send me a dozen, all different colors.
jlc@didsgn.UUCP (jlc) (02/09/88)
In article <557@naucse.UUCP>, jdc@naucse.UUCP (John Campbell) writes: > We may soon acquire an IVAS (ok, a nice 1K frame buffer that generates > RGB and sync output signals). We also have some cable TV bandwidth left. > Is there a way to put a monitor a long distance away from the box? Can it > be done over a TV channel? > > Speak simply since I don't know much about what I'm talking about. I'm > not even sure I know the difference between composite video and RGBsynch. > > Anyone that can take a little time to educate me will be rewarded in heaven. > Let's keep it simple !!! 1) To sync or not to sync: If your are talking of an RGBsync composite signal, the 3 basic color signals and all the synchronisation crap going with them are merge together in one signal that can be sent over 1 cable. This is the way TV works ( under differentflavors of the multiplexing process called: NTSC, SECAM, PAL etc..) If you are talking of a SET of R G B signals with composite video, then the synchronisation crap is merged with one (usually the green) or more of the colorsignals. Since most of the D/A converters available now have a sync entry, it isvery easy for the hardware designer to send the sync signal to all the D/A on a display controller. Anyway it is common to say that the sync in present of the green because a lot of VIDEO MONITORS will sync on their green entry when they have a composite sync option (eg: HITACHI MITSUBISHI BARCO etc..) If you have talking of a SET of R G B signals with external sync, then each of the color signal only carries VIDEO DATA and a 4th signal carries the synchro. Now to make things easier, the sync signal can be composite or not. If it is composite then VDRIVE, HDRIVE, BLANKING etc... are merged together to make a signal. If the signal is not composite, then you can have a seperate cable per element of synchronisation. (Pass me the Aspirin plse...) 2) As far as the length of the cable(s) is concerned then it all depends of the size and interlace factor of your image. as a summary: 512x512 60hz interlaced -> 100 meters with good quality cable 512x512 60hz non interlaced -> I never tried this one but I would say 50m 1024x1024 60hz non interlaced -> 1 pixel <=> 6 nanosec. !!! -> 15 Feet max or you'all have ringing and funny -> edges 1024x1024 60hz interlaced -> I'ld say no more than 50 feet If you need a longer distance for the 1K^2 then you can use optic fiber couplers. I hope this will help and pardon my english... I'm french ___ _ __ _ ( > _// / ) / _/_ // __/_/> __. ____ --- / . . _. / /_ __. / _ // __. o ____ / / (__(_/|_/ / <__ /___ (_/_(__ (__/ / /_(_/|_<__</_</_(_/|_<_/ / <_ <_/ ...!gatech!rebel!didsgn!jlc 404 447 0274
dave@onfcanim.UUCP (Dave Martindale) (02/29/88)
In article <196@didsgn.UUCP> jlc@didsgn.UUCP (jlc) writes: > >2) As far as the length of the cable(s) is concerned then it all depends of >the size and interlace factor of your image. >as a summary: >512x512 60hz interlaced -> 100 meters with good quality cable >512x512 60hz non interlaced -> I never tried this one but I would say 50m >1024x1024 60hz non interlaced -> 1 pixel <=> 6 nanosec. !!! > -> 15 Feet max or you'all have ringing and funny -> edges >1024x1024 60hz interlaced -> I'ld say no more than 50 feet This is simply not true. If you use good 75 ohm (NOT 50 ohm!) cable with properly-applied connectors and terminate the signal properly at the monitor using either internal or external 75-ohm terminators, you can run any length of cable you like without developing ringing and "funny edges" on the monitor, no matter what the resolution of the image. Make up cables in matched groups of 3 or 4 all the same length, to ensure that all signals arrive at the far end at the same time. You will get an overall loss of signal amplitude with distance due to cable resistance, but normally the monitor's contrast control will take care of this. If you have real amplitude problems, you can use video amplifiers to deal with it, but then the video amp's bandwidth has to match that of the signal, which may go to 100 MHz. The whole point of sending signals via a terminated transmission line is that you can send them a distance that relatively independent of the signal's wavelength.