rmrichesjr wrote:Are you planning to run individual wires from the S-video on individual wires on the CAT5 cable? If so, I don't think that would work well. As I understand it, the S-video has two grounds and two signals lines (luminance and chroma)--the old Commodore Amiga signal scheme. Those signal lines are 75 ohm and need to be constant impedance down the line for proper signal transfer. There are 'balun' devices for sending composite over CAT5 with proper impedances and such, so I suspect there may be such devices available for sending S-video over CAT5. Most likely, they require at least two matched pairs.
There are such devices. We have had good luck with 2 pairs of these:
http://www.knollsystems.com/prod-svideo.html. They are IR and S-Video only, but the quality is pretty good.
rmrichesjr wrote:If you're lookin at five wires for the RS-422 control, that's most likely RX+, RX-, TX+, TX-, and ground. If so, you could use the COAX for that ground (and not use the COAX for anything else). Just make sure to connect the ground before connecting the signal lines (and disconnect in reverse order) and put each direction (RX vs TX) on one pair to avoid crosstalk with any analog signals in the CAT5. You might also look into running RS-485, which is a half-duplex (and more) protocol on top of RS-422, if the equipment is friendly to that arrangement.
IIRC, the EVI-D70 only supports RS-422 and RS-232, otherwise, that sounds good to me.
rmrichesjr wrote:Combining analog signal and control in a single CAT5 _MAY_ introduce noise from the control bit stream into the analog signal, especially if any of the signals is not properly balanced or is not properly paired. Combining digital and analog grounds makes it very likely you will see noise injection. You might be lucky and find a combination that works for your installation, but YMMV.
Mixing digital and analog grounds is touchy (at best) in my limited experience... If you can get a demo of the system (or return it at no cost), I might try it, but I think you will have issues with it.
rmrichesjr wrote:Eventually, and probably not many years distant, cameras will likely switch from analog output to IP output. If you can find a high enough quality USB camera, you could also consider a USB camera, a USB-over-IP device for the video signal, an RS-422-over-IP adapter for the controls, and an ethernet switch at the camera location. If needed, you could run class-2 DC power over the coax or maybe use POE (power over ethernet).
If you can live with IR control, the Knoll system I linked to above will give you S-Video and control over a single CAT5/6 cable.
We have been happy with it so far, but I am debating switching to serial control as IR gets twitchy when on zoom.
Aaron Z