narco

I know that it is possible to send video signal over AC lines, but is it possible to send video signal over DC lines. The particular camera that I have in mind uses three wires. It uses the standard coaxial wire for the video signal, but the shield of that wire is also used for the negative (ground) wire for the DC. Any replies are greatly appreciated. Thank you.

tansis

This might be usefull..

Attached Files

video_maxim455.pdf (99.8 KB, 34 views)

mechie

I have worked on a camera system (Sony) that has a rack-mounting camera controller unit (CCU) and a single co-ax lead to the camera, this carries something like 20v DC to the camera (audio people would call this phantom powering), the camera is also synchronised by the CCU so that all cameras can have graphics overlaid (the opposite of genlock?).

The co-ax is something like 100 metres long, the camera has no other leads to it, this must save a few ££ on cable (but a 24v cooling fan in the camera housing is seperately powered :? as are the floodlights :roll: Oh well, that's industry for you.

I would think any camera with a common ground between co-ax screen and power could be 'powered' with a single wire, relying on the screen as power return - with the possible risk of inducing a DC offset into the video signal, this might be fine on short runs but could upset a video monitor on longer runs ?

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