Re: CCTV Video issues

[I use solid wire <solidwire@xxxxxxxxxxxxxxxxxxxx>]

On Sat, 13 Jan 2007 16:58:30 -0800, "Doug" <not@xxxxxxxx> wrote:

>Here is what I have seen in the past, its not so much that the power supply
>can't provide enough power, nor that the cable runs are so long that there
>is excessive voltage drop, but rather there is some sort of interference
>between the power and the video ground when powering multiple 12 VDC cameras
>from the same source. My experience has been that it occurs more when the
>cable runs are of greatly differing lengths. I believe it has something to
>do with the video ground and negative being common at the camera, but at the
>head end the video ground is probably tied to the chassis of the DVR and
>then to an electrical ground, while the power negatives are all common, but
>floating with respect to ground.

That reminds me of a situation I had.  I used some cheap bullet cams
one time and their chassis' were tied to video ground and power
ground.  The cams were mounted on red iron, when I pulled them off the
building and let them dangle (isolating them from the buildings' Earth
reference) the problem cleared up.

To S. Smith:

Might want to give that a try - sounds like a possible ground loop.




--
"As we know, there are known knowns.
There are things we know we know.
We also know there are known unknowns.
That is to say we know there are some things
We do not know.  But there are also unknown unknowns,
The ones we don't know we don't know."

Feb. 12, 2002, Department of Defense news briefing - (Donald Rumsfeld)