Question: It's a big job.. so we figured we'd do it right, but when everything
was plugged in, it was so wrong.
We ran everything in CAT5E and used passive baluns to make the
connections. Funny thing, the longest runs went outside of the
building to "box cameras". They look great! But the domes inside
suffer from all kinds of distortion. Even the closest camera at a mere
30ft! We're powering them all from a 12VDC Altronix power supply.
My first thought was interference caused by electrical cables or
flourecent lighting. But the outside cams take the same path as the
domes without side effects. This leads me to believe that there may be
a power issue. I'm wondering if the dome cctv video cameras don't have
the "umph" to push the signal back to the DVR cleanly. Suggestions?
Lastly, I'm looking for a portable meter to measure video strength but
I don't know what it's called to even begin searching. Help?!
Answer: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.
