IPVMU Certified | 06/08/15 08:06pm
On several of our cameras a horizontal line appeared after we rerouted wiring and installed a static switch in our access control room's intrusion panel.
1. Were the cables reterminated or replaced during the reroute?
2. Are the siamese power cables carrying AC or DC?
3. Did you change power supplies during this time?
4. How were the cables grounded before vs now, if at all?
Thanks for your quick response. No cables were reterminated or replaced other than the power source for the intrusion panel. The siamese cables are running DC power from DVTel EV216 encoders if I am not mistaken, and they are grounded at the encoders. The only power that changed was to add the static switch to provide power redundancy to the intrusion panel. The gutter is quite crowded though. We plan on pulling the intrusion system power tomorrow to see if the interference/lines go away in an effort to positively identify those power cables as the culprit.
IPVMU Certified | 06/08/15 08:32pm
We plan on pulling the intrusion system power tomorrow to see if the interference/lines go away in an effort to positively identify those power cables as the culprit.
This is a solid step and likely the easiest test.
I don't think this is a shielding issue, but the test above will be the 'smoking gun' if it is...
Can you take a picture or video. Some systems that use an "Up The Coax" control signal can send a thin black bar up in the signal. It slowly travels up the screen, and is usually 1 pixel tall, and most of the screen wide - scrolls.... In this case, you would need to turn the coax control signal off on your control equipment.
Thanks everyone for your input. We pulled the power and the lines went away. When we connected to a second static switch they reappeared. Based on these findings the interference was isolated to the power cord's proximity to the siamese cable. We have scheduled conduit installation to eliminate the problem.