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Interference On Cat5


daubs8

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Posted

I am getting interference on camera on cat5 It's not too bad and not there during monitoring periods. The interference is only there when the site turns machinery on in the building the dome is attached to. It is in the form of wavy lines a third and two thirds down the image. The cable isn't touching any 240v along it's route and is only 150m max. I have tried passive and powered baluns but all are ok until the machinery is on. Is there anything I can attach to the cat5 cable to get rid of any interference? Thanks.

Posted
I am getting interference on camera on cat5 It's not too bad and not there during monitoring periods. The interference is only there when the site turns machinery on in the building the dome is attached to. It is in the form of wavy lines a third and two thirds down the image. The cable isn't touching any 240v along it's route and is only 150m max. I have tried passive and powered baluns but all are ok until the machinery is on. Is there anything I can attach to the cat5 cable to get rid of any interference? Thanks.

I would try to work out whether the interference is coming from the PSU or from the coax, perhaps if you were to plu a test monitor directly in to the dome it will narrow the problem down.

Guest old-hand
Posted
I would try to work out whether the interference is coming from the PSU or from the coax, perhaps if you were to plu a test monitor directly in to the dome it will narrow the problem down.

To prove the coax indeed use a plug on monitor. To prove the PSU attach a battery directly to the camera.

You will probably find the machinery is on the same phase as the psu.

Posted

Is it in the form of two horizontal lines filled with wavy lines ?

If it is, its sounds like 100Hz hum ( 1 horizontal line would be 50Hz ) and is probably something to do with the power supply. AFAIK the only place your likely to find 100Hz is the output from a bridge rectifier.

Could be an earth loop, try adding a loop isolating tranny to prove it, or an isolating balun. Or see if you can physically isolate the camera itself from earth temporarily, including the earth lead in the PSU.

Posted
To prove the coax indeed use a plug on monitor. To prove the PSU attach a battery directly to the camera.

You will probably find the machinery is on the same phase as the psu.

Mmm, yes it is on the same phase. Thinking how I can resolve this? Worst case I could prob power from an adjacent building? However, thinking about it I have domes on 4 other buildings powered similarly and individually but not affected by being on the same phase??

Posted

Is the camera powered from the same location as the monitor/DVR is fitted or powered locally?

Theoretically you shouldnt have interference, it points to something else imho. Youve even mentioned the cat5 is removed from any mains cables, my moneys on power but it could be on the mains rather than the camera power.

Guest old-hand
Posted
Mmm, yes it is on the same phase. Thinking how I can resolve this? Worst case I could prob power from an adjacent building? However, thinking about it I have domes on 4 other buildings powered similarly and individually but not affected by being on the same phase??

ACT mains filters might help, see previous link.

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