waves on screen

Qualitech

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about a year ago i helped a friend install a set of HD analog dome cameras on his house that we used siamese cabling for. One of the cameras now have issues where these waves lines move across the screen at night daytime seems fine im thinking its picking up EMI interference somehow not sure. the other camera in question seems to have lost color during Daytime viewing
 

TonyR

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If it seems worse at night perhaps the siamese cable (video and 12 VDC) is picking up 60Hz interference on it's video conductor from an adjacent AC power line.
Insure none of those cables run parallel within 4 feet of power cables and if you must cross them do so at a right angle.
It's also possible that the cable has poor shielding and if it's run as stated above you might try replacing the cable.
 

Qualitech

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If it seems worse at night perhaps the siamese cable (video and 12 VDC) is picking up 60Hz interference on it's video conductor from an adjacent AC power line.
Insure none of those cables run parallel within 4 feet of power cables and if you must cross them do so at a right angle.
It's also possible that the cable has poor shielding and if it's run as stated above you might try replacing the cable.
Yea i kinda fear the fact of having to replace cable because everything was done while the house was gutted. Are there any analog cctv testers that can measure cable distsnces as well as interference or damage ? Also is it possible it can have something to do when the infared comes on it pulls more power causing the waves?
 

wittaj

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More power draw will accentuate the noise, so that is a very real possibility. I had an old analog camera that would do the same thing at night and it was because the line crossed an electric line in the attic.

Sounds like the other camera that is only in B/W during the day has a stuck filter. Sometimes taking a white piece of paper and starting about a foot out and bringing it up to the camera face can reset it (it forces the IR filter to try to engage and disengage). If not, a few bangs on the camera can jar it loose too LOL.
 

looney2ns

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Clean the BNC's and power connections with this.
 

Old Timer

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I have also seen this happen when the camera is mounted on a metal grounded surface that is grounded to the AC power system.
It causes a ground loop.
The fix, is to either insulate the camera from the metal surface, or to use a couple of balun (transformer) to convert the 75 ohm unbalanced to
balanced, then back to unbalanced. Or if you can find it a 75 Ohm to 75 Ohm un-un.
This breaks up the ground on the video signal, and thus removes the 60 hz hum.
This will also take out the hum when the siamese cable is ran alongside AC wiring some of the time in mild cases.

The easiest is use a couple of these, with a short piece of cat 5 cable in the middle.
 
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Qualitech

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I have also seen this happen when the camera is mounted on a metal grounded surface that is grounded to the AC power system.
It causes a ground loop.
The fix, is to either insulate the camera from the metal surface, or to use a couple of balun (transformer) to convert the 75 ohm unbalanced to
balanced, then back to unbalanced. Or if you can find it a 75 Ohm to 75 Ohm un-un.
This breaks up the ground on the video signal, and thus removes the 60 hz hum.
This will also take out the hum when the siamese cable is ran alongside AC wiring some of the time in mild cases.

The easiest is use a couple of these, with a short piece of cat 5 cable in the middle.
I have also seen this happen when the camera is mounted on a metal grounded surface that is grounded to the AC power system.
It causes a ground loop.
The fix, is to either insulate the camera from the metal surface, or to use a couple of balun (transformer) to convert the 75 ohm unbalanced to
balanced, then back to unbalanced. Or if you can find it a 75 Ohm to 75 Ohm un-un.
This breaks up the ground on the video signal, and thus removes the 60 hz hum.
This will also take out the hum when the siamese cable is ran alongside AC wiring some of the time in mild cases.

The easiest is use a couple of these, with a short piece of cat 5 cable in the middle.
so basically your saying to replace the siamese cable for that drop and install cat 5 with two baluns. Im accustomed to using baluns on other installs but never knew the difference in balanced or unbalanced. just to be sure you said 75 ohm unbal to 75 ohmunbal is preferred
 
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Old Timer

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so basically your saying to replace the siamese cable for that drop and install cat 5 with two baluns. Im accustomed to using baluns on other installs but never knew the difference in balanced or unbalanced. just to be sure you said 75 ohm unbal to 75 ohmunbal is preferred
You can use a short piece of cat 5 between the baluns, so it's all at the DVR.
In other words, the siamese cable comes to the dvr. Remove the cable from the DVR and insert a BNC female to female connector.
Then place a 75 ohm balun on the female BNC. Then place a short piece of CAT 5 cable in the balun. The other end of the CAT 5
will go into a second balun and the male BNC on the second balun will connect to the DVR.
This breaks up the ground on the coax from the siamese cable, so it does not allow a ground loop.

This is a little bit of a work around, but easy to do and you do not have to replace the siamese cable.

If you could buy a 75 ohm to 75 ohm transformer (unun) you could use one part, but they are hard to find.
 

Qualitech

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You can use a short piece of cat 5 between the baluns, so it's all at the DVR.
In other words, the siamese cable comes to the dvr. Remove the cable from the DVR and insert a BNC female to female connector.
Then place a 75 ohm balun on the female BNC. Then place a short piece of CAT 5 cable in the balun. The other end of the CAT 5
will go into a second balun and the male BNC on the second balun will connect to the DVR.
This breaks up the ground on the coax from the siamese cable, so it does not allow a ground loop.

This is a little bit of a work around, but easy to do and you do not have to replace the siamese cable.

If you could buy a 75 ohm to 75 ohm transformer (unun) you could use one part, but they are hard to find.
Ok i get you so this loop would remain pernament in the dvr if so you would need a extra spare 2 ports on the dvr to play with
 

Old Timer

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Ok i get you so this loop would remain pernament in the dvr if so you would need a extra spare 2 ports on the dvr to play with
No spare ports needed. you put the balum in series with the coax coming into the DVR. You can use the same port.
By using a balum in line with the video, you break the ground connection but let the video through. The second balum just gets you back to 75 ohm coax.
 
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