Wavey Lines

[rossibufc 0]

Hi,

I need some help regarding wavey lines on cctv pictures. I have done an installation on a building over 3 floors. On the ground floor the pictures are perfect but on the 1st and 2nd floors the pictures have wavey lines on screen back at the DVRs which are on the ground floor.

Any help would be great.

Cheers.

[vin2install 0]

use a ground loop isolator and see if that clears it up. What kind of wires are you using?

[bpzle 0]

make sure your cables are ran far away from high voltage lines/ equipment.

[rossibufc 0]

use a ground loop isolator and see if that clears it up. What kind of wires are you using?[/quote

 

I have tried humbug ground loop isplators but no change in picture. Using RG59 Cable.

[rossibufc 0]

make sure your cables are ran far away from high voltage lines/ equipment.

 

 

How far is far away?

They run for about 4metres parrallel about 1ft away from armoured cables. However I got the electrician on site to turn off the power to these cables to see if the pictures would change but no joy.

[tweak'e 0]

did you check the power at the camera? could simply be low voltage.

the other thing is is earth loop through the power cable. also sometimes you can get problems when the floors are on different power phases.

[rory 0]

check the camera locally first and see if the video is good, then go from there.

[bpzle 0]

definetley check voltages at the cameras with a meter.

 

how are your powering the cameras? are they all sharing the same distributed power supply? is this AC or DC? how long is the run? what size gauge is the power cables to the cameras? Try temporarily hooking up power with one of those wall wart power supplies closer to the problem cameras and see if that helps. That would help isolate the problem. If its DC voltage a cheap trick around potential ground loop issues is to seperate the power sources on the problem cameras.

[rossibufc 0]

All cameras are powered from 2 x 10 way 5A Powerplex 12v dc psu. All CCTV circuits in the building are on the same phase. I have also tried powering one of the cameras from a 12v 7Ah battery for a few minutes to see if this helped but no change.All voltages at the cameras are in and around 13 to 13.5v.

The power cable is 2 core 0.75mm flex and cable runs are between 5 to 60 metres so not long runs although RG59 runs are between 50 to approx 100 metres.

Also checked camera locally with test monitor and picture is perfect.

I have also just installed 2 x monitors with built in camers on the ground floor with the video run in twisted pair cable and baluns and these have the same lines although all other cameras on ground floor are perfect.

[rory 0]

Check connectors on the bad cameras, then once verified those are all okay, maybe the cable is near high voltage as mentioned. Also, did you try the cameras on a monitor at the DVR end, without the DVR?

[rossibufc 0]

Check connectors on the bad cameras, then once verified those are all okay, maybe the cable is near high voltage as mentioned. Also, did you try the cameras on a monitor at the DVR end, without the DVR?

 

I haven't tried on a monitor without DVR and will give it a go.

I think it must be to do with mains voltage somewhere but cannot find where as i have already got the electricians on site to cut power to 1st and 2nd floors but no change in pictures. And now the 2 monitors on the ground floor with same lines.

Its really starting to annoy me now.

[bpzle 0]

ya.... that's sounding more and more like a dud DVR

[rossibufc 0]

ya.... that's sounding more and more like a dud DVR

 

Possibly but the cameras in question are not all connected to the same DVR as I have 7 DVRs on site and these cameras are spread over different DVRs. There are over 100 camers but only 1st and 2nd floors and now the 2 monitors on ground floor that have these lines.

[Kiwi 0]

All cameras are powered from 2 x 10 way 5A Powerplex 12v dc psu. All CCTV circuits in the building are on the same phase. I have also tried powering one of the cameras from a 12v 7Ah battery for a few minutes to see if this helped but no change.All voltages at the cameras are in and around 13 to 13.5v.

The power cable is 2 core 0.75mm flex and cable runs are between 5 to 60 metres so not long runs although RG59 runs are between 50 to approx 100 metres.

Also checked camera locally with test monitor and picture is perfect.

I have also just installed 2 x monitors with built in camers on the ground floor with the video run in twisted pair cable and baluns and these have the same lines although all other cameras on ground floor are perfect.

When you tested the camera on a battery were both the normal + and - power wires disconnected? Are the cameras that are OK v.s. not OK of the same type? In particular simple cameras usually have the power (-) connected internally to the video shield, often contributing to ground loops.

 

In my minimal experience I've seen a wavy picture from either insufficient voltage at the camera, or a ground loop between the (-) and video shield. Also having long untwisted power wires raises a flag for me but the battery test should remove that possibility.

[rory 0]

I just had a wavy picture on a camera actually, it was simply a bad camera, possibly the power board. It was a camera module so I just replaced it with one from another camera.

[tomcctv 190]

what type cameras are you using. your power supply is only 0.5amp per camera. this is too small for your cable runs.

[rossibufc 0]

When you tested the camera on a battery were both the normal + and - power wires disconnected? Are the cameras that are OK v.s. not OK of the same type? In particular simple cameras usually have the power (-) connected internally to the video shield, often contributing to ground loops.

 

In my minimal experience I've seen a wavy picture from either insufficient voltage at the camera, or a ground loop between the (-) and video shield. Also having long untwisted power wires raises a flag for me but the battery test should remove that possibility.

 

All cameras are of same type Mark Mercer static domes and as you say - is connected to video shield.

All voltages at the cameras are above 13v and I have tried a humbug ground loop isolater.

On the battery test the power wires were disconnected but the lines were still there.

[rossibufc 0]

what type cameras are you using. your power supply is only 0.5amp per camera. this is too small for your cable runs.

 

Ground floor cable runs are slightly longer but no problems with same cameras and power supplys.

[rory 0]

Sounds like you are going to have to trace those wires and see what high voltage is running near them.

[Kiwi 0]

I'm thinking more high current than high voltage. One last thought - is the metal dome body inadvertently grounded?

[rossibufc 0]

I'm thinking more high current than high voltage. One last thought - is the metal dome body inadvertently grounded?

 

None of the domes are metal all plastic(or whatever it is).

[shropna 0]

Does anybody know Lithuanian language?

Because I'm sometimes do some courses about lighting protection, ground loops, "bad" coaxial cables, etc.....

But my PPT's is only lithuanian....

But, one of examples:

[shropna 0]

So, main things, to have no "wavy lines":

Use good coaxial cable. Main resistance requirements - 2 ohms per 100m shield, not more than 10 ohms central conductor.

But, main thing, is avoiding ground loops, caused by powering from "accident" locations, grounding camera to pole, and etc.....

[cess 0]

hi... I also experience that thing upon my installation at fourth and fifth floor.... may I ask what cause the wavy lines at the video output? my DVR is located at ground floor and the cameras experiencing wavy output is the two cameras at the fourth and fifth floor same location. thanks for the help