Site with terrible interference

[westy1]

Good Evening,

 

I recently took over the maintenance of a large office complex with a system of 30 cameras linked to one DVR, at least half of the cameras have interference which presents as a tearing picture in most instances. I just wondered what advice you may have for removing the problem or at least minimising it as much as possible.

 

Thank you in advance

[datadiffusion]

Analogue cameras?

 

Humbug device?

[al-yeti]

2 hours ago, westy1 said:

Good Evening,

 

I recently took over the maintenance of a large office complex with a system of 30 cameras linked to one DVR, at least half of the cameras have interference which presents as a tearing picture in most instances. I just wondered what advice you may have for removing the problem or at least minimising it as much as possible.

 

Thank you in advance

What steps have you carried out so far to isolate the problem

[westy1]

I have tried another wall mount power supply but with no improvement, I also switched some cameras just to see if the problem carried over but my guess would be groundloop. I was thinking of trying some groundloop isolators like these https://www.dtsdigitalcctv.co.uk/proddetail.asp?prod=CON701.

 

Never used them before but I can't think what else might be causing it, I've ran out of ideas so maybe just clutching at straws. Any other ideas welcome.

[MrHappy]

change to 24vac & convert to 12v at every camera

[sixwheeledbeast]

It will need some investigation work to find out where the interference is getting on the system.

From what you have said I would start looking for a ground loop initially, so a good start on commercial is things like the cameras mounted on metal surfaces.

Ground loops are the type of thing that can effect multiple channels when there could only be one channel at fault so disconnect any with a fault until all is clear.

Testing for AC in the mV range on the cable is another way to locate. Test and reconnect until you narrow it down.

 

[aissecur]

Assuming its a coax based system and not CAT 5, can you review the cabling routes on the cameras with issues?

Do they run through any switch rroms?

Are the cables routed next to any LV / HV cables?

[al-yeti]

14 hours ago, westy1 said:

I have tried another wall mount power supply but with no improvement, I also switched some cameras just to see if the problem carried over but my guess would be groundloop. I was thinking of trying some groundloop isolators like these https://www.dtsdigitalcctv.co.uk/proddetail.asp?prod=CON701.

 

Never used them before but I can't think what else might be causing it, I've ran out of ideas so maybe just clutching at straws. Any other ideas welcome.

Strange question for you , do you see a potential on the earth ? Of the coax and DVR 

[westy1]

17 hours ago, MrHappy said:

change to 24vac & convert to 12v at every camera

Have you tried this from experience or is it just a suggestion?

3 hours ago, aissecur said:

Assuming its a coax based system and not CAT 5, can you review the cabling routes on the cameras with issues?

Do they run through any switch rroms?

Are the cables routed next to any LV / HV cables?

Cables do not run near any other cables or lighting.

[MrHappy]

1 hour ago, westy1 said:

Have you tried this from experience or is it just a suggestion?

 

central 12v power supply(s) ?