Jump to content
Security Installer Community
westy1

Site with terrible interference

Recommended Posts

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

Share this post


Link to post
Share on other sites

Analogue cameras?

 

Humbug device?


So, I've decided to take my work back underground.... to stop it falling into the wrong hands

 

Share this post


Link to post
Share on other sites
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

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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


Mr:)

Share this post


Link to post
Share on other sites

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.

 

  • Like 1

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites
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 

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites
1 hour ago, westy1 said:

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

 

central 12v power supply(s) ?


Mr:)

Share this post


Link to post
Share on other sites

24Vac supply may remove interference. This is often due to there design isolating a ground loop from via the PSU.

Similar effect to isolating a ground loop via "humbug" loop isolation on the signal cable, just on the power side.

 

You didn't mention much else about the installation either, UTP or coax, power supply locations, camera types and transmission type, any tests etc.

Tearing like in your OP would always make me think ground loop, hence my post.

  • Like 1

Share this post


Link to post
Share on other sites

It's coax runs of no more than 25 metres per camera. I am going to test the groundloop isolators on several runs and see what happens. If all else fails I think I will try the 24V power root and use volatge converters. Thank you for the recommendation on that.

Share this post


Link to post
Share on other sites

It's best to use humbug devices as a last resort. They are handy for locating the type of fault initially but if you can solve it in the field that's the best.

As I say take the time to remove the cameras and add/test them, like I said in post above.

Share this post


Link to post
Share on other sites
2 hours ago, westy1 said:

It's coax runs of no more than 25 metres per camera. I am going to test the groundloop isolators on several runs and see what happens. If all else fails I think I will try the 24V power root and use volatge converters. Thank you for the recommendation on that.

 

is it an easy job to try running cameras of 12v batteries ?

  • Upvote 1

Mr:)

Share this post


Link to post
Share on other sites
On 14/02/2020 at 01:07, james.wilson said:

Qfa

I had a similar situation with a system I took over   

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.