westy1 Posted February 10, 2020 Share Posted February 10, 2020 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 Quote Link to comment Share on other sites More sharing options...
datadiffusion Posted February 10, 2020 Share Posted February 10, 2020 Analogue cameras? Humbug device? Quote So, I've decided to take my work back underground.... to stop it falling into the wrong hands Link to comment Share on other sites More sharing options...
al-yeti Posted February 10, 2020 Share Posted February 10, 2020 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 Quote Link to comment Share on other sites More sharing options...
westy1 Posted February 10, 2020 Author Share Posted February 10, 2020 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. Quote Link to comment Share on other sites More sharing options...
MrHappy Posted February 10, 2020 Share Posted February 10, 2020 change to 24vac & convert to 12v at every camera Quote Mr Veritas God Link to comment Share on other sites More sharing options...
sixwheeledbeast Posted February 11, 2020 Share Posted February 11, 2020 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. 1 Quote Link to comment Share on other sites More sharing options...
aissecur Posted February 11, 2020 Share Posted February 11, 2020 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? Quote Link to comment Share on other sites More sharing options...
al-yeti Posted February 11, 2020 Share Posted February 11, 2020 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 Quote Link to comment Share on other sites More sharing options...
westy1 Posted February 11, 2020 Author Share Posted February 11, 2020 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. Quote Link to comment Share on other sites More sharing options...
MrHappy Posted February 11, 2020 Share Posted February 11, 2020 1 hour ago, westy1 said: Have you tried this from experience or is it just a suggestion? central 12v power supply(s) ? Quote Mr Veritas God Link to comment Share on other sites More sharing options...
aissecur Posted February 12, 2020 Share Posted February 12, 2020 how long are the camera runs? Quote Link to comment Share on other sites More sharing options...
sixwheeledbeast Posted February 12, 2020 Share Posted February 12, 2020 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. 1 Quote Link to comment Share on other sites More sharing options...
westy1 Posted February 13, 2020 Author Share Posted February 13, 2020 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. Quote Link to comment Share on other sites More sharing options...
sixwheeledbeast Posted February 13, 2020 Share Posted February 13, 2020 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. Quote Link to comment Share on other sites More sharing options...
MrHappy Posted February 13, 2020 Share Posted February 13, 2020 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 ? 1 Quote Mr Veritas God Link to comment Share on other sites More sharing options...
james.wilson Posted February 14, 2020 Share Posted February 14, 2020 1 hour ago, MrHappy said: is it an easy job to try running cameras of 12v batteries ? Qfa Quote securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
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