NotHeardofThat1 Posted March 19, 2015 Posted March 19, 2015 Hi. Bit of a long shot but here it goes, Camera cables run through to first 16 way DVR, then all those will go from their individual video outs to another DVR in another building. Recording on both DVRs. Long story short we've found we only get a clear picture on both DVRs if we power the first DVR from the same building as the furthest DVR, tested with a long extension cable. I'm assuming the buildings are on different electrical phases and that is the reason. Is there a way to stop the interference? I don't think a humbloc is designed for this issue? It's not just a bit of rolling, the pictures drop in and out Any help much appreciated! Quote
sixwheeledbeast Posted March 19, 2015 Posted March 19, 2015 I am assuming both buildings only have single phase supply? Where are the camera's powered from? Humbug's are for earth loops, there is a possible issue of an earth loop, but really a humbug is only masking the issue anyway. Have you tested P2P, sync etc? Quote
james.wilson Posted March 19, 2015 Posted March 19, 2015 Id say its an earthing issue. Im assuming dc cameras? Whats the dvr? 1 Quote securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount.
Nova-Security Posted March 19, 2015 Posted March 19, 2015 Long story short we've found we only get a clear picture on both DVRs if we power the first DVR from the same building as the furthest DVR, tested with a long extension cable. I'm assuming the buildings are on different electrical phases and that is the reason. Most probably or an earthing issue as James said, when we do big sites all cameras are 24ac and DVR in main building and lodge one have to be fed from same phase. Quote www.nova-security.co.uk www.nsiapproved.co.uk No PMs please unless i know you or you are using this board with your proper name.
NotHeardofThat1 Posted March 19, 2015 Author Posted March 19, 2015 (edited) Cameras are 12v dc, powered locally. they have no issues with either DVR on either phase, only when both DVRs are connected. They are located in another building too. I thought it was an earthing issue so I plugged in the DVR with the earth out the plug, bit naughty but just to test, but still had the same issue. Saying that the monitor would have still been earthed... And connected to that DVR. I don't know what I was proving as I couldn't have left it without an earth anyway. I don't know what P2P or sync is I'm afraid? Edited March 19, 2015 by RShaw Quote
james.wilson Posted March 19, 2015 Posted March 19, 2015 peak to peak and sync voltage should be 0.7 on the video and 0.3 on the sync pulses. Some dvr's dont like it to stray to far (assuming its analogue) the fact it works on the same phase id say your vid voltages are ok. Also a lot of dvr's arnt earthed (dc) but if you had your monitor connected and that was earthed drpiing the dvr earth wouldnt of proved anything.I still reakon its an ground loop. Quote securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount.
Alpat Systems Posted March 20, 2015 Posted March 20, 2015 Use a UPS on the DVR on another note... This is also a common fault with data networking when one network switch is on one phase and connected via Cat5/6 to another on another phase. You get around this by connecting them together via fibre optic cables. Quote
sixwheeledbeast Posted March 20, 2015 Posted March 20, 2015 I don't know what P2P or sync is I'm afraid?Values of P2P as close to 1.00v and Sync 300mV, you need a CCTV signal tester like a Ranger for those. Cameras are 12v dc, powered locally. they have no issues with either DVR on either phase, only when both DVRs are connected.It does sound like an earth loop then. I'd agree with UPS. Quote
NotHeardofThat1 Posted March 20, 2015 Author Posted March 20, 2015 Yup ground loop. Humblock sorted It! Thanks for the responses Quote
james.wilson Posted March 20, 2015 Posted March 20, 2015 **** earth then at one place Quote securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount.
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