Hi and Thanks for accepting me to this group. I was wondering can anybody help me. The pub that is two doors away from me has installed am Nvr camera system fed directly from the NVR by PoE to the cameras . The system is causing me interference on HF bamds 14, 17,21,24,28, mhz at approx 30 khz steps. I am a complete novice where NVR and Poe is concerned I was wondering if the system was directed through a router on a LAn would it help. Any suggestions to cure this would be greatly appreciated. . The owner is cooperating. Thanks in advance for any help.
Interfernce to HF amateur Radio
- Thread starter Shep138
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NoloC
Getting comfortable
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- Nov 24, 2014
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Hi Shep. You'd probably be better served asking in a Ham forum as this is more of a generic "interference" question rather than an "NVR -POE" question.
Start by determining which device is causing the interfence. Unplug cam lines at the nvr one at a time. The NVR may need a ground. RF chokes can be had cheaply on Amazon and some experimentation on the cat5/6 cables may help. Often this is a switching power supply. Frustrating QRM.
Good luck and 73
Start by determining which device is causing the interfence. Unplug cam lines at the nvr one at a time. The NVR may need a ground. RF chokes can be had cheaply on Amazon and some experimentation on the cat5/6 cables may help. Often this is a switching power supply. Frustrating QRM.
Good luck and 73
Many thanks for the advice best 73
Starglow
Getting comfortable
The first thing I would do is to make sure the NVR / camera system is actually the source of RF interference. Ask the owner to shut it down and see if the interference stops and if so turn it back on to see if it comes back. The NVR system should have been RF emissions tested and certified to help prevent situations like this so if you're sure the NVR is the interference source then the NVR manufacturer or EU regulatory agency (similar to the FCC in the US) should be notified. The NVR manufacturer should have the regulatory emissions compliance report on file for that device assuming they did what they're supposed to do. 
I have already done this , had it switched off it is the source Ofcom are also involved. Although I doubt they will do anything. thanks for your replyThe first thing I would do is to make sure the NVR / camera system is actually the source of RF interference. Ask the owner to shut it down and see if the interference stops and if so turn it back on to see if it comes back. The NVR system should have been RF emissions tested and certified to help prevent situations like this so if you're sure the NVR is the interference source then the NVR manufacturer or EU regulatory agency (similar to the FCC in the US) should be notified. The NVR manufacturer should have the regulatory emissions compliance report on file for that device assuming they did what they're supposed to do.
tigerwillow1
Known around here
30 kHz is suspiciously in the typical power supply switching frequency. If it was leaking out of the POE ports, the camera wires could make nice antennas. With the owner cooperating I'd go to isolation. Unplug all the cameras, then plug them in one-by-one, observing the interference level with each change. Could be a simple grounding issue, too.
Thanks for yhe reply the problem is that the nvr has an internal power supply so I cannot put ferrite on it. Iknow the unit has not got a ground wire on it. I wonder if that would help.Thanks Again
No replace the SWITCHING power supply! (hint hint).
RF is getting induced upon the system. The antennas are the
wires running to the cameras. Or think of it as an upside down vertical
antenna with the ground plane in the rafters.
73 2u2
RF is getting induced upon the system. The antennas are the
wires running to the cameras. Or think of it as an upside down vertical
antenna with the ground plane in the rafters.
73 2u2
If a linear power supply could be used it would solve the problem .The problem is the smps is internal of the nvr. Thanks fo your help
tigerwillow1
Known around here
I once used an RV power converter to trace a buried 120 volt wire, using an AM radio along the wire path. The converter puts nasty switching noise out of its power cord. It wasn't good enough to trace the wire very far, but worked a little bit.
Oldtechguy66
Pulling my weight
Maybe, maybe not so much. Linear primary supply would be clean - but don't forget, it typically drops the supply to 48V DC (POE). Inside the NVR, more switchmode drops to 12, 5, 3.3, etc. So, might help, but don't bet on it curing all the RFI unless you could go linear with all the B+ supplies... expensive, bulky, and HOT. Also,the IP cams are have their own internal SMPS. They likely contribute as much as the NVR. I have same problem with pretty much ALL network gear. It's extremely "noisy" (RFI), and having much audio eqpmt/tuners in same room causes me many headaches. Ferrite chokes, shielded LAN cable, cleaner PS's all help; but in the end, I found the only thing that helps sometimes is distance ( 1/R^2)... or a faraday cage LoL. Unfortunately in your case, with the low freq RFI and "antenna LAN cables", getting far enough away from the noise on HF freqs is going to be difficult. But as bad as some networking equipment is, the one device that causes me more RFI than anything is LED lighting. Some are worse than others, but NONE I have seen yet are even close to being "clean". LED PS's are notoriously noisy, and with proliferation of them now, unfortunately the noise is here to stay. I used to complain about noisy fluorescent lights... but no more.
My suggestion would be if the owner will allow replacing the LAN cables with STP (not UTP), that may help, though probably not practical. Most people won't go that route due to cost, and the stiffness of the cable vs UTP. Grounding may help, but remember RF ground is not same as eqpmt service ground (service grounds can be very noisy). May take some trial and error to locate best RF ground (I use a grd rod array at my shop, but that's not always feasible). RFI has always been a bear, but nowadays it's a grizzly with an attitude with SMPS's in everything.
Good luck
tigerwillow1
Known around here
IMO no need to guess since it's easy to check it out. Take the system down to one camera while still observing the interference. At the camera end, use a POE splitter to power the camera. If the interference changes, the camera has something to do with it. If it doesn't change the NVR is highly incriminated. For more evidence, run the camera off of a POE switch or injector and see if there's interference produced. No need to have the NVR powered up for this. A further data gathering test would be to use a POE splitter on the camera end and drive a ~5 watt passive load instead of the camera.
Good thinking on the LED angle, since the cameras are certainly PWMing the LEDs, so an obvious 2 part question is (1) Are the camera LEDs in use, and (2) Any interference changes when they are on and off?
Oldtechguy66
Pulling my weight
Excellent points. I test my POE cams with an old bench (linear) 12v DC supply, since most IPC's have an aux 12v input for non-POE LAN use. With the IPC isolated on a clean supply, easy to determine how much RFI they produce. In my experience, it varies much - but most I've run across are not too noisy compared to the NVR, but some cams are MUCH worse than others. I don't notice significant increase in RFI noise at night when backlight IR LEDs active, but it all depends on what freqs I'm monitoring, and proximity. I found that ferrite chokes help some, but using and carefully routing STP cable helped most... but with all the other computer & network gear in my shop, it's just a little more noise...
When the next Carrington level CME hits, it won't matter anyway Many thanks for all the help and suggestions , I guess I need to identify if the interference is coming off the internal smps on the nvr and going down the cables to the cameras first, or is it from the actual cameras. I will take all the ethernet cables out of the nvr and put them back in one by one and see if I can narrow it down, the chap from ofcom has not been in yet with his equipment so he may help with that. If it was off the smps internal of rhe nvr I was thinking of buying an identical one with no hard drive and seeing if I could put ferrite beads on the internal supply leads, and if it works just swap his hard drive over. The other thing I was wondering is it possible to reduce the power levels to each individual camera .it is the noise and clicks I can hear more than anything like a ringing /whine and click. I am about fifty yards away from the cameras and at the moment they are all internal. Once again thanks everybody for your help.