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Detecting 868Mhz radio interference

Old 16 December 2018, 04:01 PM
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ALi-B
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Default Detecting 868Mhz radio interference

This has been an on/off ongoing issue of mine with my heating system (EvoHome) which operates on said frequency.

It gets worse at this time of year, which is annoying. Folk on other forums suffer similar, namely with the BDR-91 units. Everything else is fine, but I have several that suffer weak/intermittent signal and swapping them with ones that work seemed to mostly solve the issue now the two most troublesome units are closest to the base station. However today I find a third unit acting up, so this is getting a bit of ****.

I believe there are two issues going on; The BDR91 (Demand Relay Units that switch the zone valves on/off) units themselves have issues and degrade over time....its the only part of the system that is directly mains powered so I suspect their internal switching power supplies could be causing interference. The only way to prove this is to replace them and pray the new ones have been updated and from a more reliable batch (I had BDR91s at my old house with a CM927 controller with zero issues). I disassembled everything and noted the aerial PCB on the BDR-91s is slightly shorter than everything else, so I extended it a touch with a flying lead - this did slightly improve reception on the worst behaving unit.

Second issue is interference from other sources. Namely switched mode power supplies found in EVERYTHING, even sodding light bulbs! All made in china with their typical quality fade, especially when it comes radio interference suppression and compliance; For example my uncle's dashcam cigar supply would completely wipe out the FM reception of every car radio in a 50yard radius!!

I know my outdoor lights interfere...now isolated (saves on the 'leccy ). I "think" the PSU on my Sony TV interferes a little. I have a number of faulty/semi faulty LED light fittings made by JCC lighting that I so suspect are also causing radio noise, and today I found out that either my genuine iPhone charger or HP laptop supply is also interfering (comms issue on two BDR-91s...switch off chargers which were on the same socket, bam! coms restored). So this is getting silly.

So what I want to do is find a easier way of detecting radio interference...particularly on 868MHz, although 2.5Ghz and 5Ghz wouldn't be a bad idea either.

THEN, how the hell do I go about suppressing it...if for instance my TV PSU is interfering, how the hell do I go about it? Stick ferrite cores round every power wire? Is there something that could be done with the mains supply at the consumer unit which could possibly be radiating interference though the main or earth? If the BDR91 units are creating their own interference, its 99% likely to be their own built-in switched mode supply then I probably could remove it and power it from a external supply....but that's assuming I can source a high quality PSU that doesn't produce radio noise, doesn't interfere and doesn't degrade with time....nightmare!

Technology, eh?

First things first though...how the hell do I go about finding the source of interferences?....switching off suspect devices isn't really working as there is a 15 to 30min lag with the units detecting signal loss so I have to do it two or three times to confirm it, so that can be upto 1.5 hours per device, I just don't have that much spare time!

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Old 16 December 2018, 07:40 PM
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Wouldnt a scanner on that band work on the 800MHz?
Might be worth popping your location up, then a member like myself may be able to assist there.
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Old 17 December 2018, 12:49 AM
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What kind of scanner are you talking about? I maybe willing to buy one if it serves a good purpose as BDR91s are 54 each and I have four of the bloody things, three of which are suspect. I guess it’s a radio scanner? If so would the noise from a PWM switched mode supply be easy to differentiate from digital communications, I guess it’s all going to sound like a fax transmission, however switchingthings on/off should be able to make a instantly distinguishable difference, so certainly an avenue worth investigating.

Based south of Birmingham
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Old 18 December 2018, 12:18 PM
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Spotted this
https://www.metageek.com/training/le...erference.html

I did mean a radio scanner yes, I got a cheapo TTI,
Amazon Amazon

Or join up to somewhere like this on FB, and ask if there is a local member who can pop over and scan for you,
https://www.facebook.com/groups/hatcomm/
Most are Ham users, so will be better equipped than myself, and love a good turkey hunt.
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Old 18 December 2018, 07:03 PM
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Cheers, think I may buy a scanner. Seems a handy thing to have...I have an old HiFi receiver that for some reason extended beyond the normal radio bands and would pick up all sorts. Not to forget the Droitwich clock signal, although I guess most stuff that can do LW will do that.
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Old 18 December 2018, 11:09 PM
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Call ofcom and let them make a visit to check for interference, they are the governing body for radio and telecommunications
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Old 19 December 2018, 10:40 AM
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Originally Posted by ALi-B View Post
Cheers, think I may buy a scanner. Seems a handy thing to have...I have an old HiFi receiver that for some reason extended beyond the normal radio bands and would pick up all sorts. Not to forget the Droitwich clock signal, although I guess most stuff that can do LW will do that.
Being in Brum I bet you will find loads on the PMR bands(400 MHz and around)
Be an interesting listen at the weekends lol
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Old 19 December 2018, 10:43 AM
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Originally Posted by sti-chris View Post
Call ofcom and let them make a visit to check for interference, they are the governing body for radio and telecommunications
This is after much hoop jumping, and 12 weeks of keeping a very precise diary,
BT also have a team (Reins iirc) that do this if they believe that the interference is causing BB issues etc
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Old 04 January 2019, 06:27 PM
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This has been on hold until the crimbo lights come down as they seem to also interfere!

Since found Gen 2 smart meters may operate on 868mhz as well, and I’m due to have one installed FFS. ..I’m awaiting for information from a npower tech bod to confirm this and advise me on what exactly it transmits on this frequency, how often and if it can be disabled. As the last thing I want is a sodding meter resulting in no hot water when I want a shower (one way to save energy I guess ).
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