RFI from BT Home Hub

Noise and interference issues?
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Alex Cator
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RFI from BT Home Hub

Post by Alex Cator » 03 Feb 2015 14:24

In my house we have a BT Home Hub. It is our router.
I have noticed that it causes so much radio frequency interference to the quarter of the house that it's in, as seen with a Tecsun PL-390. All these reports will be about when the antenna of the Tecsun is not extended at all, and the Tecsun is in front of the Home Hub.

At around 21 dB, there is what sounds like normal FM white noise, but it is severe noise. It appears on all frequencies. The Tacolneston BBC nationals have static added to their stereo signals, and Classic FM (also Tacolneston) is too fuzzy to be stereo. Reception of Kiss FM (Ipswich) on 106.4, is similar to that of Classic FM. BBC Suffolk (104.6, Great Barton) is very weak and can hardly be heard. Heart on 96.4 (also Great Barton) is droned out completely, and no Stoke Holy Cross signals can be heard. Blank carriers appear on various frequencies, including one OIRT one, and also 88.0 and 100.0 MHz. The 100.0 one is 47 dB, and the room it's in has very poor reception of Radio Norwich 99.9, thanks to that blank carrier from the Home Hub. MW and SW are strongly affected as well, with a high level of noise, and no legitimate radio stations are present at all on MW or SW. Nothing of even BBC Five Live (693) is there at all.
Does anyone know why a BT Home Hub would cause a high level of RFI, that even has an effect on Tacolneston? People in Norwich probably have very bad signals of Norwich 99.9 if they own Home Hubs, then! Is it related to the router itself, or the WiFi transmitter? Would there be less or no RFI if I used an Ethernet cable? There was no RFI in that area if the Home Hub was switched off, so it was definitely the Home Hub to be blamed for that RFI! :(

Kind regards,
Alex Cator.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
Mobile: Ford Fiesta (Style, 2013) and Ford Focus (2012) car radios
Portable: Tecsun PL-390, Grundig G5 (2 x 110kHz), Etón G8

satnipper
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Re: RFI from BT Home Hub

Post by satnipper » 03 Feb 2015 14:42

It may be the switch-mode power supply for the router.

Alex Cator
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Re: RFI from BT Home Hub

Post by Alex Cator » 03 Feb 2015 15:38

Maybe it is the power supply, then. Do WiFi signals ever interfere with FM radio reception when the WiFi signal is very strong? It can be a little bit of a worry when modern digital signals, that you rely on, interfere with the good old FM and AM analogue signals, if they do, and I'm not sure that they would. Kinda wish the radio spectrum wasn't clogged up with 2.4 GHz digital communications.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
Mobile: Ford Fiesta (Style, 2013) and Ford Focus (2012) car radios
Portable: Tecsun PL-390, Grundig G5 (2 x 110kHz), Etón G8

Andrew Webster,Wigan
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Re: RFI from BT Home Hub

Post by Andrew Webster,Wigan » 03 Feb 2015 16:14

What version of HUB do you have?

As Stuart said the SMPSU could be the cause or the hub itself especially if the capacitors are failing which is the biggest problem with modern equipment.
I have some BT home hubs here was given to as people chuck there old stuff my way for recycling lol.

I am on Virgin and my router does not emit any QRM and they are close to my tuners.
What we need is someone else with the same router to do a check and see if they all radiate QRM or whether it yours that is faulty.

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

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John Faulkner, Skegness
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Re: RFI from BT Home Hub

Post by John Faulkner, Skegness » 03 Feb 2015 19:06

FWIW, my Sky modem/router emits noise too and travels along the cable to my main computer, which is hard-wired. This produces noise across band 2 on the Elad and XDR. The laptop, which uses wifi and sits next to the desktop computer, doesn't receive the interference at all on either receiver.

Alex Cator
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Re: RFI from BT Home Hub

Post by Alex Cator » 11 Feb 2015 19:39

The QRM came out of the Home Hub itself, not the power supply. Pity we use BT Infinity, so I cannot use a normal ADSL router. My parents object a lot to ADSL, and they hate ADSL so much that BT Infinity will be installed at the new house. I'm not that bothered, and I would just use ADSL if I had my own house, just so I could use a low-noise router that wouldn't emit QRM. Well, that would actually depend on the Internet-related needs of my wife, if I had one, which I do not, but I probably will when I move to my own house. All I need to do is switch off the Hub when I DX, if I'm using the PL-390 in that part of the house. I respect the wishes of my parents, and their fibre-optic requirements, as they watch BBC iPlayer on the TV, and my dad's work computer keeps cutting out when connected to at home if ADSL was used. I presume one can use ADSL as well if there's BT Infinity installed, so can one? Also, could you please recommend a low-noise router that doesn't interfere with VHF, SW, MW or LW radio. Not sure about the others, but one that does not interfere with Band 2 would be great. The Home Hub emits blank carriers on 88, 100, 108 MHz and also one Japanese frequency, which I think is somewhere around 77 or 78 MHz. It also emits a lot of white noise in the 23 dB range, which is capable of causing some additional static on both Kiss (106.4, Ipswich/Mendlesham) and all the Tacolneston signals, both strong locals. The Stoke Holy Cross and Great Barton stations are all wiped out, apart from BBC Suffolk on 104.6, which can be heard ever so slightly on the PL-390 when near the Home Hub, but it is very weak and almost unlistenable. Any other semi-local and DX stations cannot be heard at all. There was a spot outside the pharmacy in East Harling where I got lots of Oxford stations (including Heart Oxford 102.6 with RDS) in today's tropo, and there was a blank carrier on 100.0 MHz in that location, that was capable of blocking Kiss 100, but it wasn't strong enough (thanks to the razor-sharp DSP) to affect Radio Norwich 99.9 in any way. Maybe that is emitted by someone's Home Hub? I would like to do a WiFi bandscan in that spot, so I can see if there is a strong Home Hub operating in the area.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
Mobile: Ford Fiesta (Style, 2013) and Ford Focus (2012) car radios
Portable: Tecsun PL-390, Grundig G5 (2 x 110kHz), Etón G8

Alex Cator
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Joined: 26 Dec 2014 14:53
Location: East Harling, Norfolk, England (QTH JO02LK)
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Re: RFI from BT Home Hub

Post by Alex Cator » 13 Jun 2015 12:43

Being a casual MW DXer, I do think BT Infinity is a good idea because from the nearest box, it's VDSL2 (SW) instead of ADSL (whose in-cable frequencies include the MW band). There are telephone wires above the driveway, and the St. John's stations are difficult on the car radio in this location due to noise. Both CJYQ and VOCM are affected. Does that mean that, even if the house has Infinity installed, ADSL is still available? I'd love that to NOT be the case, because MW DX can be difficult due to ADSL interference. Because the car radio doesn't have SW, SW interference does not matter, as my SW radios receive SW well inside the house and garden. I heard an Italian CB somewhere just after 27 MHz in SSB on my Grundig G5 (my first SSB radio). The G5 covers the entire MW and SW spectrums, and the higher end of the LW spectrum, from 150 kHz to 29.999 MHz. SW and MW reception on the G5 is superb, and LW reception is pretty good (better than the R9993 and PL-390), but not perfect, as 153, the frequency of SRR Antena Satelor from Bod, ROU, and NRK Finnmark from Ingøy, NOR, and the former frequency of Deutschlandfunk from Donebach, D, has an image of Talksport.
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
Mobile: Ford Fiesta (Style, 2013) and Ford Focus (2012) car radios
Portable: Tecsun PL-390, Grundig G5 (2 x 110kHz), Etón G8

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