Broadband U2 Interference What next?

Discussion in 'EMC Matters' started by wogga383, Jan 12, 2020 at 10:24 AM.

  1. wogga383

    wogga383 New Member

    Morning gang, assuming you can open the image attached, thanks to the wonders of SDR I am able to get a snapshot of the spectrum. I am not a RSGB member but a SWL. I live in a semi urban environment which has its ups and downs, however I suffering an unfair amount of QRM which is killing my hobby.

    Attached is what I think is U2 interference from broadband? I have BT and regardless of what I do indoors to kill interference it doesn't go so I assume it is radiating from elsewhere? How far can U2 radiate? My broadband is overhead from a pole 50m away, the BT fibre cab is 400m away and the exchange 1km. All the broadband here is BT infrastructure, we are too rural for cable.

    Can the knowledgable confirm my U2 suspicions and advise on my next steps, I will go for a wonder with a SW receiver to see if I can identify a culprit.

    Regards

    Attached Files:

  2. Ken G3SDW

    Ken G3SDW Moderator

    Hi there. a name would help please, location as well.

    I hope you have, but the very first thing you need to do is to turn off your mains supply at the main fuse box and monitor your problem with a portable RX

    This is the very first line of attack when trying to locate a problem such as yours.

    What do you mean by U2??

    What does the problem sound like as just looking at a waterfall will not locate it at all.

    You biggest stumbling block will be that is it turns out to be a neighbor and you are just an SWL listening outside amateur bands, then Ofcom will not get involved, not what you want to hear but sadly the case.

    Give me an update if you could as i am always here at all times

    73
    Ken G3SDW
  3. wogga383

    wogga383 New Member

    Cheers for the response Ken, my QTH is near Preston in Lancashire. U2 broadband interference is discussed in the RSGB EMC leaflet 15. U2 is seen as an increase in the noise floor between 8.55Mhz and 11.95Mhz and emits from broadband equipment. I have done all the local stuff in my QTH and that does not clear it. To compound matters I have a serious buzz late afternoon to mid morning which wipes out MW and top band, that could be new neighbours.

    I have attached a better shot which clearly shows a corresponding increase in level
    between 8.55Mhz and 11.95Mhz.

    Regards

    Pete




    Screenshot 2020-01-12 at 13.39.23.png View attachment 1296
  4. Ken G3SDW

    Ken G3SDW Moderator

    Can you categorically say Pete that you have turned off your mains supply.

    As for you saying U2 interference then i just wanted to know that you understood what it stands for.

    73
    Ken G3SDW
    Last edited: Jan 12, 2020 at 4:01 PM
  5. wogga383

    wogga383 New Member

    Ditched my mains several times Ken, I am working on getting the SDR on a laptop so I can test completely mains free and see the spectrum. I have isolated all my appliances and lighting apart from the SDR computer and it still appears, even tried a different computer. As far as testing it with a portable radio it appears to cover a fair area in the street, getting a definitive direction is proving difficult? As for my new MW/160m interference it came on at 1643 UTC today, it’s got to be my neighbours, just been out in the street and covers a fair distance but seems to come from our end of the Terrace, yes a Terrace not much separation. I have already pre warned the newbies next door, they seem reasonable and will co-operate.
    I am using a Wellbrook ALA1530LN in the attic, I have changed a few things outside so I can now move it outdoors away from the building and hopefully try and null out the U2? If I can’t sort it I will tackle BT. Frustrating thing is I am only 500m from open countryside, but surrounded by housing and noisy electrical items.
  6. Ken G3SDW

    Ken G3SDW Moderator

    Well sounds as if you have the dreaded VDSL interference, re radiated by over head phone lines as you may well know.

    It will no doubt be someone local to you with a self router install, with some multiple extensions, but to get Ofcom involved then you dont stand a chance, BT will not get involved either, they will tell you that there systems do not cause any interference as the guys on the phone do not understand EMC problems at all.

    Try and find out if you can if anyone recently has had Super fast broadband installed of late, that maybe a good place to start.

    Sadly in your position being an SWL then the ones who can help will not cooperate.

    Thats as much as i can do, sorry as i dont make the rules, thats down to Ofcom

    73
    Ken
    G3SDW
  7. wogga383

    wogga383 New Member

    Thanks Ken, I will do all I can my end. I don’t mind taking on BT, I’m a customer after all! I will see how I get on and let you know. I see there was a thread 2 years ago but no further response from the complainant? Shame it would of been interesting. The VDSL could of been there a while I am just returning to the hobby so not in a good place to start. I will update you on progress or not as it may transpire. I have a background in EW so know a bit about jamming :)
    Regards
    Pete.
  8. Ken G3SDW

    Ken G3SDW Moderator

    Dont waist your time with engaging with BT you will not get anywhere at all, its been tried before by bigger guys that you, trust me, jamming then again dont waist you time either, and by the way i dont not condone that at all.

    73
    Ken G3SDW
  9. wogga383

    wogga383 New Member

    I wasn't implying I was going to do anything underhand Ken! I have been reading around and Ofcom seem to be in denial as well? Still going to try BT I have nothing to lose.
  10. Ken G3SDW

    Ken G3SDW Moderator

    Have fun as you will go around in circles

    Ken

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