Ofcom 2nd VDSL Investigation Report published.

Discussion in 'Investigations New Technology' started by Carl G3XGK, Nov 28, 2019.

  1. Carl G3XGK

    Carl G3XGK New Member

    Ofcom has recently published (last week) the results of it’s 2nd VDSL RFI investigation.

    It can be viewed here ..

    https://www.ofcom.org.uk/research-a...ctrum-assurance-analysis-of-bt-openreach-vdsl

    Interesting reading. It appears that most problems are caused by customer’s wiring, which BT Openreach has told Ofcom it has no control over.


    However, it does have control over the Amateur Radio band 20dB notches which would reduce the noise in the Amateur bands for over 90% of the RSGB survey reported cases to below the background normal noise floor, and was the solution that BT designed into the equipment itself and advised the ITU to included in the ITU international spec G993 to resolve this problem. And would overcome the customer wiring problem listed above.

    This has however been ignored by Ofcom in the report. I wonder why ?


    Although there were 650+ VDSL reports identified by the RSGB in 2017 in their VDSL survey, of which over 1300 took part, it seems Ofcom have only had 30 cases reported in the last 5 years: perhaps if you have VDSL RFI still, it might be time to raise a report online with Ofcom on their website, it only takes a few minutes and a few clicks.


    The Annex to the report has an error, the 160m (1.810-2.000MHz) Amateur Radio band has been omitted from section A3, despite it being clearly in the VDSL2 spectrum (138kHz-17664KHz) in the 998ADE17 plan.


    73

    Carl G3XGK
    G0SZI likes this.
  2. G0SZI

    G0SZI New Member

    Hi Carl,
    I believe the reason OFCOM have few reports as VDSL causes very broadband noise it is not always easy to identify in the first instance without the correct knowledge and observations. As given a choice many people will prefer to speak to somebody in person they will telephone OFCOM (as I did) to be told they will not investigate Broadband noise as I was. This leaves you feeling rather helpless and unlikely to submit a complaint. I have telephone wires perpendicular to the ends of my 80 mtr dipole that although not my own cause me a real headache. Many times operation on 80 and 40 mtrs are impossible for me. I have even recently purchased a Ciro Mazzoni Baby loop but although placed a distance from the telephone lines it still causes considerable noise.
    As far as I'm concerned OFCOM are a absolute joke and are not taking action where a clear issues of harmful interference are taking place and to say that customer wiring in the home is beyond their control is a load of twaddle. Enforce the provider of VDSL ensure their provision of a service does not cause interference as you say perhaps by making sure the Amateur bands are completely unused in VDSL modems.

    To say that Against the backdrop of an estimated 25 million VDSL installations, the overall the impact of VDSL remains extremely small. Over the past five years Ofcom has received an average of six complaints a year is in my mind akin to saying
    Stabbing in London are only affecting a very small minority compared to the rest of the population so we won't use our powers to bring the offenders
    in all cases to task.

    A Very Angry G0SZI
  3. Ken G3SDW

    Ken G3SDW Moderator

    Andy i understand what you are saying, but have you spoken the the RSGB EMCC ??
  4. Carl G3XGK

    Carl G3XGK New Member

    Hi Andy


    Sorry to hear about your dealings with Ofcom on the phone.


    I really do think the best way is to fill in their form online.


    It is not difficult to identify VDSL RFI Noise presence, Take a look at RSGB EMC leaflet 15.


    https://rsgb.org/main/technical/emc/emc-publications-and-leaflets/


    The EMCC also has a program ‘Lelantos’ written by Dr. Martin Sach G8KDF, the current chairman of the EMCC, which they can use to confirm VDSL2 on your radio reception, as Ken will confirm.


    In the RSGB Committee report on page 56 of the April 2019 RadCom it mentions...

    “We still have trouble trying to get Ofcom to respond to cases of HI to the amateur radio service. Having had discussion with other national regulators at international meetings, we are of the view that Ofcom is far worse than average at ignoring HI. Our efforts are therefore directed at raising awareness and empowering our Members to complain convincingly. Ofcom will only respond if they get large numbers of complaints”

    HI is of course Harmful Interference.


    So if those who took part in the VDSL survey and found they had VDSL2 HI problems all complained to Ofcom their remit would be somewhat different than it is in the current report.
    Ofcom will I am sure be aware of the RSGB 2017 VDSL survey report and the numbers, ...but they have not had the direct complaints.


    Have a look at the online form and see what you think Andy.


    Best regards

    73

    Carl G3XGK
  5. Ken G3SDW

    Ken G3SDW Moderator

    Dont know if you have noticed one thing about Ofcoms position on this one.

    Its the very same as when PLT reared its ugly head many years ago, about 2008.

    The word used then and used now is "Proportionality", in a nut shell then loads out there mate but very few complaints.

    Nothing has changed with there position at all.

    73
    Ken G3SDW
  6. Carl G3XGK

    Carl G3XGK New Member

    Hi Ken


    Thank you for your reply and comments.

    Yes, I have noticed the four words they use of which one is Proportionality. These words seem to come from the Communications Act 2003, which describes how Ofcom evaluate complaints.

    However, this covers all Communications; Post, TV programs, Broadband, Telephone and others which Ofcom deal with today.

    But when a TV program is watched by say 10million people, and only a few complain, Ofcom still looks into it.


    There is a big difference between PLT and VDSL as regards Amateur Radio.

    PLT has the Amateur Radio HF bands notched, so you don’t hear any PLT in the HF bands.

    VDSL does not, it goes right across all the HF Amateur radio bands (160M to 20M).

    I don’t know when or who got the PLT ‘notched’ for the Amateur Radio HF bands, but I am guessing it was not Ofcom.


    Best regards

    73

    Carl G3XGK
  7. Ken G3SDW

    Ken G3SDW Moderator

    Thats down to a lot of work behind the scenes Carl, but i am fully aware of the difference with PLT and VDSL, i was just pointing out how Ofcom hide behind words and statements like this.

    They use it to there advantage each and every time.

    73
    Ken
    G3SDW
  8. Carl G3XGK

    Carl G3XGK New Member

    Hi Ken

    Thank you for your reply.

    Yes, I agree they do use this reason time and time again.


    So the way to prevent this is to raise the number of complaints. Hence my mention previous that if the 600 Amateurs who had VDSL RFI problems identified, reported it, then the ‘Proportionality’ part would surely no longer be relevant ?

    The fact that it is appears to be due to apathy on our part.


    Do you happen to know the real reason the PLT Amateur band notches came about and who arranged it ?


    I ask because the technical reason or justification could also be relevant to getting VDSL notched as well.


    Best regards

    73

    Carl G3XGK
  9. Ken G3SDW

    Ken G3SDW Moderator

    Sorry for the delay in getting the info that you required Carl.

    It appears that it was the manufacturers who done this but who influenced them i do not know, but look at the attached screenshot and for me i think i know and sure you will spot it too.

    73
    Ken G3SDW

    Attached Files:

  10. Carl G3XGK

    Carl G3XGK New Member

    Hi Ken

    Thank you for the interesting info. There seems to be an awful lot of AM spectrum that is outside the HF Amateur radio bands, so that is notched as well.

    Did not realise that there was so much notching in the PLT domestic systems.

    I am starting to hear what sounds like PLT on 50MHz nw, as well. Unless it is G.Fast.

    Kind regards

    73

    Carl G3XGK
  11. Carl G3XGK

    Carl G3XGK New Member

    Hi all


    Further to Ofcom’s 2nd report on their Spectrum assurance of BT Openreach VDSL interference investigation, I wrote to Ofcom regarding a couple of points about the latest report.

    My questions and the reply maybe of interest to other Radio Amateurs who are experiencing VDSL based interference on the UK HF bands.


    My questions in the letter ;-


    I would also like to discuss two items that appear in your report.




    (1) You have said in para 6.4 “Openreach have stated that VDSL emissions can be affected by inadequacies in their customers in-home wiring, a matter beyond their control”.




    This current problem would largely be overcome if the protection notches that are listed in ITU-T G993 [1] (the protection notches which BT themselves fought to have included in the spec) were implemented by BT Openreach, making the customer in-home wiring problems irrelevant.




    It was BT themselves, during research of the VDSL product, discovered the egress problem, and designed the solution of the protection notches into the development of the equipment as standard.




    These software remotely enabled notches, if you are not aware, would reduce the emissions by 20dB and for most VDSL interference affected Radio Amateurs would place the VDSL interference noise below the noise floor at their locations. [2] Thus making the customer in-home wiring problems for over 90% of VDSL interference affected Radio Amateurs irrelevant.




    As these protection notches are available for enabling in the VDSL equipment, why have you not mentioned these protection notches anywhere in your report ?




    (2) You stated in the report para 6.5 “Over the past 5 years Ofcom has received an average of 6 complaints a year”.


    During 2017 the RSGB conducted a survey online to establish the VDSL interference issues with Radio Amateurs in the UK. They had over 1300 replies to the survey, and identified 650+ cases of VDSL based radio interference. So over 50% of those who responded to the survey were experiencing VDSL based radio interference causing degraded reception.


    I believe this was discussed with yourselves during meetings with the RSGB in spring 2018 and is available for public viewing on the RSGB website. [3]




    How is it that you are not aware of these numbers ?






    [1] ITU-T G993.2 specification VDSL




    [2] ITU-T G993.2 page 35/36.




    [3] rsgb.org/main/files/2018/10/vdsl-RFI-Impact-interim-report.pdf





    The reply from Ofcom :-


    In response to your first question, specifically the omission of reference to ‘protection notches’. This was not within the scope of the surveys or report. The report documented further technical surveys conducted by Ofcom focusing on evaluating corrective measures by Openreach on electromagnetic emissions from cables carrying VDSL.




    In regards to your question concerning the number of interference complaints attributed to VDSL emissions. Whilst I am aware of the RSGB survey which you have referenced, I can confirm that the average number of complaints regarding VDSL radio interference which are received by Ofcom is 6 per year.



    I think it is clear from this that in order for Ofcom to recognise the extent of VDSL interference, Radio Amateurs in the UK with VDSL based interference degrading their reception really must go online to the Ofcom portal and make a complaint so that it is logged with Ofcom. It really cannot be much clearer that this is what is required.


    Best regards

    73


    Carl G3XGK
  12. Ken G3SDW

    Ken G3SDW Moderator

    The problem being that if you do a FOI request concerning the actual amount of complainants and there basic locations, they will not divulge anymore than that due to GDPR then Ofcom will tell you that they do not keep record, that personally i do not believe.

    You me and me and anyone else who contacts them are just being laughed at and although they have replied to you then we are no more forward in getting things done.

    Well done for trying

    73
    Ken G3SDW
  13. Ken G3SDW

    Ken G3SDW Moderator

    Now this make more sense and when it comes off will solve a multitude of sins Carl.
    73
    Ken
  14. Carl G3XGK

    Carl G3XGK New Member

    Hi Ken


    FTTH will be very useful in clearing the VDSL RFI problem for sure, but on the practical side, how long will it take to move 25 million VDSL users to FTTH/FTTP and will everyone be able to afford it ?


    Enabling the already available BT designed ‘notches’ at RFI problem locations will be much quicker.


    Nearly 4 months ago the RSGB had a meeting with Ofcom regarding Ofcom’s tests on VDSL RFI cases at three amateur locations. After the meeting it was stated that Ofcom was happy for the RSGB to reopen talks with BT Openreach.


    And the RSGB said it would be seeking a meeting with BT Openreach to discuss the implementation of the amateur band notches.

    Would you know if this meeting has taken place or if it is ever going to happen ?


    Best regards

    73

    Carl G3XGK
  15. Ken G3SDW

    Ken G3SDW Moderator

    Hi Carl, your first question about how long will it take, some years i feel and maybe not in our life time.

    Enabling notches, yes that would be much quicker but i somehow dont think that will happen, well not anytime soon.

    As for the meeting, well not yet but it will be forthcoming soon.

    That is as much as i can tell you at this time Carl.

    73
    Ken G3SDW

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