In the previous articles we have looked at the cause, effect and legal aspect of PLT. In this section we will look at the evidence available from the FOIA applications known to be made so far.

We have uncovered the current legal position of the technology with the organisation which is responsible for its availability in the UK. The story has not been a happy one for anyone who enjoys shortwave radio in any capacity. But it doesn’t stop there; there’s a new kid on the PLT block and he’s looking to bully you off your stereo FM radio, screw up the international VHF air communications and a lot more besides. And he’ll never get an ASBO. . .

 

The problem with making applications under FOIA is that it can be a ‘bit of a game’ insomuch that if one asks too generalised a question, the responses can be equally general and if one is too specific, it can narrow down the response too far, leaving one equally in the dark. I’m afraid that in this instance it is 30-15 to OFCOM, but I did at least score. . . I managed to obtain some of what I was looking for but confess that the application was a little knee-jerk due to the preceding exchange. My apologies for that.

I hope that what follows is sufficiently succinct to present a ‘feel’ for the current thinking at OFCOM, it does contain an alarming conclusion regarding Amateur Radio and to a lesser-extent, SWL so I urge all who are interested in this to read carefully and think carefully before posting a response here. I recommend that this is used as the launch vehicle; with careful debate and application of some intelligence, we can ask “the right questions”, for it is only the “right questions” that will yield the results.

Dear Mr Coleman

Freedom of Information: Right to know request

Thank you for your request for information which Ofcom received on 11 January 2010 and has considered under the Freedom of Information Act 2000 (‘the Act’). I apologise for the delay in responding to you. As explained in my email of 11 February 2010, Ofcom required this additional time because some of the information requested had to be considered under an exemption which exempts Ofcom from releasing the information, to which a public interest test applies.

You asked for the following:

“• Minutes from any committee meetings where PLT was discussed, from the beginning
of 2009 to date.

• Minutes from the meeting which resulted in the 'extra spectrum above 30MHz report'
being commissioned.

• Disclosure of full details of the "Independent" compiler of the PLT report (subject to
any DPA restrictions), including all communications, written and electronic regarding
instructions as to 'extent and limitations' of said report.

• Evidence of the independent status of the report compiler and his or her ability to
present an unbiased report.

• Records of any formal Compliance Tests held by OFCOM regarding PLT.

• Verification from committee meetings that should the report find that PLT is
incompatible with the current EMC Directive 2004/108/EC (or derived EMC 2006
Regulations) that OFCOM will take enforcement action.”

1 - Minutes from any committee meetings where PLT was discussed, from the
beginning of 2009 to date

R: Please find enclosed document FHQ-09-0037, which contains the relevant notes from a Policy Executive meeting held on 12 November 2009.

2 - Minutes from the meeting which resulted in the 'extra spectrum above 30MHz
report' being commissioned.

R: Please find attached the minutes of the meeting between Ofcom and PA consulting at which the extra spectrum above 30MHz was discussed.

3 - Disclosure of full details of the "Independent" compiler of the PLT report (subject
to any DPA restrictions), including all communications, written and electronic
regarding instructions as to 'extent and limitations' of said report.

R: Details of the independent compiler of the report can be found here http://www.paconsulting.com/. The following communications between Ofcom and PA consulting are also attached as requested. The original invitation to quote - PLT-ITQ, and 6 E-mails containing correspondence between Ofcom and PA Consulting.

4 - Evidence of the independent status of the report compiler and his or her ability to
present an unbiased report.

See answer to question 3.

5 - Records of any formal Compliance Tests held by OFCOM regarding PLT.

R: Ofcom cannot disclose the information you have requested. This information falls under the exemption in section 30 of the Act. Section 30 is concerned primarily with preserving the integrity of certain proceedings and investigations which public authorities have the power or duty to conduct. This is information that was recorded by Ofcom for the purposes of its functions relation to EMC criminal investigations. In applying this exemption we have had to balance the public interest in withholding the information against the public interest in disclosing the information. The attached annex to this letter sets out the exemption in full, as well as the factors Ofcom considered when deciding where the public interest lay.

6 - Verification from committee meetings that should the report find that PLT
is incompatible with the current EMC Directive 2004/108/EC (or derived EMC 2006
Regulations) that OFCOM will take enforcement action. [Edit: LOL, well, it was worth a shot. . .]

R: Ofcom does not hold this data.

 

Having considered the communications sent under the FOIA request, I have concluded that it would add volume but not clarity to this scrawl so I have elected to omit it. However should you truly be interested, it is available from the UKQRM Yahoo Group.

What now follows are the minutes from a progress meeting which Ofcom had with PA Consulting.

 

FHQ-09-0037-D_A Page 1 of 4 26/10/09

PA CONSULTING GROUP

UNDERSTANDING THE LIKELIHOOD AND EXTENT OF RF

INTERFERENCE CAUSED BY IN-HOME PLT DEVICES

Meeting No 2: Full Team Progress Meeting

Riverside House, London

Tuesday 20th October 2009

10:30 - 11:30hrs

MINUTES OF MEETING AND ACTIONS ARISING

Note: The following people have actions against them in the minutes: please read these

minutes and ensure you carry out your actions in a timely fashion: PA

Item Action

Leader

Action by

ATTENDEES

The following attended the meeting:

[redacted]

[redacted]

[redacted]

[redacted]

[redacted]

[redacted]

[redacted]

[redacted]

analysis)

Apologies were received from [redacted].

The planned meeting start time was 10:00 but was delayed until

10:30 by a fire alarm.

GENERAL

The meeting followed the attached slide set “FHQ-09-0034-OP_A Ofcom Progress Meeting 20-10-09” These slides summarised the “work in progress” final report sent to [redacted] on 17/10/09 with the main aim of the meeting being to check the overall approach and direction of the study so far.

FHQ-09-0037-D_A Page 2 of 4 26/10/09

[redacted] highlighted that these results are subject to review and change but give an indication of the direction of the study so far.

1. UPDATE OF PROGRESS AGAINST PROJECT PLAN

[redacted] presented on update on progress against the project plan. This showed remaining work to complete the study to be:

· Complete modelling of interference scenarios

· Complete sensitivity analysis of results and draw conclusions on interference mitigation techniques

· Restructure final report to reduce the size of the main body and make top level conclusions clearer

2. SUMMARY OF THE FINAL REPORT AND FINDINGS TO DATE

[redacted] presented a summary of the “work in progress” final report as per the attached slide set “FHQ-09-0034-OP_A Ofcom Progress meeting 20-10-09”.

3. FEEDBACK AND DISCUSSION OF THE FINAL REPORT

Questions and feedback were interspersed with item 2 as follows:

· [redacted] asked if smart notching had yet been proven. [redacted] indicated that ETSI had undertaken a plugtest with Sony and shown smart notching to be feasible for SW radio signals. [redacted] was concerned about detecting very low power victim signals such as in amateur radio bands. [redacted] indicated that as amateur radio bands are usually notched by default in PLT devices there is no need to apply smart notching to these.

· [redacted] commented that ITU-T SG15 were looking at notching in PLT devices and were proposing increasing the power outside the notches to maintain the data rate. [redacted] pointed out that as well as the direct power increase this could reduce the notch depth due to intermodulation.

Action: PA final report should comment on the feasibility of smart notching for different Victim Receiver types and any adverse effects that this may cause outside the notched region.

· [redacted] asked if the fact that Sony owned the IP for smart notching would inhibit this technique being mandated in standards. [redacted] indicated that while this complicates the issue, it is a fairly standard situation in standards like 3GPP that vendors will own IP that is essential to implementing that standard. In this case ETSI have arrangements with such vendors that they will licence their IP at a fair cost so that royalty fees do not prohibit other vendors from implementing the standard. Something similar could perhaps be done for smart notching in PLT.

 

Action: PA final report should include comments on how IP related to smart notching could be handled if smart notching was mandated in standards.

[redacted] was concerned that PLT devices offering 1Gbps data rates were operating up to 300MHz and asked if the PA study was considering Victim Receivers above 30MHz. [redacted] clarified that the study only looked at Victim Receivers from 2-30MHz as EMC regulations are much clearer and stricter above 30MHz and equate to a drop in injected power from PLT devices of 30dB. After some debate it was agreed that PA would think about how much extra work it would be to consider systems above 30MHz and report this to Gary as an option for extending the current scope.

Action: PA to consider extra work involved in including victim systems above 30MHz and report this to [redacted] as an option for extending the current scope.

[redacted] was keen that the criteria for assessing interference should be based on the rise in the background noise level caused by the PLT devices. [redacted] explained that the interference criteria in PA’s model is based on a 3dB rise in the background noise level with the noise levels taken from ITU-R P.372 for radio amateurs and professional users and on broadcasts planning guidelines of 3.5uV/m for SW radio listeners. This approach was accepted.

[redacted] and [redacted] were keen that interference from PLT devices was not simply modelled as an AWGN interference source but that the effect of receiving an OFDM signal in a narrowband Victim Receiver was taken into account. [redacted] and [redacted] clarified that the study had looked at results from the UWB community who also use a wideband OFDM signal and have examined the effect of UWB on a narrowband receiver. In the worst case scenario the UWB signals acts as an impulsive noise source and worsens performance by 2dB. This has been taken into account in calculating the interference criteria in the study.

Action: PA final report to show clearly how the effects of receiving a wideband PLT signal in a narrowband Victim Receiver are accounted for in the simulation model.

[redacted] indicated that the “work in progress” report would be reworked to reduce the main body and more clearly draw out the top level conclusions. In addition the modelling results would be added to this once the issues with Seamcat were resolved. [redacted] indicated that he would prefer to wait until the reworked draft report was available before circulating it within Ofcom for comment.

06/11/09

FHQ-09-0037-D_A Page 4 of 4 26/10/09

Action: PA to refine “work in progress” report and provide a draft final report to [redacted] for review by Ofcom.

4. ANY OTHER BUSINESS

With nothing further to discuss the meeting closed at 11:30

 

The minutes of this meeting reveal some of the thinking both at Ofcom and PA Consulting. For completeness I now provide the thoughts I expressed to UKQRM having read through the FOIA material.

 

1.     The report looks to be heavily biased by the results from SEAMCAT.  For those who don’t know of this tool, it is a statistical analysis instrument intended to determine the potential of interference under user-specified scenarios. I believe SEAMCAT to be an excellent tool – in the right hands –and in the right situation. I do not believe SEAMCAT to be a valid instrument for this report and if the final version is heavily biased based on this statistical analysis I suspect that we will have a very big hill to climb to convince the uninitiated of the fallibility of the results.

2.     The published reference to the report on OFCOM’s website indicates that it is an investigation into “the likelihood and extent of interference caused by PLT…” The ITQ Specification and the above minutes however make it very clear that OFCOM are looking to mitigation as their saviour. With clear emphasis placed on ITU SG15, it seems quite apparent that OFCOM are less concerned with the present condition and how to remedy it than to ensuring a sound manufacturing process to placate the corporate contingent.

3.     It would seem that OFCOM are pinning their hopes on “Smart Notching” however for that technology to work effectively, the “Smart Notcher” needs to have a receiver and antenna system consistent with all local Spectrum Stakeholders and in addition needs to know which station they are listening to. Hmmmm I bet Sony haven’t put a patent on that one yet. . .

4.     I am pleased to note that there was ONE reference to intermodulation, woefully inadequate though it was. I will come back to this.

5.     “Action: PA final report should include comments on how IP related to smart notching could be handled if smart notching was mandated in standards.” Now OFCOM are asking a third commercial party how to make Policy – this is getting dire. . .

6.     “[redacted] was concerned that PLT devices offering 1Gbps data rates were operating up to 300MHz…” I have not read the specification for G.hn but if it is proposing using frequencies up to 300MHz then we have reason to be very concerned indeed.

7.     The limits agreed.  In 2003 the ARRL published the results from a detailed study in to BPL  and its current and potential effects. PLT is not BPL and (sweeping generalisation) most H.F. emitters have discrete geographical scope. However, since PLT has been observed over 500m from the point of utilisation, multiple overlapping PLT interference, concatenated with intermodulation products will present a similar overall distribution pattern. The BPL figures carefully calculated by the ARRL indicated a 60dB differential to the levels expected at an ‘average’ amateur station. Also, ‘worst case scenario’  impulse noise worsens performance by 2dB. Clearly these people haven’t seen the YouTube video with one single HomePlug making S9+15dB and obliterating everything. . .

The point which I would most like to focus on for a moment is the topic of intermodulation. From above you will see that my initial comment was that I was glad to see a reference to it but that the reference was woefully inadequate. I have had time to consider this while formulating my next batch of FOIA questions.

Due to the redacted names, it is not entirely certain which person from which organisation is speaking. The comment:

[redacted] was concerned about detecting very low power victim signals such as in amateur radio bands. [redacted] indicated that as amateur radio bands are usually notched by default in PLT devices there is no need to apply smart notching to these.

has somewhat left me troubled as to which organisation made the statement: “amateur radio bands are usually notched”. Since during our excursion through the foregoing material regarding the limits set by legislation has already demonstrated that intermodulation counteracts the notches and takes the conducted levels to a point which would fail a test with a Notified Body. If this statement was made by a representative of PA, this would indicate that the report may not be as thorough or technically orientated as one might expect given the sensitivity of the material.

Now this might seem a little picky since we are looking at minutes rather than a formal document but I am a little bothered by the expression “usually notched”. Is this a simple fork slip of the tongue, a blatant dismissal of the validity of amateur radio or an emphasis of the point? Regretfully we will never know but it is simply something I noticed.

Moving swiftly onwards we come to my point No.5. If the persons present were all politicians doing their best to understand a technical topic, they could be forgiven for making a comment like ‘asking for comments on how such & such should be handled’ but we are not talking about politicians here, we are talking about professionals in a highly technical engineering field who are involved in making decisions which could involves tens or hundreds of thousand people in the twitch of an eyebrow. To be asking a commercial third party for help with policy is very troubling indeed.

If you recall, earlier in this text I made an odd reference to a new kid on the PLT block. My penchant for silly phrases notwithstanding, there was a more sinister side. In the YouTube video I released in 2009 I made a statement at the end indicating that a new PLT standard was fresh out of the boiling pot. It’s called G.hn. An amazingly understated name for such a grand idea – Gigabit Ethernet over mains. Yes folks that’s right, gigabit PLT. . .

It’s not enough to smack the radio SW radio users around the chops with a wet kipper, so we’ll use a shark this time. At the time I was struggling with some health issues and never took the time to investigate the standard. That was my undoing because little did I know that UKQRM weren’t aware of this new standard. As it turns out the undoing is even greater than I had feared since if you were paying attention to the minutes you will have noted that G.hn is set to use frequencies right up to 300MHz.

Momentarily stepping back into my arithmetic shoes, that is a wavelength of 1 metre. So at the highest frequency any cable run over around 15cm will have the potential to be a moderate radiator and anything over 25cm even better (or should I say worse).

No doubt the same banal claims of notching will be etched across the foreheads of the PLT consortium representatives but for cryin’ out loud – 300MHz? I take it then that the following will be notched and/or have adaptive notching:- (this is not at all definitive)

 

Service	Frequency from	Freq. to
Amateur, Marine, Civil air, SW Broadcast	1.8	30.0
Cordless telephones, base unita	30.9	31.3
Military	31.5	40.3
Baby monitors	40.6	40.7
Military	41	47.4
Cordless phones	47.4	47.6
Radio station talkback	47.6	49.5
Baby monitors, walkie talkies	49.5	50.0
Amateur	50.0	52.0
BBC outside broadcast + some military	52.0	53.0
Community radio/ /radio linkback	53	54.8
Military	54.8	55.0
Community radio/ /radio linkback	55.0	69.5
Amateur	70.0	70.5
Fire Brigade	70.5	71.5
MOD/Ofcom/Customs/Military	71.5	77.3
Taxi/St John Ambulance/Military/OB	77.5	80.0
Scotish Emergency Network	80.3	81.2
Taxis & other mobile / Military	81.2	87.5
VHF FM radio, BBC/commercial	87.5	108.0
Airband, civil, some military	109.0	139.5
Services (gas, electricity, water)	139.5	140.6
….

Almost half way to 300MHz and I’ve lost the will to live. The ‘real’ data that this table was drawn from, 300MHz was on page 294 (A4). So then obviously the PLT consortium have found a way to prevent the radio frequency energy from being radiated from the unshielded wiring (sorry no-can-do, that’s an immutable law of physics).

One can only conclude then that for this ‘standard’ to work, another form of mitigation has been employed to prevent the multiplex channels from interfering with narrow-band radio equipment which is used with almost no gaps from 30MHz to 300MHz.

 

At the time of writing, another FOIA request has been put to Ofcom with a further 17 questions regarding PLT. I will report back with the results in due course.