Power Line Networking - some thoughts

[BOAC]

PLN is a growing area of research and development. I have 2 adapters running successfully. The frequency used lies in the 'short wave' and is the subject of some unsuccessful lobbying by radio hams due to interference on that band.

The latest move is into the VHF spectrum, up to 300Mhz. Here the prospect of interference becomes more of a nationwide issue. This video (http://www.youtube.com/v/z3yVu5IfaEY&hl=en_US&fs=1&rel=0), although not particularly scientific, is effective in showing what might happen, and it is of interest that some of the frequencies onto which the technology may move could interfere with 'advanced' broadband distribution, eg VDSL. OfCom have produced a report.

[call100]

I can't believe he was called Nigel........Not really explaining anything there. For example what distance was that interference experienced at? Is it only interfering with localised radio's etc? Is it just those items on the same electrical circuit or will next doors radio be affected?:confused:

Please make it brief as Nigel has just bored the pants of me!!:bored::zzz:

[green granite]

The frequency used lies in the 'short wave' and is the subject of some unsuccessful lobbying by radio hams due to interference on that band.

The EMC Directive of the European Union requires that:

Equipment shall be so designed and manufactured……..to ensure that ……the electromagnetic disturbance generated does not exceed the level above which radio and telecommunications equipment …… cannot be operated as intended (Essential Requirements (1) in Annex 1, relating to Article 5 of the Directive)

Furthermore, although the PLA units, as measured by RSGB and other test houses, are helpfully notched to minimise interference in the amateur frequency bands, they nevertheless produce conducted emissions which will result in interference across much of the rest of the HF Radio Spectrum. The conducted emissions significantly exceed the limits defined in the benchmark relevant international standard CISPR22 (Harmonised EU Standard EN55022).

full article here on the RSGB web site Power Line Telecommunications (PLT) news page | Radio Society of Great Britain (http://www.rsgb.org/plt/)

[BOAC]

Is it only interfering with localised radio's etc? - I have no idea - OfCom do and the CAA have reportedly expressed an 'interest' since the spectrum contains most Public Service stuff, including Mil UHF.

I agree 'Nigel' should have had some half (heck, why not completely) naked ladies to spice up his video:)

Some of the PLN trial is now apparently up in the low GHz band (2-3).

[Mike-Bracknell]

Not-very-interesting-fact-of-the-day...


I used to work with the guy who invented Powerline. The earliest trials had lamp-posts in Manchester delivering an unhealthy amount of radio interference. :)

[Astral_Flyer]

Our local club has donated £1000 to the RSGB fund to fight against PLT devices that don't meet the EMC directive. Of course it does raise the issue as to how the rogue units managed to pass the tests in the first place. It has been found that many of the units examined, at one stage had unfilled spaces for filtering and other components. That suggests that they might have been fully populated when they were tested, and then the production units were produced without certain items.

During one of the recent demonstrations at our club. It was found that modern units do seem to be within the specifications of the directives. So maybe we are seeing things turning a corner, and the problem of PLT devices will go away. What happens to the money that people have put into the spectrum defence fund is likely to be used in future battles that we will inevitably face from new 'toys' that come onto the market.

Astral

[Keef]

I don't know where they are, but out here in rural Suffolk I can hear gently warbling carriers all over the 430-440 MHz band. They are coming in off the aerial (removing it removes them) but are clearly not amateur. They aren't as rough and unstable as SMPS noise, but as to what they are...

Some time when I'm bored, I'll go out and DF them.

PLT should never have been invented! Stick it in coax and send it underground, I say.

[radeng]

CAA are definitely somewhat unhappy. With them going up to 300MHz and beyond, the cumulative effect of a lot of them could make ILS useless when landing on 27, plus problems for comms.

Plus the effects on social alarms at VHF - the 'granny necklace' that she pushes the button on when she falls over, and remote monitoring of pacemakers etc.

[Guest 112233]

Are those 430 MHz warbles an harmonic of other transmissions ? - What are the propagation modes for this frequency - line of sight I would imagine. Is there special range equipment for tracing weapons drops etc.

[Astral_Flyer]

out here in rural Suffolk I can hear gently warbling carriers all over the 430-440 MHz band. They are coming in off the aerial (removing it removes them) but are clearly not amateur. They aren't as rough and unstable as SMPS noise, but as to what they are...
You will find that the range of frequencies in question are used by a whole host of users. It is a shared band with radio amateurs. Remotes for car keys use 433.92Mhz +/- 100Khz in addition to that I seem to recall that building sites use various spot frequencies for cranes. That is something to do with making sure that jibs do not collide. The list is fairly long as to other users of 430-440 Mhz.

Astral

[Keef]

Oh yes, the band is certainly shared. But I'm getting LOTS of unmodulated carriers, warbling slightly. They could be umpteenth harmonic of something lower down the spectrum, but what would produce so many of them?

When I'm bored some time, I'll go out and DF them.

[mixture]

PLN is a growing area of research and development.

In your personal life perhaps, but not in the world at large.

In the cabled world, fibre is the future. Much R&D effort is going into continually driving down the costs. The more near term future is driving down the cost of 10Gb copper for various applications.

Wireless technology will continue to develop, but will never replace physical infrastructure.

[Saab Dastard]

In the cabled world, fibre is the future. Much R&D effort is going into continually driving down the costs.

And driving up the speeds - the standards for 40 and 100 Gigabit Ethernet were ratified in June this year.

100Gbps over SMF up to at least 40Km - that's a nice prospect. :ok:

SD

[mixture]

100Gbps over SMF up to at least 40Km - that's a nice prospect.

Indeed. And is a prime example of why fibre is the future. :ok:

Powerline technology has always been, and will remain niche residential market technology for the home-owner to play with on the weekend. It's never going to get any traction in the business world, and therefore any interest in ploughing R&D funds into it is unlikely, and whatever limited investment does happen is going to be purely for the low hanging fruit manufacturers. :ok:

(all my own personal opinion of course.....)

[AnthonyGA]

Fiber is still the most promising high-speed, long-distance networking technology. Mixing network traffic with power distribution is a fundamentally bad idea and it rather surprises me that anyone has even implemented it. It has the same safety margin as, say, changing all the working voltages on a motherboard to plus or minus 240 VDC.

Superimposing a tiny, precise data signal on a huge, imprecise, high-powered power distribution circuit? The whole idea makes me nervous—no thanks. I'll keep the ADSL line.

[BOAC]

In your personal life perhaps, but not in the world at large.- no, not even in 'my life', actually, but having become 'involved' in looking at various aspects of (UK) rural broadband issues, it is apparent that there are several companies looking at PLN to solve the 'digital divide' since BT are (understandably) not interested in spending money for small return. As well as PLN there are trials of running fibre ALONG the power line network. There are trials in place of both.

Until the coalition get their ducks in a row and sort out the BT side of things so that we can develop a national cohesive network based on fibre there may well be PLN broadband distribution to rural areas.

I have been whinging at OfCom and Mr Vaizey to grip this BT thing or we will finish up with umpty dumpty different distribution systems all over the UK, few of which will be 'compatible' in terms of creating a uniform national distribution system. What BT appear to be doing at the moment is waiting until a rural community self-funds an expensive alternative distribution, and then nipping in and undercutting with a fibre supply - which I think is a deplorable practice and needs urgent government action.

[Guest 112233]

Please correct me if I'm wrong, but in the 50' and 60's, did not the old CEGB have a data messageing system that was based on superimposing high freq signals on the wires that carried the grid. An old example of powerline networking - Analog I think.

CAT III

(As usual off topic.)

[Saab Dastard]

As well as PLN there are trials of running fibre ALONG the power line network. There are trials in place of both.

Why do they need trials for running fibre along the power line network? Energis (National Grid) did it successfully 15 years ago. I was working for them at the time...

SD

[mixture]

there may well be PLN broadband distribution to rural areas

Admittedly my techie knowledge of PLN is limited, but a quick bit of research suggests the same old limitations still exist that make it unattractive for commercialisation..... it won't cross phases, its quality varies depending on the electrical load on the lines etc. etc.

I suspect you'll more likely see flying pigs before you see Cisco Systems or Juniper Networks start bringing out carrier kit to drive PLN networks.

I understand the issues facing the rural divide, I really do. However PLN is not the answer. Fixing the number of issues constraining fibre deployment (e.g. the taxation of dark fibre by the government etc etc) would be a much more productive use of Mr Angry from the village letters. :ok:

As tempting as it is, I'm not going to be drawn into the old BT debate. But briefly, I think competition should be encouraged rather than "doing something about BT" ... which will probably only end up giving them another pie to stick their fingers into.... just like their artificial chinese walls that they operate at the moment ! BT need to learn the hard way.

[seacue]

PLN (BPL) appears to be a failure in the USA. As I understand it, the last trial system has been shut down. It required too many repeaters to be economical in rural areas. Other methods such as ADSL, TV Cable and FioS (fiber) have won in urban areas.

[Mike-Bracknell]

Another snippet of trivia from my addled brain...

I was in Minsk last summer, and was told that Powerline is all the rage over there, where hundreds of flats in blocks are given shared internet access via it.

[BOAC]

But briefly, I think competition should be encouraged - perhaps you should be working for DCOMS. I can give you Ed's phone number.:)

Yes - I'm all for that, but the argument that the NATIONAL network - telephones/copper(aluminium:eek:) is already in place is a powerful one. When you look at the 'desperation' of rural communities and the wide ranging solutions they are using you see a totally fragmented network which can not easily be integrated and is always at risk from the 'lesser players' often involved collapsing.

I remain convinced that the telephone network infrastructure should never have been part of the privatisation - it is a national asset and has security and defence sidelobes.

[mixture]

- perhaps you should be working for DCOMS. I can give you Ed's phone number.

I'll swap you phone number and email for Ian Livingston at BT .... :cool:

but the argument that the NATIONAL network etc. etc.

hmm... we could debate this until the cows come home. BT only have a historical monopoly on the last mile copper network. Outside of that historical monopoly, you have to understand there is no such thing as a single national network.

The biggest part of the problem is that implementation cost varies widely depending on where exactly your rural community is located, and the size of the community. That is the reason for the necessity of wide ranging solutions.

Yes there are savings to be made by each community not re-inventing the wheel. But at the same time, it's never going to be commercially viable for a corporate behemoth the size of BT to offer a solution on the terms you want.

Anyhow, this is all going a bit too in-depth for an average PPRuNe posting. But I'm willing to give you the benefit of one or two more back and forths via PM if you want.

it is a national asset and has security and defence sidelobes.

Hence the existence of the CPNI and various other lesser known protective initiatives.

[BOAC]

I'll swap you phone number and email for Ian Livingston at BT - been there, done that, thanks. It works.it's never going to be commercially viable - no argument there - hence the need for a different approach. I await Ed's deliberations with interest. It just annoys me that a community spends time and money (£30-40k+) on setting up a network where BT will not - for 'commercial reasons' - and then BT suddenly 'find' it is commercially viable.

Thanks for the offer, but I think no thanks at the moment.

[mixture]

It just annoys me that a community spends time and money (£30-40k+)

In most cases, you'll get more for your £30-40k going it alone then you would writing a cheque to BT for the same value. :ok:

Anyhow.... good luck with your endeavours.

[BOAC]

writing a cheque to BT for the same value:D:D:D:D:D