Interference from PLT was debated in the UK Commons last night. At least an attempt was made to do so: the BIS minister preferred instead to ignore the questions and focus on the bearded minority. The matter was raised by Mark Lancaster, MP for Milton Keynes North, as an adjournment debate comprising a statement and response …
Way off beam
It seems that you have no grasp of the subject, the problem is that there is no real way to keep the RF inside the cable. Consequently it will escape and affect other things. You will obviously understand that most aircraft will probably have to be grounded. During the 1970's a CB with only about 4 watts did that as his frequency multiplier due to poor SWR blocked both the landing frequency from then West Drayton and also all the emergency vehicles at London Airport.
You can imagine it :- Tango Charlie 13 take bzzzztatatatssszta roger. Useful!
As a former Elect tech for the USAF and radio op BFG and instructor radio for ATC and running my own business as an electrical contractor, let alone being a radio amateur I have a wee understanding of the rammifications. It will only be a brain dead who sanctions this again. Anyway, I thought that this was thrown out several years ago after tests revealed economically flawed problems.
Guess I will have to connect an RF transformer to the mains and crash out a CQ EDF.
Why don't the beardies just start using Skype instead? Then everyone's happy!
Not a solution!
Does Skype work without the Internet?
Does Skype work up a mountain?
Does Skype work when a hurricane/tornado/typhoon/tsunami/earthquake has taken out the power?
Completely missing the main point of amateur radio...
Amateur radio isn't *just* about having a natter - although we do that too - if it was you'd have at least half a point.
It is, by definition, an experimental hobby - and fundamental to that experimentation is the ability to transmit and receive signal by radio, otherwise you're unable to do the very science you're licensed to do... which may involve propagation studies, may involve circuit design, aerial design, or involve developing new digital modes and the supporting software to get a signal through under extreme circumstances - as well as training and practice for disaster-preparedness.
The fact many of us are able to continue working indefinitely in the absence of mains power or indeed any other infrastructure makes us extremely useful in disaster situations - we do form part of the 'disaster plan' of most local authorities in the UK and beyond as we'll still be working when everything else has stopped.
God forbid we have the sort of disaster here they had recently in Japan, or Haiti... but if that happens, us 'beardies' will be helping keep you alive when nobody else outside the military can communicate further than they can shout.
So PLT isn't a problem then?
After all, if the mains power and comms infrastructure are down, there's no interference with you guys :D
@Richard North--Also, radiocommunications is unlike others, it's always only a step above the noise.
People not involved in radiocommunications often do not realise that just about all wireless/radio communications struggle with various forms of electrical noise. Wireless signals compete with every conceivable form of noise generated both by nature itself, lightening, solar disturbances, aurora borealis etc. as well as human-made electrical disturbances such as from motors, electrical switches, RF heating and other competing transmitting devices.
In addition to all that interference, radio circuits (paths) are incredibly lossy. The loss of signal from the transmitter to receiver can be (and usually is) enormous. Path loss figures of 120-140dB or more are not uncommon. Because of these huge losses, radio engineers are always concerned with how much margin there is between the received signal and the noise--so much so that the signal-to-noise ratio (expressed in dBs) for a given circuit bandwidth is essentially the most significant engineering parameter in wireless communications.
To illustrate the point, a powerful television transmitter can have a power output of between 100kW and 1MW yet the received signal at the typical TV set is so infinitesimally small that if amplified a thousandfold would probably not light the tiniest of pea lamps.
Keeping radiocommunications working efficiently is a remarkably complex and sophisticated engineering operation. Over the last 100 or so years since Marconi spanned the Atlantic, many complex rules have been formulated under the auspices of ITU (International Telecommunications Union) with the express purpose of optimizing and finely balancing competing demands for radio spectrum from various radio services. Interference and noise being one of the predominant concerns for the international regulation.
Into this mix comes PLT/PLC/BPL bulldozer. This broad-spectrum signal--which is better suited to modem-to-modem communications--pays no credence to the delicately balanced mix of incredibly minute radio signals contained within the specialized, especially-allotted radio frequency bands designed specifically to minimise interference. PLT just blankets the lot. To make matters worse, the PLT signal (which ought to be contained within a shielded cable to stop it radiating), is in fact connected to the world's biggest 'antenna'--the world's power grid.
Whilst regulators and PLT companies pay lip service to minimizing interference by tailoring the spectrum to work around some of the more susceptible wireless circuits, it is essentially tokenism. Whilst some radiocommunication circuits initially appear better off--usually only in specific areas--PLT is radiating everywhere--across cities, up into the ionosphere etc. In essence, PLT can be likened to a diffuse fog that's enveloped the radio spectrum across the whole planet, thus PLT is effectively increasing the noise floor with which existing services have to compete. It's interference pollution of the very worst kind. It's environmental damage to the radio spectrum on a level akin to or worse than the Alaskan Exxon Valdez oil spill disaster; yet except for small numbers of radio amateurs, few others complain.
Why this unmitigated disaster ever happened is still open to debate and a full analysis (but I briefly touched on a couple of issues earlier).
The writer of solution falls into the title category, try using skype from an aeroplane, or for landing it.
Not just PLT
A lot (most, if not all) of compact florescent lighting splatters right across the spectrum.
It could be that OfHalfWits decided that PLT was emitting less than CFL so it's ok, but in 5-6 years time CFL will mostly be dead (LED prices are in freefall) and PLT will still be around. :(
Somewhat biased - don't tar all PLT kit with the same brush
Some chipsets for PLT clearly use higher frequencies for speed gain whilst others do not. There are 2 main chipsets on the market that everyone is using to beat on PLT in general. The original kit supplied by the largest UK telecoms company for one, who are now using something different which should not cause the same issue.
Sorry, you are wrong!
All chipset, be they DS2 or the new VHF-based Gigle, cause un-acceptable radio interference when used over un-balanced mains wiring.
@AC / Re chipsets
"All chipset, be they DS2 or the new VHF-based Gigle,"
You're missing Intellon - used by many/most of the HomePlug stuff. The notching is also configurable by firmware.
" cause un-acceptable radio interference when used over un-balanced mains wiring."
'cause radio interference' - the degree of acceptability is dependent on many more factors than the chipset and vanilla firmware in a PLT device.
PS. There's a hell of a lot of ACs around at the moment - any particular reason ?
@Anonymous Coward -- Uh? Put Dracula in charge of the blood bank eh?
"The original kit supplied by the largest UK telecoms company for one, who are now using something different which should not cause the same issue."
Are you really saying that because the largest UK telecoms company is a supplier that it has no vested interest?
Doesn't everybody make rewiring the house with CAT5e/6 a priority as soon as they move in?
I, for one, welcome the opportunity to drill holes through walls, and drag cables through buried hosepipes, and crawl through insulation-filled dusty loft spaces, and risk life and limb on dodgy rafters in the name of establishing a reliable network connection between one side of the house and the other.
I find the experience of appearing on Google's wifi database disturbing. And broadcasting my network traffic several blocks via powerlines is unappealing too. (Granted it's encrypted, but how long will the algorithm remain publicly unbroken?)
Shielded cabling for me, thank you very much. I like my signals crisp and guarded.
As a radio ham I keep wondering what would happen if I lodged a complaint with OFCOM/BBC about PLT causing me as a ham interference......
If it was the other way round and I as a ham was causing interference it would potentially be investigated and I could be asked to stop for a period...
Do we think they will ask said PLT user to unplug for a period...
Or is it same old one rule for one etc....
It's happened, according to Ofcom....
...272 times. And with resolutions in 230 odd of those cases.
In most cases BT Vision installations are the culprit, and BT know that the Comtrends are problematic so they come round and remove them and hardwire with ethernet cable instead. However, Ofcom say they don't have the powers to compel this so if the BT Vision customer refuses the cabled approach then there is currently a stand-off.
@Tim P re "can't be done cleanly"
"can't be done cleanly" is shorthand for will not be practical technically or economically in an environment where legacy-designed mains cabling is in use, ie 99.99%+ of all premises in existence.
Legally speaking, vendors should be able to provide demonstrations that their product will meet CE requirements in a realistic environment. It's not supposed to be down to objectors to show where the product fails the requirements.
Anyway, you say it can in principle be done. I say it's unrealistic,
I say if recabling is required to ensure CE compliance of PLT kit, why not put in proper LAN cables at the same time so that there is zero risk of PLT-related emissions? (Because the PLT business model disappears, that's why, obviously)
Happier with the new form of words now Tim? The net effect is the same, PLT can't be done cleanly in the real world in any practical sense.
Re : @Tim P re "can't be done cleanly"
'"can't be done cleanly" is shorthand for will not be practical technically or economically'
If i'd known that convention, i'd not have said a word.
"Legally speaking, vendors should be able to provide demonstrations that their product will meet CE requirements in a realistic environment. It's not supposed to be down to objectors to show where the product fails the requirements."
"Anyway, you say it can in principle be done. I say it's unrealistic,"
I also agree with both - there is no confict here.
"I say if recabling is required to ensure CE compliance of PLT kit, why not put in proper LAN cables at the same time so that there is zero risk of PLT-related emissions? (Because the PLT business model disappears, that's why, obviously)"
Yep - i've been saying for months.
"Happier with the new form of words now Tim? "
Yep - that was my whole objection. I just hate absolutism.
"The net effect is the same, PLT can't be done cleanly in the real world in any practical sense."
I agree with that too.
"you say it can in principle be done. I say it's unrealistic,"
I wrote: you say it can in principle be done. I say it's unrealistic,
Tim wrote: I also agree with both - there is no confict here.
There is indeed no conflict, that's why I chose those words, but had neither time nor space to explain explicitly.
Anyway, we're agreed, as are most (all?) logical-thinking independent-minded people on this subject, as they have been since (e.g.) the RadioCommunication Agency's DSL/PLT/RF Technical Working Group(s) back in 2001.
But WTF can folk actually *do* about this? Please don't suggest "write to your MP", mine's a useless timewaster, and so are most of them.
off topic ps:
El Reg: Captain Cyborg is back! The recently invisible Kevin Warwick is on BBC Today as I type this.
Lies, D*** lies and the utterances of OFCOM
A telling little revelation:
@Anonymous C. #1 -- Good link.
Why do the amateurs have to do all the running on this?
It backs up my earlier assertion that the regulators are more interested in keeping their options open for a future career than they are in properly serving the public.
"Why do the amateurs have to do all the running on this?"
... because the rest of us don't have handy devices to measure the interference properly?
A selection of interesting "articles".
The last is interesting.
@Anonymous C. #2 -- Likewise, good links.
As previous, thanks.
from that RSGB link
That is indeed well worth reading.
Didn't the RSGB used to have spectrum defence fund or something? e.g.
Can any kind reader confirm whether it's still active?
I particularly liked the non technical (not to mention nonsensical) nature of "Ofcom has said that failure to meet a standard does not mean a product is non-compliant. "
When I were a lad, things that met relevant standards were known as "compliant", and things that didn't, weren't.
Obviously I'm behind the times. But in an era when the IEE Newsletter could be mistaken for T3, maybe that's my problem. Does the IET even have a stated corporate position on the PLT subject, or are their folks at HQ just waiting for their next award for magazine layout+design?
Whose name is on Comtrend's published Declaration of Conformity? If these named individuals, rather than their corporate employers, had to be individually accountable for their actions (y'know, "lie to us and we lock you up", kind of thing) would these things work out any different?
Thank you, have a good weekend.
Just a point
Many of us "amateurs" are also proffesionals. If we were for example lorry drivers, does making us being on motorcycles make us amateur drivers, does driving an ambulance for a living but driving a car at weekend make you a weekend driver.. To feel enthusiastic about ones chosen proffesion enough to also dabble in its various forms does not make us amateurs.
Possibly in these days the name is a misnomer, however, seeing as many of us also work within allied fields, or continue after retiring should really give us a better chance to convey to others the various situations.
Hence many of us may feel inclined to coment to the adverse anonymously to preclude potential situations as could develop.
If the so called investors were REALLY serious then they would look at Wimax, total removal of all phone lines, each person with a FREE phone in his location, really fast internet access and the like. CHEAPLY, say £20,000 1 time payout and virtually no running costs apart from electricity.
Therefore it is in the interest of idiots like the MP who uttered the daft statement and other do gooders to take heed. There are sufficient lines (intended pun) of routing for the internet and telephone without recourse to dubious practices. The removal of all the copper wire precluding theft for scrap and replacing with Fibre will allow speeds up to silly speeds, let alone the reduction of exchanges and the like and interference from outside sources will be of major importance, so to spend vaste sums of money on aforesaid systems instead of the fibre is a course that will only be beaten for stupidity by the DAB system that has more holes than a collander and is now not being considered for the EU.
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