Re: Apples and Oranges

Wrong on so many levels!

The meter in your property does not stop conducted emissions from mains-powered devices in your property from radiating back along the wires to other houses in your street, or vice-versa. If those mains cables are overhead, as in many villages, they will become aerials and radiate. In order to establish a clean mains signal, you would need a 100A-rated common-mode choke; and that would be the size of a fridge!

PLT's Orthogonal Frequency Division Multiplexing signal injected onto mains wiring is at such a high level that it radiates along all of the phases, neutrals and earths in your property (with the earths connecting to the neutrals at the incoming supply as part of the PME installation). This signal is also conducted to neighbouring properties who are on the same 415V phase, and all properties on the same transformer thanks to the common neutrals. This signal is further radiated along the earth wires of the properties and up each lamp-post in the area. This is physics and you cannot change that!

You are right, in that PLT is not a particularly large concern to Radio Amateurs if notched correctly; however, CB users are quite pissed as their allocated bands are wiped out. It should be noted that each part of the planet is divided into three ITU zones, and each zone has slightly different operating frequencies allocated for amateur radio. So a device with notches for ITU zone 3 is not necessarily any good in zone 2. Of course, with non-linear devices, such as switched-mode power-supplies on the main wiring, the notches become useless and fill up with intermodulation products.

As others have mentioned, with these devices failing to comply with the EMC Directive's "essential requirements", they fall over and lock up in the presence of powerful radio fields. A fully licensed radio amateur can legally transmit up to 400W - maybe more in the future if the UK's rules are harmonised. If your precious PLT devices fall over due to a lack of RF immunity, there is sod-all you can do about it, you have no grounds for complaint and no-one to complain to!!

Re: Apples and Oranges

Dogged old chap, you can promise us all you like, but just because in your case you can't detect any interference from PLT does not mean that there is no interference in a great many other places and instances.

Every test result from accredited test laboratories had produced evidence of massive failures in compliance with EMC limits such as EN55022B, failures by as much as 40dB. That translates into 100 times the range of interference that is deemed acceptable, i.e. only interfering over 10m or so, but now apparently it's acceptable to do so over 1km.

The whole premise of power line networking is in error, mains wiring is not sufficiently balanced to suppress radiation when energised in the manner that PLT devices do it. Why do you think that real networking uses cables with 60dB balance between the internal twisted pairs? They don't do it for any reason other than it being essential for reliability and security.

I do wish that you would have a look at the documented evidence of the problem rather than saying that people with decades of experience of working in the EMC industry (and not just on the gamekeeper side either) are wrong.

@A.C. -- Re: Apples and Oranges

"The product described here uses the person's in house power wires to transmit data, and (similar to X10) is not likely to extend much beyond their power panel, thus not a great concern to Radio Amateurs."

"is not likely to extend much beyond their power panel" <== Not so!

Let's leave amateurs out of the equation for a moment as it can be argued that there's not many of them and they're only engaging in a hobby* anyway. However, there's a more general and significant argument which goes like this: one person or so using HomePlug-type equipment at home won't cause any noticeable interference, (this is essentially true and would cause very little concern), however, when many thousands do so it becomes a substantial problem. Even if these users are widely separated so that clusters of interference won't occur locally, it does cause interference on a global scale by raising the noise floor across large areas of the radio spectrum (it's a bit like the plastics/plastic bags accumulating in the ocean issue).

Increasing the noise floor across the RF spectrum has serious implications for all sorts of services--not just amateurs. These services are very important services such as emergency communications, government services and the military just to mention a few. Because of the nature of these services, the method of regulation, local rules covering what employees can say, ITU implications etc. it's often very difficult for individuals involved in these organisations to speak out, so it turns out that the amateurs are usually the only ones left to do the shouting for everyone else. (When you think of it, things really suck bigtime in government when officials who should be doing the shouting can no longer speak out with impunity over such issues.)

Nevertheless, it's of such concern to some organisations that they've had to speak out. NATO is very concerned about the increasing noise floor across the spectrum and the organisation says so in this document:

RTO TECHNICAL REPORT R-IST-050 HF Interference, Procedures and Tools (Interférences HF, procédures et outils) Final Report of NATO RTO Information Systems Technology (IST)

http://ftp.rta.nato.int/public//PubFullText/RTO/TR/RTO-TR-IST-050///$$TR-IST-050-ALL.pdf or

ftp://ftp.rta.nato.int//PubFullText/RTO/TR/RTO-TR-IST-050///$$TR-IST-050-ALL.pdf

Noise floor references: Exec Summary; 2-7, para 2; 2-8, para1; 2-10, para 3; Specific BPL/PLC references: 2-14; 2-16 & 2.17, 4-5, 5.2, Annex B.

The fact is that all forms of BPL/PLC/PLT/HomePlug are and remain a threat to communications services and ultimately should be eliminated/banned.

___

* This comment is a little disingenuous, amateur radio operators no longer have the high profile they once did but they're one for the few groups in society who actively work with communications electronics as a hobby. They provide useful communications in an emergency and are a good source of fodder for communications and other technical industries.

Moreover, because of the nature of their hobby, amateurs have an extensive--almost innate--understanding of the radio spectrum, radio propagation and interference as their communications signals usually are only a few decibels above the background noise. In fact, I've seen cases where radio amateurs have had more knowledge about the subject of RF interference than the professional engineers who were investigating it.

As electronic circuits and designs continue to become more proprietary and secret and are locked away in corporations (something that was very foreign only a few years ago), across the community, the radio amateurs are probably the last bastion of general electronics knowledge that's still unencumbered and freely available.

@motoh - - Re: Apples and Oranges. Uh??

"...are different creatures entirely"

Uh? Why?

The definition would have made them identical when I was learning engineering. Have the laws of physics changed or something?

Please explain!

@dogged - - Re: Apples and Oranges

"you'll see is anecdotal bollocks about Powerline networking"

This is the Goebbels line -- spin enough bullshit and people will believe you (but unlike Goebbels you're an amateur, as you haven't fooled anyone).

The fact is you're either provocatively buying an argument or totally clueless, I strongly suspect the latter!

BPL/PLC/PLT HomePlug etc. is an abomination of a 'technology' in every respect. In fact, it's concept is flawed in so many ways that I contend that it's not even a technology, hence the quotes.

I'm not going to bother to list the diabolical issues that surround BPL/etc., as they've been well canvassed many times here at El Reg and elsewhere. Clearly, you're the type who can't think for yourself outside matters of self-interest, so you need a good authoritative reference to put you straight: I refer to the NATO document "RTO TECHNICAL REPORT, TR-IST-050, HF Interference, Procedures and Tools", the links of which are in another of my posts to this forum. Methinks however, your mind will be too closed to read it.

As I've pointed out elsewhere, this is an issue for everyone in communications. Amateurs are the most vocal for reasons that I've also enunciated--which incidentally, shouldn't be the case--but they're far from the only ones worried and complaining about he matter. When we've the likes of NATO, BBC, international broadcasters, radio astronomers and many other communications users worried and complaining then it's bloody clear there's something very wrong with this crap.

In future, get the real facts first. That way you'll avoid making an arse of yourself in public.

Re: Apples and Oranges

Utter crap! I have serious noise issues and can't hear even most local stations. I have everything engineered to the last filter. I have a rather good station, but cannot hear over the noise. BTW my station is independent of the mains, and I have positively identified the noise source as PLT from 3 neighbours who have disconnected them for me and the noise has gone when they do.

I am also in the progress of pulling together the resources to video that conclusively prove that they are RF devices radiating over the spectrum, and that they also have inadequate security allowing others to know what data you are sending about the house/street/town - lets just say, I'd never suggest you could or should use them for banking, Wi-Fi is more secure. Furthermore you should know that during a lift it's quite possible to see PLT signals going a lot further than the other side of town - half way around the planet, further increasing the chance of someone scraping your banking details by a money poor and time rich highly intelligent and motivated hacker.

I don't recommend them on many levels and you shouldn't either.

With regard to you microwave - microwaves haven't really given HF spectrum noise for decades. Noise around 2.4GHz maybe, but not much below 1GHZ.

Re: Hamateur radio?

Come now... A simple search on yon Internet will show things are still nicely active. At least with those that would like to be able to communicate long distances without touching the Internet, in case for example of natural disaster. In the States it's called ARES, amateur radio emergency system. Granted, HF can be more like chatroulette, but some like that for the surprise.

So yes, the advantages of the internet are information density, and consistent contact.

Re: @dogged- HAMs

yo have never meta radio ham personally so you cannot comment on what your saying , if it was not for radio hams the mobile phone, tv satallite coms all this stuff would never have benn invented .

radiohams know a lot more about rf that you do . plus these guys have been ising radio without causing interference for a very long time and thye do know how to fix it , plts do not conform to the standards and devices severaltimes now suppied by bt have had to be removed form the market and changed deu to the problems they cause.

I f you get an ofcom visit because of your plt device causing rf spectrum abuse you can get fined and sent to prison , as there are other services using these bands as well ie cosatgaurd/police around 150mhz, airtraffic 118mhz to 130mhz all deivces could and can cuase problems there as well , you also have the miltary freq on hf whch means you may get yourself in alot of trouble.

Re: Who knows what a "leaky feeder" is?

Oh, Luv'a'Duck.

I wonder how many folks have been surprised that their iphone/fondleslab/Nokia-piece-of-history/whatever works fine in a metal Faraday Shield?

Oh, wait.

We call them 'Lifts' nowadays. (I'd say 'Elevator' rather than the British version, but given the date...didn't think I'd get a sober response)

Leaky feeders to the rescue! Actually you don't need to carefully 'damage' the co-ax for it to be 'leaky'.

Simply outsource the cable manufacturing. Job done!