12 posts • joined Wednesday 17th June 2009 10:05 GMT
Electromagnetic compliance affects us all.
It's not just Radio Amateurs and Short Wave listeners that are affected, the Electromagnetic Conformance industry are also deeply concerned with PLT. The EMC Journal has been running articles written by some of the leading figures in the field who cannot understand why Ofcom are allowing PLT to market.
Ofcom seem willing to allow PLT products onto the market that exceed agreed acceptable emissions levels by a factor of about 1000 . These have been demonstrated to cause harmful interference, so are paving the way for other manufacturers to disregard the law by cutting their production costs by not fitting costly suppression components. This is the big problem. Opening Pandoras box to disregard EMC law has consequences for everyone. At the moment its HF spectrum; next it may be your baby monitors and then FM.
The whole idea of EMC law was to ensure that electronic products don't interfere with each other. It has worked very well up until now.....
Why is if that If you put a piece of paper on any surface that a cat has access to, you can guarantee that cat will have to plonk itself down on it. Even uncomfortable things on a comfortable bed have to be sat on.
Nothing is sacred?
It's like flogging a beer brewed in the UK as "Stella Artois - Belgiums original beer" - How can a beer brewed in a different county/country/brewery have thesame name as the originalbeer? A load of old toss.
Another beer that I won't be buying.
The word on PLT
There are a couple of things that you "I'm OK, pull up the ladder mate" PLT advocates do not seem to be able to understand or grasp. Let me explain them.
I) Amateur Radio is not Luddite or out-dated.
When the Twin Towers came down, cellular and emergency comms went off-air because infrastructure was on top of the towers. Radio Amateurs went in to establish emergency communications networks.
When the Boxing Day Tsunami occurred, it was Radio Amateurs that were involved in relief efforts.
Amateur Radio is also part of a number of US disaster relief plans.
If your mobile phone network goes titsup, your phone is useless. Our kit still works.
II) PLT is a better use of spectrum than Amateur Radio (et all)
PLT is not an enabling technology. It is a convenience and competing technology to WiFi, Bluetooth and wired networking. It uses spectrum between about 2.4MHz and 28MHz which just happens to already be allocated to Broadcast, Aeronautical, Military, Amateur and other users.
The fundamental issue is that PLT's do not comply with the essential requirements of the Electromagnetic Compatibility Regulations. These state:
(2) Equipment shall be designed and manufactured, having regard to the state of the art, so as to ensure that:
(a) the electromagnetic disturbance it generates does not exceed a level above which radio and telecommunications equipment or other equipment cannot operate as intended...
This isn't just a little bit of text from a standard; this is UK law. ALL products have to comply with this. Go look it up for yourselves. http://www.opsi.gov.uk/si/si2006/20063418.htm
It also states that to affix a CE mark on a product, it has to conform to the essential requirements. PLT products do not conform to this, and this is the reason for legal action.
PLT products also do not comply with EMC regulations that they claim conformance to (eg EN55022 in the case of the Comtrend DH10-PF). This has been proven by the UKQRM group under certified laboratory test conditions. The upshot of this is that the EMC regulations (ie the law that prevents one thing interfering with another) go out of the window. Allowing PLT opens the door to any crap hitting the market and flouting the law. Today it's affecting the Short Wave spectrum; what if it was FM or DAB next? I for one would piss myself laughing.
As has also been mentioned, there are real concerns regarding PLT interfering with VDSL, but some simple tests have indicated a possible effect on standard ADSL (intermodulation effects maybe?). ADSL BT vision users may want to do tests with something like speedtest.net with and without their PLT modems running just as a check. It doesn't matter if the supplied Comtrend UPA PLT's are transferring data; they are transmitting garbage 24/7 regardless.
There have also been instances of BT supplied Comtrend PLT's interfering with customers 27MHz wireless keyboards and mice.
Do BT care? Those nice people who illegally trialled Phorm without letting anyone know?
Which frequencies and mode were you listening to in your tests?
The Comtrend PLT junk are UPA. UPA are on-air 24/7 even when they have no data to transfer. Remember - One DS2 equipped piece of UPA junk is just as bad as the another. You can spray a turd a myriad of colours, but it's still a turd and still stinks. HPA are junk, but at least they only poll each other when not transferring data. They still make a racket when transferring.
Did you know that there were bleats on the BT support pages from PLT users who were having problems with their 27MHz keyboards and mice being interfered with by their Comtrend UPA junk? No?
Regarding testing - I have had very scientific tests done in a real UKAS accredited test lab and UPA products fail conducted emissions specs that they claim compliance to by a massive margin; approximately 30dB or 1000x over most spectrum to 30MHz.
If you are on ADSL, also do a quick check and see if there is any difference in line speed with or without your PLT's running.
BT seems to be quite keen on interfering with itself.
Also have a look at: http://www.theregister.co.uk/2009/01/15/bt_vision_interference/
The reason for complaints about breakthrough interference in the "olden days" was because the TV's were not designed to be immune to radio signals that the TV was not supposed to pick up. The introduction of CE marking ensured that manufacturers produced equipment that was designed to tolerate strong out-of-band fields.
To carry the CE mark, a product has to comply with the Essential Requirements which state:
4.—(1) A reference to “essential requirements” in relation to equipment is a reference to the
requirements set out in paragraph (2) and in the case of fixed installations shall include the
requirements set out in regulation 5.
(2) Equipment shall be designed and manufactured, having regard to the state of the art, so as to
(a) the electromagnetic disturbance it generates does not exceed a level above which radio
and telecommunications equipment or other equipment cannot operate as intended; and
(b) it has a level of immunity to the electromagnetic disturbance to be expected in its
intended use which allows it to operate without unacceptable degradation of its intended
It's (b) that applies to tv's, ensuring that by design, your tellybox shouldn't pick up my transmissions, and giving us Amateurs less hassle due to crap TV design.
Note that (a) applies to PLT. It does cause demostrable interference (see http://www.theregister.co.uk/2009/01/15/bt_vision_interference/ ), yet are being allowed onto the market in droves. Ofcom are simply not doing their job as regulator.
The turd that won't flush is that it makes a joke of electromagnetic compatibility law, allowing any old crap to market and affecting virtually any spectrum they like. It's Short Wave now, but what if it was interference to your TV, baby monitors, radio reception, car remote control etc?
The first PLT's that BT were peddling also used the CB band, causing BT users problems with their 27MHz wireless mice and keyboards. Now there are recent reports of interference with ADSL systems causing significant reduction in bandwidth to BT's own product. These things are belching out radio junk even when they are not transferring data. Their emissions are about 1000x over levels that they profess to comply with (EN55022).
Give it to PLT and get PLT off Short wave. Easy! Gets Ofcom out of their current noose of regulation and gives us back our spectrum!
Bye bye Ofcom
Time you went.
How a regulator can have commercial interests is beyond me, and the fact that they are blatantly failing to legislate against the wholesale of illegal PLT equipment (read BT Vision Comtrend Power Line adaptors).
It's all about who has fingers in which pies and fcuk the law if I can get a directorship or commercial gain out of allowing thinggs through the back door. Ofcom is run by
Die Ofcom, and give us back the RA. Ofcom is run by Bureaucrats rather than technically capable Executives and it's just about making money with no regard to quality of service (read DAB vs FM) and existing services (read short-wave broadcast).
DAB = Dead and Buried
DAB is shit. It sounds shit and as I understand things, it's going to be superceded. DRM? Thats a joke, what with all the PLT shit clogging up the HF spectrum making it unuseable.
Load of wank. Is Carter going to pay me the £1k that my FM tuner cost me? Cunts.
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