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?