Posted by: GW7AAV | April 19, 2011

BBC Proves PLT Wipes Out DAB

Apparently the BBC has finally boarded the train that radio hams have been trying to get out of the station for some time and done some tests on how PLT devices interfere with radio reception. The report here explains that high speed Internet via PLT leaks RF out of the wiring to fill the house, and neighbourhood, with unwanted interference. An article by Bill Ray at the Register explains with damning clarity.

 Certain sections of Rays article say a lot that explains the belligerent attitude that our complaints as radio hobbyist have received from OFCOM and Government alike…

 The first PLT systems used frequencies between 2 and 30MHz (confusingly known as High Frequency, HF, despite being way down the dial by today’s standards), and thus only interfered with the kit of radio hams and the like. But the need for speed has pushed some devices into the 50-305MHz band (Very High Frequency, VHF) where FM and DAB like to play, which is when the BBC got interested.


 Ofcom still maintains that all the complaints about PLT come from one lobby group, and the problem is only preventing “one man” from pursuing his “hobby”.

 The irony that the government is pushing two incompatible technologies should come as no surprise, as no one with more than two brain cells to rub together would ever get involved  in politics anyway. Just another example of how the worship of mammon takes priority over doing what is right these days.

 Apparently when PLT is working well it completely blocks DAB reception and can make broadcast FM unintelligible, however if the devices are struggling for a connection the interference drops down to just the HF bands. I suspect if the PLT devices are interfering with our reception then the chances are we are interfering with its operation, therefore our very presence on HF may actually compound our reception problems by forcing an increase in data traffic as data packets are lost and the rate of retries goes up every time we transmit.

 The big question is how to fight this menace and the incompetent belligerence we are seeing from OFCOM. Legal action is slow and expensive and likely to be ineffective. Taking hostages at OFCOM might just get you in to a little trouble and forget the RSGB or writing to the Times, we have tried that already. What we need is to fight fire with fire and up the ante. Suggestions I have heard include deliberately feeding RF into the mains via a close coupled antenna, modifying a PLT device so that when it is turned on it jams other similar devices nearby and spiking the mains using an unsuppressed motor. Not that I am suggesting anyone tries these ideas but it does seem that some form of direct action is the only answer. We need something better, we need someone to listen and act rather than saying “It does not effect me so why should I care”.

 What we need is the military to see the threat to communications that this technology poses. After all what would the army do if something was jamming there comms? Call in an air strike, that’s what.

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