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Homeplug user – “should I feel guilty about ham radio?”

In the foreseeable future, you’ll be able to get a home network running at Gigabit rates, just using your mains cable. Already, you can get 100 megabits on HomePlug power-line communications (PLC) systems. And then, you discover that radio amateurs are petitioning the Government to have these banned!

Power line comms, says one amateur radio site, is destroying freedom of speech.

 “It is marketed as ‘HomePlug’ by branding and is supported by a 'bully-boy' pressure group of large self interested companies called The HomePlug Alliance,” says the background to the petition

Well, does it cause problems?

The answer rather depends on who you are. If you’re a spokesman for the HomePlug Alliance (or any of its members) then “Absolutely not!” would be your response. You’d say, as Jonathan Lishawa did, that he’s “working closely with Ofcom and BT to overcome any interference issues.”

Lishawa is managing director of Comtrend, which provides Powerline adaptors for use with the BT Vision service. He told Keith Stuart (a year or so ago):

"We had to answer lots of questions from BT, we had to go through exhaustive field trials, and we had to conform to all the EMC certifcation, as well BS1363 parts 1,2,3. I can't stress this enough, we'd like to engage with the Radio Society, but in a constructive manner. It is a concern, but we believe we've addressed and continue to address that concern.”

The official HomePlug response is that they’ve solved the problems. Yes, there is the potential to produce radio interference and yes, if you buy a PLC box and plug it into the mains, and it spoils someone else’s legal right to use shortwave radio, then someone from Ofcom will pop round and tell you to stop. But! – there’s technology to prevent this: notching.

HomePlug devices have this ability: to “notch out” wavebands which are used by other people. The normal PLC transmitter doesn’t just use one channel, but hundreds; it can do without any one with no detectable effect. So you just find the frequency that’s causing the problem, and get a competent engineer to re-program your HomePlug device to avoid it. No, it’s not a job for the beginner. But it can be done.

But it’s not just radio hams who suffer. It’s easy, as one HomePlug fan scathingly put it, to dismiss them as a bunch of dinosaurs and to recommend that they switch to “a modern communications system!” – but what about wireless computer keyboards? Or mice? They certainly can get affected:

"I have just installed BT vision with a pair of Comtrend adapters, and now my wireless Logitech keyboard and mouse do not work properly ( act like they are drunk )  miss letters and work slow. I can turn the problem on and off simply by putting the Comtrend adapters in standy or on , so they are the cause of the problem,”  wrote Steven Routly in the Comtrend Forum.

And the BT support guy admitted it was a problem. Solve it – basically, by moving your Comtrend-powered device further away from the keyboard, or switching to WiFi instead of HomePlug.

You can’t, says the old proverb, make an omelette without breaking eggs. HomePlug makes a nice omelette, no doubt… but walk carefully over those shells.