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From Richard Hankins

You state that: “Households that choose to use broadband internet delivered by new systems that route data down the mains power cables may be denied access to short-wave radio broadcasts” (6 December, p 26).

In fact the situation is far worse than that. It’s not only the households that choose this form of internet access that will have their short-wave reception mucked up, but also neighbours who are connected to the same branch of the mains power distribution network. Unfortunately, the data signals also go to those households, whether they have signed up for broadband internet or not.

There are further concerns. Short-wave signals propagate around the globe by reflection from the ionosphere. If only a few people get broadband by power line, signals radiated afar will be at too low a level to cause a problem. But the cumulative effect of hundreds of thousands of people using this technology, could become a real threat to worldwide short-wave broadcasting, communications, navigation and so on.

This problem can only be predicted by mathematical modelling. Rolling out this technology and waiting until everyone feels its effect is unthinkable.

Broadband delivered by power line offers nothing that can not be offered by other technologies, such as ADSL by phone line, terrestrial wireless links and satellite wireless links. I believe this is merely a “me-too” bid by the power companies to muscle in on what they see as a promising market.

Unfortunately, pollution of the short-wave spectrum is an inevitable side effect of internet delivery by mains power cable – and now that we are forewarned, such pollution should be stopped before it starts.

Ross-on-Wye, Herefordshire, UK