An old television set displaying static.
Enlarge / An old television set.

Getty Images | Jeffrey Coolidge

A 400-resident village in Wales suffered 18 months of DSL Internet outages each morning until the culprit was identified as electrical interference from an old TV set.

The residents of Aberhosan mysteriously experienced the outages each morning at 7am. Openreach, a BT subsidiary that provides Internet service in the UK, replaced old cables in the village in an attempt to stop the outages.

« Unfortunately, this didn’t resolve the problems and so they began sleuthing for electromagnetic interference with the aid of a spectrum analyzer, » according to an article in ISPreview today. The article has a lengthy quote from Openreach engineer Michael Jones, who said, « Not being able to solve the fault for our customers left us feeling frustrated and downbeat, but we were determined to get to the bottom it. » Jones explained what happened next:

Having exhausted all other avenues, we wanted to do one final test to see if the fault was being caused by a phenomenon known as SHINE (Single High-level Impulse Noise) where electrical interference is emitted from an appliance that can then have an impact on broadband connectivity.

By using a device called a Spectrum Analyzer we walked up and down the village in the torrential rain at 6am to see if we could find an « electrical noise » to support our theory. And at 7am, like clockwork, it happened! Our device picked up a large burst of electrical interference in the village.

The source of the « electrical noise » was traced to a property in the village. It turned out that at 7am every morning, the occupant would switch on their old TV which would in turn knock out broadband for the entire village.

As you can imagine, when we pointed this out to the resident, they were mortified that their old second-hand TV was the cause of an entire village’s broadband problems, and they immediately agreed to switch it off and not use [it] again.

DSL susceptible to interference

The resident’s promise not to use that TV again has let the village’s broadband network get back to normal. It’s not clear how long each morning’s outage lasted or why the interference propagated throughout the whole village, as opposed to just affecting the TV owner’s house. We contacted Openreach with a few questions today and will update this article if we get a response.

DSL lines are susceptible to electromagnetic interference from CRT (cathode ray tube) TVs and other devices, as US ISP Sonic notes in a help article. Fiber lines, by contrast, deliver data traffic using light instead of electrical signals. OpenReach reportedly plans to connect Aberhosan to fiber later this year, which could help prevent future outages, but copper DSL lines heading into homes might remain in place if this isn’t a full fiber-to-the-home upgrade.

Residents are understandably relieved that the immediate problem has been solved. « We’ve had engineers coming to visit all the time and none seemed to know what the problem was, » one man told the Daily Mail.

« We don’t know who this person is with the TV but I’m going to find out, » a woman told the newspaper.