Dan Dalessandro, a television repairman, was one of several ham radio aficionados who went to investigate. At first, he said, all he picked up were “little blips” on a signal detector, but on one block — and at one house in particular — the signal was extraordinarily powerful.
By Saturday afternoon, City Councilman Chris Glassburn announced that the mystery had been solved: The source of the problem was a homemade battery-operated device designed by a local resident to alert him if someone was upstairs when he was working in his basement. It did so by turning off a light.
“He has a fascination with electronics,” Mr. Glassburn said, adding that the resident has special needs and would not be identified to protect his privacy.
The inventor and other residents of his home had no idea that the device was wreaking havoc on the neighborhood, he said, until Mr. Glassburn and a volunteer with expertise in radio frequencies knocked on the door.
“The way he designed it, it was persistently putting out a 315 megahertz signal,” Mr. Glassburn said. That is the frequency many car fobs and garage door openers rely on.
“There was no malicious intent of the device,” he said in a statement.
The battery on the device was removed and the signal stopped. “It was a relief,” Mr. Glassburn said.
More broadly, the case is a reminder of the power of radio frequencies, Professor Wandt said.
“They are not inherently dangerous to a human being,” he said. “But they could cause mass chaos in our technologically advanced society in ways we cannot predict.”