FCC: Devices Interfere With DTV

by John Eggerton -- Broadcasting & Cable, 8/6/2007

The FCC said last week that all the new portable spectrum-sensing devices it tested failed digital-TV interference trials.

As promised, the FCC released results of its tests of the mobile devices it is considering allowing in the so-called white spaces of the DTV spectrum. Now the results buttress broadcasters’ concerns that the devices will interfere with DTV reception.

While the FCC said that newer models might be better and more testing was needed, the devices it did test did not get a passing grade.

“This report determined that the sample prototype white-space devices submitted to the commission for initial evaluation do not consistently sense or detect TV broadcast or wireless microphone signals,” the commission said, striking a blow to the hopes of companies looking to use the spectrum for portable devices like PDAs and game controllers.

“Our tests also found that the transmitter in the prototype device is capable of causing interference to TV broadcasting and wireless microphones,” it said.

In one test, where a DTV signal could be received by a TV at the test site, “the scanner reported its channel to be free or available 40%-75% of the time with an average of 58.2% of the time.”

An earlier FCC test of TV sets found interference to eight models tested.

The FCC has said it would allow fixed wireless devices in the band, which broadcasters do not object to, but it is also considering mobile and even unlicensed mobile remote-sensing devices as a way to further the Bush administration’s goal of more-flexible and -efficient spectrum use.