As promised, The FCC has released results of its tests of the mobile spectrum-sensing devices it is considering allowing in the so-called white spaces of the DTV spectrum, and they buttress broadcasters' concerns that the devices will interfere with DTV reception.
While the FCC said newer models might be better, and that 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 computer companies and others 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% to 75% of the time with an average of 58.2% of the time."
An earlier FCC test of TV sets had found interference to all 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.
Broadcasters have countered that it will instead threaten the DTV transition by causing massive interference, a warning the FCC studies appear to bear out.
Certainly the Association for Maximum Service Television, the broadcasters' spectrum policy watchdog group, was seeing it that way. "Hopefully this will put an end to the debate about using TV channels for unlicensed personal and portable devices," said MSTV President David Donovan. "It confirms everything MSTV and the television industry have said over the past three years."
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