Tests appear to confirm worry over white space devices, wireless mic interference

Tests of two prototype unlicensed TV spectrum devices by the FCC showed that they did not consistently detect the presence of wireless mic systems in use.

Two prototype white space devices (WSDs) failed to consistently sense the presence of wireless mic transmissions on the TV band in testing performed by the FCC Office of Engineering & Technology.

A report from the OET released July 31 summarizing the results of initial testing found that one prototype device “was generally unable to sense wireless microphones” and the other turned in “mixed” results when tested in various situations.

The tests, conducted at the FCC Laboratory, were the result of a commission proceeding considering whether fixed devices should be allowed to operate on TV white spaces after the 2009 DTV transition. Besides evaluating how such devices would impact over-the-air TV reception, the tests were also intended to determine if WSDs could sense the presence of wireless mic systems in use and avoid interfering with them by identifying and selecting unused spectrum.

For the tests, three Part 74 wireless mic systems were used: two consisted of a receiver and two mics, and another of a receiver and one mic. The mics had the ability to operate on TV channels 41 to 51.

According to the report, Prototype A was unable to reliably detect the presence of the wireless mic systems when in use. Prototype B did better overall, but still turned in a mixed performance.

To learn how the WSDs performed in relation to TV transmissions, see “ FCC OET report paints ugly picture for White Space Devices.”