Monday Evening Links > White space tests get mixed results

In the most recently concluded tests, Motorola claims its geolocation-based technology got high marks for avoiding interference with existing spectrum holders, while a field test of spectrum sensing technology at a major sporting venue proved that that technology is not up to snuff in avoiding interference with broadcast-based microphones.

Over the weekend, spectrum sensing prototypes were tested by the FCC at the FedEx field in Maryland prior to Saturday's game between the Washington Redskins and the Buffalo Bills. Shure, a microphone manufacturer said in a press release issued Sunday that the spectrum-sensing white-space devices caused "harmful interference to wireless microphones" during the live event.

"Simply stated, the prototype devices were unable to consistently identify operating wireless microphones or distinguish occupied from unoccupied TV channels," said Mark Brunner, Shure's senior director of public and industry relations. "More troubling, the devices failed to detect the presence of wireless microphones when switched on--an occurrence that takes place multiple times during any NFL game."

Motorola, which uses a totally different method for avoiding interference, agrees that sensing technologies don't always work appropriately. That's why the company uses GPS-based geolocation technology and an FCC data base of known spectrum license holders to pick and choose when white spectrum is available.

Google said in a policy blog last week before the microphone test at FedEx field that the sensing technology may not work as well as some had hoped.

The FCC is currently compiling results from its testing, and it's expected to release a full report of the results within the next few weeks after it concludes all field tests of the current technology.