First-generation technology fails white space test

Broadcasters fear that the use of unlicensed devices might interfere with DTV reception.

Last week, the FCC released results of its initial tests of the mobile spectrum-sensing devices that might open the use of white spaces in the digital technology spectrum. To put it simply, the devices failed miserably, causing significant interference.

Broadcasters fear that the use of unlicensed devices might interfere with DTV reception. The FCC said the first-generation devices did just that.

The technology will need to be improved, and more testing is needed to determine if those devices work. The commission is not abandoning its intent to use white spaces and will continue with testing.

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

The commission said, however, “several features that are contemplated as possible options to minimize the interference potential of WSDs, such as dynamic power control and adjustment of power levels based on signal levels in adjacent bands, are not implemented in the prototype devices that were provided.”

Though television broadcasters got a boost in their arguments that use of unlicensed devices in white space should be prohibited, the FCC said it is “committed to working with interested parties to continue the process of investigating the potential performance capabilities of TV white space devices.”

The commission intends to invite interested parties to participate in an on-site visit to the FCC Laboratory in Columbia, MD, to observe and discuss the test set up and procedures for evaluating the performance of these devices. Interested parties should file comments on the commission’s test reports no later than August 15, 2007.

Complete testing material is available to all interested parties through the FCC’s Electronic Comment Filing System (ECFS) at and the commission’s Web site at