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10.16.2008
Originally featured on BroadcastEngineering.com
Martin favors unlicensed white space device use with some conditions

FCC chairman Kevin Martin will support allowing unlicensed white space devices (WSDs) that meet certain criteria into spectrum used for TV and wireless mic transmission when the commission takes up the matter next month.

Speaking at a press conference on Oct. 15, Martin said he favored allowing the devices to operate of up to 100mW of power on certain white spaces in the TV spectrum and 40mW of power on channels adjacent to DTV channels. The devices must also include spectrum sensing and support for geo-location so by accessing a databases of spectrum use the device can select frequencies that do not pose an interference threat, Martin said.

The chairman’s proposal to allow unlicensed WSDs to transmit at 40mW of power on first adjacent channels “will eviscerate over-the-air digital television viewing throughout large segments of the United States,” according to Association for Maximum Service Television president David Donovan. In a written statement released following Martin’s announcement, Donovan said allowing first adjacent channel WSD operation at this power level will hit viewers living in urban apartments and townhomes particularly hard.

Martin’s announcement came on the same day the FCC’s Office of Engineering and Technology released a report detailing its findings from the latest round of prototype white space device testing.

According to the report, the latest test show moderate to strong DTV signals in adjacent channels “severely impacted” the threshold at which tested prototypes could detect signals and have the potential to impact how well they can “reliably detect TV signals within station’s service areas.”

Despite the red flag, the report’s authors said they believe that the burden of “proof of concept” has been met. “We are satisfied that spectrum sensing in combination with geo-location and database access techniques can be used to authorize equipment today under appropriate technical standards and that issues regarding future development and approval of any additional devices, including devices relying on sensing alone, can be addressed.”

The report, “Evaluation of the Performance of Prototype TV-Band White Space Devices,” details OET lab and field testing of prototype devices submitted for testing by Adaptrum, The Institute for Infocomm Research (I2R), Microsoft, Motorola and Philips Electronics North America.

The tests also reveal that the prototype white-space devices fared no better in detecting wireless mics in use when in the presence of DTV signals in adjacent channels, the report said. In such instances tested, “the detection threshold was degraded such that it affected the ability of devices to reliably detect the microphone signals,” the report said.

In his statement, Donovan said interference to licensed wireless microphones from unlicensed WSDs “will endanger live local newscasts as well as sports coverage.”

To read the FCC report, visit http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-08-2243A2.pdf.


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