by Clive Young. New York (October 16, 2008)--After months of testing and speculation in the press, the Federal Communications Commission released its 149-page report, Evaluation of the Performance of Prototype TV-Band White Space Devices Phase II, yesterday. The report states in its first paragraph, “We believe that the burden of ‘proof of concept’ has been met” for whether the spectrum sensing and transmitting capabilities of prototype “TV white space” devices are a feasible idea.
The purpose of the report was to test whether some of the proposed technologies to be used for detecting ‘unused’ white spaces in the TV spectrum, could be used for White Space Devices (WSD). While the report notes that the prototypes didn’t work in a number of aspects--in fact, few of the “communication device” prototypes even transmitted--most of the prototypes were created to simply sense TV signals and in that respect, the FCC found that they did the job well enough.
That said, it also summarizes some of the tests that were held, reporting that equipment didn't always act as expected--or intended. The report notes, "In the presence of DTV signals in adjacent channels, the detection threshold was degraded....," later adding, "...the Philips device reported all the channels on which the microphones were designated to transmit as occupied whether the microphone was transmitting or not. The I2R device indicated several channels as available even when the microphones were on."
Among the pro audio manufacturers campaigning against the White Space Devices are Shure and Sennheiser. Sennheiser's Joe Ciaudelli was unsurprised by the FCC's report, but noted that a lot of issues concerning WSDs are still in play. "Bottom line, besides the proof of concept statement, there is nothing new in this report," he said. "1) WSD devices would still be required to detect and avoid wireless mics; 2) Fixed WSD are being considered ahead of the more problematic portable units; and 3) More development is required on WSDs to meet the performance standards that have been set."
Ciaudelli noted that fixed WSDs present less of a concern for wireless pro audio manufacturers. "Fixed WSDs would be like TV stations," he explained. "They wouldn't move and would always be on. Wireless mic users could circumvent fixed WSDs in the same way that active TV stations are avoided today. Personal/portable WSDs, however, are a separate consideration."
While the report gives its findings, and in many ways, points to the next step for the on-going battle over white spaces, it also provides plenty of room for the various broadcast and wireless pro audio manufacturers fighting the legislation to work with, molding regulations and technologies that may affect their products. As a result, the clamor over white spaces and their future use by unlicensed devices is likely to continue for some time to come.
FCC Report: Evaluation of the Performance of Prototype TV-Band White Space Devices Phase II