After it revealed the results of its “white space” tests at the end of July, the FCC tried to clear up some of its signals, inviting some 50 industry heavies to its suburban Maryland lab and placing its top technology staff on the hot seat to discuss how the prototype white space devices (WSD) caused interference to DTV, cable and licensed wireless audio devices.
With a decision on mobile WSDs expected from the commission in October, broadcasters remain fearful that unleashing millions of untrackable RF-spewing consumer devices on the unused channels will derail the DTV transition, and the briefing at the lab only deepened their concerns.
The mid-August briefing seemed to be an attempt by the FCC Office of Engineering and Technology to demystify its testing process and push back on any suggestion it was not being sufficiently transparent in its testing.
For the FCC, the tests are uncharted territory and there’s disagreement about how low a DTV signal the WSDs should have to detect. NAB and MSTV have argued that even detection of –116 dBm may be inadequate, and MSTV President David Donovan noted that at the discussion at the FCC lab, staff agreed that –114 dBm detection may not be sufficient.
“If you’re not sure whether –114 dBm is going to protect DTV, then why are you testing at –114 dBm?” Donovan asked. Others disagree. “No one has empirically established that this level of sensitivity is necessary to protect viewers from harmful interference,” wrote a coalition including the New America Foundation and the Media Access Project.
Donovan also said field tests should be done in more real-world situations, in places like New York (with its post-9/11 weak DTV signals and wireless users from law enforcement to Broadway), and the hills of rural Pennsylvania. “And I didn’t hear a commitment to that,” he said.
OET staff repeatedly stressed the time-consuming nature of the tests and noted that they had to carefully pick the most representative tests possible to maximize their useful data...
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