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FCC Releases White Space Interference Report
Washington - Jul 31, 2007 - On Oct. 12, 2006, the Federal Communications Commission adopted a first report and order and further notice of proposed rule making in ET Docket Nos. 04-186 and 02-380, 21 FCC Rcd 12266 (2006) authorizing the operation of new low power devices in the TV broadcast spectrum at locations where individual channels/frequencies are not being used for authorized services. These supposedly unused frequency areas are commonly referred to as TV white spaces. In that action, the Commission stated that its laboratory would conduct a testing program to assess the potential for interference from low-power devices. On Dec. 21, 2006, the FCC's Office of Engineering and Technology (OET) issued a public notice (DA 06-2571) asking interested parties to submit prototype TV white space devices for testing. Two parties provided prototype personal/portable white space devices to the FCC Laboratory for testing.
The OET has released two technical reports on initial measurement studies relating to the above devices that were performed by its laboratory: Initial Evaluation of the Performance of Prototype TV-Band White Space Devices (OET Report FCC/OET 07-TR-1006 Prototype Devices Report) and Direct-Pickup Interference Tests of Three Consumer Digital Cable Television Receivers Available in 2005 (OET Report FCC/OET 07-TR-1005 Direct Pickup Report). The two reports are available through the FCC's Electronic Comment Filing System (ECFS) at www.fcc.gov/cgb/ecfs.
While this issue appears to only affect TV reception, it is a concern for radio broadcasters as well. The theory that an unused TV channel in a market is wasted spectrum is false because broadcasters routinely use these unused TV channels for wireless mics and other communications. This is especially true during any kind of media event where multiple itinerant RF users converge in a single location, such as a sporting event or during news coverage. TV broadcasters also cite that allowing unlicensed devices will wreak havoc with the DTV transition already underway.
The FCC proposal stipulated that the new unlicensed wireless devices must first scan the spectrum to ensure that they do not interfere with another device. Again, this concept is flawed because even if an unlicensed device senses no activity at one moment, new authorized users could appear at any moment.
The FCC's lab tests on devices submitted by Microsoft and Philips showed that they do not consistently sense or detect TV broadcast or wireless mic signals. Even when strong TV signals existed, the unlicensed devices under test failed to accurately detect the TV signal 40 to 75 percent of the time.
Interested parties may file comments on these reports no later than Aug. 15, 2007. Reply comments are due no later than Aug. 27, 2007. All filings should reference ET Docket No. 04-186.
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