Quantifying the Impact of Unlicensed Devices on Digital TV Receivers
Project Award Date: 09-01-2006
The Federal Communications Commission proposed in Docket 04-186 to allow sharing of underutilized TV broadcast spectrum by unlicensed devices that could determine that the spectrum in question was not used. Even sophisticated unlicensed devices may under certain circumstances have incidental emissions in TV bands. Although the primary emissions from these devices--those used for communicating--would not be in an active TV band, incidental out-of-band emissions (resulting from the limits of radio technology) might fall in an active TV channel. Limits on this need to be clearly established.
The fundamental cause of this problem is that TV receivers are designed to meet conflicting requirements: they must be very sensitive, must cover a large tuning range, and must be sold at moderate cost. Of necessity, design compromises must be made to meet these goals, and as a result such receivers generally have little resilience to undesired signals in the TV band. Unlicensed devices using the white spaces in the TV spectrum will need to be designed within limits appropriate to this environment.
Interference with a user's digital television viewing is likely only when there are a substantial number of unlicensed devices transmitting simultaneously in the vicinity. ITTC researchers will develop a proposed limit for unlicensed devices in TV spectrum. They will create a simple and reproducible testing method to verify that a proposed unlicensed device meets the limit.
Primary Sponsor(s): New America Foundation