Filling in white spaces: The move away from analog TV
The looming shift from analog to digital television signals in February 2009 will open a prime set of frequencies to new uses. Nationally, UHF channels 52 to 69 are being cleared for public safety communications and broadband wireless services. Regionally, significant chunks of unused airwaves could open up between channels, depending on how many stations are broadcasting in the area.
These "white spaces" are the subject of an intensifying debate in Washington. Broadcasters, sports leagues and some TV manufacturers started an advertising blitz this week urging policymakers not to let portable devices transmit on those bands of spectrum. They are opposed by a coalition of high-tech firms and consumer electronics companies that want to use the vacant TV airwaves for high-speed Internet access, home networks and other digital services.
The broadcasters have raised some legitimate points, but their concerns amount to more of a caution sign than a red light for the Federal Communications Commission. If portable devices can be made in a way that avoids interference with digital TV and related signals, they should be allowed into the market.
The public has much to gain from the efficient use of TV spectrum. Allowing such prime airwaves to be used without licenses could yield the same sort of innovation explosion that fueled the growth of unlicensed Wi-Fi devices and services, which have transformed home computer networks and coffee shops around the globe.
Avoiding interference is a prerequisite - no one wants new devices interfering with the TV signals of neighbors - and that's a relatively easy task in rural areas with few local TV stations. In cities such as Los Angeles, the airwaves are more saturated with licensed uses - not just TV programs but signals from medical equipment, public safety agencies, the wireless microphones used by news and sports crews, even astronomers. Yet a study earlier this year found that even in densely populated areas of the Northeast, at least 15 channels will be left vacant after the analog TV cutoff in 2009.
Tech companies argue that they can address all of the broadcasters' concerns about portable devices. Sensors can detect which frequencies in the area have no usable TV signals, they say, and the devices' transmissions can be limited to prevent them from bleeding into occupied channels.
These claims should be tested with prototypes in densely populated areas. If they succeed, the results can guide the FCC's requirements for white-space use. Viewers shouldn't have to put up with interference on their new digital TV sets, but that's no reason to leave empty airwaves empty.