By Mitchell Lazarus
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Those who actually read these blog postings (both of you) are well informed about the controversy over unlicensed devices on vacant TV channels -- often called "white space" spectrum.

Much of the dispute centers on the wisdom of allowing handset-type units that a consumer can carry around, sometimes called personal/portable devices, that use TV frequencies. Unless these can be made smart enough to identify and avoid occupied TV channels when taken from one place to another, they will threaten interference to viewers' off-the-air reception. Designing in adequate protection is difficult because a large outdoor TV antenna can receive signals too weak for detection by a hand-held device. Proponents have yet to satisfy the FCC that non-interfering personal/portable devices are feasible.

Motorola, which hopes to make money selling the handsets, recently proposed to simplify the problem by dividing the personal/portables into two categories. The more common consumer units would use relatively simple technologies for avoiding occupied TV channels: they would monitor directly for TV signals, and also receive a local beacon signal that identifies vacant channels in the area. To minimize any residual risk of interference, these would operate only at low power, below that of typical Wi-Fi units. Higher-powered units, intended for rural areas and commercial or enterprise use, would have to add a GPS receiver and a look-up table for determining the vacant frequencies at any location. They would operate at maximum Wi-Fi power.

The broadcasters have not yet made their reaction public.

The Motorola paper is at this link.

        

 

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