IT companies like Dell, Google, HP, Intel, and Microsoft are squaring off against broadcasters, joined by some cell phone service providers, in a battle for control of the remaining unlicensed spectrum.

The opposing sides in the battle over white spaces are launching aggressive new advertising and lobbying campaigns this week aimed at influencing the FCC and Congress to support their respective stances on the unused and unlicensed white spaces spectrum.

The Wireless Innovation Alliance is running ads in Washington publications covering Congress criticizing the National Association of Broadcasters, which has long argued that devices operating in the white spaces could cause interference. The WIA membership includes Dell, Google, HP, Intel, and Microsoft.

Targeting the broadcasters, the WIA ads show an old TV set captioned: "If the NAB had its way, this would be your living room." The ad also states that technologies like FM radio, cable TV, and VCRs initially were opposed by the NAB.

The broadcasters, joined by some cell phone service providers, are arguing in their ads that devices tailored for white spaces haven't passed tests conducted by the FCC. Zeroing in on the issue, the NAB ads ask: "If the devices fail in pristine lab conditions, can you really trust them in the real world?"

Although devices proposed by Microsoft, Motorola, and Philips haven't passed the FCC's rigorous testing to date, the WIA companies maintain interference problems can be overcome. Google, for instance, has proposed the use of geolocation measures that it believes will protect broadcast TV signals from interference. A $10 beacon could be all that's needed, Google argues.

"We are proposing a 'safe harbor' for wireless microphones in channels 36-38," wrote Google counsel Richard Whitt, Google's Washington telecom and media counsel, in a recent letter to the FCC. "No TV white space device would be permitted to transmit in these channels. This will also protect medical telemetry devices and radio astronomy services, which are licensed to use channel 37."

The FCC has said it will announce a schedule for field testing the devices after lab tests have been concluded.