The Federal Communications Commission (FCC) is slated to begin testing next week devices to use the so-called "white spaces," the spectrum between digital TV channels, for wireless broadband Internet access. The testing will initially consist of a four-to-six week lab test of equipment that will allow ISPs to access this spectrum, followed by another six-week field testing period.

"The field tests will be conducted at a variety of locations to provide information on the performance of the devices under real world conditions," the regulator said in a statement.

However, efforts to use white spaces between digital channels may impact wireless microphones and other technologies that have historically relied on these frequencies. The technology is also opposed by groups of companies for various financial and technical reasons. The opponents include mobile-phone operators such as Sprint Nextel Corp and a coalition of television broadcasters that includes representatives from General Electric Co.'s NBC and CBS Corp.

This is not the first round of testing by FCC engineers on white spaces equipment. Earlier prototypes allegedly did not reliably sense the presence of television transmissions or other incumbent users. This determined the FCC to claim the devices are not acceptable for use in their current state and no further testing was deemed necessary. Further pressure from Microsoft and other members of the White Spaces Coalition have determined the FCC to reverse its ruling and conduct further tests.

Google, which is also part of the White Spaces Coalition, has done its own white-spaces testing and submitted its results to the FCC in December. Other members include Dell, HP, Intel, Philips (which managed to demonstrate working prototypes to the FCC), Earthlink, and Samsung Electro-Mechanics.

For this round of tests, four companies submitted devices: Microsoft, Adaptrum, Motorola and Philips.