Wireless transmitters in VHF, UHF 'white spaces' will be tested again

Despite an admittedly poor showing from the first prototype for a wireless networking device supposedly capable of harmlessly transmitting alongside VHF and UHF TV channels, the FCC said today it's giving the device another go.

The US Federal Communications Commission announced yesterday it is proceeding with plans to conduct a second round of tests on a controversial new technology that leverages unused or under-utilized frequencies in the VHF and UHF TV spectra for low-power wireless networking devices.

Microsoft, Motorola, and Philips will be among the companies testing devices that send signals where the US currently deploys analog broadcast television channels, including the bands that the FCC intends to auction off for private use beginning just next week.

Although it isn't yet clear how these companies would utilize these so-called "white space" transmitters assuming they become approved, the tests would determine, among other things, whether such transmitters could appropriately detect whether TV channels are in use in a given area, and steer clear of them.

The second round of testing is especially curious, since the first round -- by the FCC's own admission -- didn't fare so well.

Last July, the FCC conducted tests on what it called "Prototype A," which had been submitted for review in March by the White Spaces Coalition. Most prominent among that group have been Dell, Google, HP, Intel, Microsoft, and Philips, although Samsung has also been associated with the group. (Motorola, Nokia, and Ericsson have worked jointly on a similar project.)

It was tested to see if it could detect whether an analog or digital TV signal occupied any given point in its transmitter range, and if so, steer clear of its frequency bands. The subcategories of that test included whether it could detect channels too weak to be displayed by a display device had one actually been attached.

"In general, the Prototype A scanner did not provide consistently accurate determinations on an overall basis or with respect to any of the subcategories in the field tests," read a report to the FCC by its Technical Research Branch laboratories on July 31 (PDF available here). "First, these tests found that the Prototype A scanner often reports a channel to be available, or vacant, when the broadcast signal is expected to be present."

Second, the report went on, the prototype was only capable of accurately detecting the presence of an NTSC analog broadcast channel about four times in five, a strong DTV signal about one time in four, and a weak DTV signal about one time in 15.

The results raised the ire of the National Association of Broadcasters, which represents the stations whose signals could conceivably be interfered with by such conceivable devices as certain brands of MP3 players that network with others in the same brand, or certain makes of handsets that feature broadband access to home-based transmitters.

In a statement this afternoon, the Association's vice president of media relations, Dennis Wharton, wrote, "NAB's paramount objective remains the delivery of interference-free digital broadcast television to more than 100 million American households. We are not opposed to new technology; however, given the failing grade performance and incomplete implementation of the devices submitted in the first round of tests, we have a high degree of skepticism whether tests of these devices will demonstrate that a practical service using portable devices can be introduced without jeopardizing DTV service."

Since the report was issued last July, the NAB has garnered the support of nine senators and 61 representatives in Congress, though that support has yet to culminate in specific anti-white-space-device legislation. The lawmakers have, however, associated themselves with Wharton's prior comments that the leaders of the White Space movement -- particularly Microsoft and Google -- are "playing Russian Roulette with digital television."

The second round of testing will begin next Thursday at 10:00 a.m., and will be open for inspection by the press and interested parties.