SpectrumTalk

Google white space device prototype

Busy Week of White Space Action

It's been a busy week here in Washington, my home town. Down at the lab of our local communications commission there have been all sorts of visitors, like Magi at Xmas time, bearing gifts or promises of gifts. Fortunately, unlike the advocates of the status quo for large affluent TV broadcasters who skirt the Commission's ex parte rules with apparent impunity, these visitors believe in and act in the letter and spirit of transparency. Thus there is a paper trail where we can follow the action.

Actually, a little earlier on November 16 Motorola came by with the first recent present. Motorola described it as follows

"(It) uses geo-location database that is augmented by sensing algorithms to determine which TV White Space channels are available for use. The device also can be configured to perform testing of the DTV sensing algorithms but is not a normal operational mode of the device."

No pictures were included, but I saw the device at the Lab and it is rack mounted in an 18" high rack.

On December 4, Google dropped by.

(The) Google representatives demonstrated broadband spectrum sensing technologies that reliably detect DTV signals well below the noise floor. The broadband DTV sync signals gave reliable power level estimates, even when the pilot is deeply faded, removing the need for large margins. preliminary figures from the initial phase of the testing support an average sensitivity of -120 dBm.

The picture at the top of this post was included in their submission to FCC.

Then on December 5, Adaptrum, Inc , a client of mine, dropped by with its unit.

Dr. Haiyun Tang of Adaptrum and Steve Jones of FCC Laboratory with Adaptrum White Space Device (WSD) at delivery to FCC for testing,

Adaptrum said in its filing

The Adaptrum device is different from others that have been discussed on the public record in that it is not based frequency domain processing and threshold detection of DTV pilot tone power. Rather, it uses the whole 6 MHz of the DTV signal and contains a time domain matched filter. This greatly increased bandwidth permits greater sensitivity than pilot tone detectors.

Note that the Google and Adaptrum filings were made almost simultaneously and that both systems appear to use the same type of time domain processing.

Also on December 5, my former boss, Ed Thomas, met FCC downtown on behalf of both Microsoft and Philips. The filing says

During this meeting, Mr. Thomas made arrangements for Microsoft and Philips to submit devices to OET for the next round of white space prototype testing, and the parties discussed white space testing logistics, including potential dates for laboratory and field tests.

Are Microsoft and Philips now combining forces and working on a common device? The letter is ambiguous so we will see.

FCC staff reports that the "8th Floor" has now said that all submitted devices will be tested in parallel and publicly with observers from the interested public - please don't throw peanuts at the FCC staff. This apparently includes both bench tests and field tests. A problem appears to be how to find homes to test these in where an unlimited number of observers can wander in and out. Stay tuned.