Google's asked the United States' Federal Communications Commission (FCC) to let it play with millimetre-wave technology America-wide for two years.
In a filing that's sparked “Project Loon coming to America?” speculation, the company has filed a heavily-redacted request with the FCC for permission to run unspecified experiments in the 70 GHz and 80 GHz bands.
Those same bands were part of an application in October 2014 for Google to run tests in California.
Google's public FCC filing is heavily-redacted, mostly related to the name of the entity it wants to run the tests, antenna characteristics, and specific locations.
Google promises that users with specific geographic licenses in the 70 and 80 GHz bands will be protected: GPS receivers on its unspecified experimental platform will track its location and velocity, the filing states, to comply with non-interference rules.
Other interference-prevention measures offered by Google include:
- Changing and limiting transmission frequencies to those that avoid harmful interference;
- Reducing transmitter power below the level needed for throughput optimisation;
- Reducing transmitter bandwidth;
- Aiming the relevant transmit antenna toward a different [REDACTED] receiver at an azimuth or elevation angle that is not aligned with vulnerable receivers;
- Employing cross-polarization to reduce the amount of power received by registered users employing different polarization than [REDACTED]; and
- As a last resort in cases where the above techniques would not eliminate potential harmful interference, discontinuing transmission.
While the document is too heavily redacted for The Register to declare with certainty that Americans will see Loon balloons in flight next year, one particular aspect of the filing is telling: Google's promise not to blind radio-astronomers.
“Google has a coordination agreement in place with the National Radio Astronomy Observatory (NRAO) to ensure that that operations under [REDACTED] current experimental authorizations (Call signs WH9XYD and WH2XUP) do not cause interference to radio astronomy observations at NRAO’s Owens Valley location.”
“Google is prepared to coordinate with the National Telecommunications and Information Administration to ensure that other federal operations in the band do not experience harmful interference from Google’s testing in the expanded geographic area described in this application”, the filing continues.
However, careless transmissions don't have to come from the sky to be picked up by the super-sensitive receivers on a sky-watching dish.
What we do know is that Google intends its 70/80 GHz radio tests to be mobile. If it's not Loon, perhaps the Chocolate Factory is planning using the spectrum for communicating with its self-driving vehicles.
Another application that would suit millimetre-wave communications is delivery-by-drone – in fact, this would be a better application than Project Loon, because the 70/80 GHz bands lose most of their oomph at 10 Km, around half the altitude Google's balloons fly at.
Google started toying with drone deliveries in Australia in 2014, and the company hopes to turn that into A Thing by 2017. ®