Steven J. Crowley, P.E.
Google has filed an application with the FCC to conduct drone tests in New Mexico. The company has sought confidential treatment of its application form and exhibits. All we have to go by now is one exhibit that’s been redacted for public consumption. Google provides some detail, and we can try to infer some more.
A big clue is the following:
Google recently acquired Titan Aerospace, a firm that specializes in developing solar and electric unmanned aerial systems (“UAS”) for high altitude, long endurance flights. These systems may eventually be used to provide Internet connections in remote areas or help monitor environmental damage, such as oil spills or deforestation. The STA is needed for demonstration and testing of [REDACTED] in a carefully controlled environment.
Google provides a set of coordinates bounding the test, which put it in a square east of Albuquerque and south of Santa Fe, New Mexico, centered roughly on the unincorporated community of Stanley.
[REDACTED] will transmit at frequencies between 910.0000 MHz and 927.0000 MHz. [REDACTED] will transmit at frequencies between 2400.0000 MHz and 2414.0000 MHz.
These are bands in which unlicensed operations are permitted, with 2400-2414 MHz overlapping the lower channels of Wi-Fi.
We don’t know what Google is doing with these bands, but Google says the 2400 MHz antenna is oriented such that vertical peak gain is 20 degrees below the horizon. Similarly, the 910 MHz antenna is oriented 5-90 degrees above the ground plane. This suggests the higher band is for a drone-to-ground link, and the lower band is for ground-to-drone.
The emission designators Google provides are additional information. The designator for the drone to ground link is 14M0F3F; this means it’s a 14 MHz-wide analog transmission using frequency modulation sending one channel of video: i.e., not Internet. The emission designator for the ground-to-drone link is 280KF1D; a 280 kHz wide digital transmission, frequency modulated, containing data, probably for control.
Google notes a potential conflict with federal operations:
Google understands that there may be some federal operations in the 900 MHz band in the vicinity of the test site. Google is prepared to coordinate with the National Telecommunications and Information Administration to avoid harmful interference to any federal operations.
If FCC staff doesn’t have sufficient information on those federal operations, it may ask Google to go to NTIA to get their sign off.
UPDATE (9/17): The application form that was previously unavailable is now online. It repeats some of the information on the exhibit linked above. In two separate form responses, Google says it’s testing “digital transmitters,” which seems inconsistent with the 14M0F3F emission designator; per the FCC’s Rules, the “3” specifies a “single channel containing analog information.”
UPDATE (9/30): Google’s application was granted on September 26. As to the purpose of the experiment, the Special Temporary Authorization is more explicit and concise than Google’s redacted application:
Testing of digital transmitters that support broadband access in remote areas and environmental
monitoring using solar and electric unmanned aerial systems.
With the information I have, I can’t reconcile a “broadband access” test with the drone-to-ground emission designator of 14M0F3F, which is for analog video.