Capstone datalink frequency congestion solution is close: FAA

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Two major aviation-related US government agencies are likely to solve within the next two weeks the problem of potential conflicts of usage of the 960MHz-1215MHz radio frequency spectrum earmarked for the ground-to-air datalinking used in the Capstone air safety technology demonstration programme taking place in Alaska.

Federal Aviation Administration Spectrum Office executive Mike Biggs says the aviation agencies involved, the Department of Transportation on the civil aviation side and the US Department of Defense on the military side, now "believe there is a way to resolve this conflict".

Although he declines to specify details of the proposed deal, Biggs confirms the two agencies expect to agree a solution within 14 days.

The frequency band in question was chosen by ICAO as a standard band for civil aviation datalinking and other navigation purposes because of its "good propagation characteristics".

As a result, in radio frequency terms it is "prime real estate - the equivalent of beachfront property", says Biggs. He adds that the band is highly attractive to potential aviation and other users because its frequencies propagate signals well.

The 960MHz-1215MHz band is used by the universal access transceiver (UAT) datalink technology developed independently by US government-affiliated non-profit research group Mitre Corporation and then sold to UPS Aviation Technologies for a nominal sum. UAT datalinking lies at the heart of the technology driving the Capstone demonstration.

"The band we're looking at [for UAT datalinking use] is a shared band, so we're working with both the FCC (Federal Communications Commission) and the NTIA (National Telecommunications and Information Administration)" to try to ease frequency congestion within the 960MHz-1215MHz band, says Biggs.

"There is also a military system that is sharing this band on a non-interference basis that has provided some challenges," he adds. "Hopefully we'll find our way forward in the next two weeks."

Biggs explains that the potential for conflicting use of this part of the spectrum originated with a DOD decision "20 years ago to put a new communications system into this band on a non-interference basis".

At the time no potential conflict was visible, but now, says Biggs, "our systems are more complex than 20 years ago and conflicts are coming up". However, the good news is that "all the agencies are now realising this conflict" and are working hard to resolve it.