GPS Interference Concerns Revived

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An attempt to launch a high-speed cellular network that raised alarm over GPS interference was squelched by federal regulators back in 2012, but now the same company is proposing a new network, and GA advocacy groups have banded together to oppose it. Ligado Networks, formerly known as LightSquared, claims its technology has improved, and will disrupt GPS signals only within 500 feet of its transmission towers. That’s not good enough, says the GA coalition in a letter (PDF) sent to the FAA on Wednesday. Plenty of aircraft, including drones, on a variety of missions, operate in close proximity to flight obstructions, the letter states, and therefore a loss of navigational accuracy in those areas would have “adverse impacts on the ability to safely navigate.”

The coalition asks the FAA to support further testing and evaluation of the proposed system, to be conducted by an impartial third-party organization, so “we may fully understand the impacts to GPS-dependent systems and to ensure no degradation of safety within the NAS.” The letter is signed by 11 groups representing GA interests, including AOPA, NBAA, ALPA, Helicopter Association International, National Agricultural Aviation Association and National EMS Pilots Association. Ligado said in a statement last month that it will protect certified aviation GPS devices by reducing the power level at which certain of its downlink connections operate. “This change reflects our collaboration with the Federal Aviation Administration and honors our pledge to find consensus with government and industry actors,” the company said.

An industry newsletter, Inside GNSS [Global Navigation Satellite Systems], reported on Monday that key federal regulators met three months ago to discuss the issue with Ligado but have not yet released their recommendation on whether or not to allow the development of the service. Subsequently, Ligado modified its license request, making a frequency change the company said would avoid interference with certified aviation GPS receivers. However, testing by the Transportation Department found that the limits set for certified aviation receivers did not protect receivers in all other categories, according to Inside GNSS.

Comments (2)

Install ADS-B in your airplane, they mandated. You won't be able to fly in "Rule" airspace without it after 2020, they said. Unless you do this, you won't see all the traffic on your "in" box, they warned. And -- oh by the way -- the GPS sensor in your ADS-B system MUST be an approved TSO'ed WAAS unit with the proper support software for millimeter accuracy to be transmitted to users from your airplane, they decreed. And how the heck will millions of drones be able to miss you at low altitudes if you don't do all of this, they said.

And now ... just don't fly too close to them cell towers, they're discovering.

Yeeeaaaahhhh !!!

"Bureaucracy is the death of any achievement." -- Albert Einstein

Posted by: Larry Stencel | June 20, 2018 5:18 AM    Report this comment

I'd like to see Ligado succeed, but like their previous incarnation (Lightspeed) they have a frequency license right next to GPS. Lightspeed bought it knowing full well it was for low power devices. This is probably yet another attempt to get a "free" frequency swap, i.e. to get the FAA to pressure the FCC into giving them more valuable spectrum than they bought.

This company has a product that will likely muck with more than airplanes, it will muck with millions of low power GPS devices including (but not limited to): Tractor Trailers, Tractors (Farm), Automotive (personal cars/trucks), delivery vehicles (UPS, FedEx), and so on. All because they want to transmit at a much higher power than the frequency they bought allows. I say if they want to do that, then they need to either buy new spectrum in a high power band OR pay to replace all the GPS satellites / GPS devices. The spectrum they bought did not have some secret limitations, the limitations were well known in advance. That's why the spectrum was cheaper than the others Lightspeed/Ligado could have bid on.

They don't get to whine about limitations that were fully disclosed.

Posted by: Joe Servov | June 20, 2018 11:55 AM    Report this comment

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