LightSquared squares off against GPS worriers
Just what the competition ordered
The FCC refused to rescind LightSquared's licence over potential GPS interference, so now the general public is being courted in the hope of a less well-informed decision.
"GPS dead zones" are threatened if LightSquared is permitted to go through with its plan to deploy LTE technology in satellite frequencies. Reports, and warnings, from the US Air Force Space Command and New Scientist – to name just two – highlight the way in which GPS will spontaneously fail when LightSquared turns on its network, though none of the reports found space to mention that the FCC licence explicitly states that LightSquared will not be allowed to build anything until any potential for interference is removed.
"Can you even imagine... losing GPS reception every time you drove within range of an LTE tower?" asks Engadget reporting on comments from General William Shelton which were, in turn, motivated by reports from the GPS-kit-manufacturer Garmin, which were quoted by New Scientist, claiming that LightSquared's plans "will result in widespread, severe GPS jamming".
LightSquared has been publicly planning to deploy LTE at satellite frequencies for a year or so, since the FCC stated it was inclined to permit such things as part of the National Broadband Plan. The complaints about possible GPS interference popped up in January, when the National Telecommunications and Information Administration (NTIA) raised concerns about what would happen if LightSquared's wholesale customers were not required to provide satellite-capable handsets.
That has nothing to do with interference of course, LightSquared never intended more than a tiny fragment of its traffic to be satellite-routed, but the NTIA reckons it means more transmitters and thus an unacceptable level of interference. By coincidence, it also has a lot to do with how competitive LightSquared's network will be, and the incumbent operators were not happy when the FCC decided to drop the satellite requirement.
Not that the FCC is being weak in protecting GPS: LightSquared will be operating in neighbouring frequencies, and could generate out-of-band interference enough to interfere with the extremely low-power GPS signals, though the company claims its whizz-bang filters will prevent that. To make sure of that, the FCC requires LightSquared to help create a working group, with makers of GPS kit, to "focus on analysing a variety of types of GPS devices for their susceptibility to overload interference from LightSquared’s terrestrial network of base stations".
That group will need to file a work plan by tomorrow, and will then be required to report to the FCC monthly (PDF – para 41 onwards).
So the chances of interference with GPS are minimal, and subject to constant monitoring, and LightSquared won't be allowed to build a network until the issue has been entirely resolved. Garmin might have demonstrated interference is possible (pdf showing who and how), but it ranks pretty low on the things to worry about.
All of this is moot if LightSquared can't raise the billions of dollars it still needs to build the network. On Wednesday the company reported having raised another $586m but it is still less than halfway to the $7bn it needs (and that figure is by its own reckoning – it could require a lot more than that).
One can't help wondering if putting a little fear and uncertainty into the heads of potential investors, threatening the entire business plan with health-and-safety concerns over GPS interference, isn't just what the existing operators might have asked for. ®
For aviation users, this is a big deal
"Garmin might have demonstrated interference is possible (pdf showing who and how), but it ranks pretty low on the things to worry about."
Err, no. Try again.
For a lot of airports, the approved IFR approach (in clouds, can't see out the window) is a WAAS GPS approach. Apparently Garmin did a test with their GNS 430W that showed that Lightsquared's proposed trsanmitter can cause the 430W to fail. And if you're on approach, this means you (at the very least) have to break off the approach and try the whole thing again... from maybe a couple hundred feet above the ground... or (at the very worst) you lose situational awareness and die.
It's also worth mentioning that the NextGen air traffic control system is pretty much going to be built on GPS - how many "ATC freakouts" do we want to deal with when a bunch of blips on the controller's screen suddenly show "no position or speed info available"
I have heard (from Lightsquared themselves) that their mitigation plan involves installing filters on affected GPS receivers. For aviation that means the filter needs to meet a TSO (that isn't written yet), be approved by the FAA, the installation probably would need to be STC'ed, and then the actual filter installed properly by an A&P mechanic. It's fair to say that there's hundreds of thousands (if not millions) of dollars in paperwork there for the TSO and various STCs, plus at least a couple hundred dollars per airplane. Who is gonna pay for that?
Cheaper stuff is great, but if they really need any part of that satellite spectrum for "a tiny fragment of its (LightSquared) traffic to be satellite-routed," then they need a new plan.
most telescope arrays are in "no transmit" areas
And have explicit protection from the frequency regulator in that country. Also, sensitive arrays tend to be built in metal enclosures dozens of feet high to shield them from surrounding RF noise - after all the telescope only needs to worry about the sky, and a fairly small window of that at a time (since the planet keeps spinning!)
Will this also mess up some of the near by frequencies that are used for radio astronomy?