GPS Degradation Testing

Steve said:
https://www.faasafety.gov/files/notices/2010/Oct/GPS_Flight_Advisory__FTPK_GPS_10-03.pdf

Looks like they're checking to make sure Selective Availability is still an option.
Click to expand...
I recall these sorts of NOTAMs for years, though I don't recall the PDF to go with them. I'm not sure that we can determine that they're testing SA. I think they're likely testing a localized GPS jamming device, maybe even a portable one that can be deployed overseas. Well, maybe not so far from SA after all, except this looks like it's ground-based, while SA was, as I understand it, controlled at the satellite.
 
The NOTAM notice is the clearest to date I have seen. The map makes all the difference in the world in letting GA know where the GPS signal might be affected.
 
Is this the kind of thing where accuracy is downgraded from 1m to 10m? I have seen them in NM (Holloman area) for years now and when flying though the areas, notice nothing unusual. Would it only affect waas approaches (and missile accuracy)?
 
Given that cone-shaped affected area, I always assumed that this is something happening on the ground that might cause interference with the signal, and not SA which is something to be turned off/on at the satellites.
-harry
 
So, once the FAA has us all switched to space based navigation along with a tracking system (ADS) based on the same thing, is the plan to just shut down a big hunk of the country's air transport system when they want do test some new jammer? To me this would be equivalent to messing with half the traffic lights in a major city to test the potential for someone else to screw around with the system. And I don't think they would get away with just warning the drivers that the lights might be "degraded" for a while.

Seems to me, now that GPS is such an integral part of the national airspace system, the AOPA, EAA, NBAA, and even FAA should petition Congress to move such testing offshore to a place where it won't be so disruptive.
 
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The issue is not SA. It's figuring out how to make military GPS work in a "gps denied" environment.

"GPS denied" encompasses anything from interference overwhelming the GPS signals to deliberate spoofing of a GPS signal. There's a lot of work being done in mil circles on GPS antijam to overcome both interference and spoofing (IIRC, it's part of the M-code specs).

Even though FAA and others are moving to GPS for primary navigation purposes, it is pretty fragile and subject to jamming and interference.
 
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