From the way they are describing it, it looks like they are sending a
signal from the ground. So there is an easy countermeasure, install a
nullifying GPS-antenna and have the null pointing to the location of the
signal source.

In the beginning of GPS flight recording there where many interfering
signal sources in Italy. The way to overcome the problem was to install
the GPS antenna on a large grounding plane, which made the GPS antenna
to ignore the interfering signal sources.




Greg Arnold schrieb:
309 wrote:
On Jan 21, 9:16 pm, Greg Arnold wrote:
Does the military ever tell anyone what area is affected by the jamming?
I don't see that in the NOTAM. It seems that would be useful
information.

See https://pilotweb.nas.faa.gov/distrib...nterQuery.html

or:

!GPS 01/021 ZLA GPS IS UNRELIABLE AND MAY BE UNAVAILABLE WITHIN A 324
NM RADIUS OF 372023.4N/1160158.4W (LOCATED WITHIN THE TONOPAH TEST
RANGE) AT FL400, DECREASING IN AREA WITH DECREASE IN ALTITUDE TO 277
NM RADIUS AT FL250, 198 NM RADIUS AT 10,000 FT MSL AND 197 NM RADIUS
AT 4,000 FT AGL. THE IMPACT AREA ALSO EXTENDS INTO THE MEXICAN FIR.
1900Z-0845Z DLY WEF 0801211900-0801260845

They're describing a VOLUME about the jamming point: the higher you
are (diamond altitude, a little under FL400), the farther you need to
get away to be "unimpacted." Notice they admit the jamming area
includes Mexican airspace. Do you think Europe might be next? Plot
the lat-lon given in SeeYou, draw your circle at FL250 (yeah, it would
be nice if they gave you 17,999) and if your path flies through that
line, your record might be toast.

The 277 nm radius at FL250 roughly covers San Francisco to the west, San
Diego to the south, and Salt Lake City to the east. I am not sure that
this information is terribly helpful for pilots (power as well as
soaring) who would like to know if they can believe what their GPS is
telling them.


They've got reasons for doing this, and in the really long view, I
believe that at least SOME of what they do actually protects my
ability (privilege) to fly and soar.

I am skeptical.



-Pete