[time-nuts] GPS backup for the stationary time and frequencyuser

[Matthew Kaufman]

  On 10/8/2010 10:44 AM, J. Forster wrote:
> KISS. This seems like a lot of work for not particularily good results.

I think the point is that the results are amazingly better than the 
alternative if the medium-orbit GPS sats are all destroyed and/or 
there's jamming coming from all over the sky.

What bothers me is that I haven't figured out yet how the WAAS satellite 
configuration itself isn't usable as a wide-area GPS jammer. It is just 
a bent-pipe transponder down from 6 GHz or so to L1, so if you can 
overpower the uplink with spoofed data that interferes with reception of 
the other satellites *and* jam the C&C channels that would be used to 
shut the transponder off, you're able to jam a whole continent at once.

I'm sure this must have been considered before deployment, but I can't 
find any references to the countermeasure(s).

Matthew Kaufman