[ntp:questions] GPS Weakness Could Sink Wireless

David Woolley david at ex.djwhome.demon.invalid
Thu Dec 12 14:48:35 UTC 2013


On 12/12/13 13:57, John Hasler wrote:

>
> 1) Better front-end selectivity
> 2) Better front-end dynamic range

I don't really see how these help against all but the crudest jammers, 
which transmit pure CW carriers or are off frequency.

> 3) Directional antennas for fixed sites such as cell towers
>

That might help a bit, if you rejected signals near the horizon (which 
are good for navigation, but may be bad for time).  However, to get full 
benefit from directionality, you'd need to run large phased arrays and 
steer their beams to track the individual satellites.  As most military 
users want the navigation data, they would  be better off with steerable 
beams.

The military also have the advantage of a broader, L2 signal, with a 
cryptographic chipping code.



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