On 10-01-21 13:42 , Bert Hyman wrote:
In Alan Browne
wrote:

On 10-01-21 11:05 , HIPAR wrote:
'Gen. Norton Schwartz, Air Force Chief of Staff, told a conference
organized by Tuft University’s Institute for Foreign Policy Analysis
that GPS signals are particularly vulnerable in time of war since
enemies know of the reliance U.S. forces place on its highly accurate
signal'.


The US military operates mostly C/A receivers for many of its
"non-critical" operations and systems as the cost and security
requirement of P/Y receivers and operations are too high. The ability
of a sophisticated enemy to effectively jam or spoof P/Y over a
significant area is pretty low - for an unsophisticated enemy it is
close to nil.

Since the "unsophisticated" enemy is often acting as a surrogate for,
and is being supplied by, a more sophisticated one, I wouldn't be so
sanguine.

What part of:

"The ability of a sophisticated enemy to effectively jam or spoof P/Y
over a significant area is pretty low"

gave you reading problems?


Besides, jamming isn't the only threat.

The only three threats are jamming, spoofing and attacking the
satellites and ground segment.

Do you understand why P/Y is so robust in the face of jamming or
spoofing? Do you understand the power requirements to do so over the
wider bandwidth of P/Y?

The entire point of my reply is that the US military has, despite its
access to P/Y receivers, gone whole hog into using C/A receivers due to
very low acquisition, integration and operating costs. Much due to the
complexity and security requirements of handling keys for P/Y receivers.
This is exacerbated by the use of contractors who, while often able to
get COMSEC for their organization and employees, still results in a
security headache where keys are required for receivers. C/A
conveniently bypasses this while raising a vulnerability. (And a small,
localized vulnerability at that).

As to attacking satellites, the origin of the attack would be very
clear, very fast and those countries able to do so are not likely to do
so unless WW III breaks out.

Attacking the ground segment, even if successful, would have 0 immediate
effect on navigation/timing quality. Backup ground segments would take
over immediately.n