'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'.

http://www.dodbuzz.com/2010/01/20/ba...-gps-af-chief/

--- CHAS

On Thu, 21 Jan 2010 08:05:42 -0800 (PST), 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'.

http://www.dodbuzz.com/2010/01/20/ba...-gps-af-chief/

I don't think LORAN's gonna fix it for the Air Force either.

--
The Write Many, Read Never drive. For those people that don't know
their system has a /dev/null already.
-- Rik Steenwinkel, singing the praises of 8mm Exabytes

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.

So, the military should use more P/Y receivers for "non critical"
systems and operations, not C/A. C/A is much easier to jam, even spoof,
but detecting the jammers/spoofers is pretty easy too and they can have
a missile sent up their patooties in short order.

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.

Besides, jamming isn't the only threat.

--
Bert Hyman St. Paul, MN

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

A simple to construct wide band noise jammer might be effective to
defeat a nearby receiver but I'd bet someone knowledgeable with signal/
information theory could devise a more effective jammer that attacks
the spectral essence of the of the GPS signal, perhaps based upon the
chip rate.

Check out:

http://www.navcen.uscg.gov/gps/gpsno...terference.pdf

Notice some of the 'testing' might render GPS unusable at a radius of
a hundred plus miles. They do not specify the nature of the jammer for
these tests. It might be terrestrial, airborne or, perhaps, even
spaceborne from a high powered spot beam satellite. But, jamming to
ranges within 200 miles of a specified location requires either a
super power standoff-barrage jammer or a device that attacks inner
workings of the signal.

I worked with an 'Old Crow' who could foil any signal/waveform
structure.

--- *CHAS

On 10-01-21 15:07 , HIPAR wrote:
A simple to construct wide band noise jammer might be effective to
defeat a nearby receiver but I'd bet someone knowledgeable with signal/
information theory could devise a more effective jammer that attacks
the spectral essence of the of the GPS signal, perhaps based upon the
chip rate.

Check out:

http://www.navcen.uscg.gov/gps/gpsno...terference.pdf

Dead link both above and at the USCG site. Remove the /GPS_Inter ...
for the intro text.


Notice some of the 'testing' might render GPS unusable at a radius of
a hundred plus miles. They do not specify the nature of the jammer for
these tests. It might be terrestrial, airborne or, perhaps, even
spaceborne from a high powered spot beam satellite. But, jamming to
ranges within 200 miles of a specified location requires either a
super power standoff-barrage jammer or a device that attacks inner
workings of the signal.

I worked with an 'Old Crow' who could foil any signal/waveform
structure.

The problem with jamming GPS is bandwidth and area (power). The more
effective that you want to be, the more power is needed. This is part
of the reason why the P/Y code is spread out over 10x the bandwidth of
the C/A code - to make it more difficult (expensive in power) to jam at
a standoff distance. Any old crow should be able to tell you the
tradeoffs while resisting the urge to tell 'war stories'.

Some military aircraft and ships also use CRPA antennas which, upon jam
detection, can place a null in the direction of the jamming source
effectively eliminating the jamming to that receiver. Likewise spoofers.

As I said earlier, I would bet the General's comments reflect more the
broad use of C/A by the military in various support and communications
functions, as well as by contractors than by specific threat to true
military equipment using keyed P/Y receivers.

On 10-01-21 18:25 , Alan Browne wrote:
On 10-01-21 15:07 , HIPAR wrote:
A simple to construct wide band noise jammer might be effective to
defeat a nearby receiver but I'd bet someone knowledgeable with signal/
information theory could devise a more effective jammer that attacks
the spectral essence of the of the GPS signal, perhaps based upon the
chip rate.

Check out:

http://www.navcen.uscg.gov/gps/gpsno...terference.pdf

Dead link both above and at the USCG site. Remove the /GPS_Inter ... for
the intro text.


Notice some of the 'testing' might render GPS unusable at a radius of
a hundred plus miles. They do not specify the nature of the jammer for
these tests. It might be terrestrial, airborne or, perhaps, even
spaceborne from a high powered spot beam satellite. But, jamming to
ranges within 200 miles of a specified location requires either a
super power standoff-barrage jammer or a device that attacks inner
workings of the signal.

I worked with an 'Old Crow' who could foil any signal/waveform
structure.

The problem with jamming GPS is bandwidth and area (power). The more
effective that you want to be, the more power is needed. This is part of
the reason why the P/Y code is spread out over 10x the bandwidth of the

Oops - 20x the bandwidth as P/Y receivers use L1 and L2. You would have
to jam across both to deny PVT to a P/Y receiver.

C/A code - to make it more difficult (expensive in power) to jam at a
standoff distance. Any old crow should be able to tell you the tradeoffs
while resisting the urge to tell 'war stories'.

Some military aircraft and ships also use CRPA antennas which, upon jam
detection, can place a null in the direction of the jamming source
effectively eliminating the jamming to that receiver. Likewise spoofers.

As I said earlier, I would bet the General's comments reflect more the
broad use of C/A by the military in various support and communications
functions, as well as by contractors than by specific threat to true
military equipment using keyed P/Y receivers.

Alan Browne ) wrote:
with editing...
: Besides, jamming isn't the only threat.

: The only three threats are jamming, spoofing and attacking the=20
: satellites and ground segment.

Then there are four.
The greatest threat with sophisticated equipment is that it
come into the enemies' possession.

Regards. RAF

On 31 Jan 2010 12:32:17 -0700, Roy A. Fletcher wrote:

Alan Browne ) wrote:
with editing...
: Besides, jamming isn't the only threat.

: The only three threats are jamming, spoofing and attacking the=20
: satellites and ground segment.

Then there are four.
The greatest threat with sophisticated equipment is that it
come into the enemies' possession.

Regards. RAF

And a fifth danger: as with all military equipment we'll allow the
contractors to sell it to them for a profit. Then taxpayers will be forced
to fund the next round of technology.
--
Mike Russell - http://www.curvemeister.com