"Steve Firth" wrote in message
.. .
Wayne.B wrote:

On Sat, 17 Jul 2010 11:22:42 +0100, Boo
wrote:

I understood that "selective availability mk2" (or whatever it's known
as) is
the capability to selectively deny access to GPS signals over limited
geographical areas, maybe this has some bearing ?

It would be limited mostly to "line of sight" distances, and Cuba is
not known for being a technical power house with unlimited financial
resources.

You and the previous poster are giving the appearance of not knowing
what selective availability (SA) is. SA is a feature of GPS that permits
the civilian positioning feature of GPS to be subject to a psuedo random
position error. This error affects all GPS units within a particular
area and is only "line of sight" in that it affects all units within
line of sight of particular satellites, so the area can be huge or
indeed global as it was until 2000 when the feature was turned off. Your
comment makes it appear that you are confused between jamming and SA.

At present GPS is denied in particular areas using other means which are
less susceptible to correction. SA could be defeated by the use of dGPS
and the US have stated it will never be turned back on again.

You seem to have been attempting to claim that GPS cannot be jammed or
denied, in this you are wrong. The methods used are not however public
knowledge although from time to time NOTAMS and similar publications
will indicate in which areas GPS is being denied for trials.


Exactly right Steve,
Washington DC and Fort Hood in upstate NY are just
two places I have personal knowlege of where GPS is
munged for security purposes.
Regards,
JR

On Sat, 17 Jul 2010 20:25:22 -0400, "JR" wrote
(with clarity & insight):

Washington DC and Fort Hood in upstate NY are just
two places I have personal knowlege of where GPS is
munged for security purposes.
Regards,
JR

I've been using plain ol' GPS devices in & around DC for years with no
issues. What am I missing?

Wayne R. wrote:

On Sat, 17 Jul 2010 20:25:22 -0400, "JR" wrote
(with clarity & insight):

Washington DC and Fort Hood in upstate NY are just
two places I have personal knowlege of where GPS is
munged for security purposes.
Regards,
JR

I've been using plain ol' GPS devices in & around DC for years with no
issues. What am I missing?

a) A brain.
b) A clue.

Not necessarily in that order.

"Wayne R." wrote in message
...
On Sat, 17 Jul 2010 20:25:22 -0400, "JR" wrote
(with clarity & insight):

Washington DC and Fort Hood in upstate NY are just
two places I have personal knowlege of where GPS is
munged for security purposes.
Regards,
JR

I've been using plain ol' GPS devices in & around DC for years with no
issues. What am I missing?

I have a Ram Mount in my GMC Yukon we use as a travel car, On this mount I
place a laptop and more recently
a Netbook computer on the Ram and use MS Streets & Trips with a USB "puck"
as the
GPS receiver/antenna. On the many trips south from Pa to Fla as I use the DC
Beltway and with the GPS in
tracking mode it becomes "lost". The 1st time this happened I thought it
was the unit itself and told it to
recalculate the route from my current location. It couldnt determine my
current location until we were merging
back onto I-95. It simply didn't know where it was. Weather was not a factor
(clear skies) nor was it
a lack of GPS signal (it still showed as tracking 8 sats). This "problem" is
repeatable 100% of the time
on various trips thru the area.

Similarly, During a trip for my daughters wedding and subsequent trips to Ft
Hood, when approching
base housing the same thing happens. Every time.
When I asked my son-in-law about it he would only say "Yeah, kinda neat
huh?"
In conversations with my youngest daughters soon-to-be-husband who was home
on leave from
Jihadistan, he indicated that even there a few sites are so protected.

Now, in northern NJ and northern Wi there are coverage gaps where the GPS
can't
resolve it's location, but these are a different situation as the unit tells
me it can't find itself and why.
Not so with the DC & Ft. Hood issues.
Regards,
JR

JR wrote:

Now, in northern NJ and northern Wi there are coverage gaps where the GPS
can't resolve it's location, but these are a different situation as the
unit tells me it can't find itself and why. Not so with the DC & Ft. Hood
issues.

Wayne is refusing to admit that jamming occurs, however here's a typical
British NOTAM from 06-June-2007:

"GPS SIGNAL JAMMING TRIALS. JAMMER LOCATED WITHIN 0.5 [nautical miles]
OF 5016N 00516W (PORTREATH, CORNWALL). ACTIVITY MAY AFFECT AIRCRAFT
WITHIN 6NM RADIUS FLYING BELOW FL300 [30,000 feet] ... DURING TRIAL
PERIODS, GPS RECEIVERS MAY SUFFER INTERMITTENT/TOTAL FAILURE, OR GIVE
INCORRECT POSITION INFO ..."

Note the last part, it's not just jamming as in drowing out the signal
with noise, it's more subtle than that the jamming may involve feeding
the GPS incorrect position info. This, in the World According to Wayne,
cannot happen and any claim that it does happen is some sort of appeal
to irrationality.

On Sun, 18 Jul 2010 15:13:57 +0100, (Steve Firth)
wrote:

any claim that it does happen is some sort of appeal
to irrationality.

Steve, with all due respect I think you've got all the claims to
irrationality pretty well covered.

Cheers.

Wayne.B wrote:

On Sun, 18 Jul 2010 15:13:57 +0100, (Steve Firth)
wrote:

any claim that it does happen is some sort of appeal
to irrationality.

Steve, with all due respect I think you've got all the claims to
irrationality pretty well covered.

yawn

Anything to contribute other than vacuous abuse "Wayne"? No, that's
obvious.

On Sun, 18 Jul 2010 09:56:35 -0400, "JR" wrote
(with clarity & insight):

"Wayne R." wrote in message
.. .
On Sat, 17 Jul 2010 20:25:22 -0400, "JR" wrote
(with clarity & insight):

Washington DC and Fort Hood in upstate NY are just
two places I have personal knowlege of where GPS is
munged for security purposes.
Regards,
JR

I've been using plain ol' GPS devices in & around DC for years with no
issues. What am I missing?

I have a Ram Mount in my GMC Yukon we use as a travel car, On this
mount I place a laptop and more recentlya Netbook computer on the Ram
and use MS Streets & Trips with a USB "puck" as the GPS
receiver/antenna. On the many trips south from Pa to Fla as I use the
DC Beltway and with the GPS in tracking mode it becomes "lost". The
1st time this happened I thought it was the unit itself and told it
to recalculate the route from my current location. It couldnt
determine my current location until we were merging back onto I-95.
It simply didn't know where it was. Weather was not a factor (clear
skies) nor was it a lack of GPS signal (it still showed as tracking 8 sats).
This "problem" is repeatable 100% of the time on various trips thru
the area.

Similarly, During a trip for my daughters wedding and subsequent trips to Ft
Hood, when approching base housing the same thing happens. Every time.
When I asked my son-in-law about it he would only say "Yeah, kinda neat
huh?"
In conversations with my youngest daughters soon-to-be-husband who was
home on leave from Jihadistan, he indicated that even there a few sites are
so protected.

Now, in northern NJ and northern Wi there are coverage gaps where the GPS
can't resolve it's location, but these are a different situation as the unit tells
me it can't find itself and why.
Not so with the DC & Ft. Hood issues.
Regards,
JR

I've found places where I've seen repeatable problems with one type of
receiver but not another. (Sometimes problems come & go, and in those
circumstances I've attributed it to constellation/reflection
variations.)

I've spent a lot of time near the White House, Pentagon, Ft. Meade,
Langley, etc., in DC without any loss of lock - some of the places
that seem most likely to have constant jamming?

When your receiver "tells me it can't find itself and why", what does
it say?

"Wayne R." wrote in message
...
On Sun, 18 Jul 2010 09:56:35 -0400, "JR" wrote
(with clarity & insight):

"Wayne R." wrote in message
. ..
On Sat, 17 Jul 2010 20:25:22 -0400, "JR" wrote
(with clarity & insight):

Washington DC and Fort Hood in upstate NY are just
two places I have personal knowlege of where GPS is
munged for security purposes.
Regards,
JR

I've been using plain ol' GPS devices in & around DC for years with no
issues. What am I missing?

I have a Ram Mount in my GMC Yukon we use as a travel car, On this
mount I place a laptop and more recentlya Netbook computer on the Ram
and use MS Streets & Trips with a USB "puck" as the GPS
receiver/antenna. On the many trips south from Pa to Fla as I use the
DC Beltway and with the GPS in tracking mode it becomes "lost". The
1st time this happened I thought it was the unit itself and told it
to recalculate the route from my current location. It couldnt
determine my current location until we were merging back onto I-95.
It simply didn't know where it was. Weather was not a factor (clear
skies) nor was it a lack of GPS signal (it still showed as tracking 8
sats).
This "problem" is repeatable 100% of the time on various trips thru
the area.

Similarly, During a trip for my daughters wedding and subsequent trips to
Ft
Hood, when approching base housing the same thing happens. Every time.
When I asked my son-in-law about it he would only say "Yeah, kinda neat
huh?"
In conversations with my youngest daughters soon-to-be-husband who was
home on leave from Jihadistan, he indicated that even there a few sites
are
so protected.

Now, in northern NJ and northern Wi there are coverage gaps where the GPS
can't resolve it's location, but these are a different situation as the
unit tells
me it can't find itself and why.
Not so with the DC & Ft. Hood issues.
Regards,
JR

I've found places where I've seen repeatable problems with one type of
receiver but not another. (Sometimes problems come & go, and in those
circumstances I've attributed it to constellation/reflection
variations.)

I've spent a lot of time near the White House, Pentagon, Ft. Meade,
Langley, etc., in DC without any loss of lock - some of the places
that seem most likely to have constant jamming?

When your receiver "tells me it can't find itself and why", what does
it say?

Wayne, the receiver will tell me GPS signal not available (usually weather
related), or will indicate not enough Sats
to resolve position. And it will display how many sats it "sees".

With the DC and Ft Hood issues it says nothing.
It just doesn't work.

Regards,
JR