"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