I'm curious as to the EXACT DoD restriction on civilian GPS units
regarding speed and altitude. I'm aware that the restrictions are for
speeds 1000kts AND altitudes 60,000 ft. However, I've heard
conflicting information that the 1000kts speed restriction only
applies to the horizontal direction (ex. a rocket going straight up at
1400kts and 70,000 ft might not be restricted).

This would make sense if the primary purpose of the units is to
prevent foreign governments or "groups of malcontent" from using
civilian GPS units in their own missile technology, which would
require a higher groundspeed velocity to strike other targets.

Thanks in advance for any insight!
Dave

David Harper wrote:
I'm curious as to the EXACT DoD restriction on civilian GPS units
regarding speed and altitude. I'm aware that the restrictions are for
speeds 1000kts AND altitudes 60,000 ft. However, I've heard
conflicting information that the 1000kts speed restriction only
applies to the horizontal direction (ex. a rocket going straight up at
1400kts and 70,000 ft might not be restricted).

This would make sense if the primary purpose of the units is to
prevent foreign governments or "groups of malcontent" from using
civilian GPS units in their own missile technology, which would
require a higher groundspeed velocity to strike other targets.

Thanks in advance for any insight!
Dave

The velocity restriction is 3D limiting use for military weapons.

Sam Wormley wrote:


The velocity restriction is 3D limiting use for military weapons.


Is this not easily gotten around by buying from sources not
under the control of the US government?

Does not one assume that our enemies have suitable
chips, and that the larger enemies have full use of the
military capabilities of the system, easily obtained by the
spies which we know pervade our military?

Doug McDonald

Doug McDonald wrote:
Sam Wormley wrote:


The velocity restriction is 3D limiting use for military weapons.



Is this not easily gotten around by buying from sources not
under the control of the US government?

Does not one assume that our enemies have suitable
chips, and that the larger enemies have full use of the
military capabilities of the system, easily obtained by the
spies which we know pervade our military?

Doug McDonald

And anybody can make their own GPS receivers... Selling those
capable chips away is not in the best interest of the US military.

Sam Wormley wrote:
\


Does not one assume that our enemies have suitable
chips, and that the larger enemies have full use of the
military capabilities of the system, easily obtained by the
spies which we know pervade our military?

Doug McDonald


And anybody can make their own GPS receivers... Selling those
capable chips away is not in the best interest of the US military.


You post is not parseable.

What I am saying is that any "significant" enemy such
as Russia, China, India, France, etc., perhaps Pakistan,
would have spies who would get either the plans or specs
or sample of military capable chips, which would then
be locally made.

Doug McDonald

Sam Wormley wrote in message news:nDg2d.59739$D%[email protected]_s51...

The velocity restriction is 3D limiting use for military weapons.

That's what I originally THOUGHT, but I contacted Garmin about the DoD
restriction about reaquisition time after exceeding the DoD limitation
on speed over 60k ft (and then slowing down). I was given the
following reply:

"The restriction (imposed by the DOD) of horizontal velocity over
60,000 feet
will take effect. There will be no position reporting during that
power
cycle."

I noted the word 'horizontal'. So I says:
"If I understand your answer correctly, I could be at 120,000ft with a
vertical velocity of 1100kts and a horizontal velocity of 200kts, and
the GPS unit would still output position data, and would be free of
the DoD restriction. Is this statement correct?"

And him says:
"Sir, as I asked the OEM sales Rep. As he described it, it was only
for
horizontal velocity. He did not indicate the same for vertical
velocity. I
will try to get in touch with him again. I do believe your statement
to be
correct. Let me make sure that I understood the restriction
correctly."

And after a day, I get confirmation. He spoketh:
"Sir, the answer is that vertical velocity does not apply. GPS main
function
is for horizontal velocity."

So I'm wondering if it is a common misconception that the velocity
restriction is 3D, or if the guy at Garmin was smoking crack...?


Dave

Just curious, did you ask how many angels can dance on the head of a pin?

Doug McDonald wrote:

You post is not parseable.

What I am saying is that any "significant" enemy such
as Russia, China, India, France, etc., perhaps Pakistan,

I wonder what makes you put France in this line of "significant" US
enemy's.

--
Joop van der Velden -

(Bad Idea) wrote in message . com...
Just curious, did you ask how many angels can dance on the head of a pin?

Seeing as how sounding rockets easily exceed 60,000 ft and 1000kts
(vertically, but not horizontally)... no.

Doug McDonald wrote in message ...
Sam Wormley wrote:


Does not one assume that our enemies have suitable
chips, and that the larger enemies have full use of the
military capabilities of the system, easily obtained by the
spies which we know pervade our military?

Doug McDonald


And anybody can make their own GPS receivers... Selling those
capable chips away is not in the best interest of the US military.


You post is not parseable.

Check you parser. It made sense to me.

What I am saying is that any "significant" enemy such
as Russia, China, India, France, etc., perhaps Pakistan,
would have spies who would get either the plans or specs
or sample of military capable chips, which would then
be locally made.

Doug McDonald

There's more to PPS than just having the chip/spec. You're reaching.


Regards,
Jon