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Re: GPS SA and Network Timing
From: Owen DeLong <owen () delong sj ca us>
Date: Wed, 26 Sep 2001 09:44:13 -0700


Robert E. Seastrom wrote:
"Hire, Ejay" <Ejay.Hire () Broadslate net> writes:


In our next episode of Militant dictator How-to, we'll show you how to
upgrade an antique scud missile to with a guidance system capable of 3-meter
accuracy for less than $500.00 per unit..  Stay tuned!


Somehow, I find it difficult to believe I'm dignifying this with a
response (much less a public one), but here goes:
Every commercial GPS unit that I have ever seen has a speed which, if
exceeded, will cause the unit to shut down (usually until
power-cycled).  It varies from unit to unit, but in every observed
case was substantially (several times) less than the speed of such
weaponry in flight.  Commercial units also have altitude limits, with
the same consequences for exceeding them.  Integrating an OEM GPS
module with existing avionics systems' targeting mechanism so it can
actually cause the missile to adjust its course is left as an exercise
to the local defense systems integrator.

I know my Garmin 195 functions in real life up to about 462 knotts.  I
don't know what it's shutdown point for real life is, as I haven't ever
been able to deploy it in an environment going faster than that.

I also know that in simulator mode, it is good to about 1000 knotts.

If I remember correctly, the SCUD is subsonic.  As such, I believe the
Garmin would handle it.

Resist the cycle of content-free posts to NANOG...

                                        ---Rob



Owen


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