Archived posting to the Leica Users Group, 2007/02/25

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Subject: [Leica] Re: GPS
From: lrzeitlin at optonline.net (Lawrence Zeitlin)
Date: Sun Feb 25 14:59:42 2007
References: <200702251913.l1PJDDaC075644@server1.waverley.reid.org>

On Feb 25, 2007, at 2:13 PM, Marc wrote:

> The Chinese are building rockets to knock out the
> GPS satellites.  They tested one about a month
> ago, successfully.  No satellites, no GPS.
>
> And the Air Force still requires celestial
> navigation for aircrew -- and they do have
> precision chronometers and updated almanacs on
> their aircraft.  It would be more than a bit
> embarrassing if the Chinese took out the GPS grid
> and our bombers on the way to clobber the PRC had
> to stop to ask directions.

Marc,

Not to quibble too much but there are 24 GPS satellites in orbit. In  
addition there is a parallel and functional Russian system which uses  
different frequencies. US military equipment is capable of using the  
Russian system but most civilian gear is not. Only 3 satellites are  
needed to get a position fix. With 4 satellites you get altitude as  
well. On my $100 Garmin pocket sized GPS receiver I can get 8  
satellites at one time. For information on GPS check (http:// 
www.garmin.com/aboutGPS/)

It required a herculean effort for the Chinese to knock out one  
satellite. By the time two or three are disabled by hostile fire,  
ICBM missiles will be on the way. ICBMs, SAC bombers and missile  
carrying submarines don't rely solely on GPS anyway. They are guided  
by inertial navigation systems. We are safe until the Chinese find a  
way to disable gravity.

Larry Z


Replies: Reply from red735i at earthlink.net (Frank Filippone) ([Leica] Re: GPS)
Reply from lwwesson at gmail.com (leo wesson) ([Leica] Re: GPS)
Reply from marcsmall at comcast.net (Marc James Small) ([Leica] Re: GPS)