Archived posting to the Leica Users Group, 2007/02/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Larry, Couldn't figure out which model was 100$... Leo On 2/25/07, Lawrence Zeitlin <lrzeitlin@optonline.net> wrote: > > > 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 > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >