Hi If you are at ICBM mid course altitudes, there are a *lot* of sat’s visible …. (at least compared to being on the ground).
Bob > On Aug 14, 2017, at 9:04 PM, jimlux <jim...@earthlink.net> wrote: > > On 8/14/17 5:12 PM, Bob kb8tq wrote: >> Hi >> >> At the time all this was figured out, the idea of the military needing nav >> at the poles >> was pretty far fetched. They accepted a bit of degradation in those regions >> as a result >> of this thinking. >> > > I don't know about that - I think it was more that it was "good enough" > everywhere, all the time. > > And polar nav, pre-GPS, was really tough - Omega had the same ionosphere > problems that GPS has, etc. > > I recall reading somewhere that one of the justifications for GPS was more > accurate midcourse guidance for ICBMs and those trajectories tend to be > polar. OTOH, in that application you also have IMU and (potentially) star > tracker data. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
