In message <[EMAIL PROTECTED]>, Hal Murr ay writes: > >> A spherical error volume is a crude approximation, actually it is an >> ellipsoidal with as the height error is usually significantly larger >> than the other positional errors which also may have different rms >> errors. > >Why is the height error usually larger? Is that just geometry? Do I get >good height data if there is a satellite close to overhead?
Yes, it is geometry, and yes a sat overhead does help, but not as much as if you also had one underneath :-) The lack of signals from the lower half of the space around you means that no matter where you are, the height solution is never going to be more than half as good as the horizontal solutions. In the polar band I mentioned before, we only have sats in a quarter of the space around us and therefore we're even worse off. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
