In message <[EMAIL PROTECTED]>, Rex writes: >On Wed, 03 Jan 2007 22:18:58 +0000, "Poul-Henning Kamp" ><[EMAIL PROTECTED]> wrote: > >>But for a band closer to the poles, from roughly 66 to 56 latitude, >>where we have no sats in half the plane and only occasionally pick >>up signals across the polar hole in the constellation, the ellipsoide >>actually isn't one, and its axis are not aligned with the coordinates >>we care for. > >You say, "the ellipsoide actually isn't one". I don't understand what >that might mean. Care to elaborate?
It is not an ellipsoide, it is some other weird ballon-animal shape. >To be more specific: Say at the equator, some GPS reciever determines >its lat/lon position within +- 3 meters but height +- 10 meters. If you >move the same receiver to Sweden, I assume the position accuracy gets a >bit worse. Does the height accuracy change by the same relative delta or >a different one. Well, Sweden is a bit unspecific because it has a large N/S span, but for Denmark, yes: the receiver will do a lot worse. In practice the vertical uncertainty in Denmark is 10 times the horizontal. >While we are at it, for a decent quality positional GPS receiver, what >fraction worse would be the typical height accuracy vs the position at >some mid latitude like north US or mid Europe? I would expect 3x to 5x worse, but that is just a qualified guess. -- 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
