I thought right now near same like you. I thought about the speed of satellites, But also right now i had another idea. With the signal form two satellites, and a known high over sea it should be possible to locate you on north or south of earth (only two possibilities). This would be nice if you go on a mountain and you are standing in front of a "signpost" (google translated) with meters over Sea value to get faster your first fix. A simple question "Are you in the North of earth?" would be enough to get only one possibility.
BTW: Agreed with Abdelrazak Younes (Mail entered while writing). ---------------------------------------- > Date: Thu, 30 Oct 2008 18:24:26 +0000 > From: [EMAIL PROTECTED] > To: community@lists.openmoko.org > Subject: Re: General GPS Question > > On Thu, 30 Oct 2008 18:09:47 +0000 > Matthias Camenzind wrote: > >> The satellites are moving around. So on a different time the position >> is different. > > There is a number called the "dilution of precision" which quantifies > the factor by which the accuracy of the GPS reading is reduced by the > positions of the satellites. For instance, if a reading were from three > satellites all positioned close to the zenith, the accuracy would be > reduced compared to how it would be if they were widely spaced apart. > > To see how this works, visualise how the GPS correlator calculates your > position by the intersection of spheres centered on the satellites, and > consider how this would be affected by an inexact measurement of the > radii of the spheres. Then consider how that would in turn be affected > by the positions of the satellites. > > While in theory your suggestion would work, the geometrical dilution of > precision would be HUGE, and so the measurement would overall be very > inaccurate. > > Tom > > -- > > Thomas White > Department of Materials Science and Metallurgy > Electron Microscopy Group (PhD Student) > University of Cambridge / Downing College > > _______________________________________________ > Openmoko community mailing list > community@lists.openmoko.org > http://lists.openmoko.org/mailman/listinfo/community _________________________________________________________________ Die neue Generation der Windows Live Services - jetzt downloaden! http://get.live.com _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
