On Wednesday 23 January 2008, ground control picked up the following transmission from [EMAIL PROTECTED]: > Citeren Schmidt András <[EMAIL PROTECTED]>: > > 1. The map of a GPS map viewer application turns when you turn > > the machine so it is always aligned with the environment (this > > feature is included on some GPS tools.) > > A handheld GPS use the change in position measured by GPS to > determinate the direction of movement and is able to turn the display > in that direction. > > In fact, when the GPS is working like it should (IE very good with > the planned chipset) this is the best way to calculate the heading. > > Most important: it's already there in the phone.
Use case: I'm hiking in the mountains, heading 0 degrees (due north) at 5 km/h. I stop because there's something interesting off to the left, and I want to get its exact bearing (let's assume that's something like 283 degrees). So I rotate the GPS so "up" points at the object of interest. Results: Handheld with internal compass (for example, many Garmin units) can give me correct bearing to the object. Neo thinks bearing to the object is 0 degrees, since I'm not moving and you can't compute rotation about axis with GPS signal only. Failure mode: Stationary GPS is more subject to false readings due to reflection than moving GPS. Due to reflections, Neo might think I'm moving in some random direction, and give a bogus heading that appears reliable. _______________________________________________ OpenMoko community mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/community
