On 28/09/2010 01:35, Tobias Bieniek wrote: >> Does XCSoar use GPS height or barometric height for final glide and >> terrain clearance calculations? If it uses barometric height, does it >> (can it) compensate for changes in QNH pressure?
> Barometric height if available. Yes, we can compensate QNH settings. > After a short discussion we decided that we don't want to use the > barometric altitude that the B500 gives us due to the big error margin. > GPS altitude is more precise in this case. This means that the "H Baro" > infobox will stay at "---" when a B500 in connected. Sorry about that, > but I guess you also prefer no data over wrong data... I would think for final glide calcs, the best source of altitude data is (in order of accuracy): - Barometric altitude with QNH correction. (Can this be done automatically before take off?). - GPS altitude. - Barometric altitude without QNH correction. (Often out by 100's of feet). - Barometric "flight levels" rounded off to 100' as per the B500. I know the B500 uses barometric pressure and outside air temperature to provide corrections to TAS and vario readings. The "flight levels" data would be good enough for this purpose. I am not sure which altitude source it uses for its internal final glide calcs. I will have to find something else to display in that box with the "---" indication ;-) Thanks Ian ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Xcsoar-user mailing list Xcsoar-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xcsoar-user
