On Fri, 21 May 2010 19:40:18 -0400, Eric Perko wrote: > I don't see any notion of standard deviation of the fix in the gpsd > message format. That is _really_ important - am I just missing the > field in the gpsd message (I couldn't find any documentation on what > each field in that message actually means or what units it has, any > hints?). That's epe in GPSStatus (err in gps_common/GPSInfo [below]). Here's a cleaned-up version of the gpsd_client message, with the UTM fields and some descriptions added: http://bit.ly/8YqWrS Some things that I think need to be cleared up in that: What should we do with read/reported values other than the basic horizontal/vertical/altitude readings? GPSd reports ground speed, climb speed and direction (which I believe are all calculated from a series of position readings), magnetic XYZ, acceleration XYZ (from an accelerometer), gyro XYZ and temperature [as well as whether each of those is available]. IMO a standard GPS message should include GPS-derived speed, climb and track, but I'm not sure whether the others should be included. I'd like to have a shared GPS library that implements things like: * conversion from lat-long-alt to UTM * calculation of Xdop from the directional components * calculation of speed, climb and track from a series of lat-long-alt readings - Ken