Ground altitude not zero in ArduPlane - GPS

 Hi All.   Switching over from working ArduCopter to try the APM 2.5 in a plane.  Set up everything yesterday and have found that the Altitude reported in the telemetry to the ground station is showing ~700m instead of 0.  This is pretty close to the ASL altitude of Las Vegas so trying to determine if I have something configured wrong, if reporting is wrong, or other?  I did cycle the APM several times and get the same results.  With ArduCopter I think it was correctly reported as 0 home / starting altitude.  

One other item of note, I struggled for a few hours trying to get the ArduPlane firmware loaded switching from ArduCopter.  It would get 90% through the 'reading hex' status bar and then report communication lost.  Found that this was caused by having the Mission planner in a connected state to the APM instead of disconnected (similar to using terminal mode).  Maybe add this as a note in the 'how to' sections for loading firmware. 

Todd

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  • With your permission I will ask this again: why do one need a GS for setting HOME ALT to ZERO for it to be reflected in his minimosd? if both ASL and AGL are on the telemetry stream, one would only agree that this should not be set by GS as GS is not always in use.

     

    Am I talking nonsense :-) ?

     

  • Same here: Can't get HOME ALTITUDE to show zero in MINIMOSD HOME_ALT. I can only wish to get a short and to the point answer how to show both above sea level alt as well as home at zero height. Running apm-mega 2.73, minimosd fw r620. minimosd is set to show these two: Altitude & Home Altitude - both showing same value which is the absolute above sea level height.

     

    Tnx in advance.

  • Developer

    Yes, it's normal in arduplane to use the altitude-above-sea-level instead of the altitude-above-home.  When I've discussed it with Tridge, the rationale for using above-sea-level is that planes tend to fly further and so terrain altitude changes becomes more important and the people would rather plug in a real altitude after looking at a terrain map (actually this can be done from within the mission planner i think).

  • I'm an arduplane user and just thought that was normal. I was always confused but figured I was missing something. I probably still am - all I know is that when I toggle the button for "set alt = 0" in mission planner I wonder what that affects in terms of home altitude, target alt, waypoints, etc. Documentation isn't clear. I'm sure someone knows.
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