z coordinate off significantly

[GISADMIN5]

I installed get xyz extension on my handheld GPS unit. When I take points out in the field and load them into ArcMap it will bring up the x,y, and z information in the attributes but the z information is off anywhere from 50-80ft in elevation. Is there a reason for this? Can this be fixed? If so, how?

[BrettBlack]

Your GNSS unit is likely storing the ellipsoid height, not the orthometric height, which would give the difference in heights you describe.

ArcPad does not utilize a geoid model, just the ability to enter a constant geoid separation value in the GPS Preferences. What GNSS hardware are you utilizing. If a survey unit exporting NMEA data you could possibly enter the geoid model for orthometric values.