DeLorme Earthmate GPS PN-30 User Manual page 70

To calibrate the compass
1. From the Satellite Page or the Compass Page,
go to MENU > Calibrate > Calibrate Compass.
OR
From any page, go to MENU > Device Setup >
Compass & Altimeter > Calibrate >
Calibrate Compass.
2. Follow the on-screen instructions to calibrate
the compass.
Altimeter Calibration
There are three options for calibrating the altimeter.
By default, the device is set to auto-calibrate the altimeter
using GPS elevation; however, manual calibration using
the known elevation or barometric pressure provides
greater accuracy.
Additional Information
68
Auto-calibration uses the average GPS elevation as a
basis for the barometric elevation. Adjustments are made
to take into account changes over time in the barometric
pressure, unrelated to changes in elevation. As the
elevation adjusts (typically in 2-3 minutes), "Calibrating"
displays in the bottom right corner of the Satellites Page.
If you are using the Elevation: Barometer info field on
any page, it displays a red exclamation point.
Note that the unit settings used in the Known Elevation
and Known Pressure fields are from the units set on
your device. To change the units, go to MENU >
Device Setup > Units > Pressure.