JDC Electronic SA Geos 11 - Manual (Page 16)

Select the lower block and display the measuring mode in
relation to relative pressure (it flashes), then keep pushing
the
button down. starts flashing on the upper block.
Release the button as soon as you enter the calibration
function (screen opposite). Use the
button to select which
way the setting is made ( increment, decrement), then set the value of
the pressure using the button. Pressing briefly on the button sets the
value in increments of 0.1 unit. Keep the button down to set increments
of one unit. Release then press the button again for a faster setting.
Repeat a second time the “release/keep down” operation to obtain
increments of 10 units and repeat a third time if you wish the setting to go
in 100-unit increments. Confirm and exit the calibration by keeping the
button down. The instrument goes back to the standard screen.
QFE height
In aeronautics, the QFE height corresponds to the difference between
the flight altitude and the altitude of the landing runway (the runway is
at 0 metre). It is also possible to use this function to measure any
height/depth, the height of a building, or the depth of an abyss for
instance.
The QFE value is calculated in relation to the atmospheric pressure of
the landing runway. When you are on the runway (at ground level), the
QFE is equal to the absolute pressure.
Two scenarios are offered to you when determining your height/depth:
1. You are at ground level (on the landing runway), in which case reset
the height to zero (see next Section). Your instrument will display
0.0m (0ft) when you are on the ground, then the value will
increase/decrease depending on whether you are ascending or
descending.
2. You are in flight (or in an elevated or deep position) and you have the
exact value of the QFE (pressure at ground level), in which case
calibrate the QFE pressure (see next Section), and your instrument
will then display your height. You will be back to 0.0m (0ft) when
you are on the ground.
Resetting the QFE value (at ground level) to zero
Select the lower block and display the measuring mode for the QFE
height (it flashes), then press the
button for 2 seconds.
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