JDC Electronic SA Geos 11 - Manual (Page 15)

Select the lower block and display the measuring mode in
relation to altitude (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 altitude 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. Remark:
Setting the altitude is limited to the plausible range with regard to the
pressure currently being measured.
If you do not know your altitude, you can find it by calibrating the QNH
pressure, provided you know the latter exactly.
Resetting the maximum altitude and the QFE height
Select the lower block and display the measuring mode that you wish to
reset (it flashes), then press the
button for 2 seconds.
Selecting the unit of measurement in relation to pressure
The instrument features 2 units of measurement in relation to pressure,
with the choice between:
hPa (hectopascals, equivalent to the millibar) and inHg (inches of
Mercury).
To change the unit of measurement, select the lower block (it flashes),
then keep the
button down; when the desired unit appears, release the
button to confirm your choice.
Calibration of relative pressure (QNH).
The relative atmospheric pressure is a value that is calculated at sea
level on the basis of the local absolute pressure. As a result, it is taken
as a reference to assess the atmospheric conditions and the evolution
of weather throughout the country. This is the value shown on TV and
radio weather bulletins. It is also the aeronautical atmospheric pressure
(Q) at Nautical Height (NH) given to air pilots by the control tower in
order for them to know their exact altitude in the area.
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