6）Mechanism Of Altitude Measurement - Seiko S833 Instructions Manual

(6) Mechanism of altitude measurement
・This watch estimates altitude from atmospheric pressure based on the relationship between altitude
and atmospheric pressure of the International Standard Atmosphere specified by the International Civil
Aviation Organization (ICAO).
・On the basis of the altitude calibrated at a place with a known altitude, the change in atmospheric pressure
measured is converted to the change in altitude, and the current altitude is calculated and displayed.
In the illustration below, the altitude is calibrated at a starting place of ascent etc. (200 m). Then,
the difference in altitude (400 m) is measured based on the atmospheric pressure change caused by
ascent, and is added to the calibrated value to display the altitude after ascent (600 m).
・Because change in atmospheric pressure is converted into altitude, altitude display may vary according
to atmospheric pressure change even if altitude measurement is made at the same place.
4
Hight above
sea level
Sea level
[CAUTION] Correct measurements cannot be made under the following conditions:
・When atmospheric pressure has changed significantly due to weather change;
・When temperature has changed significantly ; and
・When the watch has received a strong shock.
160
(Current altitude = Calibrated value + Measured value)
Signpost etc.
200m
600m
Measurement
（400ｍ）
Calibration