Trume TR-MB5, User Manual

Page: 73 / 121

Notes on Measuring Altitude
Mechanism for measuring altitude
The watch is a pressure altimeter that calculates altitude from the atmospheric pressure. By using the atmospheric
pressure at the current location, the relative altitude is calculated based on the relationship between the altitude and the
atmospheric pressure for International Standard Air (ISA) determined by the International Civil Aviation
Organization (ICAO).
1,013.25 1,013.25
hPa hPa
955 hPa 955 hPa
901 hPa 901 hPa
0 m 0 m
500 m 500 m
1,000 m 1,000 m
Relative altitude Relative altitude
Atmospheric pressure Atmospheric pressure
at the current location at the current location
1,013.25
hPa
955 hPa
901 hPa
0 m
500 m
1,000 m
Relative altitude
Atmospheric pressure
at the current location
Note:
The relative altitude is calculated from the atmospheric pressure, temperature, and the sea level pressure for the
international standard atmosphere at your current location.
❏
Atmospheric pressure at current location: Value measured with built-in pressure sensor
❏
Temperature at current location: 15 °C
❏
Sea level pressure: 1,013.25 hPa
If the atmospheric pressure changes due to weather conditions or the temperature at the measurement location, the
actual altitude and the relative altitude will not match. Therefore, the watch comes with a feature to calibrate the
deviation in the relative altitude.
The calibration value is added to the relative altitude and this altitude is displayed on the watch.
Displayed
altitude
(1,345 m)
Calibration
value
(25 m)
Relative
altitude
(1,320 m)
Example Example
About the altitude calibration feature
By setting the actual altitude at a location where you already know the altitude, the difference between the relative
altitude measured at that location and the actual altitude is stored in the watch as the correction value by the altitude
calibration feature.
MB52 (TR-MB5) User’s Guide
Altitude Measurements (ALT)
73