CatEye Q3A - Manual (Page 62)

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Altitude measurement function
This unit measures the atmospheric pressure using a built-in pressure sensor and
determines the altitude. It estimates the altitude using the relation between the altitude
and pressure of ISO 2533 (Standard atmosphere), which was developed based on the
international standard atmosphere specified by the International Civil Aviation Orga-
nization (ICAO). Generally, a conventional pressure sensor is affected by temperature
and can cause a large margin of error, but this unit is temperature-compensated and
records 1 meter resolution. This unit is designed not to reflect the change in atmo-
spheric pressure to the altitude measurement except during a ride; therefore, the alti-
tude is less prone to weather changes, so while not in motion, value shift is minimal.
The altitude measurement may change temporarily when going outside from an indoor *
room. This is due to a rapid temperature change, and is not a malfunction. It will return
to the normal value after a while.
Sea level altitude correction
There are 2 ways to correct the sea level altitude with this unit. It is recommended to
correct the sea level altitude just before measurement, taking either following methods.
The sea level altitude correction screen is displayed in Setup mode in the * MENU, or is
shortcut to from the orthrometric height screen in Clock mode or in Sports mode.
• REF (sea level altitude correction): Enter the altitude at the current point.
Enter the actual value at the point where the sea level altitude is
well known, such as along the seashore, or at a sign on the moun-
tain, etc.
Press and hold * MODE1 and SSS, or MODE2 and SSS, simultaneously
on the setting screen to reset the corrected value to the default value (a
value according to ISO2533).
• HOME (home altitude setting): Apply the altitude set beforehand.
Preset the sea level altitude at your home in advance. Move to the ALT
HOME screen, and then return to Clock mode or Sports mode by
pressing MENU or the relevant shortcut. Then, the sea level altitude
changes to the preset value. You can start with the correct sea level
altitude by setting home altitude before starting from your home.
Timing for updating the sea level altitude, ascending
altitude, and temperature
The timing for updating the sea level altitude, ascending altitude, and temperature
data differs depending on whether the Sports mode is in measurement or is
stopped.
Condition Timing for updating
When the Sports mode is in measurement, and a speed sensor signal is received 5 seconds
When the Sports mode is stopped, or no speed sensor signal is received 5 minutes
This is also valid in Clock mode. *
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Basic knowledge of the altitude measurement