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Operation Guide 2894
3
• In some areas, barometric pressure is expressed in millibars (mb) instead
of hectopascals (hPa). It really makes no difference, because 1hPa = 1mb.
• You can select either hectopascals (hPa) or inchesHg (inHg) as the display
unit for the measured barometric pressure, and Celsius (°C) or Fahrenheit
(°F) as the display unit for the measured temperature value. See “To select
the temperature, barometric pressure, and altitude units”.
• See “Barometer and Thermometer Precautions” for important precautions.
Barometric Pressure Graph
Barometric pressure indicates changes in the atmosphere. By monitoring
these changes you can predict the weather with reasonable accuracy.
This watch takes barometric pressure measurements automatically every two
hours (at the top of each even-numbered hour), regardless of its current
mode. Measurement results are used to produce barometric pressure graph
and barometric pressure differential pointer readings.
The barometric pressure graph shows readings of previous measurements for
up to 30 hours. The horizontal axis of the graph represents time, with each dot
standing for two hours. The rightmost dot represents the most recent reading.
The vertical axis of the graph represents barometric pressure, with each dot
standing for the relative difference between its reading and that of the dots
next to it. Each dot represents 1hPa.
The following shows how to interpret the data that appears on the barometric
pressure graph.
A rising graph generally means improving weather.
A falling graph generally means deteriorating weather.
Note that if there are sudden changes in weather or
temperature, the graph line of past measurements may run
off the top or bottom of the display. The entire graph will
become visible once barometric conditions stabilize.
The following conditions cause the barometric pressure
measurement to be skipped, with the corresponding point on
the barometric pressure graph being left blank.
• Barometric reading that is out of range (260 hPa/mb to 1,100 hPa/mb or
7.65 inHg to 32.45 inHg)
• Sensor malfunction
Not visible on
the display.
Barometric Pressure Differential Pointer
This pointer indicates the relative difference between the most recent
barometric pressure reading indicated on the barometric pressure graph, and
the current barometric pressure value displayed in the Barometer/
Thermometer Mode
• Pressure differential is indicated in the range of ±15 hPa, in 1-hPa units.
• The barometric pressure differential pointer is not displayed when the
displayed current barometric value is outside of the allowable measurement
range (260 to 1,100 hPa).
• Barometric pressure is calculated and displayed using hPa as the standard.
The barometric pressure differential can also be read in inHg units as
shown in the illustration.
Pressure differential
examples in the
illustration are indicated
in 10 hPa/0.3 inHg
steps.
Current pressure
less than most
recent measured
pressure
Points to 9 o'clock for
differentials outside
the range of ±15 hPa/
±0.44 inHg.
Current pressure
greater than most
recent measured
pressure
Barometric pressure
differential pointer
inHg values
hPa values
To turn display of the barometric pressure differential pointer on
and off
1. In the Barometer/Thermometer Mode, hold
down E until
SET
appears in the upper
display area.
2. Release E, and wait for four or five more
seconds until either
OFF
or the current
reference temperature value (if set) start to
flash. This is the setting screen.
3. Press D twice to display the pointer on/off
setting screen.
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About Barometric and Temperature Measurements
• Barometric pressure and temperature measurement operations are
performed as soon as you enter the Barometer/Thermometer Mode. After
that, barometric pressure and temperature measurements are taken every
five seconds.
• The ACT indicator flashes on the display while a measurement is in
progress.
• You can also perform a barometric pressure and temperature measurement
at any time by pressing B in the Barometer/Thermometer Mode.
Altimeter
The watch's altimeter uses a pressure sensor to detect current air pressure,
which is then used to estimate the current altitude based on ISA (International
Standard Atmosphere) preset values. You can also specify a reference
altitude, which the watch will use to calculate your current altitude based on
the value you specify. Altimeter functions also include storage of
measurement data in memory and an altitude alarm.
Important!
• This watch estimates altitude based on air pressure. This means that
altitude readings for the same location may vary if air pressure changes.
• The semiconductor pressure sensor used by the watch for altitude
measurements is also affected by temperature. When taking altitude
measurements, make sure the watch is not subjected to temperature
changes.
• To avoid the effect of sudden temperature changes during measurement,
keep the watch on your wrist in direct contact with your skin.
• Do not rely upon this watch for altitude measurements or perform button
operations while sky diving, hang gliding, or paragliding, while riding a
gyrocopter, glider, or any other aircraft, or while engaging in any other
activity where there is the chance of sudden altitude changes.
• Do not use this watch for measuring altitude in applications that demand
professional or industrial level precision.
• Remember that the air inside of a commercial aircraft is pressurized.
Because of this, the readings produced by this watch will not match the
altitude readings announced or indicated the flight crew.
How the Altimeter Measures Altitude
The altimeter can measure altitude based on its own preset values, or a
reference altitude specified by you.
When you measure altitude based on preset values
Data produced by the watch's barometric pressure sensor is converted to
approximate altitude based on ISA (International Standard Atmosphere)
conversion values stored in watch memory.
When you measure altitude using a reference altitude specified by you
After you specify a reference altitude, the watch uses that value to convert the
current measured barometric pressure value to altitude.
• To determine the height of a tall building, for
example, specify zero for the reference
altitude value while you are on the ground
floor. Then when you go to a higher floor, the
altitude displayed by the watch will indicate
the height from the ground floor. Note that
you may not be able to get a good reading if
the building is pressurized or air-conditioned.
• When mountain climbing, you can set the
reference value in accordance with a marker
along the way or altitude information from a
map. After that, the altitude readings
produced by the watch will be more accurate
than they would without a reference altitude.
400
B
A
4. Press C to toggle display of the barometric pressure differential pointer
on (
ON
displayed) and off (
OFF
displayed).
5. When the setting is the way you want, press E to exit the setting screen.
Displaying Your Current Altitude
You can use the procedure described in this section to display your current
altitude. If you leave the watch in the Altimeter Mode, it will regularly update
the displayed altitude value, and indicate reading-to-reading changes in the
altitude graph at the top of the display.
Important!
• The procedure in this section simply displays values indicating your current
altitude, without storing them in watch memory. For information about
recording altitude readings in watch memory, see “Saving Altitude Data”.