Casio 2872 Altimeter, About Barometric and Temperature Measurements, Barometer and Thermometer Precautions, How the Altimeter Works, Altitude Indicator

Operation Guide 2872

About Barometric and Temperature Measurements

To take an altitude reading

•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 barometer automatically takes measurements every three hours (starting from midnight), regardless of what mode you are in. The results of these measurements are used for positioning indicators in the barometric pressure indicator display area.

•You can also perform a barometric pressure and temperature measurement at any time by pressing E in the Barometer/Thermometer Mode.

Barometer and Thermometer Precautions

• The pressure sensor built into this watch measures changes in air

pressure, which you can then apply to your own weather predictions. It is

not intended for use as a precision instrument in official weather prediction

or reporting applications.

Altitude indicator Temperature

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Altitude

Timekeeping Mode time

Pressing D in the Timekeeping Mode or in any of the other sensor modes enters the Altimeter Mode and automatically starts altitude measurement.

•It can take up to four or five seconds for the altitude reading to appear after you enter the Altimeter Mode.

•The Altimeter Mode screen also displays the current temperature. See “Barometer/ Thermometer” for more information.

•During the first three minutes after entering the

Altimeter Mode, theindicator flashes on the display and measurements are taken every five

seconds. After that, theindicator disappears as measurements are taken every two minutes.

• Sudden temperature changes can affect pressure sensor readings.

• Temperature measurements are affected by your body temperature (while

you are wearing the watch), direct sunlight, and moisture. To achieve a

more accurate temperature measurement, remove the watch from your

wrist, place it in a well ventilated location out of direct sunlight, and wipe all

moisture from the case. It takes approximately 20 to 30 minutes for the

case of the watch to reach the actual surrounding temperature.

Altimeter

A built-in altimeter uses a pressure sensor to detect the current air pressure, which is then used to estimate the current altitude. The watch is preprogrammed with ISA (International Standard Atmosphere) preset values, which are used to convert air pressure readings to altitude values. If you preset a reference altitude, the watch will also calculate the current relative altitude based on your preset value. Memory is also provided for the storage of altimeter data.

Important!

•This watch estimates altitude based on air pressure. This means that altitude readings for the same location may vary if air pressure changes.

•This watch employs a semiconductor pressure sensor, which is affected by temperature changes. Make sure that the watch is not being exposed to temperature changes while you are taking altitude measurements.

•To avoid the effect of sudden temperature changes on measurement, wear the watch so it is in direct contact with your wrist during measurement.

•Do not rely upon this watch for altitude measurements or perform button operations while engaging in sports where there are sudden altitude changes, while sky diving, hang gliding, or paragliding, or while riding a gyrocopter, glider, or any other aircraft.

•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 by the flight crew.

How the Altimeter Works

With the Preset Values (No Reference Altitude)

•The watch measures the air pressure at your current location and uses the built-in ISA values to convert it to the equivalent altitude.

•Pressing D causes the measurement operation to restart from the beginning of the cycle described above.

•Altitude is displayed in units of 5 meters (20 feet).

•The measurement range for altitude is –700 to 10,000 meters (–2,300 to 32,800 feet).

•The measured altitude may be a negative value in cases where there is a reference altitude value set or because of certain atmospheric conditions.

•The displayed altitude value changes to xxxxx meters (or feet) if a measured altitude falls outside the measurement range. The altitude value will be displayed again as soon as the measured altitude is within the allowable range.

•You can change the unit of measurement for the displayed altitude values between meters (m) and feet (ft). See “To change the altitude unit”.

Altitude Indicator

In the Altimeter Mode, the altitude indicator shows the current altitude reading in meters (m). As shown in the illustration below, the altitude indicator is divided into two zones: one for 0 to 999 meters, and one for 1000 to 10,000 meters.

Though you can specify either meters or feet for the watch’s altitude measurements, the altitude indicator always shows altitude in meters.

1000+ meter zone

0-999 meter zone

The above altitude indicator indicates an altitude of approximately 4,340 meters.

•The 0-999 meter zone starts from the 12 o'clock position (0 meters), and indicates altitudes in 20-meter units.

•The 1000+ meter zone indicates altitudes in 1000-meter units.

Setting a Reference Altitude

After you set a reference altitude, the watch adjusts its air-pressure-to-altitude conversion calculation accordingly. The altitude measurements produced by this watch are subject to error caused by changes in air pressure. Because of this, we recommend that you update the reference altitude whenever one is

With a Reference Altitude

•If you set a reference altitude, the watch uses that value when calculating altitude based on air pressure.

•To determine the height of a tall building, set the reference altitude to 0 on the ground floor. Note, however, 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 you do this, the altitude readings produced by the watch will be more accurate than they would be without a reference altitude.

400

available during your climb.

To set a reference altitude

								1. In the Altimeter Mode, hold down A until
								OFF (flashing) appears or until the display
		ll l l l l			ll			goes blank. This is the setting screen.
		ll l l l l			ll			• If the display goes blank, it means there is a
		l				l		• If the display goes blank, it means there is a
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	l						l	reference altitude value. Release A and
l							l	reference altitude value. Release A and
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	l					l	l	wait for four or five seconds until the value
		l				l		wait for four or five seconds until the value
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appears.

2. Press D (+) or B (–) to change the current reference altitude value by 5 meters (or 20 feet).

• You can set the reference altitude within the range of –10,000 to 10,000 meters (–32,800 to 32,800 feet).

• Pressing D and B at the same time returns to OFF(no reference altitude), so the watch performs air pressure to altitude conversions based on preset data only.

3. Press A to exit the setting screen.