CASIO PRL20SJ-8T
Owner's Manual

3. Press C to show the barometric pressure calibration display. At this time, �OFF� or the barometric pressure value should be flashing on the display. � The �OFF� indicator appears when the factory setting is being used for the calibration. 4. Each press of D increases the displayed barometric pressure by 1 hPa/ mb, while pressing B decreases it. Holding down either button changes the value at high speed. � Pressing B and D at the same time returns to the �OFF� display. 5. After calibrating the barometric pressure, press A to return to the Barometric Pressure/Temperature Display. � If you do not operate any button for a few minutes while the barometric pressure digits are flashing, the flashing stops and the watch goes back to the Barometric Pressure/Temperature Display.

4. After calibrating the temperature, press A to return to the Barometric Pressure/Temperature Display. � If you do not operate any button for a few minutes while the temperature digits are flashing, the flashing stops and the watch goes back to the Barometric Pressure/Temperature Display.

ALTIMETER FUNCTIONS
A built-in altimeter uses a pressure sensor to detect the current air pressure, which is then used to estimate the current altitude in accordance with ISA (International Standard Atmosphere) values for altitude and air pressure. If you preset a reference altitude, the watch will also calculate the current relative altitude based on your preset value. Altimeter functions also include data storage 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. � Sudden changes in the weather make it impossible to produce accurate altitude readings. � This watch employs a semiconductor pressure sensor, which is affected by temperature changes. When taking altitude measurements, be sure to do so while ensuring that the watch is not exposed to temperature changes. � Do not use this watch while participating in sports where there are sudden altitude changes. Also, do not use this watch for applications that demand professional or industrial level precision. This watch should not be used while engaging in the following activities: sky diving, hang gliding, paragliding, gyrocopter riding, glider riding, etc.

THERMOMETER FUNCTIONS
A built-in temperature sensor measures temperature and shows the measured value on the display. The thermometer can be calibrated. Important! 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 off all moisture from the case. It takes approximately 20 to 30 minutes for the case of the watch to reach the actual surrounding temperature.

About temperature measurements
Temperature measurements are taken automatically every five minutes, regardless of what mode the watch is in. Measured temperature values can be viewed in the Timekeeping or Altimeter Modes. Temperature measurements are taken every five seconds for the first three minutes after you display the Timekeeping Mode�s Barometric Pressure/Temperature display, or after you enter the Altimeter Mode. After that, temperature measurements are taken every five minutes. � Temperature measurement data can be recalled along with altitude measurement data.

Applications
When no reference altitude is preset:
� The watch produces approximate altitude readings.

When a reference altitude is preset:
� Before beginning the climb, set the reference altitude to 0 m at the foot of the mountain. This makes it possible to determine the difference in altitude between the reference point and your destination. � To determine the height of a tall building, set the reference altitude to 0 m on the ground floor. Note, however, that if the building is pressurized or air conditioned, you may not be able to get a good reading. � To determine the difference in altitude between your house and another location, set the reference altitude to 0 m at your house, and then check the reading when you arrive at the other location. � When mountain climbing, you can input the altitude from a marker as your reference altitude, which will then let you know your altitude as your climb proceeds. The following conditions will prevent you from obtaining accurate readings:

Understanding the temperature display
1. Use C to enter the Timekeeping Mode. 2. Press D to display the Barometric Pressure/Temperature Display.

A

B

Temperature
P

°C
hPa mb

C

D

( Barometric Pressure/Temperature Display ) � The display shows �� �.� °C� if a measured value falls outside the range of �20.0°C to 60.0°C. The normal display will return as soon as the temperature returns within the allowable range. � For details on viewing the temperature in the Altimeter Mode, see Understanding the altimeter display.

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When air pressure changes because of changes in the weather Extreme temperature changes When the watch itself is subjected to strong impact

Calibrating the temperature measurement
The temperature sensor of this watch is calibrated at the factory before shipment and further adjustment is normally not required. If noticeable error is found in the temperature readings produced by the watch, you can adjust it to correct the error. Important! Incorrectly calibrating the temperature measurement of this watch can result in incorrect readings. Carefully read the following before doing anything. � Compare the readings produced by the watch with those of another reliable, accurate thermometer. � If adjustment is required, remove the watch from your wrist and wait for 20 or 30 minutes to give the temperature of the watch time to stabilize.

About altitude measurements
There are two types of altitude measurements: those for displayed data (Altimeter Mode measurement) and those for memory data (memory measurements; See Memory measurements).

Altimeter Mode measurement
This type of measurement is performed only when the watch is in the Altimeter Mode. As soon as you enter the Altimeter Mode, measurements are taken every five seconds for the first three minutes. After that, measurements are taken every two minutes. The display unit for Altimeter Mode measurements is 5 m, and the display range is 0 to 6000 m. � The measured altitude may be a negative value in cases where there is a reference altitude value set or because of certain atmospheric conditions.

To calibrate the temperature
A B

°C
hPa mb

C

D

1. In the Timekeeping Mode, use D to display the barometric pressure and temperature. 2. Hold down A until the display clears. �OFF� or the temperature value should be flashing on the display. � The �OFF� indicator appears when the factory setting is being used for the calibration.

3. Each press of D increases the displayed temperature by 0.1°C while pressing B decreases it. Holding down either button changes the value at high speed. � Pressing B and D at the same time returns to the �OFF� display.

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