Operation Guide 2894
� 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. 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.
About Barometric and Temperature Measurements
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 (flashing) 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 Not visible on measurement to be skipped, with the corresponding point on the display. 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
� 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.
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.
Current pressure greater than most recent measured pressure
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.
inHg values hPa values Barometric pressure differential pointer
Points to 9 o'clock for differentials outside the range of ±15 hPa/ ±0.44 inHg.
B
A
400
Pressure differential examples in the illustration are indicated in 10 hPa/0.3 inHg steps.
Current pressure less than most recent measured pressure
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�.
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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