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Troubleshooting the Descent Mk1 Altimeter and Barometer

When experiencing incorrect readings from the altimeter or barometer sensors on the Descent Mk1, there are a few factors to consider that might be impacting these readings, as well as some steps that can help increase their accuracy.

Note: This article does not deal with depth readings of the Descent Mk1.



Understanding the Altimeter and Barometer

Select and option below to learn more.

Understanding How These Sensors WorkL'altimètre barométrique des montres de plein air utilise la pression barométrique pour déterminer les changements d'altitude, ainsi que les changements de pression causés par les conditions météorologiques. Les montres de plein air surveillent en permanence la pression barométrique pour déterminer quel mode est le plus approprié à un moment donné.

  • Auto (réglage par défaut) - La montre surveillera les changements et basculera automatiquement entre les modes altimètre ou baromètre.
  • Altimètre- La montre est verrouillée en mode altimètre et tous les changements de pression auront un impact sur la lecture de l'altitude. Ce mode est le meilleur pour les activités comprenant de nombreux changements d'altitude.
  • Baromètre - La montre est verrouillée en mode baromètre et tous les changements de pression seront pris en compte en raison des conditions météorologiques et des changements de pression ambiante. Ce mode est plus approprié pour les activités avec peu de changements d'altitude.

Note: Water in the barometric sensor port can cause the watch to read incorrect elevations. After doing water based activities, always allow the watch to air dry before troubleshooting the barometric altimeter. 


Factors that Impact Barometric Altimeter Measurements
  • Rapid changes in weather
    • The unit will resume accurate altimeter readings when weather conditions settle.
    • If experiencing rapidly changing weather, consider calibrating the sensor after conditions have settled.
  • Extended periods of time in a fixed location
    • For best accuracy, +/- 50 ft (~15 m), calibrate the pressure sensor to a known elevation on regular basis.
  • Moving to and from climate controlled or pressurized environments (indoors to outdoors)
    • Consider calibrating the sensor while you are outdoors. 
  • Debris blocking sensor port
    • Fluctuating barometer data or lower/higher than expected altitude may be caused by water, or debris in the sensor port (located between the Start/Stop and Back/Lap buttons).



Troubleshooting the Altimeter and Barometer

Manually Selecting a Barometer Mode

It is possible to manually lock the watch into the Altimeter mode if your activity involves changes in elevation or lock it into the Barometer mode if your activity is in a relatively flat area. Barometer mode is also useful if you are more interested in your watch notifying you of impending weather changes instead of elevation changes.

Selecting a Mode
  1. Hold UP to open the main menu
  2. Select Settings
  3. Select Sensors & Accessories
  4. Select Barometer
  5. Select Watch Mode
  6. Select a mode


Calibrating the Altimeter

To maintain accurate readings when using the altimeter and barometer on these watches, the sensors needs to be periodically calibrated. By default, the watch will calibrate automatically using the GPS elevation reading whenever a new activity is started. However, depending on the GPS signal strength, these elevations can be off by as much as +/- 400 feet.

The sensor can also be calibrated manually, providing an accuracy of within +/- 50 feet. To maintain this level of accuracy the watch will need to be periodically calibrated over time. For the best accuracy, it is recommended to do this hourly.

Altimeter Calibration
  1. Hold UP to open the main menu
  2. Select Settings
  3. Select Sensors & Accessories
  4. Select Altimeter
  5. Select Calibrate

After selecting Calibrate, the watch will ask to calibrate using a current known elevation or by using the GPS elevation reading, or toggle the Auto Calibrate setting on or off.

Note: After going for a dive, allow the watch to air dry before calibrating the altimeter. 



Other Factors to Consider

Some factors that might impact the function of the altimeter and barometer include: rapidly moving air entering the sensor port while participating in high speed activities; climate controlled buildings which can have slightly different pressure indoors compared to the ambient pressure outside; and soap, dirt, or salts from sweat which can clog the sensor port. 

Cleaning the Sensor Port

Debris blocking the sensor port will need to be rinsed free. The sensor port is located on the right side of the watch, between the Start/Stop and the Back/Lap.

  1. Run low pressure, warm water over the sensor port
  2. Gently remove any visible debris 
    IMPORTANT: Do not put any objects into the sensor port!
  3. Shake away excess water and allow to air dry
  4. Calibrate the altimeter