Technical Note — Decagon VP-4 Temperature, Humidity and Pressure Sensor

Larry Pitts

Created: ; updated: .

The Tech Notes, OBS-USR-TN012-R1-LTR and OBS-USR-TN012-R1-A4, Decagon VP-4 Temperature, Humidity and Pressure Sensor, are available for printing and downloading.

The Decagon VP-4 is a microclimate sensor. Use the VP-4 sensor in microclimate and evapotranspiration studies. As part of the Observant Global system, the device can monitor:

  • air temperature
  • relative humidity
  • barometric pressure
  • vapor pressure

The VP-4 sensor comes with a 16 ft (5 m) cable. The Solo Sensor Accessory Pack (required to connect this sensor to the Solo) contains an additional 16 ft (5 m) cable and a junction box to join it to the Solo's existing cable. If appropriate, the resulting 32 ft (10 m) cable length may be trimmed to a more suitable length.


The VP-4 can be mounted to the same pole as the field unit. Cabling can be routed internally or externally. If external routing is preferred, ensure all cabling is contained within suitable UV stable conduit and secured to the pole and VP-4. A drain hole may be added to the lowest point of the conduit if there is a chance of moisture ingress. Please refer to the C3 or Solo User Guides for further cable routing options and information. 

The VP-4 is housed in a solar radiation shield to prevent the possibility of sunlight on the sensor causing false readings of elevated temperatures. The radiation shield is most effective when located where there is adequate ventilation.

Contact Observant if you wish to connect more than one such sensor to a single field unit.



Configuration and Usage 

Monitor Card



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