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Sensor calibration

After a sensor has been deployed, it is ready to detect fires ONLY after the sensor has been calibrated.

Sensors require 14 days after deployment to be calibrated to the environment in which it has been deployed. During this time the sensor does not detect smoldering fires.

Other cases where sensors do not detect smoldering fires include after sensors run gas scans which require time to return to ready-state and after sensors being in any way interacted with which require at least 5 days to return to steady-state.

Warning

Interacting with deployed sensors (1) after they have been calibrated and "settled in" causes errors with sensor values and could also reset the sensor calibration. Furthermore, if a sensor is moved to a new location, the sensor automatically runs the calibration process. Dryad, therefore, strongly advises leaving the sensors alone once they are deployed.

  1. Interactions include: touching the sensors, moving the sensors, being in proximity to the sensors, vehicles operating nearby. Essentially, it is bringing any source nearby the sensors that could trigger a fire detection process.

Calibration periods (by type)

  • 14 days are required for initial calibration.

    After a Silvanet sensor has been deployed, the device's requires 14 days to calibrate, to "settle in" to the environment in which it has been deployed. After calibration, the gas sensor environmental readings have stabilized to an optimal level of sensitivity and ready to detect fires

  • 30-60 minutes are required for the sensor to return to normal values after gas scans.

    After a sensor runs gas scans to test air quality, the sensor needs no more than 30-60 minutes to be ready to detect fires.

  • 5 days are required for sensor recalibration after interactions with the sensor.

    Any interactions with the sensor cause a complete recalibration which takes at least 5 days for the sensor to be ready to detect fires.

Initial sensor calibration

When a sensor is delivered to the user, it is ready to be deployed, charged up and calibrated. No additional settings need to be made to the device.

Sensor calibration duration

Sensor calibration duration

Charge sensors - 1 day

After the sensor is installed on a tree and synced to the Silvanet Cloud using the Dryad Deployment app, 1 day is required to fully charge the supercapacitors. Once charged, the sensor’s solar panel continuously charges the supercapacitors(1), except of course during the night.

  1. Power supply is stored in supercapacitors rather than rechargeable batteries as rechargeable batteries can potentially ignite. Consequently, using batteries would defeat the purpose of a wildfire detection system.

Calibrate sensor - 14 days

After the sensor has been fully charged, the sensor begins a calibration process that takes 14 days. An algorithm running in the sensor automatically performs this calibration to adapt itself to the typical environment in which the sensor has been deployed. The gas sensor does this by running gas scans for several days and uses the results to build an initial model (an air quality value, an IAQ) of the environment within range of the sensor.(1) It then deploys this model and sets an auto-trigger configuration. This optimizes the sensor for fire detection and ensures any false positives are eliminated (sending fire alerts when there is no fire).

  1. A sensor's gas detection range is approximately 80 to 100 meters, depending on the topology.

Sensor ready

After the 14 day calibration period, the sensor is ready to detect fires.

Return to normal values after gas scans

If the Bosch gas sensor performs gas scans, the sensor needs to return to normal values (baseline IAQ) before it can perform another valid gas scan. However, the sensor may continue to run gas scans afterwards due to a continuous decline in air quality. As soon as the sensor is no longer running gas scans, the sensor begins to stabilize and return to normal values.

The stabilization period is at least 30-60 minutes. This time period allows for the dissipation of any smoke retained inside the sensor mesh (a small pot with a mesh cover used by the gas sensor). Ideally, the longer the wait, the more time the smoke has to dissipate. While the sensor is resetting, it does not measure any changes to the environment.

30-60 mminutes for sensor to return to normal values after gas scans

30-60 minutes for sensor to return to normal values after gas scans

Recalibrate after sensor interactions

If any interactions occurred with the sensor after deployment, 5 days are required to recalibrate the sensor. Interactions include being moved by an animal or human or even being touched or breathed upon. This interaction causes a repeat of the calibration process, but not a full 14 day recalibration. This is why attaching the sensor at least 3 meters above the forest floor is important. Furthermore, if the sensor is moved to a new location, it automatically runs the calibration process again.

5 days for sensor to recalibrate after interactions with sensor

5 days for sensor to recalibrate after interactions with sensor

Typical sensor interactions

The Bosch gas sensor in the Silvanet sensors is very sensitive to any changes in the environment including something as simple as touching them or moving them. Interactions with a sensor triggers the fire detection process. Interacting with sensors includes:

  • Touching the sensors, such as adjusting the angle of the sensor or attempting to pull it off from a tree

  • Moving the sensors to another tree or redeploying the sensor on the tree

  • Being in proximity to the sensors such as breathing on the sensor

  • Exhaust from vehicles (especially diesel trucks) near the sensors

  • Bringing any source of VOCs near the sensor such as cigarettes or machinery

Additional resources