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.
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, IT AUTOMATICALLY RUNS THE CALIBRATION PROCESS. DRYAD STRONGLY ADVISES LEAVING THE SENSORS ALONE ONCE THEY ARE DEPLOYED.
- Interactions include: touching the sensors, moving the sensors, being in proximity to the sensors, vehicles operating nearby. Essentially, it is bringing any source that could trigger a Phase 1 alert nearby the sensors such as cigarettes, machinery or even breathing on the sensor.
14 days are required for initial calibration.
After a Silvanet sensor has been deployed, the device's BME866 gas sensor 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
2-4 hrs are required for the sensor to return to normal values after gas scans.
After a sensor runs gas scans to test air quality (Phase 2 process), the sensor needs at least 2-4 hours 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.
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.
- 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).
- A sensor's gas detection range is approximately 80 to 100 meters, depending on the topology.
After the 14 day calibration period, the sensor is ready to detect fires.
Return to normal values after gas scans
If the gas sensor inside the Silvanet sensor performs gas scans as a result of triggering Phase 1 and Phase 2 alerts, 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 2 - 4 hours. 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.
Recalibrate after sensor interactions
If any interactions(1) 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.
- Sensors are very sensitive to any changes in the environment, including something as simple as touching them or moving them. Any interaction with a sensor triggers a Phase 1 alert and subsequent processes. See details below.
Typical sensor interactions
The 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. Any interactions with a sensor triggers a Phase 1 alert, which in turn triggers a Phase 2 process causing the sensor to perform a set of gas scans to determine if it has detected a fire.
Interacting with sensors includes:
Touching the sensors (hitting it, attempting to pull it off the tree)
Moving the sensors (swinging it around the treenail)
Being in proximity to the sensors (breathing on the sensor)
Exhaust from vehicles, especially diesel trucks, driving nearby the sensors
Other environmental sources that could trigger a Phase 1 alert such as cigarettes or machinery