# Silvanet Wildfire Sensor (Gen 2)

Dryad's Silvanet Wildfire Sensors are attached directly to trees using tree nails to detect environmental air quality within a radius of 80 m to 100 m (260 ft to 320 ft).

These solar-powered devices monitor the microclimate of the forest using an internal gas sensor along with a Machine Learning model to detect the presence of a smoldering fire within range of the sensor.

{% hint style="info" %}
**Smoldering fire**

A smoldering fire is defined to be a slow, flameless combustion of a biomass material such as forest floor material, branches, leaves, and so on.
{% endhint %}

<figure><img src="https://2403147378-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKqvtUjx9C2FEFg7nicAx%2Fuploads%2Ff1wToyqHS1nKhVSANP2Z%2Fsilvanet-sensor.jpg?alt=media&#x26;token=fe0bb56c-c4a7-4cff-8b17-c6af05f3eecd" alt="" width="375"><figcaption><p>Silvanet Wildfire Sensor</p></figcaption></figure>

## Key features

* **Attached directly to trees**\
  The Wildfire Sensor is designed with a sturdy loop that allows the device to be attached directly to trees using treenails (permanent attachment) or with garden wire (temporary use only).
* **Solar powered**\
  Energy is harvested by its built-in solar panel to allow the sensors to operate without the need of batteries. Energy is stored in supercapacitors which provide maintenance-free operation for 10 to 15 years. Storing energy is supercapacitors rather than batteries is a precaution against the device itself starting a fire. As an added benefit, this avoids the use of lithium and other toxic materials.
* **Bosch gas sensor**\
  The Wildfire Sensor includes a Bosch gas sensor that combines ultra-low-power Air Quality sensing with a precise gas sensing mode. Carbon monoxide, hydrogen and VOCs (Volatile Organic Compounds) are detected at the ppm level with built-in artificial intelligence (AI) to reliably detect a fire and avoid false positives.
* **LoRa/LoRaWAN connectivity**\
  Connectivity to the Silvanet Network (Mesh Gateways and Border Gateways) is provided by a LoRA-integrated radio to send and receive messages across a robust LoRaWAN-enabled mesh network. This network allows the sensors to be deployed across large forested environments or along linear areas such as rail lines, power lines and hiking paths.

## Delivered components

Wildfire Sensors are shipped in a box containing the following components:

* Ten Silvanet Wildfire Sensors
* Ten treenails and spacers (to keep the sensor away from the tree bark)

## Dimensions and weight

The dimensions of the Silvanet Wildfire Sensor are (LxWxH) 19 cm x 9.2 cm x 1.34 cm. It weighs 136 g.

<figure><img src="https://2403147378-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKqvtUjx9C2FEFg7nicAx%2Fuploads%2Fu9cmMacwWyn2NdQyPUWP%2Fsensor-dimensions.jpg?alt=media&#x26;token=501096c5-b751-4535-a546-4d2f8e65d705" alt="" width="563"><figcaption></figcaption></figure>

{% hint style="info" %}
**Ingres protection:** Ingress protection of the housing is IP67. This means the housing is completely protected against dust and is watertight.
{% endhint %}

## Environmental detection

The Silvanet Wildfire Sensor uses a Bosch gas sensor to monitor the microclimate of the forest. It is a low-energy hydrogen sensor that detects the presence of a smoldering fire over distances of up to 115 m.

The gas sensor detects the presence of CO (Carbon Monoxide), H2, (Hydrogen), VOCs (*Volatile Organic Compounds*) and VSCs (*Volatile Sulfur Compounds*). It detects VOC and VSC compounds at <20 ppm. It monitors the microclimate of the forest by providing measurements under the following conditions:

* Air pressure: 300hPa to 1100 hPa
* Humidity: 0% to 100%
* Temperature: -40°C to 85°C

## Energy harvesting

The Silvanet Wildfire Sensor includes a 60 mm x 60 mm solar cell on its front housing. It continuously generates energy during the daytime and recharges the device with sufficient power for the next 24 hours. After sunset, it begins to discharge until sunrise. After sunrise, it begins to recharge to 100% within about an hour.

{% hint style="info" %}
Sufficient ambient light is available in forests to provide sufficient light for the solar panel. Forests are never entirely dark during the day, even with a thick forest canopy.
{% endhint %}

Each day the solar panel harvests 7Ws in the constrained conditions of a forest.

As a precaution against the device itself starting a fire, the sensor stores its energy in supercapacitors rather than batteries.

The solar panel provides sufficient energy supply to support continuous operation over a 24 hr period while still having enough reserve power to support the powering of the gas sensor and to send a burst of messages when a smoldering fire is detected.

## Energy consumption

The Silvanet Wildfire Sensor has very low energy consumption which is provided by its built-in solar panel. The two key components that consume energy are the gas sensor and the LoRa radio. The gas sensor consumes \~3.9 mA in standard gas scan mode.

The Wildfire Sensor consumes the following energy:

```
0.7 mW per day (63 Joule per day)
```

This allows it to operate in a shaded location for \~6 hrs.

## Idle/active modes

Normally, the Silvanet Wildfire Sensor is in idle mode. Every 60 seconds it enter active mode to read the air quality. Then, every 2 hours it reads the environment, after which it sends a single packet to the Silvanet Cloud Platform via Mesh Gateways and Border Gateways.

These data packets contain normal (non-fire detection) environmental data which includes temperature, pressure and humidity internal values. These values are then displayed in the [Site Details section of the Site Management app](https://docs.dryad.app/dryad-documentation/silvanet-suite/silvanet-sma/site-view).

## Supercapacitor Energy Storage

The Silvanet Wildfire Sensor uses a set of supercapacitors to store energy for use by the radio, gas sensor and other components. It stores the energy for day-to-day tasks and has a reasonable amount of reserve power to operate the gas sensor and radio module in case a potential fire is detected. As supercapacitors have an expected lifespan of 10 years or more, the sensors are essentially maintenance free. This allows for an expected lifespan of the sensor between 10 and 15 years.

Supercapacitors have a high capacity but a small maximum voltage of 2.7 V so a series of capacitors are loaded to 4 V. Capacitors are fully charged to 5.2 V.

{% hint style="info" %}
**Why use supercapacitors:** Power supply is stored in supercapacitors rather than rechargeable batteries as they can potentially ignite. Consequently, using batteries would defeat the purpose of a wildfire detection system.
{% endhint %}

## Calibration

After deployment, the Wildfire Sensor requires 14 days to calibrate. Until then it can generate false-alarms. See [Sensor Calibration](https://docs.dryad.app/dryad-documentation/silvanet-deployment/deploy-sensors/sensor-calibration) for details.

***

{% hint style="info" %}
For deployment information, see [Deploy Wildfire Sensors](https://docs.dryad.app/dryad-documentation/silvanet-deployment/deploy-sensors).
{% endhint %}


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