Case study: When IoT means Internet of Trees

Author : Carsten Brinkschulte, CEO, Dryad Networks & Ingo Seehagen, Field Application Engineer Avnet Silica

01 March 2022

The Silvanet Mesh Gateway (L) connects multiple LoRa star networks into a daisy-chain with greater reach. The Silvanet Border Gateway (R) brokers communications between the mesh of LoRa networks & the internet.
The Silvanet Mesh Gateway (L) connects multiple LoRa star networks into a daisy-chain with greater reach. The Silvanet Border Gateway (R) brokers communications between the mesh of LoRa networks & the internet.

It’s increasingly important to spot forest fires quickly, because of the enormous damage they can do. California’s Dixie fire, for example, which began in mid-July 2021, consumed almost 4000km2 of forest by the end of September that year. And we’re facing more & more wildfires, with great swathes of the planet’s surface vulnerable to them. But sensing forest fires is hard, because forests are big & lack infrastructure...

This case study was originally featured as the cover story in the March 2022 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.

So, as Carsten Brinkschulte, CEO at environmental IoT start-up, Dryad Networks and Ingo Seehagen, Senior Field Application Engineer at semiconductor & electronics component distributor, Avnet Silica tell us here, the Berlin-based start-up is developing sensors and networking technology to address the issue…

Dryad’s Silvanet solution includes three pieces of sensing and communications hardware, RF networking technology that extends the reach of low-power radio wide area networks (LoRaWANs), and a cloud analytics platform.

The Wildfire Sensor is solar powered. It measures temperature, humidity, air pressure and key gas concentrations. It uses a low-power microcontroller to implement a LoRaWAN network, and to run machine learning (ML) algorithms that cut the amount of data it has to communicate to the cloud. The sensor is designed to work for up to 15 years without maintenance or a battery.

The Mesh Gateway uses a chipset from Semtech to implement the LoRaWAN protocol. LoRaWANs usually have a star architecture, which limits their reach. Dryad extends the LoRaWAN with proprietary RF technology that links its gateways into a mesh of star networks, which can reach more deeply into a forest.

A map of global vulnerability to wildfires
A map of global vulnerability to wildfires

Carsten Brinkschulte, Dryad CEO says: “The mesh is the magic of what we’re doing.”

Dryad’s solution also includes Border Gateways that link the mesh network to the internet, using 2G, GPRS or 4G cellular protocols – or even the SWARM satellite network.

The sensor nodes, mesh networks and gateways deliver pre-processed data to the Silvanet Cloud Platform, which handles the forest fire detection and health monitoring.

The engineering challenge

Implementing all this involves complex engineering challenges. These include issues such as firmware development for energy-constrained data analytics, IoT security, LoRaWAN implementation, standards compliance, creating proprietary RF links between mesh gateways, cloud platform development and more.

Brinkschulte continues: “A key challenge for us is the ultra-low power design of the sensor hardware. We need to work in an environment where we have very little energy input, yet we must do something complex. We need to scan for gas compositions and run ML software, it needs to work reliably, and we need to detect fires very quickly – so one challenge is to select the right ultra-low power components.

Wildfire detection
Wildfire detection

“At the same time,” he added, “price is key because we will need to put hundreds of thousands, if not millions, of Wildfire Sensors into a forest for the system to work, and the price of each component determines the system cost.”

Partnering for market insights

Semiconductor and electronics component distributor, Avnet Silica is helping Dryad explore its options. Dryad’s initial design uses an ultra-low power STM 32 WL microcontroller, because it integrates a LoRaWAN radio and can analyse sensor data on-chip.

“We have to do that at the sensor, because we do not have enough bandwidth to transmit all of the sensor data to the cloud,” said Brinkschulte. But Dryad is open to other options, too.

“We really appreciate the really competent discussions we’re having with Avnet Silica,” he said. “They are bringing a lot of ideas which may optimise the performance of the system.”

The network architecture of Silvanet
The network architecture of Silvanet

Dryad is trying to reduce the hardware’s power and costs, “…and that’s a constant discussion that we’re having on which chipsets to use. We need to have it really low cost and ultra-low power, because if you halve the power, you can halve the size of the solar panel, which is one of the key price-driving factors.”

Dryad is also using super-capacitors to store energy from the solar cells.

“If you can reduce power consumption, you can reduce the capacity of the super-capacitors, which would also drive down the price,” said Brinkschulte. “Selecting the right components is definitely where Avnet Silica has the competency to advise us.”

Avnet Silica is also helping Dryad understand supply constraints for various parts.

“When you try to roll out your network and the quantity goes up, you need to have the microcontrollers and other parts delivered on time,” said Ingo Seehagen, Senior Field Application Engineer at Avnet Silica.

Silvanet Device Family
Silvanet Device Family

Dryad’s vision

According to Brinkschulte, wildfire sensing is just the first application of Dryad’s technology.

“This is a generic IoT communications infrastructure for the forest,” he said. “There are tonnes of applications once our infrastructure is in place, including soil moisture, tree growth, sap flow, anti-logging alerts using sound detection, and emergency communications.”

Dryad continues to rely on Avnet Silica as it ramps production to hundreds of units to populate 10 pilot projects around the world.

Brinkschulte said: “What is impressive is the amount of attention that we are getting and the professional support that we are receiving. Avnet Silica’s support is an investment in our future and that’s very impressive from our perspective.”

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