Mole: An underground soil moisture sensor linked to the cloud

Mole is based on a new sensor concept. The device consists of an underground LoRa transceiver which transmits radiowaves to a buried collector. From measurements of the electromagnetic loss, soil moisture estimates can be retrieved if soil type/texture is well known. The transceiver also embeds the communication capability: a concentrator, located onboard a UAV, will connect to the Internet. The cost of the solution is in the order of 10-30% wrt traditional approaches.
Technology validated in relevant environment.
Fidelity of breadboard technology increases significantly. The basic technological components are integrated with reasonably realistic supporting elements so they can be tested in a simulated environment. Examples include “high-fidelity” laboratory integration of components.
The communication protocol between the radio transceivers has been designed and implemented by IDESIO. It is a proprietary solution. The communication between the nodes, and with the drone gateway has been tested several times. Two PoCs have been already performed successfully with relevant stakeholders. Next steps will consist in testing the underground communication in a relevant environment and in quantifying the accuracy of soil moisture retrievals.

How does it work?

It is known that radiowaves (below 1 GHz) can propagate underground with a loss rate that depends on the soil type and moisture content. LoRa is a novel wireless technology for the IoT (Internet of Things) even much more robust to power losses than its predecessors. It is expected that LoRa waves can travel underground up to about 10-20 m. Two radio transceivers can exchange signals and make possible to provide indirect estimates of soil moisture content without the need for an ad hoc sensor. The soil moisture value is computed locally and then transmitted by the receiving node to a surface gateway. The latter will forward data to the Internet through, for example, a UAV repeater which is flying above the area.