Measuring Soil Moisture, Rainfall, Temperature and Humidity with SensorData Devices

By Alex Pope.

Sensing for Agriculture and agronomy

We have a history of working with Agricultural related projects and sensors every since we first added SDI-12 support to our original G52S Solar device. Our SensorData range grew out of these experiences with the aim of having a low-cost battery-powered device that will last a full season on a set of "off the shelf" batteries while powering both the various sensors and sending the data on the LPWAN network. They also have a GPS module to make sure that you know exactly where your sensors are - makes it really easy to visualize on a map!
We also have a great range of asset tracking devices on Sigfox, LoRaWAN, and 2G, 3G, LTE-CATM1, and NB-IoT.

Today we have variants of the SensorData using different LPWAN technology:
  1. SensorData LoRaWAN
  2. SensorData Sigfox
  3. there is a cellular (LTE-CATM1 and NB-IoT) version in design
We supply the devices to System Integrators - people that understand how the various sensors work and want to integrate their data with their own software platform.
We supply the SensorData protocol / payload formats so that you can parse the data out and integrate into whichever system you want.

Our devices work with a range of different SDI-12 sensors in the market, plus the SensorData is versatile enough to allow other sensors to be attached:
  • digital inputs: eg tipping rain gauge, gate open / close, water trough float switch levels
  • analog inputs: eg sensors that output an analog value, battery voltages
  • I2C: we have our own rugged temperature sensor and a humidity sensor, and there are numerous other options that use I2C


Our Setup

We have a SensorData Sigfox and a SensorData LoRaWAN in our office garden at our production facility in Johannesburg South Africa.
We have some interesting sensors attached:
  • Both devices have soil moisture probes from our partners at Aquacheck (the SensorData devices will talk to any SDI-12 sensors). The probes give the soil moisture, as a percentage, from 6 sensors within the probe. The probes are about 1m long and buried in the ground.
  • One has a Digital Matter Ambient Sensor. This measures temperature and relative humidity.
  • One has a tipping rain gauge attached to a digital input. The device counts the tips as pulses. Each pulse is 0.2mm of rain.
  • Both are getting a GPS fix every 24 hours.
They are all polling the sensors every 30 minutes. They read the sensor values, and transmit them on their respective networks.
 

SensorDemo Platform

To make life a bit easier to test and get going with the SensorData devices we have developed a very simple demo web application. We use this to demo the devices and it is an easy way to visualize the data coming from the devices.

Our SensorData devices are reporting to our SensorDemo platform: http://sensordemo.digitalmatter.com/. Check out the data for yourself at that link.
You will need to enter the Device Serial numbers to see the data:
Sigfox: 21F5B4 
LoRaWAN: 70B3D57050000574

The actual devices in this example are connecting on the following LPWAN networks:
Sigfox - Sqwidnet runs the local SA network
LoRaWAN - Comsol runs a public network in SA. We can see 6 gateways from the office. They use Actility as the network server.
 

Rainfall Data

Here is the pulse count on a graph - each pulse is a rain gauge tip. Each tip is 0.2mm. Jo'burg is dry now, so this is us putting some water through it.

Soil Moisture Data

The probe has 6 sensors reported as percentages:


Temperature and Humidity

Our office in Johannesburg has glorious autumn weather!