The Medusa gamma Soil Moisture Sensor (gSMS) is a gamma-ray spectrometer that records stationary soil moisture content. The system is mainly designed for agricultural purposes. It can be used to derive the moisture content hourly and generate input for decision-making on adding water to the field.
The gSMS sensors use the same mDOS interface as all the other Medusa sensors, however there are three main differences.
1. The recording frequency of the sensors (spectrometer, GPS (optional), and PTH (optional) are configured at an interval of 60 seconds. All data recorded in this 60-second interval is summed and then stored for the spectrometer. The GPS and PTH data are averaged. This is the raw data stored on the sensor.
2. Data is summed for 15 minutes. Fifteen consecutive spectral readings are summed and synchronized to include a GPS and PTH reading. Each summed record is analyzed, and radionuclide concentrations are derived.
3. Summed data is uploaded. The fifteen-minute data, both raw and analyzed, are uploaded to the online Medusa portal. This portal can be accessed through the Medusa gSMS Portal and requires an account to access the data from the sensor. Data is uploaded at intervals of 3 hours.
The gSMS sensors are supplied with MDC-80x cables. When power is provided to the sensor, it will automatically turn on and start measuring. Access to the mDOS interface is the same as described on the Power and access page.
Power saving mode
Since the gSMS sensor has been developed for long-term outdoor usage it is equipped with a power saving function. After 70 minutes, it will turn off the LEDs, WiFi and uplink and will enter a hibernation mode where only data is recorded. To gain access to the sensors interface either the wired ethernet connection has to be used, or the sensor has to be restarted by powercycling the sensor.
The sensor is supplied with mounting clamps that can be used to attach the sensor to any pole that has a diameter of 50 mm. It is advised to mount the sensor with the connector facing down to ensure no moisture can seep through the hole in the front of the sensor where the PTH sensor is located.
The gSMS can monitor the battery's voltage to power the sensor. For this functionality, the sensing wires have to be attached directly to the positive and negative terminals of the battery. The sensor will read the voltage; the online portal will convert this to a percentage. See the pinout on the MDC-80x page for a specification of the wires used for battery monitoring.
The gSMS sensor will upload its fifteen-minute summed data to the online portal. The sensor tries to connect to this portal at an interval of 3 hours, starting at midnight, meaning it will try to connect at 3 AM, 6 AM, 9 AM, etc. Note that these times are GMT timestamps. If a connection can be established, all data on the sensor is uploaded to the portal. The data will remain stored on the sensor if no connection can be acquired.
The gSMS portal can be accessed by navigating to https://gsms.medusa-online.com/. Note that Medusa has to provide you with a account to which the detector is affiliated. Please contact Medusa if you want to use this service.
When the sensor is powered, a manual upload can be triggered, and data can be manually downloaded or deleted. This is done by using the gSMS block on the dashboard page of the interface.