Stevens Hydraprobe
The Hydraprobe is a robust sensor for the Continuous and accurate measurement of soil moisture, temperature, and salinity.
- Robust and reliable, used to ground truth NASA satellite measurements
- Uses Coaxial Impedance Dielectric Reflectometry
- SDI-12, RS485, or Modbus output options
Stevens Hydraprobe
Features
Specifications
Case Studies
Resources
Features
With stainless steel tines, and a fully potted body, the Hydraprobe can be installed into all soil conditions, along with a robust cable to provide reliable connection to an IoT node or datalogger.
Specifications
Technical Specifications
| Measurement | Accuracy | Range | Resolution |
| Real dielectric permittivity (isolated) | ± 0.5% or ± 0.2 dielectric units | 1 to 80 where 1 = air, 80 = distilled water | 0.001 |
| Soil moisture for inorganic & mineral soil | ± 0.01 WFV for most soils ± 0.03 max for fine textured soils* | From completely dry to fully saturated (from 0% to 100% of saturation) | 0.001 |
| Bulk electrical conductivity | ± 2.0% or 0.02 S/m whichever is typically greater | Up to 0.5 to 1.0 S/m (5 to 10 dS/m)*** | 0.001 |
| Pore Water EC | N/A | must have > 0.10 wfv | 0.001 |
| Temperature | ± 0.3°C | -40°C to +75°C | 0.1°C |
| Inter-sensor variability | ± 0.012 WFV (θ m3 m-3) | n/a | n/a |
Electrical And Communication
| SDI-12 | RS-485 | Modbus | |
| Power supply | 9-16 VDC | 9-16 VDC | 9-16 VDC |
| Power consumption | 1 mA idle / 25 mA active | 2.5 mA idle / 25 mA active | 2.5 mA idle / 25 mA active |
| Cable | 3-wire: power, ground, data | 4-wire: power, ground, com+, com- | 4-wire: power, ground, A, B |
| Max. cable length | 60 m | 1,219 m Non-spliced: 304.8 m |
1,219 m Non-spliced: 304.8 m |
| Baud Rate | 1200 | 9600 | 1200-115200 9600 (default) |
| Communication protocol | SDI-12 Standard v. 1.2 | Custom or open spec | Modbus RTU |
Environmental
| Operating temperature range | -40°C to +75°C** |
| Storage temperature range | -40°C to +75°C |
| Water resistance | Tolerates continuous full immersion |
| Cable | 18 gauge (SDI-12) / 22 gauge (RS-485 and Modbus), UV resistant, direct burial |
| Vibration and shock resistance | Excellent; potted components in PVC housing and 304 grade stainless steel tines |
| * Accuracy may vary with some soil textures. ** Temperature Test Certificate from -40°C to 75°C available | |
Physical Dimensions
| Length | 124 mm | |
| Diameter | 42 mm | |
| Weight | 200 g Optional slim housing version available: 184 g |
|
| Cable weight | 80g/m | |
| Sensing volume | Length: 5.7 cm Cylindrical region: 3.0 cm diameter |
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Case Studies
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Resources
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