HOBOnet TEROS 21 - measures soil water potential and soil temperature

The HOBOnet system is a cost-effective and scalable option for web-enabled monitoring of field conditions for applications such as crop management, research, and greenhouse operations. And because it’s wireless, you can deploy a network of sensors to easily monitor multiple points with a single system, while avoiding the risk of long cables that can interfere with field operations and are potentially vulnerable to nearby lightning strikes.

Sensors are easily linked to the network, and data can be accessed through HOBOlink®, Onset's innovative cloud-based software platform.

Highlighted Features

Soil water potential and soil temperature measurements with one device
A more accurate picture of the amount of water available to plants than volumetric water content sensors
No calibration required for soil type or salinity
Long-lasting and maintenance-free with durable epoxy construction
Wide measurement range: -9 to -2000 kPa

Water Potential

Measurement Range | -2,000 to -9 kPa in soils up to 10 dS/m
Accuracy* | ±10% of reading + 2 kPa from -100 to -9 kPa
Resolution | 0.1 kPa
Dielectric Measurement Frequency | 70 MHz
Temperature
Measurement Range | -40 to 60°C (-40 to 140°F)
Accuracy | ±1°C (1.8°F)
Resolution | 0.1°C (0.18°F)
Wireless Mote
Operating Temperature Range | Sensor: -40 to 60°C (-40 to 140°F)
Mote: -25° to 60°C (-13° to 140°F) with rechargeable batteries
-40 to 70°C (-40 to 158°F) with lithium batteries
Radio Power | 12.6 mW (+11 dBm) non-adjustable
Transmission Range | Reliable connection to 457.2 m (1,500 ft) line of sight at 1.8 m (6 ft) high
Reliable connection to 609.6 m (2,000 ft) line of sight at 3 m (10 ft) high
Wireless Data Standard | IEEE 802.15.4
Radio Operating Frequencies | RXW-T21-900: 904–924 MHz
RXW-T21-868: 866.5 MHz
RXW-T21-921: 921 MHz
RXW-T21-922: 916–924 MHz
Modulation Employed | OQPSK (Offset Quadrature Phase Shift Keying)
Data Rate | Up to 250 kbps, non-adjustable
Duty Cycle | <1%
Maximum Number of Motes | 50 motes per one HOBOnet Wireless Sensor Network
Battery Type/
Power Source | Two AA 1.2V rechargeable NiMH batteries, powered by built-in solar panel or two AA 1.5 V lithium batteries for operating conditions of -40 to 70°C (-40 to 158°F)
Battery Life | With NiMH batteries: Typical 3–5 years when operated in the temperature range -20° to 40°C (-4°F to 104°F) and positioned toward the sun (see Mounting and Positioning the Mote), operation outside this range will reduce the battery service life
With lithium batteries: 1 year, typical use
Memory | 16 MB
Dimensions | Sensor: 9.6 x 3.5 x 1.5 cm (3.8 x 1.4 x 0.6 inches)
Sensor diameter: 3.2 cm (1.3 inches)
Cable length: 5 m (16.4 ft)
Mote: 16.2 x 8.59 x 4.14 cm (6.38 x 3.38 x 1.63 inches)
Weight | RXW-T21-xxx sensor and cable: 103 g (3.65 oz)
Mote: 223 g (7.87 oz)
Materials | Sensor: Vinyl body with polyurethane resin, stainless steel and ceramic sensor head
Cable: PVC, UV resistant and rodent repellent
Mote: PCPBT, silicone rubber seal
Environmental Rating | Mote: IP67, NEMA 6
Compliance Marks | RXW-T11-900
RXW-T11-868
RXW-T11-921
RXW-T11-922

• The sensor is not well calibrated beyond -100 kPa. For more information on using the sensor beyond this range, see Sensor Accuracy and Calibration.

** Temperature measurement, for applicable sensors, may not be accurate if sensor is not fully immersed in medium of interest, due to longer equilibration time.