RXW-T21-xxx
HOBOnet T21 Soil Water Potential/Temp Sensor
Discontinued
Important Information
A complete system requires at least one HOBO RX3000 Remote Monitoring Station, a HOBOnet Wireless Manager, and a HOBOnet Wireless Sensor, OR one HOBO MicroRX station (which has an integrated HOBOnet Wireless Manager) and a HOBOnet Wireless Sensor. HOBOnet Wireless Repeaters (RXW-RPTR-xxx or RXW-RPTR-B-xxx) can be added to extend the range.
Overview
A wireless sensor that works with the HOBOnet system to measure both soil temperature and soil water potential, a more accurate way to measure how much water is available to plants. This sensor is designed to withstand harsh environmental conditions, and it does not require calibration for different soil types or salinity. The HOBOnet T21 is calibrated in a chamber system that allows the T21 set calibration points from -10KPa to -80KPa. With its durable epoxy coating, you can be confident these sensors can be deployed in the ground for long periods, while providing data you can trust.
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 software platform.
Features
Sensor 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
Wireless Features
- 900 MHz wireless mesh self-healing technology
- 450 to 600 meter (1,500 to 2,000 feet) wireless range and up to five hops
- Up to 50 wireless sensors or 336 data channels per HOBO RX station
- Simple button-push to join the HOBOnet wireless network
- Onboard memory to ensure no data loss
- Powered by rechargeable AA batteries and built-in solar panel
Specifications
| 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 | Up to 50 wireless sensors or 336 data channels per one HOBO RX station | |
| Logging Rate | 1 minute to 18 hours | |
| Number of Channels | 3 | |
| 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 | Image
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* 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.
Compatible items
Web-based Monitoring Systems - via remote communication
Communications
Batteries
What's in the box
- HOBOnet T21 Soil Water Potential/Temp Sensor
- Cable ties
- Screws
FAQs
Yes. For shallow installation, an auger may be used to dig to the desired depth. For deeper installations, where manual placement may be difficult, a TEROS Borehole Installation Tool may be purchased or rented from METER Group. This tool enables easy installation up to 1.8 m.
HOBOnet TEROS 11 and TEROS 12 soil moisture sensors come calibrated for most soil types. However, for soil types with high sand or salt content, the standard calibration may not be accurate. In such cases, soil-specific calibration should be used.
To determine the soil-specific calibration formula, please refer to: https://www.onsetcomp.com/support/tech-notes/calibrating-ech2o-soil-moisture-sensors-application-note
Please note too that because the HOBOnet TEROS 21 sensor measures soil water potential, it does not require soil-specific calibration.
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