HOBOnet Multi-Depth Soil Moisture Sensor

An award-winning wireless sensor that works with the HOBOnet system to measure soil moisture and soil temperature at multiple depths with a single probe. With fast and easy installation, this durable sensor and 3-segment probe measures to a depth of 45 cm (18 in).

Featuring GroPoint’s TDT5 technology with patented antenna design, this sensor measures soil moisture along the entire length of each probe segment, resulting in the largest volume of influence per measurement section. A high frequency of pulses per measurement provides precise and consistent soil moisture data.

We recommend using the optional pilot rod and slide hammer for quick and easy installation, the PILOT-ROD4 (28″) for use with the RXW-GP3.

The HOBOnet system is a cost-effective and scalable wireless sensor network 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. Sensors are easily linked to the network, and data can be accessed through HOBOlink®, Onset’s innovative cloud software platform.

Part numbers RXW-GP4-xxx and RXW-GP6-xxx, the 4- and 6-segment probes, are no longer available. Please contact sales if you have any questions.

Sensor Features

Probe length: 45 cm (18 in)
Soil moisture measurements over entire probe segment lengths
Soil temperature measurements at multiple points
Largest volume of influence per measurement (2 L volume of influence per 15 cm segment)
Advanced filtering of 400,000 pulses per measurement eliminates outlying readings and provides precise, repeatable soil moisture data
Polycarbonate housing and epoxy-sealed circuit board protect vital components during installation and throughout deployment
Easy installation with minimal soil disturbance, and no digging required when using the optional pilot rod and slide hammer

Wireless Features

Sub-GHz 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 one 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

In what environment does this data logger operate?

This data logger operates in an outdoor environment.

What measurements does this data logger support?

The RXW-GPx-xxx sensor supports the following measurements: Soil Moisture and Soil Temperature

Specifications

±0.5°C (0.9°F)

Soil Moisture: Volumetric Water Content (VWC)
Measurement Range	In soil: 0 to 0.550 m³/m³ (volumetric water content)
Accuracy	±0.02 m³/m³ (±2%) in most soils typical from 0° to 50°C (32° to 122°F)*
Resolution	0.001 m³/m³
Temperature
Measurement Range	-20° to 70°C (-4° to 158°F)
Accuracy
0.1°C (0.18°F)
Depths Measured (see below)
RXW-GP3-xxx	45 cm (18 inches) total; three soil moisture zones, six temperature depths
RXW-GP4-xxx	60 cm (24 inches) total; four soil moisture zones, seven temperature depths *NO LONGER AVAILABLE*
RXW-GP3-xxx	90 cm (35 inches) total; six soil moisture zones, eleven temperature depths *NO LONGER AVAILABLE*
Wireless Mote
Operating Temperature Range	Sensor: -20° to 70°C (-4° to 158°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-GPx-900: 904–924 MHz RXW-GPx-868: 866.5 MHz RXW-GPx-921: 921 MHz RXW-GPx-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	Maximum logging interval: 18 hours Recommended minimum logging interval:
	Using Solar Power with Rechargeable Batteries	Using Non-Rechargeable Lithium Batteries
RXW-GP3-xxx:	5 minutes year round	10 minutes
RXW-GP4-xxx:	5 minutes summer, 10 minutes winter	15 minutes
RXW-GP6-xxx:	5 minutes summer, 10 minutes winter	15 minutes
	See Battery Life specification for more details.
Number of Data Channels	RXW-GP3-xxx: 10 RXW-GP4-xxx: 12 RXW-GP6-xxx: 18
Battery Type/Power Source	Two AA 1.2V rechargeable NiMH batteries, powered by built-in solar panel or two AA 1.5 V non-rechargeable 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 non-rechargeable lithium batteries: RXW-GP3-xxx: 1 year with a 10-minute logging interval RXW-GP4-xxx: 1 year with a 15-minute logging interval RXW-GP6-xxx: 7 months with a 15-minute logging interval
Memory	16MB
Dimensions	RXW-GP3-xxx sensor length: 53.2 cm (20.9 inches) RXW-GP4-xxx sensor length: 68.2 cm (26.9 inches) RXW-GP6-xxx sensor length: 98.2 cm (38.7 inches) Sensor diameter: 3 cm (1.2 inches) Cable length: 3 m (9.8 ft) Mote: 16.2 x 8.59 x 4.14 cm (6.38 x 3.38 x 1.63 inches)
Weight	RXW-GP3-xxx sensor: 351 g (12.4 oz) RXW-GP4-xxx sensor: 408 g (14.4 oz) RXW-GP6-xxx sensor: 526 g (18.6 oz) Cable: 190 g (6.7 oz) Mote: 223 g (7.87 oz)
Materials	Sensor: Polycarbonate housing encasing epoxy sealed circuit board Cable: Polyurethane Mote: PCPBT, silicone rubber seal
Environmental Rating	Mote: IP67, NEMA 6
Compliance Marks*	Mote: IP67, NEMA 6
*Soil-specific calibration requires user post-processing in a spreadsheet program such as Microsoft® Excel® or a utility and connector as recommend by RioT Technology Corp., manufacturer of GroPoint sensors. Refer to Performing a Soil-Specific Calibration in the manual for details.