HOBOnet Soil Moisture EC-5 Sensor

	RXW-SMC-xxx	RXW-SMD-xxx
Measurement Range	In soil: 0 to 0.550 m³/m³ (volumetric water content)	In soil: 0 to 0.570 m³/m³ (volumetric water content)
Extended Range	-0.401 to 2.574 m³/m³; see Note 1	-0.659 to 0.6026 m³/m³; see Note 1
Accuracy	±0.031 m³/m³ (±3.1%) typical 0 to 50°C (32° to 122°F) for mineral soils up to 8 dS/m and ±0.020 m³/m³ (±2%) with soil specific calibration; see Notes 2 and 3	±0.033 m³/m³ (±3.3%) typical 0 to 50°C (32° to 122°F) for mineral soils up to 10 dS/m and ±0.020 m³/m³ (±2%) with soil specific calibration; see Notes 4 and 5
Resolution	0.0007 m³/m³ (0.07%)	0.0008 m³/m³ (0.08%)
Volume of Influence	0.3 liters (10.14 oz)	1 liter (33.81 oz)
Sensor Frequency	70 MHz	70 MHz
METER ECH2O Probe Part No.	EC-5	10HS
Sensor Operating Temperature Range	0° to 50°C (32° to 122°F). Although the sensor probe and cable can safely operate at below-freezing temperatures (to -40°C/F), the soil moisture data collected at these extreme temperatures is outside of the sensor’s accurate measurement range.	0° to 50°C (32° to 122°F). Although the sensor probe and cable can safely operate at below-freezing temperatures (to -40°C/F), the soil moisture data collected at these extreme temperatures is outside of the sensor’s accurate measurement range. Extended temperatures above 50°C (122°F) will decrease mote battery life.

Wireless Mote

Operating Temperature Range

-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-SMC-900 and RXW-SMD-900: 904-924 MHz

RXW-SMC-868 and RXW-SMD-868: 866.5 MHz

RXW-SMC-921 and RXW-SMD-921: 921 MHz

RXW-SMC-922 and RXW-SMD-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 Data Channels

2

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 Deployment and Mounting), operation outside this range will reduce the battery service life

With lithium batteries: 1 year, typical use

Memory

16 MB

Dimensions

RXW-SMC-xxx soil probe: 89 x 15 x 1.5 mm (3.5 x 0.62 x 0.06 in.)

RXW-SMD-xxx soil probe: 160 x 32 x 2 mm (6.5 x 1.25 x 0.08 in.)

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-SMC-xxx sensor and cable: 180 grams (6.3 oz)

RXW-SMD-xxx sensor and cable: 190 grams (6.7 oz)

Mote: 223 g (7.87 oz)

Materials

Sensor: Weatherproof

Mote: PCPBT, silicone rubber seal

Environmental Rating

Mote: IP67, NEMA 6

Notices

Note 1: (RXW-SMC-xxx and RXW-SMD-xxx) The sensor is capable of providing readings outside the standard volumetric water content range. This is helpful in diagnosing sensor operation and installation. See the Sensor Operation section for more details.

Note 2: (RXW-SMC-xxx) This is a system level accuracy specification and is comprised of the probe’s accuracy of ±0.03 m³/m³ typical (±0.02 m³/m³ soil specific) plus the mote accuracy of ±0.001 m³/m³ at 25°C (77°F). There are additional temperature accuracy deviations of ±0.003 m³/m³ / °C maximum for the probe across operating temperature environment, typical <0.001 m³/m³ / °C. (The temperature dependence of the mote is negligible.)

Note 3: (RXW-SMC-xxx) Given the nature of the sensor design and sensor operating frequency, the system has inherent susceptibilities to Radio Frequency signals. The accuracy specification when subjected to certain RFI environments, such as those outlined in IEC 61000-4-3 and IEC 61000-4-6, is reduced to 0.061 m³/m³. The system level accuracy will be particularly affected when placed in an electric field of 3 V/m or greater in the 70 MHz range. RFI mitigation practices and physical deployment changes may reduce the systems susceptibility.

Note 4: (RXW-SMD-xxx) This is a system level accuracy specification and is comprised of the probe’s accuracy of ±0.03 m³/m³ typical (±0.02 m³/m³ soil specific) plus the mote accuracy of ±0.003 m³/m³ at 25°C (77°F). There are additional temperature accuracy deviations of ±0.003 m³/m³ / °C maximum for the probe across operating temperature environment, typical <0.001 m³/m³ / °C. (The temperature dependence of the mote is negligible.)

Note 5: (RXW-SMD-xxx): Given the nature of the sensor design and sensor operating frequency, the system has inherent susceptibilities to Radio Frequency signals. The accuracy specification when subjected to certain RFI environments, such as those outlined in IEC 61000-4-3 and IEC 61000-4-6, may be significantly reduced. The system level accuracy will be particularly affected when placed in an electric field of 3 V/m or greater in the 150 KHz to 1000 MHz range. RFI mitigation practices and physical deployment changes may reduce the systems susceptibility, however will yield reduced system