| 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. |
| 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 |
| Compliance Marks | RXW-SMD-900 RXW-SMD-868 RXW-SMD-922
 RXW-SMD-921 |
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 accuracy. If deployments are planned in high RFI energy environments, Onset recommends on-site testing to determine system level accuracy.
RXW-SMD-921
