EC-5 soil moisture sensor for HOBOnet network RXW-SMC-868

The soil moisture sensor EC-5 incorporates the eCH 2 OTM EC5 sensor tested in the field and provides readings directly in the volumetric water content. The high frequency design of this sensor minimizes sensitivity to salinity and texture effects, and gives it a wide measuring range.
Wireless sensors HOBOnet communicate the data directly to the HOBO RX3000 or to hOBO MicroRX station, or transmit data via other wireless sensors to the central station.
They are preconfigured and ready for deployment, and data are accessible via HOBOlink, the innovative cloud software platform of'Onset.

Technical characteristics of the sensor:

- Accuracy of ±3 % under typical soil conditions and accuracy of ±2 % with specific ground calibration
- Measure a soil volume of 0.3 litres to take measurements at a specific depth or in a container
- The high frequency circuit (70 MHz) offers good precision even in saline and sandy soils
- Wireless features
- 900 MHz wireless mesh self-healing technology
- Wireless range from 450 to 600 metres (1,500 to 2,000 feet) and up to five jumps
- Up to 50 wireless sensors or 336 data channels per HOBO RX station
- Just press a button to join the HOBOnet wireless network
- Onboard memory to avoid data loss
- Powered by rechargeable AA batteries and integrated solar panel

Remarks:

1- The sensor is capable of providing readings outside the standard volumetric water content range. This is useful for diagnosing the operation and installation of the sensor. See the Sensor Operation section for more details.

2- This is a system precision specification and includes the probe accuracy of typical ±0.03 m3/m3 (±0.02 m3/m3 soil specific) plus the mote accuracy of ±0.01 m3/m3 at 25 °C (77 °F). There are additional temperature accuracy differences of ±0.03 m3/m3 / °C maximum for the probe in the operating temperature environment, typical

3- Given the nature of the sensor design and the frequency of operation of the sensor, the system has inherent susceptibility to radio frequency signals. The precision specification when subjected to certain RFI environments, such as those described in IEC 61000-4-3 and IEC 61000-4-6, is reduced to 0.061 m3/m3. The accuracy of the system level will be particularly affected when placed in an electric field of 3 V/m or more within the 70 MHz range. BIR mitigation practices and physical deployment changes can reduce system sensitivity.

Complementary Features:

- Measurement range in the ground: 0 to 0.550 m3/m3 (water volumetric content)
- Wide range: -0.401 to 2.574 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
- Resolution: 0.0007 m3/m3 (0.07%)
- Volume of influence: 0.3 litres (10.14 oz)
- Sensor frequency: 70 MHz
- ECH2O meter
- Test probe reference: EC-510HS
- Sensor operating temperature range: 0° to 50°C (32° to 122°F).
Although the sensor probe and cable can operate safely at temperatures below the freezing point (up to -40°C/F), the soil moisture data collected at these extreme temperatures are outside the precise measuring range of the sensor.
- 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) not adjustable
- Transmission range:
Reliable connection to a 457.2 m (1,500 ft) sight line at a height of 1.8 m (6 ft)
Reliable connection to a 609.6 m (2 000 ft) sight line at a height of 3 m (10 ft)
- Wireless data standard: IEEE 802.15.4
- Radio operating frequencies RXW-SMC-868 and RXW-SMD-868: 866.5 MHz
- Modulation employed: OQPSK (decalation of modulation by quadrature phase displacement)
- Data flow rate: up to 250 kbps, not adjustable
- Service cycle: - Maximum number of points:
up to 50 wireless sensors
336 data channels per HOBO RX station
- Log rate: 1 minute at 6 p.m
- Number of data channels: 2
- Type of battery / power source:
2 rechargeable NiMH batteries AA 1.2 V, powered by an integrated solar panel
or
2 AA 1.5 V lithium batteries for operating conditions from -40° to 70°C (-40° to 158°F)
- Battery life:
With NiMH batteries : 3 to 5 years typical when used in a temperature range of -20° to 40°C (-4°F to 104°F) and positioned towards the sun (see Deployment and mounting), operation outside this range will reduce battery life
With lithium batteries : 1 year, typical use
- Memory : 16 MB
- Dimensions:
Ground probe RXW-SMC-868: 89 x 15 x 1,5 mm (3,5 x 0,62 x 0,06 in.)
Cable length: 5 m (16.4 feet)
Mote: 16,2 x 8,59 x 4,14 cm (6,38 x 3,38 x 1,63 inches)
- Weight:
Sensor and cable 180 grams (6.3 oz)
Moth: 223 g (7.87 oz)
- Materials : PPCBT, silicone rubber seal
- Environmental Assessment Mote: IP67, NEMA 6