Principle of Operation

Monnit ALTA Soil Moisture Sensor uses a resistive granular matrix element to accurately measure the matric water potential (soil moisture tension) in the soil.

Soil Moisture Element: The soil moisture element is unique in that it takes its resistive measurement within a defined and consistent internal matrix material, rather than using the surrounding soil as the measurement medium. This unique feature allows the sensor to have a stable and consistent calibration that does not need to be established for every installation.

Temperature Element: The soil moisture sensor also comes equipped with a temperature element on the end of the soil moisture lead to make accurate soil temperature measurements as well. The temperature reading is also used for temperature compensation of the soil moisture measurements so no need to worry about getting different moisture readings just because the temperature changes.

Example Interfacing

  • Irrigation scheduling
  • Water table monitoring
  • Leak detection
  • Agronomy research
  • Environmental monitoring
  • Almost any soil moisture/status application

Features of Monnit ALTA Sensors

  • Wireless range of 1,200+ feet through 12+ walls *
  • Frequency-Hopping Spread Spectrum (FHSS)
  • Improved interference immunity
  • Improved power management for longer battery life **
  • Encrypt-RF ® Security (Diffie-Hellman Key Exchange + AES-128 CBC for sensor data messages)
  • Datalogs 2000 to 4000 readings if gateway connection is lost (non-volatile flash, persists through the power cycle):
  • 10-minute heartbeats = ~ 22 days - 2-hour heartbeats = ~ 266 days
  • Over-the-air updates (future proof)
  • Free iMonnit basic online wireless sensor monitoring and notification system to configure sensors, view data and set alerts via SMS text and email Wireless Range Comparison

*Actual range may vary depending on environment. **Battery life is determined by sensor reporting frequency and other variables. Other power options are also available.

ALTA Industrial Wireless Soil Moisture Sensor

Technical Specifications

ALTA Industrial Wireless Soil Moisture Sensor

Supply Voltage 2.0-3.8 VDC (3.0-3.8 VDC using power supply) *
Current Consumption 0.2 µA (sleep mode), 0.7 µA (RTC sleep), 570 µA (MCU idle), 2.5 mA (MCU active), 5.5 mA (radio RX mode), 22.6 mA (radio TX mode) 
Operating temperature range (board circuitry and battery)  -40°C to 80°C (-40°F to 176°F) **
Range 0-240 centibar or kPa (Water Tension)
Temperature Accuracy  ± 0.1°C
Datalogging Datalogs up to 4000 readings if gateway connection is lost 
Wireless Range 1,200+ ft non-line-of-sight 
Security Encrypt-RF ® (256-bit key exchange and AES-128 CTR) 
Weight 4.2 ounces 
Certifications 900 MHz product; FCC ID: ZTL-G2SC1 and IC: 9794A-G2SC1. 868 and 433 MHz product tested and found to comply with: EN 300 220-2 V3.1.1 (2017-02), EN 300 220-2 V3.1.1 (2017-02) and EN 60950

*Hardware cannot withstand negative voltage. Please take care when connecting a power device.

**At temperatures above 100°C, it is possible for the board circuitry to lose programmed memory


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