Principle of Operation

Monnit ALTA Wireless Humidity (RH) Sensor measures the relative humidity at the device. The sensor returns RH and temperature values to the iMonnit Online Sensor Monitoring and Notification System. The system calculates dew point from the data and stores all three data points in the online system where the data can be reviewed and exported as a data sheet or graph. Notifications can be set up through the online system to alert the user when defined thresholds have been met or exceeded.

Example Interfacing

  • Greenhouse humidity monitoring
  • Agriculture environmental monitoring
  • Art gallery and museum environmental monitoring
  • Humidor monitoring
  • General weather and environmental monitoring


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 Commercial AA Wireless Humidity Sensor

Technical Specifications

ALTA Commercial AA Wireless Humidity Sensor

Supply Voltage 2.0-3.8 VDC * 
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 batteries)  7°C to +55°C (20°F to +131°F)
Optimal battery temperature range (batteries)  +10°C to +50°C (+50°F to +122°F) 
Accuracy  ± 2% under normal conditions (0%-80% RH) **
RH operating range                             0-100% RH **
RH response time  8 sec (tau 63%) **
Datalogging Datalogs 2000 to 4000 readings if gateway connection is lost (non-volatile flash, persists through the power cycle): - 10-minute heartbeats = ~ 22 days 
Wireless Range 1,200+ ft non-line-of-sight 
Security Encrypt-RF ® (256-bit key exchange and AES-128 CTR) 
Weight 0.7 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.

**View charts on last page for more information.



ALTA Commercial Coin Cell Wireless Humidity Sensor

Technical Specifications

ALTA Commercial Coin Cell Wireless Humidity 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 coin cell)  -18°C to 50°C (0°F to 122°F) using alkaline
-40°C to 80°C (-40°F to 176°F) using lithium
Optimal battery temperature range (coin cell)  +10°C to +45°C (+50°F to +113°F)
Accuracy  ± 2% under normal conditions (0%-80% RH) **
RH operating range                             0-100% RH **
RH response time  8 sec (tau 63%) **
Datalogging Datalogs 2000 to 4000 readings if gateway connection is lost (non-volatile flash, persists through the power cycle): - 10-minute heartbeats = ~ 22 days 
Wireless Range 1,200+ ft non-line-of-sight 
Security Encrypt-RF ® (256-bit key exchange and AES-128 CTR) 
Weight 0.7 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.

**View charts on last page for more information.



ALTA Industrial Wireless Humidity Sensor

Technical Specifications

ALTA Industrial Wireless Humidity 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)  -18°C to 50°C (0°F to 122°F) using alkaline
-40°C to 80°C (-40°F to 176°F) using lithium
Optimal battery temperature range (battery)  +10°C to +45°C (+50°F to +113°F)
Accuracy  ± 2% under normal conditions (0%-80% RH) **
RH operating range                             0-100% RH **
RH response time  8 sec (tau 63%) **
Datalogging Datalogs 2000 to 4000 readings if gateway connection is lost (non-volatile flash, persists through the power cycle): - 10-minute heartbeats = ~ 22 days 
Wireless Range 1,200+ ft non-line-of-sight 
Security Encrypt-RF ® (256-bit key exchange and AES-128 CTR) 
Weight 0.7 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.

**View charts on last page for more information.

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