AL205E ALERT2 Encoder
ALERT2 Encoder
Acquire and transmit encrypted hydrometeorological measurements
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported


The AL205E is a low-power ALERT2 encoder/transmitter with one radio output port for data transmission (TX only). With its two serial ports, input from several devices is possible—including from a data logger. Connection to a data logger enables the acquisition and transmission of hydrometeorological measurements. Local administration is possible through the micro USB console. The GPS functionality provides the required time synchronization needed for TDMA transmissions, and the LEDs offer status and activity indications. The AL205E is firmware-upgradeable.

Note: ALERT2 is a trademark of the National Hydrologic Warning Council.

Benefits and Features

  • ALERT2 flood warning network compatible
  • Forward error correction (FEC)
  • 250 ms TDMA slotting
  • Low power
  • Selectable modulation output power levels
  • Works easily with Maxon and Ritron radios
  • Meets published ALERT2 Working Group Standards



Operating Temperature Range -40° to +80°C
Power Connector 2 pin, spring clip
Power Supply 9 to 17 Vdc (reverse polarity protected)
Current Drain at 12 Vdc
  • 1.4 mA (normal operation, no LEDs, no external connections)
  • ~34 mA (GPS searching)
  • ~29 mA (GPS locked)
  • ~1 mA each LED (disabled via jumper)
  • ~1.5 mA (each connected serial port)
  • ~17 mA (during message transmission)
TX Radio Modulation Voltage
  • 2 preconfigured values, selected via jumper (for use with Ritron or Maxon radios)
  • User-adjustable level via potentiometer
Clock Synchronization GPS
Clock Drift
  • 2 ppm (0 to 40°C)
  • 3.5 ppm (-40 to +80°C)
  • 2 ports
  • Custom 3-pin cable
  • 1200 to 57,600 bps
LEDs 5 status LEDs for Serial 2, Serial 1, GPS On, Clock Sync, Transmit, TX Radio On
Active GPS Antenna SMA, female
TX Radio 5 pin, spring clip (power, ground, push-to-talk, data, channel select)
Certifications FCC Part 15 Class A certified
Dimensions 19.05 x 10.16 x 3.18 cm (7.5 x 4 x 1.25 in.)
Weight 600 g (1.3 lb)


The AL205E is compatible with NHWC ALERT2 AirLink v1.1, MANT v1.1, and API v1.0. It supports ALERT2 API input, as well as ALERT2 API and ASCII output. The AL205E implements ALERT2 data concentration and ALERT2 IND interface. The encoder also implements proposed protocol extensions for Configurable Forward Error Correction. Flexible addressing support either assigns an address to the whole device or enables the customization of a specific AL205E serial port with a unique address.


AL205E Firmware v.6.1.1 (571 KB) 08-06-2020

Current firmware for the AL205E.

View Revision History