ST-21

The ST-21 replaces the ST-20. The ST-21 is functionally equivalent, but contains Telonics new transmitter module.
Campbell Scientific's ST-21 is a Service Argos-certified platform transmitter terminal (PTT). The ST-21 transfers data from the datalogger site to the Argos Data Collection and Location System via NOAA polar orbiting satellites. This Argos transmitter is well suited for remote meteorological and environmental data collection applications, including mobile and high-latitude installations. The ST-21 Argos transmitter is compatible with Campbell Scientific's CR800, CR850, CR1000, and CR3000 dataloggers.
Campbell Scientific combines a Telonics ST-21 transmitter module with a voltage regulator and our SDC communication interface, and puts them in a rugged case for use in remote, hostile environments.