The Spread Spectrum Radio Set Model AX-991 provides a direct radio link between a centrally located PC and one or more remotely located data loggers. When used in the United States and several other countries, no FCC license or government permits are required. Normally supplied as a pair of radio links, additional remote station units can be provided for multi-station systems. In a simple radio pair system communications is continuous between the central and remote. I networked operation, each remote site is polled from the central. The typical maximum line-of-sight range of the AX-991 radio is approximately 20 miles ( 32 km) .

Each radio system includes radio modems, 30 ft of low loss coax, and a high gain Yagi antenna for maximum communications range. The spread spectrum radios operate in the 902-928 mHz range using a frequency hopping technology. They operate Asynchronous, Full duplex at baud rates from 1200 to 115.2 kBaud. The remote radio is mounted inside the AutoMet Data Logger. Average power required is 180 mA at 10.5 to 18.0 VDC.