The Real-Time Basic Extension contains temperature, humidity, and pressure sensors. This extension allows automatic measurements and recording of temperature and pressure and using such data in the online processing of the output quantities of an BLS or SLS Series scintillometer to increase accuracy. The sensors are sampled by a datalogger that is installed directly at the mast. From the datalogger the sensor values are digitally transmitted to the Signal Processing Unit via a serial cable. The full-featured datalogger permits the user to upgrade or add additional meteorological sensors at any time. Due to the digital signal transmission the mast can be installed at remote locations, if an appropriate serial data link is provided, for example by using RS485 Converters or radio modems.