This course covers the Communications systems used in civil aviation, specifically focusing on data-link systems that connect traffic control stations for transmitting and receiving digital data. The course discusses three different data communication links currently in use: High Frequency Data Link (HFDL), Very High Frequency Data Link (VDL), and Satellite Communication (SATCOM). These links are used to transmit various types of messages, including Aeronautical Operational Control (AOC) messages, Controller Pilot Data Link Communications (CPDLC) messages, and Automatic Dependent Surveillance (ADS) messages.

The course also covers the properties of HFDL and VDL-2 in regards to signal quality, range/area coverage, line-of-sight limitations, interference due to ionospheric conditions, and data transmission speed.