Aero HFDL Shannon Station 7 8942 kHz
HFDL, also known as HF-ACARS, ARINC 753, ARINC 635, and HF DATALINK,is a data link that aircraft use to communicate short messages over long distances using HF signals. HFDL is defined in ARINC spec 753.
Transmissions on HF are in USB on a sub-carrier of 1440 Hz with a symbol speed of 1800 baud. Data is sent at 300, 600, 1200 or 1800 bps. HFDL can use BPSK, QPSK, and 8-PSK.