Early FANS 1/A used ACARS network to transmit data link messages from applications like CPDLC & ADS-C using VHF or HF. FANS 1/A+ used the same ACARS network to transmit data link messages from applications like CPDLC & ADS-C using VDL (VHF Data Link mode-2), HFDL, Satcom.
How different is datalink transmission over VHF and VDL ?
