From The RadioReference Wiki

Please see the SigIDWiki definition for HFDL for a technical description, software and additional information

A waterfall for HFDL can be found here

Also see the Decoding High Frequency Data Link (YouTube) video Reflectors
HF ACARS with PC-HFDL (PDF article from MT)
UDXF website links


PC-HFDL is a Windows software to decode HFDL data traffic and has been written by Charles Brain. To connect your receiver to your PC, please see the Connecting Radios to Soundcards article. The most recent version can be downloaded from the HFDL subgroup (above)

PC-HFDL Issues and Corrections

PC-HFDL screen

The best monitoring results will be achieved with the following PC-HFDL settings:

  • PREAM ON - to control the audio offset of the receiver
  • SPDU OFF - only needed temporarily ON to see the squitters of a new unknown ground station
  • MPDU ON - see the MPDU packets
  • LPDU ON - see the LPDUs within the MPDUs
  • BDU ON - see the BDUs
  • VERB ON - see more details
  • HFNPDU ON - see the routine position reports
  • HEX OFF - only needed for debugging purposes

So in short, with all options ON except SPDU and HEX, the complete session can be seen: LOG-ON of the aircraft to the ground station giving its 24bit ICAO-ID, the assignment of the 1byte sequence ID number to the given ICAO-ID by the ground station referenced in all subsequent traffic, clear distinction of MPDU packets containing more than just one LPDU, and full traffic details.