High Frequency Data Link (HFDL)

High Frequency Data Link (HFDL)

Frequencies	2.9 MHz,22 MHz
Frequency Range	2.9 MHz - 22 MHz
Mode	USB
Modulation	PSK
ACF	—
Emission Designator	—
Bandwidth	2.4 kHz
Location	Worldwide
Short Description	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.
I/Q Raw Recording	Download file
Audio Sample

HFDL, also known as HFHigh Frequency (3-30 MHz)-ACARS, ARINC 753, ARINC 635, and HFHigh Frequency (3-30 MHz) DATALINK,is a data link that aircraft use to communicate short messages over long distances using HFHigh Frequency (3-30 MHz) signals. HFDL is defined in ARINC spec 753.

Transmissions on HFHigh Frequency (3-30 MHz) are in USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) on a sub-carrier of 1440 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). with a symbol speed of 1800 baudBaud (unit symbol Bd) is the unit for symbol rate or modulation rate in symbols per second.. Data is sent at 300, 600, 1200 or 1800 bpsBits per second (bps). HFDL can use BPSKBinary Phase-Shift Keying (1 bit per symbol), QPSKQuadrature Phase-Shift Keying (2 bits per symbol), and 8-PSK8-Phase Phase-Shift Keying (3 bits per symbol).

Waterfall appearance of HFDL can be confused with the JORN radar, but HFDL can be differentiated by its narrower bandwidth and entirely different sound.

Frequencies

Current frequency table sources:

• Current HFDL system table (configuration file for dumphfdl)
• udxf.nl (text file + binary .dat file for PC-HFDL)

Samples

300 bpsBits per second (bps) Short (BPSKBinary Phase-Shift Keying (1 bit per symbol))

600 bpsBits per second (bps) Long (BPSKBinary Phase-Shift Keying (1 bit per symbol))

1200 bpsBits per second (bps) Short (QPSKQuadrature Phase-Shift Keying (2 bits per symbol))

Decoding Software

Hobby Level Software

• dumphfdl (Multichannel HFDL decoder for Linux)
• MultiPSK (restricted to 5 minutes in the non-registered version)
• You may find more information on an up to date version of PC-HFDL in the HFDL sub-group of the ACARS VDL2 group
• PlanePlotter (Not a decoder but will show aircraft decoded by PC-HFDL)
• Sigmira
• Sorcerer
  • Sorcerer Installation and Operation (PDF)
  • Run Sorcerer under Win7 (in Italian)
  • How to correct the site displays in Sorcerer

Professional Equipment/Software

• go2DECODE
• go2MONITOR
• Hoka 300-32
• Krypto 500
• Many of the newer WaveCom modems
• Wavecom W-Code

Video Examples

• Aircraft HFDL monitoring with PC-HFDL and DX Atlas
• HFDL Data-Link Aircraft ATC
• Amazing HFDL reception over central Europe
• HFDL Decoding with RTL SDR (RTL2832U), Nooelec Ham it up upconverter, SDR Sharp and PC-HFDL
• HF ACARS, ARINC 635, FUNCUBE DONGLE, SDRSHARP, SORCERER
• Decoding High Frequency Data Link (YouTube)

Additional Links

• I-56578 HFDL Reception
• shoc Database: HFDL
• WAVECOM Database: HFDL
• Wikipedia High Frequency Data Link
• Aeronautical Frequencies (HF and others) (PDF)
• What is HFDL? (PDF)
• HFDL - Some Ideas (PDF)
• ICAO Aeronautical Communications Vol. 2 (PDF)
• HFDL Waterfall at RadioReference

Additional Images

Multiple HFDL transmissions. Overdriven or faulty transmitter stage causes one of them to spread over multiple frequencies. Many HFDL transmissions, including overdriven ones HFDL (left) and JORN OTHOver The Horizon (very long range) radar (right) HFDL transmissions (left) and OTHOver The Horizon (very long range) radar bursts (right)