Difference between revisions of "HFDL"

Revision as of 21:01, 2 March 2015

What is HFDL?

HFDL is a HF data link protocol, defined in ARINC spec 635-3. The HFDL service is operated by Rockwell Collins (since 2014) through a worldwide network of HF stations. See this PDF file from the UDXF for more.

Transmissions on HF are in USB on a sub carrier of 1440 Hz with a symbol speed of 1800 baud.
Modulation is 2-PSK, 4-PSK or 8-PSK with effective bit rates of 300, 600, 1200 or 1800 bits/sec.

This topic can be discussed in our SW Data Decoding forum.

Synonyms

HF ACARS

Current Usage

This mode is utilized exclusively by fixed aeronautical stations in communications with planes, often at great distances - too far for VHF radio to accomplish. See the Frequencies in Use section for a link to a list of frequencies and sites.

Decoding

PC-HFDL

PC-HFDL is a Windows software to decode HFDL data traffic and has been written by Charles Brain. Just feed the HF receiver speaker's output into the soundcard of a Windows PC. It can be downloaded from the HFDL Yahoo group.

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.

The HFDL Yahoo group can be found here. Version 2.042 can be downloaded from this stub page

Other software that can decode HFDL

Hobby Level Software

Hoka Code 3-32P
Hoka Code 300-32P
MultiPSK
PlanePlotter (Not a decoder but will show aircraft decoded by PC-HFDL)
Sigmira
Skysweeper (Discontinued by manufacturer)
Sorcerer
- Note: It has been recently discussed on the UDXF Yahoo group that Sorcerer is using an old freq/site list - you may get correct decodes, but not correct site IDs

Professional Equipment/Software

Audio Example and Waveform

See this entry from the Signals Indentification wiki
HFDL Waveform

Frequencies in Use

The current version (Sept. 5 2014) of the HFDL database table is 49. It's available from the UDXF Modes page here in PDF.
The .dat file that can be used with the registered version of PC-HFDL can be had by joining the PC-HFDL Yahoo group and requesting one via private mail. It will NOT work with the free version.

@@ Line 3: / Line 3: @@
 HFDL is a HF data link protocol, defined in [http://www.arinc.com ARINC] spec 635-3.  The HFDL service is operated by Rockwell Collins (since 2014) through a worldwide network of HF stations. See this [http://www.udxf.nl/What%20Is%20HFDL.pdf PDF file] from the UDXF for more.
-The name is somewhat misleading, as HFDL actually describes a class of data signals; it is also referred to as HF [[ACARS]].
 * Transmissions on HF are in USB on a sub carrier of 1440 Hz with a symbol speed of 1800 baud.
@@ Line 10: / Line 9: @@
 This topic can be discussed in our
 [http://forums.radioreference.com/shortwave-data-decoding SW Data Decoding] forum.
+==Synonyms==
+* HF ACARS
@@ Line 50: / Line 53: @@
 ; Professional Equipment/Software
-* [http://www.go2signals.ch/products/go2decode/ go2decode] needs verification
+* [http://www.go2signals.ch/products/go2decode/ go2decode]
 * [http://www.hoka.com/products/code300-32/standard-version.html Hoka 300-32]
 * [http://www.comintconsulting.com/krypto500/ Krypto 500]