CPDLS

[K2KOH]

If I heard the initial correctly...anyone know about the new digital transmissions aircraft are using to transmit weather data, position reports, etc? Is this possibly an HF version of ACARS, or is it satellite transmission now?

 

[ka3jjz]

If I heard the initial correctly...anyone know about the new digital transmissions aircraft are using to transmit weather data, position reports, etc? Is this possibly an HF version of ACARS, or is it satellite transmission now?

AFAIK there are indeed airlines that do use satellites to relay weather info, and there is a HF version of ACARS, referred to rather loosely as HFDL. Charles Brain's website has both free and commercial versions of the software that can copy it.

You should be aware that there are many different classes of HFDL (HF Data Link); some are used by the military; the one that's used by the aviation industry is a very specific ARINC standard. That's the only one that Charles' software will decode.

73s Mike

 

[K2KOH]

Thanks much, Mike. I love listening to the Transatlantic flights, and CPDLC would definitely ruin it if I couldn't decode it!

73
Kieran

 

[kc2klc]

Looks like CPDLC is dead for now - check out http://www.ainonline.com/issues/06_04/06_04_bugetcutsp54.html

 

[K2KOH]

It can't be dying too quickly...New York, Gander, Shanwick and Santa Maria are still announcing no voice reports are required in their areas, they are using CPDLC full blast with aircraft that are equipped with it. Of course, there are still plenty that don't use it...

 

[Chris-M]

CPDLC

I'll be piloting a flight from Houston to Amsterdam and back at the end of this week in a Boeing 767-200. Ours are CPDLC and ADS, and also have HFDL and SATCOM. Usually the HFDL and SATCOM are automatic but the CPDLC is pilot initiated, then it is automatic throughout the Oceanic portion of the flight. I have yet to use CPDLC and ADS. The SATCOM is neat. It's like talking on a cellphone but you're out over the middle of the ocean. Generally we use HF voice position reports as we cross the Atlantic. I sometimes tune my HF receiver at home in and listen but it gets old fast. The HF ARINC decoding software sounds interesting. I'm going to try and see what I can get out of it tonight.

 

[Chris-M]

Just copied some HFDL using PC-HFDL http://www.chbrain.dircon.co.uk/pchfdl.html (the free, unsupported version). This is what I've received so far with my Yaesu FT857. Basically a bunch of jibberish that has me wondering if the $35 version is worth it. Likely not in my opinion. I am monitoring 8.912 mhz. Gonna try some other frequencies and see what I get.
This part is pretty cool though..the position of specific flights. Here's one for example:

06:22:00 UTC Flight ID = CO0031 LAT 20 16 40 N LON 63 43 45 W

Here's the rest. I cut out most of the redundant stuff.

-------------------

Preamble 300 bps 1.8 sec Interleaver FREQ ERR 1.541685 Hz Errors 1
[SPDU CRC PASS]
Version = 0 * Freq utilisation = LIGHT * ISO 8208 = Not Supported
No change, same frequency, Ground Station UP
Ground Station ID = 2 MOLOKAI - HAWAII
Frame Index = 698 * Frame offset = 1 * UTC = 06:12:18 SYNCHED
LPDU ACK codes

Preamble 300 bps 1.8 sec Interleaver FREQ ERR 4.417814 Hz Errors 10
[CRC FAIL]
FA 13 28 6A 23 FD 1B BA 6B 4D 4D 54 DC 2A 8B ...j ....k M M T ...
96 5D F7 9F 77 D9 D7 55 71 BE ED 06 2D 91 2F ....w ..U q ......
E8 69 3F D9 41 D7 65 38 15 C9 34 4F 05 F7 31 .i ..A .e 8 ..4 O ..1
15 B7 0A B1 11 DA 4F 76 D0 75 73 55 1C AE 4E ......O v .u s U ..N
D9 68 5F 57 C5 AD 0A .h .W ...

Preamble 300 bps 1.8 sec Interleaver FREQ ERR 2.642271 Hz Errors 0
[SPDU CRC PASS]
Version = 0 * Freq utilisation = LIGHT * ISO 8208 = Not Supported
No change, same frequency, Ground Station UP
Ground Station ID = 2 MOLOKAI - HAWAII
Frame Index = 696 * Frame offset = 1 * UTC = 06:11:14 SYNCHED
Database Version 26
This GS active freqs 6 10 11
GS2 ID = 14 KRASNOYARSK - RUSSIA UTC LOCKED Active freqs 2
GS3 ID = 15 BAHRAIN UTC LOCKED Active freqs 5

 

[ka3jjz]

Just copied some HFDL using PC-HFDL http://www.chbrain.dircon.co.uk/pchfdl.html (the free, unsupported version). This is what I've received so far with my Yaesu FT857. Basically a bunch of jibberish that has me wondering if the $35 version is worth it. Likely not in my opinion. I am monitoring 8.912 mhz. Gonna try some other frequencies and see what I get.
This part is pretty cool though..the position of specific flights. Here's one for example:

06:22:00 UTC Flight ID = CO0031 LAT 20 16 40 N LON 63 43 45 W

Here's the rest. I cut out most of the redundant stuff.

-------------------

Preamble 300 bps 1.8 sec Interleaver FREQ ERR 1.541685 Hz Errors 1
[SPDU CRC PASS]
Version = 0 * Freq utilisation = LIGHT * ISO 8208 = Not Supported
No change, same frequency, Ground Station UP
Ground Station ID = 2 MOLOKAI - HAWAII
Frame Index = 698 * Frame offset = 1 * UTC = 06:12:18 SYNCHED
LPDU ACK codes

Preamble 300 bps 1.8 sec Interleaver FREQ ERR 4.417814 Hz Errors 10
[CRC FAIL]
FA 13 28 6A 23 FD 1B BA 6B 4D 4D 54 DC 2A 8B ...j ....k M M T ...
96 5D F7 9F 77 D9 D7 55 71 BE ED 06 2D 91 2F ....w ..U q ......
E8 69 3F D9 41 D7 65 38 15 C9 34 4F 05 F7 31 .i ..A .e 8 ..4 O ..1
15 B7 0A B1 11 DA 4F 76 D0 75 73 55 1C AE 4E ......O v .u s U ..N
D9 68 5F 57 C5 AD 0A .h .W ...

Preamble 300 bps 1.8 sec Interleaver FREQ ERR 2.642271 Hz Errors 0
[SPDU CRC PASS]
Version = 0 * Freq utilisation = LIGHT * ISO 8208 = Not Supported
No change, same frequency, Ground Station UP
Ground Station ID = 2 MOLOKAI - HAWAII
Frame Index = 696 * Frame offset = 1 * UTC = 06:11:14 SYNCHED
Database Version 26
This GS active freqs 6 10 11
GS2 ID = 14 KRASNOYARSK - RUSSIA UTC LOCKED Active freqs 2
GS3 ID = 15 BAHRAIN UTC LOCKED Active freqs 5

Actually this last message has some fairly important information. I'd leave the 'HEX' box unchecked; unless you're really into system specs, you probably don't need it. The last 2 lines, I think, tells you what stations are active along this aircraft's path. The ground station is UPlinking data to a requestor, using DATABASE VERSION 26 data. The station is station 2, Molokai Hawaii.

Take a good look at the first line; this tells you that you received the squirt cleanly with no errors, and that the Cyclic Redundancy Check (CRC) passed; under these conditions, PC HFDL will do its job. This is a mode where what you see is what you get; there's little interpretation done by the software.

I can't seem to put my finger on it right now, but there is a site you can go to get a list of all the HFDL stations now on the air. A new one - Canary Islands - just came on, in fact. So you could use this data in 2 ways; one is to plot aircraft, the other from a purely DX point of view (from where can you receive 'squitters' - those are the broadcasts that ID the ground station)?

It takes a good deal of study to understand this information, but there are folks on the Worldwide Utility News group at QTH.net (and no doubt others) that can help.

73s Mike