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Thread: Can anyone help decode these messages?

  1. #1
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    Can anyone help decode these messages?

    Hi all,

    I'm specifically looking for parameters that allow me to calculate local atmospheric conditions at the aircraft's position, e.g. I need to know IAS/Heading/Mach number. I have the ADS-B data in parallel, so can calculate temperature, pressure and wind vector from that. Do any of the following (some company internal) type messages contain that info to your knowledge?

    First example:
    All I know from internet resources is it's a data dump from the DFDR, there's a position Lat/Lon in there (S2350E11648), but none of the other data appears to match altitude/speed or any other parameters.
    [#2 ( 0/0) 06/02/2016 02:37:12 ----------------------------------------------------------
    Aircraft reg: .VH-NXG Flight id: QF1921
    Mode: K Msg. label: H1
    Block id: 36 Ack: 15
    Msg. no: D03C
    Message :
    #DFB028000000006230000000000000002600000
    4452178600011787-002200040017S2350E11648
    -009-0090003-002000200030005-009-002
    -007-000-003-011
    00967-00180003301930008550082904400

    Second example:
    What are SA messages?
    [#2 ( 0/0) 06/02/2016 02:14:00 ----------------------------------------------------------
    Aircraft reg: .VH-NXR Flight id: QF1823
    Mode: 2 Msg. label: SA
    Block id: 30 Ack: 15
    Msg. no: S17A
    Message :
    0EV021358V/


    Third example:
    What on earth is this? Is there some heading/mach data in there perhaps (e.g. 0.785514 M, 37135.8 ft altitude)?
    [#2 ( 0/0) 06/02/2016 01:12:46 ----------------------------------------------------------
    Aircraft reg: .VH-NJA Flight id: NC1991
    Mode: C Msg. label: H1
    Block id: 39 Ack: 15
    Msg. no: F13B
    Message :
    #CFB0, 253.667, 2122.17, 87.1154, 2140.25, 87.1154, 90731, 0.785514, 1, 0, 37135.8,
    8635, -16.5873, 82096,

    Fourth example:
    "startup screen" transmission?
    [#2 ( -1/0) 06/02/2016 01:06:53 ----------------------------------------------------------
    Aircraft reg: .VH-NJA Flight id: NC1991
    Mode: K Msg. label: H1
    Block id: 39 Ack: 15
    Msg. no: F11A
    Message :
    #CFBACMF230_CRUISE_S_20160206010638S.CSV
    ACMF SNAPSHOT REPORT 2016FEB06 01:06:38
    A/C VH-NJA
    SWVER 23.1 APPVER S.7.1 APPNAME OEM.ACM
    SIZE 2201
    190LDI25.5V23.1PM-V14
    R 2016FEB06 01:06:38 T 2016FEB06 01:06:38
    -
    Block End

    Fifth example:
    [#2 ( -2/0) 06/02/2016 03:37:36 ----------------------------------------------------------
    Aircraft reg: .9V-SRM Flight id: SQ0213
    Mode: C Msg. label: B6
    Block id: 38 Ack: 15
    Msg. no: F36A
    Message :
    /MELCAYA.ADS.9V-SRM07EE31C287234908A33C1D0DEB3AB2940B890887ECEA45E A978145BD400E36F0F4C004100DAADEA8C3F4

    Any hints greatly appreciated!

    Cheers

    - Balt
    Last edited by balt; 2016-02-06 at 03:40. Reason: added a fifth example

  2. #2
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    They tend to have keyphease WXxx for weather reports. And at the time or at last report positions (with GPS coords)

    Further H1 to/from data I scraped from interwebs..
    http://acarsonline.pbworks.com/w/pag...ssage%20Labels

    #CFBFLR or #CFBWRN = Equipment failure
    #DFB*TKO or #DFBTKO = Take off performance data
    #DFB*CRZ or #DFBCRZ = Cruise performance data
    #DFB*WOB or #DFBWOB = Weather observation
    #DFB/PIREP = Pilot Report
    #DFBEDA or #DFBENG = Engine Data
    #M1AAEP = Position/Weather Report
    #M2APWD = Flight plan predicted wind data
    #M1BREQPWI = Predicted wind info request

    http://acarsonline.pbworks.com/w/pag...20%28United%29

    But it can depend on carrier. Another aussie seems to have done a bit of homework on them.
    http://www.pprune.org/tech-log/46848...ml#post6816989
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

  3. #3
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    I take it you are near south australia?

    the SA message type may be a groundstation squawk for S.A, I cant remember the format they used here but the 2 letters denoted the city it originated from (NZ based)
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

  4. #4
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    Hi, thanks for the links. Those are indeed where I got most of my info from thus far. However, they don't help me decode the messages I posted. I suspect I'd need someone from the tech department in the airlines to help as some of the coding seems airline specific. The ACARS receiver is co-located with the ADS-B feed T-YBBE1 (middle-ish of WA - I seem to have about a 200NM RX range for the ACARS messages - South Australia is a bit further away still!)

  5. #5
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    Quote Originally Posted by balt View Post
    Hi, thanks for the links. Those are indeed where I got most of my info from thus far. However, they don't help me decode the messages I posted. I suspect I'd need someone from the tech department in the airlines to help as some of the coding seems airline specific. The ACARS receiver is co-located with the ADS-B feed T-YBBE1 (middle-ish of WA - I seem to have about a 200NM RX range for the ACARS messages - South Australia is a bit further away still!)
    Can't help with ACARS but you operate T-YBBE1? I spotted it for the first time a few days ago. You're in a good location to catch quite a few planes there. Welcome.

  6. #6
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    Indeed, I'm filling a bit of a gap there. The next feeder is about 300km away.

  7. #7
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    Looks like Oblivian has answered most of your questions, but thought I would provide a little more detail for a couple of your examples.

    Second example:
    What are SA messages?
    [#2 ( 0/0) 06/02/2016 02:14:00 ----------------------------------------------------------
    Aircraft reg: .VH-NXR Flight id: QF1823
    Mode: 2 Msg. label: SA
    Block id: 30 Ack: 15
    Msg. no: S17A
    Message :
    0EV021358V/
    This is a Media Advisory message. They are generated when a link (SATCOM, VHF-ACARS, IRIDIUM, etc..) status changes (Established, Lost) and are sent over any other media link that is available.

    Code:
    0 E V 021358 V /
    
    0      = Version Number
    E      = Establishment/Loss flag (1)
    V      = Media Identification (2)
    021358 = UTC Timestamp
    V      = Current Media Available
    /      = Delimiter (May contain free text after the delimiter)
    This message indicates that at 02:13:58 UTC, the VHF-ACARS link was established and the VHF-ACARS link was available

    (1) Flags:
    E = Media Established
    L = Media Lost

    (2) Media Types:
    V = VHF-ACARS
    S = Default Satcom
    H = HF
    G = Global Star Satcom
    C = ICO Satcom
    2 = VDL Mod 2
    X = Inmarsat Aero H/H+/I/L
    I = Iridium Satcom

    Fifth example:
    [#2 ( -2/0) 06/02/2016 03:37:36 ----------------------------------------------------------
    Aircraft reg: .9V-SRM Flight id: SQ0213
    Mode: C Msg. label: B6
    Block id: 38 Ack: 15
    Msg. no: F36A
    Message :
    /MELCAYA.ADS.9V-SRM07EE31C287234908A33C1D0DEB3AB2940B890887ECEA45E A978145BD400E36F0F4C004100DAADEA8C3F4
    This is an ADS-C (Automatic Dependent Surveillance - Contract) message, which is sent to an ATSU or AOC facility for surveillance and/or route conformance. There are different reasons as to why these messages are sent, but the most common reason is due to a Periodic Contract. This is a "contract" that is setup between the aircraft's avionics and the ATSU/AOC systems, which might say something along the lines of "Send me your position every 14 mins". The message is binary encoded and then converted into hexadecimal for transmission over ACARS.

    If we have a look at your message, it can be broken down into 8 parts and decoded as follows:

    Code:
    /MELCAYA.ADS.9V-SRM07EE31C287234908A33C1D0DEB3AB2940B890887ECEA45EA978145BD400E36F0F4C004100DAADEA8C3F4
     \_____/ \_/\_____/\____________________/\__________________________________/\__________/\________/\__/
        1     2    3             4                             5                       6          7     8
    
    1. IATA destination address (MELCAYA = Melbourne Centre)
    
    2. Application type (ADS = ADS-C message follows)
    
    3. Aircraft registration (9V-SRM = Singapore Airlines Boeing 777-212ER)
    
    4. Basic Report
    	a. Position        = -25.039215, 113.754673 @ 37000 feet
    	b. Timestamp       = [HH]:37:35
    	c. Figure of Merit = Two or more NAV units are operating to indicated accuracy, TCAS is providing valid data, Accuracy is < 0.25 nmi
    
    5. Predicted Route Group
    	a. Next Waypoint     = -29.208870, 116.023521 @ 37000 feet
    	b. ETA to Waypoint   = 2028 sec
    	c. Next Waypoint + 1 = -30.553493, 116.631718 @ 23508 feet
    
    6. Earth Reference Group
    	a. True Track    = 154
    	b. Ground Speed  = 489.5 kts (906 km/h)
    	c. Vertical Rate = 16 fpm
    
    7. Meteorological Group
    	a. Wind Speed     = 13 kts (25 km/h)
    	b. Wind Direction = 240 (South West)
    	c. Temperature    = -43C
    
    8. CRC
    Hope this helps!

  8. #8
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    Hi,

    currently writing a decoder for several acars messages. Managed to decode messages from the Flight Management Computer (Routes, Load data etc.) and also Airbus (AXX) Cruise Informations (Engine Data etc.).

    How did you manage to decode the ADS data?

  9. #9
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    ADS messages can be decoded by referring to "ARINC Characteristic 745". Other handy ARINC specifications relating to ACARS are 618, 622 and 623

    A bit of creative "Googling" might yield you the document on the internet somewhere, however the publications are usually purchased from ARINC for a hefty price (not usually worth it for hobbyists).

  10. #10
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    Quote Originally Posted by ausmez View Post
    ADS messages can be decoded by referring to "ARINC Characteristic 745". Other handy ARINC specifications relating to ACARS are 618, 622 and 623

    A bit of creative "Googling" might yield you the document on the internet somewhere, however the publications are usually purchased from ARINC for a hefty price (not usually worth it for hobbyists).
    Yepp, did some googling - and found some interesting docs

    So, ADS decoding is done - also the Airbus FMS system. Currently trying to make sense of CPDLC - But the ASN.1 decoding is not that easy.

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