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Decode off-the-air Winlink message - request for programming help

Discussion in 'Working Different Modes' started by KX4O, Aug 6, 2019.

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  1. KX4Z

    KX4Z Ham Member QRZ Page

    And the funny thing.....EVERYONE should be in favor of getting such a monitor matter what their position on any of this stuff. There should be dozens of people offering help and working on portions and supporting the effort.

    Hmmm.....another idea just hit me --- turns out there is public domain code for MINICOM as well....and THAT might be another avenue to get this working quicker.......

  2. N8OHU

    N8OHU Ham Member QRZ Page

    It's not that nobody can do it, it's that nobody else wants to, because some of them believe that it should have been done by the WDT from the beginning. And those that have used the code examples that the WDT has been linking to for their own interoperable applications simply don't see that as an interesting way to spend their time. What's amusing is that what KX4O proved is little different than what is the current case with FLMSG if you don't get perfect decode of that compressed transmission.
    KX4Z likes this.
  3. KX4O

    KX4O Ham Member QRZ Page

    All true, but let's be clear... neither side has (or perhaps had) an interest in successfully decoding Winlink exchanges over the air.
    • Some Winlinkers offered a prize to anyone who can decode off the air thereby promoting its alleged security from over the air monitoring. This arguable led to an increase in its popularity as some users touted security as their reason for using it.
    • Some anti-Winlinkers pointed to this as evidence of Part 97 violations concerning "for the purpose to obscure." No doubt some had/have that purpose, but our effort here erodes that considerably.
    • Technical elites certainly made no bones about the notion ARQ relay of a compressed file was "impossible" to decode over the air. Impossible was what set me in motion since all of us with at least some familiarity with the guts of the modes and methods saw that as low hanging fruit to pick. Absolutists are funny people especially when they put their technical credibility on the line with such pursuits.
    Anyway it's been fun to watch the dialog of most who stay tuned into this subject insert modifying words into their previous claims such as "almost" or "difficult" in place of "impossible." One can argue our work here is done. From here on it's just polish.
    WJ4U and KX4Z like this.
  4. KX4Z

    KX4Z Ham Member QRZ Page

    What does WINLINK have to do with this? It was done by Roubelat.
  5. KX4Z

    KX4Z Ham Member QRZ Page

    All very true
  6. N8OHU

    N8OHU Ham Member QRZ Page

    Who developed the compression technique isn't the relevant part to those that object to Winlink's use of compression. It's that there was no apparent effort to release a way to decode what was being sent over the air, even though other similar techniques that do have available decoders have exactly the same real-time decoding issues. And that is the fatal flaw in the argument, to me.
  7. KX4Z

    KX4Z Ham Member QRZ Page

    What other similar techniques are you talking about?
  8. N8OHU

    N8OHU Ham Member QRZ Page

    flmsg, from the NBEMS suite, which uses fldigi as the modem, uses LZMA compression, and if you do not get the whole message without errors, it won't decode.
  9. KX4Z

    KX4Z Ham Member QRZ Page

    OK, can you elaborate on this for me I’m not quite sure what point you’re making.

    1. Is flmsg ARQ or just FEC?
    2. Is source code for F L. message & fldigi available?
    3. Can it route messages through several stations to reach a distant recipient? Or is it only peer to peer?
    4. Has it been adopted by any federal agency?

    ( It has been a long while since I used those, we found it easier to just teach WINLINK after we tried both. Many groups do well with the F L. digi line)

    Thanks for any answers, Gordon
  10. KX4Z

    KX4Z Ham Member QRZ Page

    Is there any existing already created decoder that allows you to read F LARQ/F LMSG / F LDGI transfer of compressed binary files, if you are not the intended recipient?

    It seems to me that they are in very nearly the same situation as WINLINK (except that their system is more primitive). One could surely build a monitor, but I am not aware of any out there at the moment.

    Am I missing something?

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