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  • som svar på: Audio decoding #9582
    Rabbe Fogelholm
    Deltagare

    It is sad to hear that the Old Lady is not fit to sing out over the oceans this summer. Let’s hope for a steady and fast recovery.

    Analyzing old recordings can be done anytime though! There is now a version 3.0.0 of the gerke-decoder program, where adaptivity against frequency drift and fading has been added.

    The program expects input in .wav format and prints out the Morse code message as cleartext. Information about audio frequency, words-per-minute rating, timing of inter-character spaces, etc can be printed too. The signal can be displayed graphically for studying dashes and dots shapes, garbled characters and such.

    Recordings in .mp3 format work well also, after converting to .wav format with some tool like Audacity.

    By default the program listens for audio in the comfortable audible range, but a different frequency range can be specified – even up at 17200 Hz if a recording of the raw antenna signal has been made.

    Find the program here: https://github.com/fowlay/gerke-decoder

    Building from source is straightforward on Linux. If you don’t have a Linux box you may instead use this pre-built executable jar: https://privat.bahnhof.se/wb748077/radio/3.0.0/gerke-decoder.jar

    Comments and ideas are always welcome.

    som svar på: Audio decoding #9220
    Rabbe Fogelholm
    Deltagare

    The UN Day SAQ transmission is approaching – so what could be a better time for an updated version of ”gerke-decoder” 🙂

    The latest addition is a decoder routine based on least-squares fitting of straight line segments to the signal data, thereby locating the dashes and dots. My hope is that this could be a bit more noise insensitive than the other decoders, which all look for on/off transitions of the signal in one way or the other.

    As before, try it out if you like: https://github.com/fowlay/gerke-decoder – if you have questions I will try to help, here or on github.

    som svar på: Audio decoding #8989
    Rabbe Fogelholm
    Deltagare

    I have uploaded a new version (2.0.1) of gerke-decoder. More filtering and decoding options are available, please see the README.md file. If you recorded one of the recent SAQ transmissions it may be fun to try and decode it. Any feedback welcome, here or on github: https://github.com/fowlay/gerke-decoder

    som svar på: SAQ transmission on October 24th 2020 (NOT FOR QSL) #8659
    Rabbe Fogelholm
    Deltagare

    Outdoor recording in Sollentuna, Sweden, JO89xk. Very damp weather and less-than-ideal antenna. Capture of the SAQ signal made directly with Audacity on laptop and exported as 44100 samples/s 16-bit mono WAV file.

    Offline analysis of the WAV file indicates that SAQ was sending at 17206 Hz?

    Using the very versatile HDSDR program (www.hdsdr.de) in CW mode I was able to write down the message of the day, after really many listenings due to poor S/N ratio. A lot of fun; thanks to all who made this possible!

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