Digital Voice Decoding with RTL SDR (RTL2832), DSD and SDR Sharp

Tried to decode some DMR/MOTOTRBO digital voice channels with DSD and RTL SDR RTL2832. Quality of decoding is quite poor but usually intelligible, not too su…

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25 replies
  1. Superphish
    Superphish says:

    Hi, The software is literally called “Virtual Audio Cable” (google for
    their download page). There’s also a free one that should work that I
    recently found called “VB-Cable”.

    Reply
  2. Станислав Лукьяненко
    Станислав Лукьяненко says:

    Most likely, my signal is not a digital voice, because it’s dynamical
    characteristics is not like for voice: signal is continious, there are some
    periodical ‘peaks’ in about 10 sec, but there are no other fluctuations.

    Reply
  4. Superphish
    Superphish says:

    Hi, for VAC is didn’t change anything, just default settings. For DSD I
    used the -xr flag as my received signal is an inverted MOTOTRBO signals. In
    SDR# I used NFM, and I found that a low filter order or 10 worked best and
    that filtered audio seemed to help a little. You’ll need to fiddle with the
    volume sliders and find a range that works well for yourself since all
    sound cards are different.

    Reply
  8. Станислав Лукьяненко
    Станислав Лукьяненко says:

    I tried to decode channel that is most likely digital voice with DSD, but
    no decoding happens. Using virtual audio cable and other settings as in
    your video (filter order to a value of 10, use filtered audio and set dsd
    to high CPU priority). What can be wrong? Video sample of my signal
    available at my channel.

    Reply
  9. Superphish
    Superphish says:

    I just tried running DSD on the sound from your video but got nothing. So
    either the video sound quality was not good enough, it’s not digital voice,
    or it is but it is a format not recognised by DSD.

    Reply
  13. Andromeda Strain
    Andromeda Strain says:

    I used VB-cable with RTL but my old computer works better with a
    discriminator feed from an old Uniden scanner. That way only one program,
    DSD, is running.

    Reply
  14. Norbury53
    Norbury53 says:

    LOL It’s about as far from London as it’s physically possible to get and be
    on dry land – bloody Yanks (shakes head) 🙂 Mind you, it’s entirely
    possible that there is a London in NZ so maybe I speak too soon… 😉

    Reply
  15. Superphish
    Superphish says:

    Hi, sadly you cannot listen to encrypted digital with this, only
    unencrypted. I don’t believe it is possible to decode encrypted currently,
    and probably won’t possible be for the foreseeable future.

    Reply
  18. bahathir
    bahathir says:

    Nice demo. 🙂 I also did the DSD, but using GNU/Linux in command line
    youtu.be /qPWD4imXXsc Yeah, a little bit complicated, but, it works 🙂
    Thank you.

    Reply
  19. Superphish
    Superphish says:

    Do you get any sort of text scrolling from DSD on this signal without extra
    command line settings? If you do but the sound is garbled, it’s probably
    digital voice but DSD detected the wrong setting. Type dsd -h into the cmd
    line to see more settings. If theres no text scrolling then it’s probably
    not digital voice, or DSD is not receiving audio properly. Make sure SDR#
    is outputting to virtual audio cable. Also, I had to set virtual audio
    cable to my default audio recorder for DSD to find it.

    Reply
  20. Tim Mattison
    Tim Mattison says:

    Digital voice decoding demo using SDR#. This is exactly what I imagine a
    lot of people are going to be doing right away. Time to sell my old
    scanner! 

    Reply
  21. Thomas Dorr
    Thomas Dorr says:

    Digital voice decoding demo using SDR#. This is exactly what I imagine a
    lot of people are going to be doing right away. Time to sell my old
    scanner! 

    Reply
  22. Johnny D
    Johnny D says:

    can you help me when i start dsd+ it just shows me what sound cards and
    stuff that I have it does not scroll showing data but on the very top it
    shows some kind of number lvl +6% s/s += and some numbers 

    Reply

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