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FreeDV and SmartSDR

N3WWL Member ✭✭
edited January 2023 in Third-Party Software

Having difficulty setting up FreeDV v1.8.6 with SmartSDR v2.8.1. Hardware setup is…

Microphone plugged in to PC line in input. Flex 6300 speakers are Bose Companion 3 which has an additional input for connected PC sound card.

I have the FreeDV waveform installed and FDV engaged in SmartSDR as well as DAX engaged. Unable to acquire PTT command via FreeDV Hamlib for Flex 6xxx, but was successful using the Kenwood TS-870 option.

Can someone help me set up the Recieve and Transmit tabs in FreeDV as well as proper settings in SmartSDR? I am certain I have something awry as I can hear the digital sound of FreeDV when trying to transmit voice. Hope I’ve successfully explained my dilemma. Thanks in advance for any help.


  • N1AI
    N1AI Member ✭✭
    > I am certain I have something awry as I can hear the digital sound of FreeDV when trying to transmit voice.

    Me too. I'm new to SmartSDR, and am running it on a new PC so there are a lot of unknowns. I too am hearing the digital carrier coming back at me on my headphones when I hit PTT. Hopefully it's a simple mistake. I do not have MON selected i.e. audio monitor is off.
  • Hi all,

    Here are the settings that work for me on the 6300 if you're using the FreeDV application:

    Receive tab:
    Input To Computer From Radio: DAX Audio RX 1 (or whatever DAX ID you're using)
    Output From Computer To Speaker/Headphones: whatever you're using for speakers/headset

    Transmit tab:
    Input From Microphone To Computer: whatever you're using for microphone/headset
    Output From Computer To Radio: DAX Audio TX

    PTT/Hamlib: Kenwood TS-2000 on whatever COM port you're using for CAT control

    DIGU mode (or DIGL if on 40 meters or below)
    DAX turned on
    PC Audio turned off/volume lowered to 0
    FDX turned on (though this probably doesn't matter)

    Let me know if that helps! If not, we can debug more closely and figure out what's going on.


    -Mooneer K6AQ (one of the maintainers of the FreeDV project)
  • N1AI
    N1AI Member ✭✭
    Thanks for the settings.

    I tried them and did not see a change.

    After more investigation, it seems the problem it is good old fashioned RFI that enters via the PC's audio path.

    I notice the strength of the sound in the headphones increases with increasing values of RF PWR on the Flex.

    I am looking at the windows 10 Sound setting app, and I do not see it showing a level when I transmit, so the sound is not being generated by the PC towards the headphones.

    I switched to USB and at full power I'm hearing a small bit of RFI, not as noticeable as in FreeDV mode, but still noticeable. When transmitting in AM it's much more noticeable.

    So, that seems to be the issue. I hadn't noticed it till now because as I once wrote this is a new PC setup for me, and I typically have the headset and mic directly attached to the FlexRadio especially when transmitting. Guess I need to consider measures to improve the PC RFI situation.

    Dave, N1AI
  • N3WWL
    N3WWL Member ✭✭

    Got it! Working properly now...thank you!

    Jay, N3WWL

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