A bit more of a layout here using an outline

  • Inputs to Pi

    • Mic

    • Headset 1

    • Headset 2

    • Radio RX Audio

  • Outputs from Pi

    • Speaker

      • RX Audio from Radio only

      • GPIO Volume knob and mute

    • Headset 1

      • RX Audio from Radio, TX audio from Headset 2

      • GPIO Volume knob and mute for each stream

    • Headset 2

      • RX Audio from Radio, TX Audio from Headset 1

      • GPIO Volume knob and mute for each stream

    • Radio TX

      • Chosen by operators from Mic, Headset 1, Headset 2

        • Maybe GPIO Driven to choose? 

        • Unmute chosen input, mute others?



Also did a visual layout to a point and it can be seen here - https://www.dropbox.com/s/gpn3skosyu0looq/audio%20interface.jpg?dl=0

On Sat, Oct 30, 2021 at 6:57 PM Christopher Hunter via People <people@lists.audioinjector.net> wrote:
> Today's Topics:
>
>     1. Ham Radio Audio Mixer (Mike Maynard)
>
>
>
> Trying to build an audio mixer for a ham radio setup.
>
> My goal is as follows:
>
> I want to take audio from the radio, bring it into the pi, and send it to
> various outputs (one for speaker, headset a, headset b....)
>
> Then, I want to take mic audio from the 'selected' device, back to the
> radio.
>
> Furthermore, I want to take mic audio from headset a and headset b, and
> pass them directly to each other (as an intercom) while they still hear the
> radio audio.
>
> I am hoping to use the Octo for this.
>
> Would this be possible?   What might I need for software to do this?  Is it
> possible there is a better solution?
>
> I assume I am going to need some sort of amplification for the
> speakers/headphone outputs?
>
> Open to suggestions!
>
>
> Mike
> K2GC
>
Mike

The Pi is superfluous - what you're trying to achieve could be done
either with relays and a bit of CMOS logic, or CMOS switches (like the
4066) and a bit of CMOS logic.  You might need some op-amps to amplify
some of the routings, and if you're using your microphone input for
amateur radio, some bandwidth limiting (simple filtering) and some
compression and limiting might be in order to maximise your "talk
power".  If you need further advice, sketch what you're trying to
achieve, and drop me a line with your sketch, and I'll give you some
pointers.

Regards

Chris


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