[AudioI] People Digest, Vol 21, Issue 10

[Christopher Hunter]

> 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