Streamlined Unit

[hudsonsecurity]

Great work here. I am trying to build a more field realistic prototype with a pi zero and a hat that has the audio output and input I think eliminating the USB is a good idea for sound quality, footprint and battery. I am currently looking for a hat that can accomplish this on the rpi zero. Have you researched this at all? Thanks.

[aarmono]

I looked into it a little but wasn't able to find a hat that had two audio inputs and two audio outputs.

Probably the most promising one I found is the Codec Zero since it has a built-in microphone and can drive a speaker; so it'd be a good candidate for something that you attached to the radio itself. But you'd still need a second audio interface, and I don't know if you can connect more than one.

[hudsonsecurity]

@aarmono you can get micro hdmi to 3.5. If we have a built in microphone you will have to keep the transceiver right next to the radio and would remove the ability to use the APKR with a push to talk or wired input from a headset. The micro hdmi will probably have to be used if we want a decent COTS solution. I have some pi z coming in soon with a USB hat to eliminate the hub at least and low profile usb audio adapters. I intend to have a 3d printed case with these ports exposed.

[hudsonsecurity]

Can you also share which hub you're using for the pi zero? Thanks.

[aarmono]

I'm just using a USB3 hub I already had with a USB OTG adapter cable. I think I bought the hub from Staples some years back.

I also tried using one of these, but I couldn't get it to work right; so I couldn't recommend it.

[hudsonsecurity]

What issue where you having? I have a similar hat coming in from adafruit.

[aarmono]

The hub didn't seem to be operating at max speed, so the audio would stutter when two audio devices was plugged in. In some cases that issue would be resolved by plugging in the OTG adapter cable even if I didn't plug anything into it.

If your hat plugs directly into the USB port instead of trying to tap into test points on the board you may have more success,

I'll also note that even my Staples USB hub was a bit flaky, where I had to plug the audio adapters into certain ports on the hub for everything to work correctly. My guess was certain ports were sharing bandwidth with each other that caused issues.

[hudsonsecurity]

Same issue with the zero4u hat. Only one downstream or something like that. I switched over to pi 3b. I got both devices loaded out and found radio input and headset out but can't seem to get any messages through. I suspect my issues lie in the settings of the radio and headset on the pi. Still diagnosing with minimal tools.

Do you have any platform where can communicate in real time? Thanks.

[aarmono]

I made a video a few months back that goes over the process I use to get two pi devices talking to each other. The gist of it is I start out just getting a Pi to speak to itself by connecting the radio out to the radio in, and adjusting the settings on the audio devices until I can hear myself through the headset. Once that's done on both devices I connect them with a cable and adjust tuning as needed, then once that's done I use radios. I find that incremental process works very well. The most common problem I find is clipping on either the radio output or radio input; the modem doesn't need a particularly strong signal to demodulate correctly.

As for real-time communication, I'm pretty out of the loop on what's in use these days. If you have a platform you use I may be able to accommodate.

[hudsonsecurity]

which headset are you running? I just realized my old headphones/mic wasn't cutting it.

[aarmono]

I use these that I had lying around, but only for testing purposes. I probably wouldn't recommend them for field use since they're quite bulky.