Distributed APRS edge devices with Balena

There’s no shortage of DIY projects in the ham radio world, in particular when it comes to mating APRS with the infinitely hackable Raspberry Pi platform. But what I haven’t seen yet that could be really useful for getting your APRS transmission around those pesky (for radio transmissions) mountains and forests we have so much of in BC, Canada is a portable, distributable system of digipeaters/igates that can patch up some of those weak spots.

Say, for example, you’re heading deep into the weeds for some very off the grid hiking/camping - usually you might extend the range of your HT by setting up your mobile back at the truck to digipeat for you, but what if that trusty TM-D710 can’t reach back to civilization either? Maybe you’re pretty close & could use a battery operated box (or several) to digipeat your signal out of the woods, so to speak. Or maybe you’ve got decent cell reception & you’d like to use your SIM card/phone/wifi hotspot as a mobile gateway. Or some combination, say drop digipeaters to cover an area until you can set up an igate configured device where there’s cell reception.

My aim with this project is to provide some options to solve this situation, in stages (hopefully I’ll be able to get to them all one day) planned like so:

  1. internet gate mode; prove out the hardware & concept
  2. digipeat mode; be able to digipeat normal APRS activity
  3. glue them together; unify the configuration and management whether you’re looking at 1 to N devices
  4. test and polish, get the UX to something, well, usable

Bonus points: it could be fun to integrate a low cost transceiver (or multiple for cross band repeating). But given how hard it is to find any hardware these days that may need to be a project for the distant future.

For starters I’ll be focusing on the internet gateway device using a TNC (source TBD, thank you very much global component shortage…) connected to a commercial VHF transceiver. I’ll be working off a Raspberry Pi 3 primarily, but I have a few other SBC’s kicking around that may prove useful too; an aim here is to keep the software component hardware agnostic so, if all goes well, any SBC + TNC combination ought to do the trick, providing it’ll run BalenaOS.

I’ll post here with updates as I get deeper into the project & overcome any stumbling points. Same for the parts list; it’ll be largely governed by whatever stock is available/buildable right now.

VA7ADG

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Busy times! Well I’ve been having no luck procuring hardware, but when/if we ever start to see supply rolling out again, here are the top two TNC options I’m seeing for a Raspberry Pi:

TNC-Pi9k6

DRAWS Hat
https://nwdigitalradio.com/products/draws™?variant=39727287337133

Word of caution: there are many devices out there that are poorly titled and look like TNC hats but are, in fact, only cases.

On the software side I’ve also seen some challenges getting the base OS up and running, but at the moment I’m beginning to suspect a hardware fault on my RaspberryPi 3 which will require some more in depth investigation (see some odd LED behaviour, plus a persistent undervoltage warning despite digging up & trying several different USB AC adapters).

Will elaborate more if I find the root cause, might save someone else some headache later on :slight_smile:

At any rate, the goto information source for getting the base OS up and running has been Masterclass Overview - Balena Documentation

Next post will have results re getting APRS services running in a block (software implementation only owing to the aforementioned lack of hardware). Currently a WIP, here’s hoping the latest builder run churns out something that’ll run on this Pi :crossed_fingers:

Quick update to summarize things thus far: the hardware shortage is a major blocker. I’ve been checking periodically and there’s still no stock to be found for a TNC which has made testing anything impossible. While I currently have a block that might work, I can’t verify that anything actually does work at the moment.

So for the time being I’m going to have to pause this project & chip away at it as time permits whenever I manage to get my hands on some functional hardware. Fingers crossed that the DRAWS hat may be available sometime this fall :crossed_fingers: :crossed_fingers: