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I've been working on open-source balloon control software [1] for my own balloon project that I've been building on/off for about six years. I am hoping to use
by chrissnell 11y ago
I've been working on open-source balloon control software [1] for my own balloon project that I've been building on/off for about six years. I am hoping to use a software modem to bridge between the RF and my AX.25 packet reader/writer [2] because I wanted to save weight. Payload weight is the name of the game in the balloon hobby--the lighter your payload, the less you have to inflate your balloon and the higher it will fly before it bursts. Even an ounce matters and the competitive altitude record balloons are invariably tiny, single-board, all-in-one payloads that are built around a single low-power microcontroller.
There are a couple of good open source options for software-based AFSK APRS modem/TNCs:
Dire Wolf: https://github.com/wb2osz/direwolf https://github.com/wb2osz/direwolf
minimodem: https://github.com/kamalmostafa/minimodem https://github.com/kamalmostafa/minimodem
You'll still need a USB sound card though, which adds weight and cabling. I would love to see some open-source SBC hardware a la Beaglebone Black or RasPi that had a high-quality sound card built onto the board and wired through a Molex-type plug that was suitable to the bumps and bounces of flying.
[1] https://github.com/chrissnell/GoBalloon https://github.com/chrissnell/GoBalloon -- This was my first project in Go and while it works well, it now looks pretty ugly to me with a year and a half of Go experience under my belt.
[2] https://github.com/chrissnell/GoBalloon/blob/master/ax25/decoder.go https://github.com/chrissnell/GoBalloon/blob/master/ax25/dec...
- Sanddancer 11y agoWhat about using one of the i2s daughterboards for the pi, instead of a usb sound card? The Pi has all-in-one shields that work out of the box, but the bbb will need a tiny bit of wiring to make it work.
- j_s 11y agoThere are some tiny USB sound cards these days! (Not sure if the quality meets the requirements though.) http://plugable.com/2014/09/23/plugable-usb-external-audio-windows-mac-linux-chromebook http://plugable.com/2014/09/23/plugable-usb-external-audio-w... http://www.audioquest.com/usb_digital_analog_converter/dragonfly-dac http://www.audioquest.com/usb_digital_analog_converter/drago...
- normaldotcom 11y agoI've been working on a balloon controller as well, although mine is incredibly bare-bones [1]. It only reports position, altitude, and temperature; but since it's so minimal it only weighs around 2 grams. For your use case, you might want to consider a small external microcontroller that handles TNC functionality, this /might/ be smaller and more lightweight than a USB sound card. Your payload controller software looks pretty awesome--nearly makes me want to launch a balloon with a full Linux single-board computer! [1] http://protofusion.org/wordpress/2015/10/featherhab-2-gram-high-altitude-balloon-tracker/ http://protofusion.org/wordpress/2015/10/featherhab-2-gram-h...
- chrissnell 11y agoI've tested my code with the TNC-Black from Coastal Chipworks and it works well. Weight isn't a huge issue on my flight; I'm focused on high altitude photography. It's just more fun for me to do things in software whenever possible. I'd really love to do the mod/de-mod in pure Go. There is an interesting example of a modem in Go but I have much more learning to do before I could write one of these for AFSK: http://bemasher.github.io/rtlamr/ http://bemasher.github.io/rtlamr/
- chrissnell 11y agoAwesome tracker, by the way! I'm super jealous of guys like you with actual engineering skills that can put together a custom integrated package on a PCB like that. Would you consider putting up your schematics and Eagle files on Github or similar?
- normaldotcom 11y agoDefinitely! I have a couple issues I need to fix on the hardware so the board runs without mods, but I plan on posting all of the hardware/firmware very soon once I get that wrapped up.