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Show HN: We chased a weather balloon across Montana and never found it (radi8.dev)

3 points by radeeyate ↗ HN
Since April, I have been working with Sam Flynn (https://drook.dev) to make this balloon payload, UpLink. We did a similar launch last year with Hack Club but this was our first independent launch.

UpLink was a 491 gram payload testing the insulation properties of 3D printing filaments, while also transmitting 320x240 images over a radio link -- up from the 18x10 images last year!

This is a writeup on our engineering process, mistakes made, and learning experiences. It covers:

- Custom electronics designed in KiCad

- Firmware design

- Results from the data we received on the ground

- Image transmission

- Launch day logistics, and where things went wrong

All hardware, software, firmware, and CAD is available on GitHub: https://github.com/radeeyate/UpLink, licensed + certified as open source hardware: https://certification.oshwa.org/us002826.html

If you just want to see the images received, I put up a gallery here: https://uplink.gallery.radi8.dev/

If you have any questions, comments, or concerns, let me know. I'm happy to answer anything!

25 comments

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macintux
Impressive level of detail, impressive work for anyone, much less high school students.
ErroneousBosh
The images seem a bit scrambled, presumably due to missing data blocks. At that low a resolution, have you considered maybe Robot36 SSTV?
radeeyate
The problem with SSTV is the power required. From some looking it seems that transmitting would need at least 5 watts. This wouldn't be feasible running on the balloon, as it was powered by Energizer Ultimate Lithium batteries.
ErroneousBosh
Oh, yeah FM transmitters can require a fair bit of power.

What is it using then, LoRA type stuff?

radeeyate
Yep, the radio link runs LoRa on the 33 cm band (915 MHz)
iberator
you should read about ham radio mate... there are some amazing protocols and modulations to save power.

And of course: 7mhz 0.5W transmitter could be heard worldwide... no jokes.

radeeyate
I have my license, and I noted about this in the post. I experimented with the U4B for tracking and found it not to be reliable enough. For the future, I'm planning on using the 70 cm ham band for LoRa.
ErroneousBosh
It's on a balloon, right?

No point pissing about. Go to 4 metres, dangle a J-pole from the bottom.

There, now you've just about got Over The Horizon capability.

verelo
Wait, so at 28k/km the temp goes up to 15C?

This is all very cool but this temperature reading caught my eye as unexpected.

radeeyate
I found that surprising too! This probably isn't a completely accurate number, as the sensor is black and likely experienced some heating from the sun. Something also worth noting is that different layers of the atmosphere experience different temperatures, so while the 15c measurement may have been a bit high, it's still pretty close to what it actually was: https://www.noaa.gov/jetstream/atmosphere/layers-of-atmosphe...
verelo
Amazing. I love that i didn't know this. When i was studying weather as part of my pilots license i noted the basic mental math that i'd lose ~2 degrees celsius per 1000ft, but never did i take a second to ask, what happens when i go up 28,000 km.
newtwentysix
the article says 28.42 km. where are you seeing 28000 km ?
happyopossum
Fun writeup! I was surprised by the part about styrofoam boxes though:

  Despite their popularity, they have a few disadvantages:

  They come in predefined sizes which mandate a certain weight allowance
  They cannot be flexible for your specific payload, making it hard to be efficient with payload layout
  They are expensive compared to more custom solutions
This shocks me, as styrofoam is one of the easiest materials in the world to cut, shape, fasten, and customize to your heart's content. I'm all for 3d printing stuff, but in the theater world we build a ton of very detailed (and shockingly durable) stuff out of foam all the time....

Buying a styrofoam box and just accepting that it's gotta be that shape and size feels like a huge waste.

rtkwe
Seems like the simple solution is a Styrofoam sheet, a $10 hot knife and some glue solves the customization problem almost trivially.
nkrisc
In my intro Industrial Design class long ago we fashioned styrofoam and many other kinds of foam into every shape imaginable with a hot wire, some utility knives, and contact adhesive. A wood rasp worked well for organic and rounded forms (wear a mask), though that’s probably not needed in this application.
radeeyate
I think another point I hadn't included was the flexibility I had with prototyping different boxes. The hardware was changing all the time, and being able to just 3d print another revision was very convenient.

If I did something like that with styrofoam, it probably would have gotten pretty expensive. The precision you get from printing was also a plus, as there needed to be slots for cameras, antennas, and circuit board mounting holes.

TylerE
What's expensive? You can buy a medium sized cooler for $5 at Walmart. That's a fair bit of foam.
wlesieutre
You can get a 4' x 8' sheet of 1" EPS insulation from Home Depot for under $20 (thicker available if you need it, costs more) along with compatible construction adhesives.

You do have to be careful with glue selection because a lot of solvents will dissolve it, but there's plenty that will work.

happyopossum
There’s something to be said for using the tools your comfortable with. I’m a woodworker by passion, and a technologist by trade so I dabble in everything from cnc to 3d printing to hand tools.

If I happened to be super comfortable with fusion360 and 3D printers and not my overstuffed workshop full of other tools, I’d probably make the same choice.

colingauvin
I live in Montana and routinely hunt the Musselshell river valley/Meagher county area. It's maybe my favorite place in the world. So few folks have been there, but spend some time there and you might just find yourself feeling depressed when you leave and not knowing why.

Glad to see other folks go through the area. The wind in Judith Gap is insane, so I'm surprised that you never found it. I'll keep an eye out when I'm out there in Sept/Oct.

Felger
"which would have otherwise been expensive for the budget of two high school students"

High school students !? You are more capable than most of adults from my country, even "of the trade" if I might say.

jmpman
I'd assume hydrogen is a significantly cheaper fill gas than helium. Other than the danger during filling, any other concerns?
radeeyate
That was really our main concern. Being our first launch, we didn't want to risk it and wanted to wait until we were more comfortable with the process until taking that step.