I wrote some code to send SSTV because everything was either proprietary and didn't work, shareware and didn't work (and often with the original author gone Silent Key so no way to get the real version), or under some vaguely-specified licence and written with Tk widgets in Fortran or some damn thing.
I wrote it about 25 years ago and can't currently find it but it's one one of these hard disks in these here blue moving crates somewhere. It'd take less time to recreate than find, I suspect, especially if I also wanted to make it build nicely in gcc from this decade.
It just grabbed from a V4L2 source, and emitted a burst of Robot36 over the soundcard. In conjunction with a heavy-duty Tait T2000-family transceiver I used it to livestream a drive across Glasgow, slowly and noisily, sending one picture per minute which gave the poor PA transistor time to cool a bit ;-)
I've been working on some electronics stuff more recently, and I designed custom PCBs which read the voltage and internal resistance of the 12V NiMH batteries used by robots in FIRST Tech Challenge. It's not always easy to know how charged or healthy the batteries are for a match, or when it's time to get rid of them. They're pretty small and are easy to assemble. Rather that having a screen (which would take precious flash and pins on the ATTiny412), it just uses a WS2812B RGB LED.
I wrote the firmware in Arduino, which was a great learning experience because I typically work with CircuitPython or Go, where I'm less constrained.
For the past year, I've been learning a lot more about electronics, and in particular, designing PCBs, getting them manufactured, and assembled. I've come a long way from where I started, making little LED flashers shaped like trees for Christmas last year (everyone has to start somewhere!) where I'm now making small products with some of the super cheap ATTiny chips and writing code for them.
I really want to get more into microcontrollers, and design some more technical projects. I've been wanting to make a portable point-and-shoot camera for a couple years, though I've never been knowledgeable in that area to do it very well. Though, I'm finally getting to that point.
On a non-electronic-designing front, I'd love to learn more about networking and radios. I'm working on my homelab right now, and just got a nice switch to connect some free 15-year-old office PCs I also have. I'd love to get into AREDN, which is a 802.11 mesh network that can run on amateur radio frequencies.
I also want to write more about my projects on my website (https://radi8.dev,) where hopefully I can share what I work on more often than I currently do.
Image data and telemetry were sent in different messages, so it wasn't too much of a bottleneck. The images were about ~100 bytes while the telemetry was roughly 40.
Thank you for the kind words!
The fluorescence was originally meant to be measured with an AS7273 spectrometer (unfortunately bought a different one, still worked fine though), and measuring ~680 nm. Certainly not a great setup but it worked fine. Light was ambient through acrylic, and I found out far too late that UV blocking effects. Despite that, I feel like the data is still somewhat valid, maybe. I did do some testing with it back on earth, though I can't remember how it correlated.
> UV light, a form of energy, is defined as light having wavelengths between 100 nanometers (nm, 1 billionth of a meter in length) and 400 nm. [...]
> Most acrylic plastics will allow light of wavelength greater than 375 nm to pass through the material, but they will not allow UV-C wavelengths (100–290 nm) to pass through.
In terms of photonic permittivity,
Glass is better for cold frames and the like, because acrylic filters out UV light.
I first got into Raspberry Pi Picos, but I've also been experimenting with Esp32's and some of the nRF chips. I mostly do CircuitPython on them but Arduino is a supported platform on those I believe.
I got a couple of RP2040 boards recently and I'm amazed at how easy it is to just get stuff done. Between the native usb support and the circuit python support it's been a breeze. I just got a couple of boards up and running uart in a daisy chain. It was intimidating, but the circuitpython docs made it relatively simple.
I'm Andrew, and I'm a high school student who participated in Hack Club's Apex program, which funded 30 students to built high altitude balloon (HAB) payloads.
My project, StratoSpore, was an attempt to use algae fluorescence as a biological sensor for detecting changes in altitude and stratospheric conditions.
This challenge involved a full electronics and software design cycle:
- I designed PCBs based on Raspberry Pi Picos for sensor logging (AS7264 spectral sensor, temps, etc) and a Raspberry Pi Zero 2 W for data processing
- Implementing a highly lossy, custom compression algorith to compress 1080p images down to 18x10 pixels for sending of LoRA (915 Mhz) along with shoving a bunch of telemetry into 45 bytes.
- Unfortunately, the payload couldn't be recovered as it is stuck in a dense forest. I also had some GPS problems and had to splice some data.
This was a huge step outside my comfort zone and taught me about hardware design, logistics, and compression.
I'd love to hear and thoughts or technical critiques on the design of software. If you have any questions, I'd love to answer them. Code/hardware is on GitHub (https://github.com/radeeyate/stratospore), and I hope you enjoy the blog post!
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