A key challenge for any system headed up into the upper-atmosphere region sometimes called near space is communicating back down to the ground. The sensors and cameras onboard many high altitude balloons and satellites aren’t useful if the data they collect can’t be retrieved. Often times, custom antennas or beacons are added to help. Looking at the cost and difficulty of the problem, [arko] and [upaut] teamed up to try and make a turn-key solution for any near-space enthusiast by building CUBEX, a wonderful little module with sensors and clever radio that can be easily reused and repurposed.
CUBEX is meant as a payload for a high-altitude balloon with a camera, GPS, small battery, solar cell, and the accompanying power management circuits. The clever bit comes in the radio back down. By using the 434.460 Mhz band, it can broadcast around a hundred miles at 10mW. The only hardware to receive is a radio listener (a cheap RTL USB stick works nicely). Pictures and GPS coordinates stream down at 300 baud.
Their launch was quite successful and while they didn’t catch a solar eclipse, their balloon reached an impressive 33698m (110,560ft) while taking pictures. Even though it did eventually splashdown in the Pacific Ocean, they were able to enjoy a plethora of gorgeous photos thanks to their easy and cost-effective data link.
At first I thought 300 baud would be useless for sending photos, but after looking at the .io page, it seems useful in a limited way. 320x240px photos at about 4kb each would take more or less 15 seconds to transmit per photo. Much better than I would have imagined, but they’re not very interesting beyond that feeling of doing something amazing for yourself. I think recovering the device and getting at the locally saved high resolution photos is still the way to go. A great job, nonetheless.
Hum, I work that out at 8×15=120 seconds unless you’re counting some fancy compression that gets you near 9600bps throughput.
It’s very likely I did the math wrong. I’m pretty bad at math and usually get the computer to do it all for me. I divided the approx. 4kb by the 300bps to come up with about 15 seconds. I see now I may have mixed bits and bytes. Where’d you come up with those numbers (for my personal improvement)?
2014 !
It even entered the 2014 hackaday prize. At least try a little bit?
Who is going to visit this guy. He did just give out a GPS invitation?