Project Horus High altitude balloon project


Future launches

The blog has been quiet since launch due to catching up with real world commitments - thanks to all who have emailed me recently to congratulate us on the launch! :)

I am planning on launching more balloons, and have been experimenting with options for flight computers - whilst the Arduino was great, it was somewhat limited by its form factor - ideally future launches will carry a custom flight computer with GPS, radio & SD logging all on the one board.

I have been working on the design of such a board - here's a picture of the current design:

Isis flight computer

Isis flight computer

The board is based around 2 ATmega 328P microcontrollers - one acting as the core of the flight computer, the other dedicated to handling telemetry. This will allow the radio telemetry to be offloaded from the core, meaning more can be done whilst the lengthy RTTY transmission takes place.

I've switched from the Lassen IQ GPS module to the Falcom FSA03, which I sourced from Esawdust. This module is far more sensitive than the Lassen, and also features the Sarantel helical antenna, which performs in most any orientation. The module is also capable of providing fix data at 4hz.

The Radiometrix NTX2 25mW transmitter is also present on the board, as is the SD card used for logging. I've also included indicator lights to make launch & setup much easier. The board has a DIL header providing connections to system voltages & data pins on the core for connecting daughterboards which will house additional sensors/equipment.

With the radio offloaded to a dedicated processor, the board will be able to log position, temperature, pressure, humidity much more frequently - resulting in better data at the end of the day.

I've also been experimenting with PCB production - I bought myself a Dremel drill press & some 0.8mm tungsten carbide drill bits, and have whipped up some simple test boards - given that I'd never tried etching PCB's at home, I was rather happy with the results on my first board, an ATmega 328P protoboard whipped up in a couple of hours.

ATmega protoboard

ATmega protoboard

I'm looking at having the main board commercially produced, and will likely hand-etch the daughterboards to go with it.

As for future launches - I plan to launch the original flight computer at least once more, likely quite soon. I'll be experimenting with a few ideas in future launches: higher baud rates, coding (error correction) & eventually bi-directional communication.

Look out for more soon! :)

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