A University of Michigan Aerospace Engineering senior design team, sponsored by Lemos International and the Michigan Exploration Laboratory (MXL), is currently developing a global high-altitude balloon module they plan to fly around the globe by January 2020 on a homebrew hydrogen balloon. Lemos International has sponsored the module’s communications subsystem by supplying UHX1/SHX1 radios to the senior design team and supporting technical help.
The team needed a small, power-efficient, tunable VHF radio transmitter to be able to transmit position and payload telemetry (imagery, weather, magnetometers, and an IMU) over a global amateur radio network while in flight at an altitude of ~45,000 feet.
The project is aimed at opening a global high altitude balloon capability for the U. of Michigan Aerospace Engineering department in order to teach undergraduate students how to design electronics hardware, how to design vehicle payloads, how to conduct long-duration vehicle operations; as well as introduce complex embedded systems, RF, and (near) space systems.
One of the big challenges for the team was coming up with an architecture for downlinking data collected by the module in flight around the globe. The team decided that the global APRS network was the best option for downlinking both position and payload data. Since MXL was very familiar with the HX1 radios used on TrackSoars, the team went to Radiometrix for a frequency-agile option. Lemos International has generously supplied the team with 4 UHX1 radios and 1 SHX1 radio in order to be able to develop the global high altitude balloon module in the scope of their senior design class. When the team ran into technical difficulties in implementing homebrew software for the radios, Lemos Int’l helped the team gather the answers they needed!
So far, the team has developed a prototype module in order to test that the system can withstand atmospheric conditions at altitude and support long-duration operations. The module is powered by a supercapacitor and solar panels and is controlled by an Atmel ATMega328P processor. They have also verified that they can operate the radios supplied by Lemos, as seen by the spectral plots demonstrating they can tune the UHX1 radio modules to desired global APRS frequencies and beacon data. A second module will be developed in order to make the module smaller and more lightweight, improve data transmission SNR, and be ready for its global flight.
The images below show a 3D Altium rendering of the prototype balloon module the team will be testing this month, spectral plots showing we can tune the supplied radios, and an image of one of the team members (Daniel Gu) testing a radio module’s tracking capabilities on a tether with a handheld transceiver.
Thank you Lemos International and Danny Lemos!
Team Members: Alex Chen (20’), Daniel Gu (‘20), Ethan Prober (‘20), Justin Schachter (‘20), Ronnie Stone (‘20)
Faculty Advisors: James Cutler (AERO/MXL), Peter Washabaugh (AERO)
- Bluetooth International
- Bluetooth USB Adaptor
- Radio Modem High Power