In 2014, I was an Iowa State University student studying electrical engineering. Through the campus amateur radio club, I learned of a group of students flying small weather balloons for fun. I had seen a few near-space balloon flights on the internet before, but had never pursued it much beyond a daydream. This sounded like fun! Now the story of where all that would take me, and the influence it held on my eventual career is a tale for another blog entry. One of the cool parts of this ballooning endeavor, however, was playing with microcontroller-based tracking solutions.

The trackers I have designed for small sounding balloons have varied in size, design, and complexity over the years. But each of them have carried a similar feature set: GPS receiver, Low power microcontroller, and RF transmitter.

From left to right: My first balloon tracker, first to actually fly, most complex, most recent

The most recent revision of the tracker is what I am calling "TelemTrack". This name needs little explaination, but more than anything just felt catchy. TelemTrack is comprised of a Microchip/Atmel ATSAMD21G18A microcontroller, UBlox ZOE GNSS receiver, and Si4063 Transmitter. Power is delivered to each component using a TPS63031 buck-boost converter, and is most commonly fed by a single-cell LiPo battery. Additionally, TelemTrack uses both high- and low-side switching MOSFETs to drive auxilliary circuits such as camera timers and a pyrotechnic flight-termination system.

TelemTrack has not been without its growing pains, and as most projects are, has been an additive work in progress. Most recently I discovered the hard way that the SAMD21's USB system does not power up below 2 volts. This was an issue when attempting to assemble a 1.8V revision of the board for experimenting with solar power. Thankfully I was still able to get the board up and running at 1.8V, and read the SPI Flash chip's contents back over UART rather than the USB mass storage system as originally designed.

I will soon be releasing the hardware and firmware for multiple versions of TelemTrack, but as I am now in the process of undertaking a larger scale reorganization of my git repositories and file management, this will wait for the moment.

More information about my balloon flights and about TelemTrack will also soon be available on my QRZ page (W0PRN). I plan to update this post with additional photos and information shortly.