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Introduction Pico 7 was the second flight of the new tracker and included many of the improvements mentioned in the last post. We also used a 20F 3.8V supercap on VIN. We also used the same balloon but with a lower free lift at 2g. Launch day The launch day had significant cloud cover again, but it was bright enough to transmit all the way up. The ascent went smoothly until it reached 7,300m when it started to descend. This was likely due to icing. Luckily it started to rise again at 2,500m and didn’t reach the ground. It went dark before reaching float but it woke up the following morning at a float altitude of 11.5km based on the pressure. As it was already over Ukraine there was significant GPS spoofing. ...

Introduction Pico 6 was the maiden flight of the new tracker. New Tracker It’s based around the STM32G071GB mcu and uses the same SI5351 clock generator and ATGM336H GPS common to other trackers such as Traquito and AG6NS. It uses the RT6150A buck boost converter to allow the tracker to be powered from as low as 1.8v. It also features mounting points to allow us to attach 2 panels to either side of the board. It also has a LPS22HB pressure sensor, which we plan to use with extended telemetry. Overall, this should allow for a lower power consumption, lighter payload and more data. ...

We used the same tracker as before but added a lithium supercapacitor in parallel with the solar cells. Initial testing showed that the tracker could complete roughly 1 transmission cycle (10 minutes) when powered by the supercapacitor with the panels in shadow. This should improve the reliability of the power supply to the tracker. We used the same pannel configuration as last time. We decided to use two Qualatex 36" balloons instead of one in an attempt to reduce the pressure in each balloon (the lift for the payload is split between the two balloons). In order to reduce the risk of static buildup we attached the balloons using a length of nylon wire so one floated above the other. ...

We used a Raspberry Pi Pico based WSPR tracker. It was powered by a 6 cell solar setup. We decided to use 10m WSPR due to the relative ease of managing the shorter antenna (compared to 20m) and good propagation during the day. We tested the setup by hanging it out of a window and managed to get a single spot roughly 15km away. Not great performance but at least we know it works. ...

We used a new custom tracker design based around the Wio-E5 STM32WL (very similar to the RAK3172) module and Quectel L80R GPS module. It had a tx interval of 5 minutes and a spreading factor of SF10 was used. It was powered using a 500mAh battery taken from a disposable vape. The whole system weighed 23g, which probably ended up being 25g after all the tape and string we added. ...