By far the largest and heaviest component on my previous tracker was the FSA03 GPS receiver, and most of that was the Sarantel antenna. That antenna is amazingly good (it picks up a signal on my desk where there’s very little direct view of the sky), but it is heavy. So having received a new GPS module from HAB Supplies with a tiny and very lightweight antenna, I was keen to try it out. The module weighs about 1.5g and is slightly smaller than the Arduino Mini Pro I use for my flight computers. That tiny white rectangle at the front is the antenna!
So first job was to connect these two up, then load some firmware to confirm the GPS is working:
Unsurprisingly, the antenna isn’t as sensitive as the helical Sarantel one. That’s not a problem for weather balloon flights though, as they have a full view of the sky.
I then added the usual set of RFM22B transmitter, BMP085 pressure/temperature sensor, and DS18B20 temperature sensor on a short lead (for measuring the temperature outside the payload). So here’s the final tracker, just needing batteries, antenna and some insulation:
Total weight of this tracker is a mere 7.5 grams (that’s less than the GPS receiver/antenna on my previous tracker!).
To test I programmed the Arduino with the software for my previous small tracker, modified slightly to use a different modulation method and to run at 6 times the speed (300 baud rather than 50). It worked fine using my Yaesu FT790R as a receiver:
I plan to fly this tracker on my next flight at the end of March.