I like flying high altitude balloons (HABs) . The normal mode of operation is APRS on 144.390 MHz and sometimes a secondary UHF APRS beacon is used. This is limited to 1200 baud and the available beacons can be heavy and/or expensive. Also you have to be a licensed amateur radio operator to control the APRS beacon. LORA is unlicensed and may open up HAB'ing to the unlicensed. Most of the beacons don't have easily accessible I/O for sensors and controls. The LORA gear comes as transceivers so control of HAB functions are possible.
For this try I had just a few days, so I ordered Adafruit Feather LORA boards and GPS shields. Combined with a 2000 mAh Lipo battery the beacon weights in at about two ounces. I 3D printed a little case for it and will string it on the flightline. The case adds about an ounce for a total of three ounces. Both the m0 and 32u4 Feather versions were tested. The 42u4's have sufficient throughput for the task and they do use less power .
I chose a 2000 mAh battery in hopes that the beacon will remain in operation for days if needed. Sometimes it is and most of the commercial beacons have a run time of a day or so.
Currently I am sending the GPS sentences with CR/LFs so they display nicely and should feed some software. I hope I don't have to convert to APRS messages - too much work.
For the beacon I am using a 6.5" piece of stranded silicone wire as a 434 MHz quarter wave whip and for the receivers I mounted the SMT uFL connectors on the Feather boards and will use mag mount roof top antennas while chasing.
I am using the RadioHead library for LORA and am trying to parse the GPS sentences to make them more readable. So far the Adafruit GPS library is fighting with RadioHead. The examples programs suggested 434 MHz so I tried listening on an RTL/SDR and a handheld ham radio. It is pretty quiet there to my surprise.
The LORA link is running at it's slowest rate with BW = 500kHz, coding = 4/8, spread = 4096 chips/symbol.
I am sending complete NMEA RMC sentences and using PC software to plot the beacon's location. I also have the receiver software output the sentence and RSSI to a log.
The code for becon/receiver and .STL for box will be posted soon. The box will be redesigned for more thermal insulation. I am going to fly the beacon soon and will post a date/time and location for the launch and predicted flight path. At it's apex the HAB will have a ~425 mile range circle.