As understand it, some of the units have been flashed with a custom firmware that communicates with a binary protocol. After figuring out that it was communicating at a baud rate of 38400 instead of the expected default of 9600, I was able to read the following:
This is followed by about 20 more ,,,,,,,,, 's every second. I've left it outside for a while and verified that the 3Dfix pin is low, so it appears the unit is obtaining a lock.
I've also tried to send it the command to switch back to NMEA protocol: $PGCMD,16,1,1,1,1,1*6B , but no luck. I'd like to put it in NMEA mode as I need some of the information that isn't included in the DIYDrones binary packet.