http://wiki.dragino.com/index.php?title=Getting_GPS_to_work_on_Raspberry_Pi_3_Model_B
/lib/systemd/system/hciuart.service:
After=dev-ttyS0.device
systemctl stop serial-getty@ttyS0.service
systemctl disable serial-getty@ttyS0.service
reboot
apt-get install gpsd gpsd-clients python-gps
systemctl stop gpsd.socket
systemctl disable gpsd.socket
gpsd /dev/ttyS0 -F /var/run/gpsd.sock
cgps -s
/etc/default/gpsd
START_DAEMON="true"
GPSD_OPTIONS="-n"
DEVICES="/dev/ttyS0"
USBAUTO="false"
GPSD_SOCKET="/var/run/gpsd.sock"