/boot/config.txt
#GPS config
dtoverlay=pps-gpio,gpiopin=18
#Disable Bluetooth
dtoverlay=pi3-disable-bt
/boot/cmdline.txt
console=serial0,115200 を削除
sudo systemctl disable bluetooth.service
sudo systemctl disable hciuart.service
sudo vi /etc/default/gpsd
# Start the gpsd daemon automatically at boot time
START_DAEMON="true"
# Use USB hotplugging to add new USB devices automatically to the daemon
USBAUTO="false"
# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES="/dev/pps0 /dev/ttyAMA0"
# Other options you want to pass to gpsd
GPSD_OPTIONS="-n"
sudo systemctl enable gpsd
sudo systemctl start gpsd
/etc/ntp.conf
#pps-Only
#server 127.127.22.0 minpoll 4 maxpoll 4
#fudge 127.127.22.0 flag3 1 refid PPS
#tos mindist 0.2
#PPS Kernel mode
server 127.127.22.0 minpoll 4 maxpoll 4 true
fudge 127.127.22.0 flag3 1 refid PPS
# GPS (SMH)
server 127.127.28.0 minpoll 4 maxpoll 4 iburst prefer
fudge 127.127.28.0 flag1 1 time1 refid GPS stratum 15
# Fix False tickers
tos mindist 0.2
