Raspberry pi3
OS: Raspbian Stretch Lite https://downloads.raspberrypi.org/raspbian_lite_latest
GPIO:https://www.raspberrypi.org/documentation/usage/gpio/
初期設定 SSH enable, Wifi, Filesystem,VSFTP（ Root ログイン書込み許可 最終的にaccess denie)
GPSD: http://www.catb.org/gpsd/
apt-get install gpsd gpsd-clients python-gps
gpsd
DEVICES=”/dev/ttyAMA0 /dev/pps0″
GPSD_OPTIONS=”-F /var/run/gpsd.sock -b -n”
############################# config.txt dtoverlay=pps-gpio,gpiopin=18 ############################# apt-get install pps-tools
ppstest /dev/pps0
apt-get install ntp
ntp.conf
# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
driftfile /var/lib/ntp/ntp.drift
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1 mask 255.255.255.0
restrict 192.168.11.0 mask 255.255.255.0
restrict -6 ::1
server ntp.nict.jp iburst prefer
server 127.127.22.0 minpoll 4 maxpoll 4
fudge 127.127.22.0 flag3 1 refid PPS
EOS
ntpq -p
watch -n 16 ntpq -crv -ccv -pn