確認系のコマンド
GPSの起動と確認
- gpsd /dev/ttyAMA0 -n -F /var/run/gpsd.sock
- cgps -s
掴んでいる衛星の数などが表示される
║ Time: 2016-08-06T06:49:37.000Z ║║PRN: Elev: Azim: SNR: Used: ║
║ Latitude: 35. N ║║ 65 46 184 20 Y ║
║ Longitude: 139. E ║║ 71 21 031 00 Y ║
║ Altitude: 58.8 m ║║ 72 68 071 00 N ║
║ Speed: 0.2 kph ║║ 77 04 241 00 N ║
║ Heading: 0.0 deg (true) ║║ 78 13 291 00 N ║
║ Climb: 0.0 m/min ║║ 79 06 330 00 N ║
║ Status: 3D FIX (7 secs) ║║ 86 25 102 16 N ║
║ Longitude Err: n/a ║║ 87 60 032 00 N ║
║ Latitude Err: n/a ║║ 88 31 325 00 N ║
║ Altitude Err: +/- 46 m ║║ ║
║ Course Err: n/a ║║ ║
║ Speed Err: n/a ║║ ║
║ Time offset: 0.745 ║║ ║
- killall gpsd (動作確認のためだけなので）
ntpdの動作確認
- PPSの動作を確認する
# cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
# Parameters can be specified after the module name.
pps-gpio << pps-gpio がロードされることを確認
# ppstest /dev/pps0
trying PPS source "/dev/pps0"
found PPS source "/dev/pps0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1470466087.999157683, sequence: 272511 - clear 0.000000000, sequence: 0
source 0 - assert 1470466088.999161067, sequence: 272512 - clear 0.000000000, sequence: 0
source 0 - assert 1470466089.999163435, sequence: 272513 - clear 0.000000000, sequence: 0
- config を確認
# cat /etc/ntp.conf
~~
server ntp.nict.jp iburst prefer << PPSを使う場合基準時間の参照先 prefer の設定が必要
server 127.127.22.0 minpoll 4 maxpoll 4
fudge 127.127.22.0 flag3 1 refid PPS
~~
- 動作確認
# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
PPS(0) .PPS. 0 l - 16 0 0.000 0.000 0.000
*ntp-a3.nict.go. .NICT. 1 u - 64 1 5.696 109.951 2.323
# ntpq -c rv
associd=0 status=0115 leap_none, sync_pps, 1 event, clock_sync,
version="ntpd 4.2.8p3-RC1@1.3265-o Sun May 31 10:04:59 UTC 2015 (1)",
processor="armv6l", system="Linux/4.1.19+", leap=00, stratum=1,
precision=-18, rootdelay=0.000, rootdisp=8048.425, refid=PPS,
reftime=db500c70.26574bc5 Sat, Aug 6 2016 16:12:48.149,
clock=db500c71.e36d3c1e Sat, Aug 6 2016 16:12:49.888, peer=53328, tc=4,
mintc=3, offset=110.674804, frequency=-19.973, sys_jitter=0.003815,
clk_jitter=34.903, clk_wander=0.000
stratum=1 << PPS参照のため
offset=110.674804 << 110msecのズレを表す、NTPDを起動した直後ではoffset幅が大きいが、しばらくすると収束する。
5分位経つと、以下のように 30μsec 程度まで縮まった。
# ntpq -c rv
associd=0 status=0115 leap_none, sync_pps, 1 event, clock_sync,
version="ntpd 4.2.8p3-RC1@1.3265-o Sun May 31 10:04:59 UTC 2015 (1)",
processor="armv6l", system="Linux/4.1.19+", leap=00, stratum=1,
precision=-18, rootdelay=0.000, rootdisp=1.225, refid=PPS,
reftime=db500dd0.264b3e58 Sat, Aug 6 2016 16:18:40.149,
clock=db500ddf.d6defe38 Sat, Aug 6 2016 16:18:55.839, peer=53328, tc=4,
mintc=3, offset=0.035973, frequency=-19.183, sys_jitter=0.125790,
clk_jitter=9.062, clk_wander=0.157