chrony - BYO-NTP/recipes GitHub Wiki

Install chrony

curl -sS https://byo-ntp.github.io/tools/chrony/install.sh | sh

source code, discussion

Restart

For reference, use when needed.

service chronyd start  # FreeBSD

service chrony restart # Linux

Observe

chronyc tracking
chronyc sources
chronyc sourcestats

Tip: add -v to show a legend

After adding the REFCLOCK line(s) and restarting chrony, see what chrony thinks of the new refclock:

chronyc sources

MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
#- NMEA                          0   4   377    10   +219us[ +219us] +/-  224us
#* PPS                           0   4   377     9    -23ns[  -32ns] +/-  166ns
^- -----------------             1   6   377   661  +3304us[+3276us] +/-   44ms
^- ----------------------        2   7   377     9  -1115us[-1115us] +/-   67ms
^- -------------------           3   6   377    20  -1820us[-1820us] +/-   18ms

PPS is locked on and NMEA offset is under a µs, this is quite good!

Monitor

Let chrony run for a hour and see how close your build is to the reference:

  1. Measure your offset
  2. Use something like telegraf + influxdb + grafana for statistics.

References