I have a GPS app that runs on a Raspberry Pi. The system is powered off most of the time, but on startup needs to sync time very quickly using PPS.

It looks like the makestep directive is the way to do this. Which of the following would be better?


makestep 0.01 10

makestep 0.01 -1

The first would make adjustments during the first 10 updates, while the second would do so continuously, correct? Note: none of the apps running would be adversely affected by jumps in the clock (they would benefit by having more accurate time).

Here is my complete configuration file:

server 0.us.pool.ntp.org iburst
server 1.us.pool.ntp.org iburst
server 2.us.pool.ntp.org iburst
server 3.us.pool.ntp.org iburst

refclock PPS /dev/pps0 lock NMEA refid PPS
# Setting for 2, 3, 4, 5, 10 updates per seconds
refclock SHM 0 offset 0.1 delay 0.2 refid NMEA noselect

# In first ten updates step the system clock instead of slew
# if the adjustment is larger than 0.01 second.
makestep 0.01 10

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Allow NTP client access from local network.
allow 192.168
allow 172.20

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