[time-nuts] NTP, PPS and < 10 us offsets

Rob Kimberley robkimberley at btinternet.com
Wed May 15 07:20:23 EDT 2013

Check if you have a Max Poll setting in your config file. 

max poll 5 = 32 seconds
max poll 6 = 64 seconds
max poll 7 = 128 seconds 


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Miguel Barbosa Gonçalves
Sent: 15 May 2013 01:31
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] NTP, PPS and < 10 us offsets


I am trying to figure out why NTP takes so long to react to oscillator
changes... I want it to track the PPS from a Trimble Acutime as closely as

When checking ntptime on startup I see that the NTP daemon is using PLL and
starts the adjustment interval at 8 s. It then increases to 16, 32, 64, 128
and stops at 256.

I read in the documentation that this limit should be 128 but is now 256.

--- start from http://www.ntp.org/ntpfaq/NTP-s-config-adv.htm --- intervals
57 says that there were 57 calibration intervals. When PPS pulses are
arriving, this number should increase. Each frequency adjustment requires a
good calibration interval. The length of the current calibration interval
can be found as interval 128 s (128 seconds is the default maximum length).
Remaining numbers count abnormal conditions as explained below.
--- end ---

How can I make it stop earlier? At 64 s for example?

Any ideas?

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