[ntp:questions] Long term disciplining against 1PPS reference only

Dan Drown dan-ntp at drown.org
Fri Oct 19 20:47:32 UTC 2018

Quoting "Charbonneau, André" <Andre.Charbonneau at nrc-cnrc.gc.ca>:
> Recently I've been trying to get one of my NTP server (a Raspberry  
> Pi), to stay synchronized to a 1PPS signal coming from a Rb clock  
> over long periods of time when all other sources are unavailable.   
> The NTP server on the RPi is configured to have a couple upstream  
> stratum 2 servers, plus the 1PPS driver, and a local clock driver.
> Reading more about this, it is documented (Computer Network Time  
> Synchronization 2nd edition, by D. L. Mills, section 3.11.4) that I  
> should be using the following command to tell NTP to keep the 1PPS  
> synchronization even if no other sources are present:
> "tos minsane 0"

Looks like this code was added around 2 years ago to ntpd/ntp_config.c:

                 case T_Minsane:
                         val = tos->value.d;
                         if ((int)tos->value.d < 1)
                                 tos->value.d = 1;
                         l_minsane = (int)tos->value.d;

I've verified that changing the minimum from 1 to 0 in that code lets  
this feature work again.  Can you give that a try?

More information about the questions mailing list