[ntp:questions] ntpd - gpsd communication

ah at avtodoria.ru ah at avtodoria.ru
Thu Jun 4 19:15:00 UTC 2020


I have time jumps made by ntpd because gpsd sometimes puts wrong data to SHM because of wrong data from gps receiver(very bad chips)

I have only one time source in ntp.conf — with PPS enabled

I want to add another two internet sources for stability but at first i want to emulate wrong data from gpsd to see how ntpd will make this time jump.

As first step i read data from SHM when gpsd worked correctly at 14 p.m. today UTC+3 for 30 minutes

And after that i stopped gpsd and launched my own binary at 17:30 p.m. UTC+3 writing that old data to SHM. I expected the great offset and the time jump after some time(as it was when receiver lied) but what i saw was:
- without binary launched ntpd had no updates — it’s correct (no data — no action)
- with binary launched ntpd had a little offset for all 30 minutes without any attempt to correct system time

please give me some help!! Maybe i don’t understand ntpd — gpsd communication correctly or smth else

Thank you in advance

More information about the questions mailing list