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Strangely accurate RTC time on Debian

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amyk:

--- Quote from: SiliconWizard on May 16, 2024, 10:39:12 pm ---Also to answer the OP, not all RTCs on motherboards are born equal. 10 seconds per day of RTC drift is about 115 ppm, which is about average (not good) for a *basic* crystal-based oscillator, and proof in itself that it's not network-synced.

But 0.3 s of drift over 15 days would be 0.23 ppm, which, while not completely impossible with a good TCXO, is completely unlikely to be what you get with any consumer PC RTC, so it's evidently network-synced.

--- End quote ---
I think PC RTCs were much more accurate in the days when they were not expected to be network-synced. I have some old PCs which drift at most a minute per year.

RoGeorge:

--- Quote from: Logan on May 16, 2024, 10:37:32 pm ---
~$ timedatectl status
               Local time: Thu 2024-05-16 22:32:31 UTC
           Universal time: Thu 2024-05-16 22:32:31 UTC
                 RTC time: Thu 2024-05-16 22:32:31
                Time zone: UTC (UTC, +0000)
System clock synchronized: no
              NTP service: n/a
          RTC in local TZ: no

--- End quote ---

Looks like it's not synced.  You've been lucky to have a very good RTC.  :-+
The ultimate test would be to physically disconnect the LAN cable/wireless, and see if it keeps the same accuracy. 

Question is, how much its frequency will change with time, with battery voltage, and with temperature.

My Ubuntu machine reports this:

--- Code: ---~$ timedatectl status
               Local time: Fri 2024-05-17 09:24:36 EEST
           Universal time: Fri 2024-05-17 06:24:36 UTC
                 RTC time: Fri 2024-05-17 06:24:36
                Time zone: Europe/Bucharest (EEST, +0300)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no
~$

--- End code ---

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