when i disable ntpd,
my time from date will faster 50s than internet time only half day time
The ntpd do sync the time every 30min plus calculates a time drift compensation. If you donāt have a local time server or gps time server that fix the time when you turn off ntpd, then the time drift you see is normal. Pretty much any time drift i normal since the router doesnāt have a time circuit.
The router likely has no RTC chip, and apparently the CPU frequency is slightly off.
Some first hand clock experience I haveā¦
I build digital clocks a long time ago with 32,762kHz crystals.
But to calibrate these clocks you canāt measure on the crystal since the probe change the capacitance of the resonator.
But the clock circuit had a 1Hz output for calibration.
But to make a clock that was within a handful of minutes drift every half year when daylight saving time shifted I had to have a special frequency counter that could measure 1Hz signals and the measured output had to be at least 1.00000Hz after crystal calibration with the 6th decimal unstable.
Worst electronics to hold time is devices that use grid power 50/60Hz because the power grid is never 50/60Hz. That frequency is always floating around a little.
Another problem is EMC compliance āspread spectrumā functions if the clock use cpu frequency for time.
But for civil low cost time keeping then ntp system is the only meaningful way to go.
I am right now working on a LOOONG time project at home to have a RTC server in the network that serves time synced with ntp. But I have trouble getting the server to give time from the RTC chip when offline. But as I said this is a long time, low budget project so one day I guess it will workš
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