[ntp:questions] ntpd -q and driftfile

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Wed Mar 23 05:08:22 UTC 2011


>> oh, come off it. Your reaction time is nowhere near what ntp -q would
>> give you. Using ntp -q run once every hour, and assuming say a 20PPM
>> drift for the crystal, his clock would be out by less than a 100 ms due to the
>> drifting, and your reaction time with your watch ( and wyour watch) are
>> nowhere near that accurate. 

>Actually, it is on the borderline of the achievable.  You phase lock 
>your finger bounces to the second ticks and just go that little further 
>on the exact time.  It's certainly good to 200ms and possibly good to 100ms.

That would be a fun project for a science fair.
  Build a setup.  Collect a lot of data.
  How much does it vary?  For one person, between people, ...
  How close can you get if you are trying to set a clock?
    Can you calibrate the person and subtract off a constant?
    What if you get multiple samples?

Many years ago, my boss did that sort of stuff.  I think he said that
normal reaction time from light-on to button-press  was 250 ms.  It's
faster if there is no penalties for false presses.

-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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