[time-nuts] Visual clock comparison

David J Taylor david-taylor at blueyonder.co.uk
Sat Apr 18 03:02:59 EDT 2015

From: Chris Albertson

It would be an easy experiment to get two analog clocks and put them
side by side.  You would not even have to set them to the "true" time,
just to each other.  Let one run slower and wait until you can see a

Clocks on a computer screen are different because the screen is
refreshed one order of about 100 times per second.  They move in
jumps, not continuously.

Ears are better than eyes at this.  If you choose the "right" tick
sound.  The best one sounds like a drummer hitting the metal rim of
his drum to make a "click" sound.  Some people can hear if two clicks
are just a few milliseconds apart or not.  Beware of the speed of
sound.  It is very slow, about 1 milli sec per foot of distance.  You
clocks must be very close to each other or the delays will be

Yes, sound (from co-sited speakers) would likely be the best comparison 
choice.  I have a speaking clock running on a couple of PCs and the 
differences are obvious.  With an impulse such as you suggest, even more so.

If you want to try a simply visual comparison, I have a simple analog clock 
for Windows:


and a digital clock for Windows and Linux:


I've not written a sound comparison tool for Linux or Windows.

SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 

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