[time-nuts] A Time-Nut's Worst Nightmare

Lachlan Gunn lachlan at twopif.net
Sat May 11 03:10:29 EDT 2013

>From https://github.com/akafugu/vetinari_clock :

	The firmware has a 'random' sequence of pulses which over 32 seconds
	moves the second hand 32 times. This sequence is long enough to give
	the appearance of randomness without unnecessarily consuming
	processor cycles. I chose 32 seconds as it means the pattern is
	offset from the 60 second rotation of the minutes. The 'random'
	is 128 steps (and is therefore checked 4 times a second). This means
	clock moves between 0-4 times within each actual second. By moving
	more or less in each of the 32 seconds the clock looks random,
	the sequence always moves the clock exactly 32 seconds in the 128

So there is no long-term drift, it seems, beyond that of the crystal.  I've
pulled the pseudo-random tick sequence out of the source code and found the
Allan variance, shown here:



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jim Lux
Sent: Saturday, 11 May 2013 2:19 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] A Time-Nut's Worst Nightmare

On 5/10/13 6:52 PM, Ed Palmer wrote:
> Part of me thinks it's cute, part of me wants to kill it.  :-)
> https://www.tindie.com/products/akafugu/vetinari-clock
> Ed

but.. what is the actual distribution? Is it white phase or white frequency?

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