[time-nuts] How to get 32.768KHz from 10MHz

Jim Lux james.p.lux at jpl.nasa.gov
Thu Jul 24 01:03:57 EDT 2008

Quoting Jim Palfreyman <jim77742 at gmail.com>, on Wed 23 Jul 2008  
09:11:32 PM PDT:

> In response to Jim Lux's email I checked out the NASA tech brief.
> According to them to run a sidereal clock you should set the frequency to
> 32,859.27577 Hz.
> Now the length of the sidereal day is 23:56:4.091 seconds. This is
> 23.934469722 hours. That is, the sidereal clock must cover 24 "hours" on the
> clock in 23.934469722 real hours. That is, it must run 24/23.934469722 times
> as fast. Hence it's crystal needs to be at 32768*1.002737904=32,857.71563469
> Hz not the 32,859.27577 as stated.
> Interestingly if you multiply 32767*1.002737904 you get the above result.
> I think they have made a mistake. My guess is the author is very computer
> literate and typed in 32767 without thinking!

That author being me, you're probably right.

I remember checking the Mars clock time against a variety of other  
sources over a few weeks, but I don't recall checking the sidereal time.


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