[time-nuts] Sidereal timekeeping

cook michael michael.cook at sfr.fr
Wed May 18 05:35:12 UTC 2011


Le 16/05/2011 00:29, iovane at inwind.it a écrit :
> You are right, the right value for the crystal would be about 32859.27, but I
> thought that such a difference could be compensated in the circuitry, that's
> why I omitted the decimals.
>
before you get into grinding I have a question on your chosen frequency. 
It doesn't square for me.

     1,002737909350795  solar/sidereal time ratio

              x 32768  crystal frequency

32857,72   required frequency for sidereal clock with 2^15 divider chain



> Regarding the 2^15 division, forget for a moment the second as we know it, and
> consider a shorter (sidereal) second. Our crystal which makes 32859.27
> oscillations in our ordinary second, will make 32768 oscillations in the
> shorter second. The ratio is saved and we will have the shorter second I'm
> looking for. Hope I've been clear.
>
> Antonio I8IOV
>
>> ----Messaggio originale----
>> Da: michael.cook at sfr.fr
>> Data: 16/05/2011 0.14
>> A: "iovane at inwind.it"<iovane at inwind.it>
>> Ogg: Re: [time-nuts] Sidereal timekeeping
>>
>> Le 15/05/2011 23:39, iovane at inwind.it a écrit :
>>>> I don't think this will work as the divider chain will give wrong length
>>>> seconds.
>>> Michael,
>>> I'm just looking for shorter seconds, in order to keep sidereal time with
>>> ordinary clocks.
>>   Antonio,
>> Yes I figured that, but I thought the frequency wrong for the 2^15
>> division. The ration for siderial/solar time according to
>> wiki is 1⁄1.002737909350795, using your value I got 1/1,002777099609375
>> , which makes your day 86160,723089564, rather than 86,164.090530833.
>> Quite a bit short.  My maths may be wrong though.
>>> Antonio I8IOV
>>>
>>>
>>
>>
>
>
>





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