[time-nuts] Sidereal seconds

[mike cook]

Le 02/03/2012 05:13, Neville Michie a écrit :
>
> A possible solution is to take mean time (from a TBolt 10MHz) and 
> divide it by 9,972,695.7 to give a PPS(sid) signal that can run a 
> digital clock dial and give one second(sid) ticks to phase the 
> pendulum. It may be simpler to divide by 9,972,696 to stay with 
> integer division and have an error in the order of a second per annum. 
> (which we have from leap seconds anyway).
> TVB made some picDIV chips with a synch pin that do a similar task, 
> but have I got the number correct? 
   number looks ok , at least according to the usual sources.
> and are there other nuts that would like to add a sidereal clock to 
> their clock vaults to make it worth while to make such a chip?
Yup, I guess that would be a useful extension to the code.  You would 
just need to change the delays to fit a 2493174 instruction count for a 
10MHz input.
> If I set up the sidereal clock then I can use my theodolite to check 
> time against the stars.
More of a challenge I think. Harrison is reported to have used 
occultation by buildings from a known observation point. It would be 
probably be easier than keeping a theodolite precisely orientated over 
long periods of time.
> cheers,
> Neville Michie
> Sydney
> Australia
>
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