[time-nuts] Sidereal seconds

[aartmolsen at comcast.net]

Forty years ago I made a sidereal rate generator that inserted 128 pulse for every 46751 counted ("solar" frequency) pulses. The ratio of 46879/46751 is an accurate sidereal rate, good to 1 second in about 650 years. I used some CD4029 presettable counters to count down from 46751 and used two outputs differing by 2**7 to generate the 128 pulses, So this may be useful if you can come up with a method that can similarly count pulses and add some. 


Aart Olsen 

----- Original Message -----
From: "Neville Michie" <namichie at gmail.com> 
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com> 
Sent: Thursday, March 1, 2012 10:13:37 PM 
Subject: [time-nuts] Sidereal seconds 

I have a problem with two pendulum clocks that interfere with each 
other, even though they are bolted to a brick wall on bedrock 
foundations. 
A solution to this problem is to run one on mean time the other on 
sidereal time. Then I can analyse the operation of each of them. 
Now there is a problem with sidereal time that neither the GPS system 
or WWV transmit reference signals for sidereal time and the 
method of converting mean time to sidereal by calculation is 
difficult for clock synchronisation. 
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? 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? 
If I set up the sidereal clock then I can use my theodolite to check 
time against the stars. 
cheers, 
Neville Michie 
Sydney 
Australia 

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