Make that -1.85 seconds per YEAR!
John WA4WDL
--------------------------------------------------
From: "jmfranke" <jmfra...@cox.net>
Sent: Friday, March 02, 2012 11:10 AM
To: "Neville Michie" <namic...@gmail.com>; "Discussion of precise time and
frequency measurement" <time-nuts@febo.com>
Subject: Re: [time-nuts] Sidereal seconds
I used a PLL to convert 60Hz solar to 60Hz sidereal by multiplying by 1465
and then dividing by 1461. The error is -1.85 seconds per day (see: Reid,
Frank and Honeycutt, Kent;"A Digital Clock for Sidereal Time," Gleanings
for ATMs, Sky and Telescope, July, 1976, pp.59-63).
John WA4WDL
--------------------------------------------------
From: <aartmol...@comcast.net>
Sent: Friday, March 02, 2012 10:48 AM
To: "Neville Michie" <namic...@gmail.com>; "Discussion of precise time and
frequency measurement" <time-nuts@febo.com>
Subject: Re: [time-nuts] Sidereal seconds
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" <namic...@gmail.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@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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