[time-nuts] Sidereal seconds

[jmfranke]

Make that -1.85 seconds per YEAR!

John  WA4WDL

--------------------------------------------------
From: "jmfranke" <jmfranke at cox.net>
Sent: Friday, March 02, 2012 11:10 AM
To: "Neville Michie" <namichie at gmail.com>; "Discussion of precise time and 
frequency measurement" <time-nuts at 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: <aartmolsen at comcast.net>
> Sent: Friday, March 02, 2012 10:48 AM
> To: "Neville Michie" <namichie at gmail.com>; "Discussion of precise time and 
> frequency measurement" <time-nuts at 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" <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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>
>
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