[time-nuts] Cesium Mechanical Chronometer

[Dan Kemppainen]

Hi,

I agree with tom, winding may be an issue.

If that could be overcome, would it be possible to injection lock the 
clock with a piezo or other small mechanical actuator? Something mounted 
to the clock body that 'pings' it periodically may all that's needed to 
pull it where you want it to go.

One would think it would be nice to do this project without having to 
modify the clock significantly, or risk damaging it.

If you do succeed I'd be interested in reading the results. A fun 
project, in my opinion.

Dan




On 1/30/2020 3:18 PM, time-nuts-request at lists.febo.com wrote:
> Message: 7
> Date: Thu, 30 Jan 2020 10:35:11 -0800
> From: Tom Van Baak<tvb at LeapSecond.com>
> To:time-nuts at lists.febo.com
> Subject: Re: [time-nuts] Cesium Mechanical Chronometer
> Message-ID:<e775549d-4368-2ade-e338-7e208e07f09e at LeapSecond.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> That would be a fun project. There are examples of measuring a M21 on
> Bryan's site:
> 
> https://www.bmumford.com/mset/tech/chrono/
> 
> Here are phase and ADEV plots for my M21:
> 
> http://leapsecond.com/pages/m21/
> 
> That page also shows you a typical chronometer rate card, which provides
> the key "paper clock" advantage over using the clock dial alone.
> 
> I use a piezo pickup to extract timing pulses from the clock. The audio
> waveform isn't pretty but you can form a low jitter 1PPS out of it.
> Laser sensors give a cleaner signal but are more difficult to use with
> an M21.
> 
> Running a GPS/CSAC + M21 in a master/slave arrangement should be easy,
> although I don't know how you'll handle the rate card corrections.
> 
> Running them in phase lock will be much harder. You can probably
> discipline the CSAC from the M21 using RS232 commands to the CSAC. But
> to discipline the M21 from the CSAC requires that you have a way to
> dynamically adjust the rate of the M21 at ppm levels. That's going to be
> tricky, given that high-end compensated chronometers like this are
> specifically designed to be as immune to internal and external changes
> as possible. One avenue may be the winding interval: notice the slopes
> of the phase plot.
> 
> The biggest problem I had with long-term data collection was re-winding
> the chronometer. If you design a non-invasive auto-winder as part of
> your project, please contact me.
> 
> /tvb