[time-nuts] GPSDO TC & Damping

Richard Moore richiem at hughes.net
Fri Jan 9 23:05:34 EST 2009


On Jan 9, 2009, at 2:24 AM, time-nuts-request at febo.com wrote:

> Message: 2
> Date: Fri, 09 Jan 2009 10:27:05 +0100
> From: Magnus Danielson <magnus at rubidium.dyndns.org>
> Subject: Re: [time-nuts] GPSDO TC & Damping
>
> Dick,
>
>> Well, like many here, I don't actually have the equipment, especially
>> the reference std., to do these MDEV, ADEV and other analyses, so,
>> since I use the GPSDO for a frequency standard and not for UTC, I
>> thought I'd get the expert opinions. Magnus has several times
>> indicated here that a TC laying somewhere in and around 100 to 1000
>> secs is probably optimum.
>
> I think you have misinterpreted my postings. I never claimed it was
> optimum, or at least never intended to. I think 100 secs is good for
> doing additional experiments with damping parameters. It would be
> interesting to see just how low the bulb may go. This only since it is
> obvious that it makes such a clear difference at 100 secs. It's a  
> choice
> out of measurement and interpretation practicality, not optimum from a
> use perspective. If you consider my postings you would see that I  
> rather
> promote the concept of adjusting the time constant dynamically to
> situations rather than say 1234.5678 seconds is the optimum.
>
> Cheers,
> Magnus

Sorry, Magnus, I didn't mean to put words in your mouth. I was  
remembering last Fall, when you suggested that people look at your  
ADEV plot and to be mindful of the of the bounding slopes of the  
curves. If I've mis-remembered the emphasis or the facts, I do  
apologize. I thought your argument then, as I remember it, was strong  
and valuable. Seems like it gave a good range of possible values to  
use for Tau in the measurements.

I probably won't go far beyond the capabilities of the TBolt, such as  
implementing a PID controller with dynamic control of variables using  
a microcontroller and LPGAys and writing my own software, but I love  
it when you talk that way.

Best,
Dick Moore





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