[time-nuts] Thunderbolt Loop Damping

Arnold Tibus Arnold.Tibus at gmx.de
Tue Jul 8 12:01:15 EDT 2008

On Tue, 8 Jul 2008 06:55:04 -0700, Tom Van Baak wrote:
>Yes, it's quite flexible and you can have a lot of fun replacing
>the OCXO. I'm assuming a number of you will be trying this
>in the coming months.

>But even with the onboard OCXO, it allows you to change the
>time constant which can make a noticeable difference in the
>mid-term stability of the GPSDO. I'll dig out plots I made last
>year if you're interested.


Perhaps there is not much to earn with it, but I thought as well about 
to replace the OCXO with a 10811 for test purpose etc. 

I am very much interested as well to see how to set the time 
constant in conjunction with the damping factor properly with the 
original onboard oscillator and, if already performed by somebody, 
with an other type. 
Would be great if you and others would share your/ their experience!

What are the parameters to be watched with TBoltmon, 
what are the goals, to get the lowest variation on the 10 MHz ppb 
What about the PPS value in ns UTC? 
If I do slight modifications specially on the time constant I get 
the indication drifting very slowly away, but the 10 MHz ppb 
does not vary much...
Under this circumstance I do not see how to set the ns offset for pps.

Is it necessary to compensate for the antenna cable delay and 
how I can do it? (pps offset?)

I guess that the outcome will be to not make much modifications !?

Arnold T.

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