[time-nuts] Tbolt issues

EWKehren at aol.com EWKehren at aol.com
Fri Sep 2 09:13:41 EDT 2016

 would you please share your settings, this is exactly what we are  looking 
for. We are doing it by trial and error but your expertise will help  
English not being my native language linguistics are some time a  problem
In a message dated 9/1/2016 6:26:32 P.M. Eastern Daylight Time,  
csteinmetz at yandex.com writes:

Bert  wrote:

> maybe some one smarter than us can working with the  parameters that Tbolt
> makes available better performance can be  achieved

I am quite sure of that

> the frequency is being  changed to compensate for time

Yes, the PPS is steered by making slight  adjustments to the OCXO 
frequency.  But you can make these  adjustments as arbitrarily small as 
you want with the setup  parameters.  I run my Tbolts with pretty tight 
limits on the  frequency adjustments.

> and we do not care about ADEV, we care  about the actual
> frequency at that moment it goes in to the measuring  device

There is no "there" there.  One never makes a frequency  measurement at 
just one instant -- the measurement will ALWAYS be done  over a macro 
time interval (very often, one second, sometimes 0.1, 10,  100, or 1000 
seconds).  We never observe, and have no way to know,  the instantaneous 
frequency (as you put it, "the actual frequency at that  moment it goes 
into the measuring device") -- so how can we care about  it?  The only 
thing relevant (or even meaningful) is the average  frequency during our 
measurement interval.

xDEV tells us half of  what we want to know -- how stable our oscillator 
is from one measurement  interval to another.  We would also like to know 
what frequency it is  wobbling around -- the "centroid" frequency, if you 
will (to borrow a  geometric term).  (Mathematicians can argue for days 
about which type  of "average" is appropriate here -- the rest of us just 
pick one and carry  on.)  ADEV does not tell us this "centroid" frequency 
directly, but  it can be extracted from the same measurements we took to 
calculate  ADEV.

I think you are being misled by a belief that the linguistic  construct, 
"instantaneous frequency," has real meaning in the world.   It doesn't.

Best  regards,


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