[time-nuts] Oops - wrong URL for tvb plot!

[SAIDJACK at aol.com]

In a message dated 4/10/2007 18:44:58 Pacific Daylight Time,  
tvb at LeapSecond.com writes:

Knowing  or calculating the sample rate is useful: 15-20
samples/second seems OK for  a 53132. But if you were
to measure it you would come up with a more exact  number.

One way to do this is time the collection of 1000  samples.



Hello Tom,
 
(BTW - I don't like the reply feature of AOL, I can't keep your original  
post prefixed with > etc. I think part of the reason is that the HTML stuff  
get's deleted by the server).
 
Thanks for the info. I did do what you suggested, and I get 22.74 samples  
per second free-running over several hours.
 
That makes the 0.1s Tau look nice.

When using the timers' internal delay of 0.1s, I would expect  the result to 
be slightly skewed, 1s + 50ns on average I would think since the  measurement 
period has to be added as well?
 
Presently, I am doing cross-correlation measurements using the  53132A:
 
   * Fury GPSDO (single AT-cut OCXO) against my FTS-4050 Cs
 
   * one Fury AT-cut GPSDO against our Fury Rubidium prototype  (our secret 
project using a low-cost Russian Rb as the Fury OCXO)
 
   * Fury Rb against PRS-10 Rb, PRS-10 is GPS disciplined as well  with ca. 7 
hour time constant
 
   * PRS-10 Rb against FTS-4050 Cs.
 
   * Fury double-oven SC-cut unit against the best of all other  oscillators 
(tbd)
 
I do have some preliminary data which is very interesting:
 
  * The counter noise is dominant below 1s as you had mentioned.  How can I 
do 0.001s measurements with such a noisy counter?
 
   * Our Fury Rubidium GPSDO prototype against the PRS-10 is  the most stable 
combination, dropping below 1E-011 above 7s intervalls
 
   * The FTS-4050 is almost one magnitude more noisy than the  Rubidiums at 
100s intervalls. In fact it never catches the Rb's. I am a bit  dissapointed by 
that. Of course it should be better long-term if GPS is  completely turned 
off :)
 
   * All measurements get close to, or drop below 1E-012 at  around 2000s 
intervalls (even the cheaper single-oven, AT-cut OCXO!).
 
   * The two Rubidiums drop below 1E-012 at around 1600  seconds.
 
All measurements done using Ulrichs' Plotter ADEV utility.
 
bye,
Said
 
 
 
 



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