[time-nuts] Thunderbolt behaviour with long time constants.

[WarrenS]

Looks to be mostly a plot of the 5370B's noise floor at low taus.
You may need something a couple of decades better if you want to measure the 
Tbolt at that tau setting.

BTW, You should NOT set the TBolt's TC to >999 sec. I  have found that the 
control can become somewhat unpredictable, AKA S/W bug.

ws

*********************
----- Original Message ----- 
From: "Mark Spencer" <mspencer12345 at yahoo.ca>
To: <time-nuts at febo.com>
Sent: Tuesday, February 08, 2011 7:48 PM
Subject: [time-nuts] Thunderbolt behaviour with long time constants.


First apologies for the zipped attachement.

I thought some members of the mailing list might find the attached plot of 
the
performance of my Thunderbolt to be interesting. After looking at the
performance of my Thunderbolt with a time constant of 225 seconds which 
seems to

be about right for my Thunderbolt, I noticed that the Allan deviation 
appeared
to be be reduced at high values of Tau (approx 2,000 seconds..)

I then changed the time constant of my Thunderbolt to 2,000 seconds and 
compared

the two plots. I'm quite surprised at the result and the similarity between
the peformance at low values of tau with the two different time constants.
I took 4 readings per second with a 5370B, hence each unit of tau on the 
graph
is approx .25 of a second.

I'll likley try other time constants in the future