[time-nuts] ADEV query Timelab and TICC

GandalfG8 at aol.com GandalfG8 at aol.com
Sun Mar 19 12:08:31 EDT 2017

Yesterday I used one of John's excellent TICC modules for the first  time 
and initially set up a quick test using the 10MHz output from a  Thunderbolt 
as the frequency reference to measure the 1PPS from an  Oscilloquartz Star4 
GPSDO, with the TICC output feeding a USB3 port on a Windows  10 PC running 
the 64 bit version of Timelab 1.29.
I'll attach a copy of the test plots I'm referring to but just in  case 
this doesn't get through I've also uploaded it to....
Using the basic settings as described in the TICC manual the first  run was 
for 1 hour and seemed fine so I decided to extend the run time to 6  hours. 
The first 6 hour test started to follow the 1 hour plot as expected and I  
watched this on and off and can confirm it did so up to somewhere between  
the 100s and 1000s points on the x-axis, but some time after that the 
complete  plot shifted upwards and then continued to completion to produce the 
magenta  trace.
I wasn't watching when it shifted so don't know if it was a jump or a  
gradual shift but did see it continue until completion. When I repeated the 6  
hour test, again without changing anything, and hoping to observe the  effect 
as it happened, it produced the green trace which was what I'd been  
expecting to start with. Since then I've made other test runs and again all  seems 
to be as expected.
I'm probably missing something obvious but don't understand what's  
happened here so any suggestions would be welcome.
Throughout the tests I have been simultaneously streaming data  from the 
Star4 to Lady Heather via a "proper" serial port on the same PC so did  wonder 
if there might be some form of data conflict but it doesn't seem to  have 
shown up as any obvious form of corruption and hasn't repeated  itself.
Nigel,  GM8PZR 
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