Hi It’s a pretty good bet that the “upper” trace has a noise pop in it. One of the wonderful things about ADEV is that a single noise event can impact the whole curve. That is a bit non-intuitive. It is indeed how the math works and how the testing comes out in the real world.
Bob > On Mar 19, 2017, at 12:08 PM, GandalfG8--- via time-nuts <[email protected]> > wrote: > > 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.... > > https://www.mediafire.com/?9bue90yp1e8ueu6 > > 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 <Star4+ > 170318.png>_______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
