[time-nuts] ADEV query Timelab and TICC
kb8tq at n1k.org
Sun Mar 19 16:45:01 EDT 2017
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.
> On Mar 19, 2017, at 12:08 PM, GandalfG8--- via time-nuts <time-nuts at febo.com> 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....
> 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>_______________________________________________
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