[time-nuts] ADEV query Timelab and TICC

[Tom Van Baak]

> I have sent a couple of files to Tom.  They were taken simultaneously from
> an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to
> 1Hz.  The glitches were on the PPS trace, but not on the PicDiv trace, so
> I'm fairly confident the TICC was working correctly.
> 
> Orin.

Hi Orin,

Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 points). Everything looks fine with the exception of 8 glitches. These are sometimes obvious jumps in phase, which cause massive spikes in frequency. Two plots attached.

Almost every data point is within a few ns of each other. This is good. The standard deviation is a fraction of 1 ns. But once in a while there is a relatively massive phase jump. This is bad. Interestingly these 8 phase jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The full list is (ns units):

24.575
24.724
24.831
25.047
25.087
25.549
25.589
49.623

25 * N ns is not random. So I think this is not a Windows problem, not a USB problem, not a TimeLab problem, not a TICC problem either.

It makes me wonder if this is a LTE-Lite problem. If Said or Keith from Jackson Labs is around -- is there anything on the LTE-Lite board that's close to 20 or 40 or 80 MHz? At this point I kind of trust Orin's data and I kind of trust the TICC. So when I see monster 25 ns phase jumps it makes me think there's a problem with the GSPDO board itself.

(Please realize that only on time-nuts may we can use the words "monster" and "25 ns" in the same sentence; the rest of the world has larger problems)

/tvb
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