[time-nuts] ADEV query Timelab and TICC

timeok timeok at timeok.it
Mon Mar 20 03:56:19 EDT 2017


   All,
   the similar problem I have verified using the HP5065A and HP5061B 1PPS output, the dividers are pratically unusable for ADEV measurements. The 5/10MHz output of the same instruments using the TAPR divider are ok, so these dividers have some spike noise problems. It can be seen even using other TIC as The HP53132A.
   Luciano
   www.timeok.it


   Da "time-nuts" time-nuts-bounces at febo.com
   A "Discussion of precise time and frequency measurement" time-nuts at febo.com
   Cc
   Data Sun, 19 Mar 2017 20:03:29 -0700
   Oggetto Re: [time-nuts] ADEV query Timelab and TICC
   > 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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