[time-nuts] ADEV query Timelab and TICC

John Ackermann N8UR jra at febo.com
Mon Mar 20 12:16:53 EDT 2017

I noticed with the TICC that the very high peak voltage on the 5061, 5065, etc. PPS causes trigger errors.  Putting a 50 ohm load at the TICC channel input helped a lot, or an attenuator might even be better.

These HP units have a very short pulse width that peaks at something like 20v into a high impedance.  It doesn't​ seem to hurt the TICC input circuit, but causes ringing that results in perceived jitter.  Knocking that down to TTL level solves the problem.

On Mar 20, 2017, 12:01 PM, at 12:01 PM, timeok <timeok at timeok.it> wrote:
>   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
>> 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,
>   > 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
>(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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