Hi Charles,
This triggered some thoughts. :)
On 07/06/2013 06:28 AM, Charles P. Steinmetz wrote:
So, for proper operation in +/- TI mode, use external arming to remove
the ambiguity when the trigger events cross from + to - and back, and
make sure you have adjusted the triggering properly for
Not only: consider that most time interval counters have a minimum
measurable interval (Racal 2351 is 2ns) and slowly crossing PPSes can
be a problem to measure when they are about to cross. In my opinion it
is always better to displace the PPSes, easily done when using GPSDOs
and by using stable
Hi Azelio,
On 07/06/2013 05:05 PM, Azelio Boriani wrote:
Not only: consider that most time interval counters have a minimum
measurable interval (Racal 2351 is 2ns) and slowly crossing PPSes can
be a problem to measure when they are about to cross. In my opinion it
is always better to displace
Magnus, you are right, I forgot to mention that without a
time-stamping counter it is better to offset the PPSes. With a time
stamping counter more cases can be treated such as a free oscillator.
On Sat, Jul 6, 2013 at 8:53 PM, Charles P. Steinmetz
charles_steinm...@lavabit.com wrote:
Magnus
Or have I misunderstood what you were saying?
But what happens if, over a day, your DUT 1PPS wanders ahead and/or beyond the
REF 1PPS? This is common with GPS 1PPS boards or with too-accurate house 1PPS
references or when comparing poor quartz with a GPSDO.
One symptom is that all your TI
On 07/06/2013 08:53 PM, Charles P. Steinmetz wrote:
Magnus wrote:
For +/- TI mode, using a separate ARM does not help either, since
either of the channels suffice as trigger, and the relative timing is
resolve dynamically by the counter. For most time, the dead-time will
be hidden, but for
Hi Azelio,
On 07/06/2013 10:22 PM, Azelio Boriani wrote:
Magnus, you are right, I forgot to mention that without a
time-stamping counter it is better to offset the PPSes. With a time
stamping counter more cases can be treated such as a free oscillator.
Agreed.
Many of the issues can be
On 07/06/2013 11:02 PM, Tom Van Baak wrote:
Or have I misunderstood what you were saying?
But what happens if, over a day, your DUT 1PPS wanders ahead and/or beyond the
REF 1PPS? This is common with GPS 1PPS boards or with too-accurate house 1PPS
references or when comparing poor quartz with
Charles,
On 07/07/2013 12:30 AM, Charles P. Steinmetz wrote:
But what happens if, over a day, your DUT 1PPS wanders ahead and/or
beyond the REF 1PPS? This is common with GPS 1PPS boards or with
too-accurate house 1PPS references or when comparing poor quartz with
a GPSDO.
I generated the
Jim,
Really annoying feature of HP counters.
If you slowly drift from a positive period to a negative one, it will indicate
negative numbers for a while.
Then almost sudden it will do the jump to 0.9 seconds.
I found that adding a phase delay (long cable) helps keep the numbers
Hi
Another simple solution -
If you are using a GPSDO as a PPS source, use the cable delay to offset the pps
you are using as a reference by a microsecond. That's worked on every GPSDO
I've tried it on.
No it really doesn't solve the problem, it just covers it up. Post processing
the data
Not only HP counters. I have never seen a TI counter that outputs
negative values. I use the cable delay or user delay feature of GPSes
to delay one PPS to the other so that the result is always positive. I
have seen that only oscilloscopes can handle negative time interval
values. Maybe that the
Folks,
I'm struggling to understand this button and how it reports intervals. It's
supposed to show negative when the Stop is before the Start.
When I connect up two clocks sending out 1PPS and say the one connected to
Stop is ahead then sometimes I'd get -123.45 ns (say) and sometimes it
flips
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