[time-nuts] +/- TI button on 5370B

Azelio Boriani azelio.boriani at screen.it
Sat Jul 6 16:22:46 EDT 2013


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_steinmetz at lavabit.com> 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 longer runs where A/B timing diverge, it can create the same issues as
>> the remaining time from the STOP to the START (as the sequence now has been
>> assigned and maintained) can become to short to cover up the dead-time.
>
>
> But that is the thing about using ARM as I described -- the sequence is NOT
> maintained, it is generated fresh every period (every second, in my
> example).  So every period, you get a + or - TI reading depending on which
> trigger event (START or STOP) occurs first after the ARM pulse.  Of course,
> this depends on the START and STOP events always being much closer to each
> other than 1/2 the measurement interval (in my example, two 1 pps signals
> that are always within 100 mS of each other; in reality, this could even be
> 300 mS if the ARM pulse is accurately located).
>
> I did not have any trouble with a dead zone.  I think this is because if the
> counter misses a trigger, it will always be re-armed before the next
> terminating trigger event occurs, so it would just not report a time for
> that period.
>
> Or have I misunderstood what you were saying?
>
> Best regards,
>
> Charles
>
>
>
>
>
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