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

Azelio Boriani azelio.boriani at screen.it
Wed Jun 12 05:16:23 EDT 2013


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 Wavecrest counters can handle negative TI, I
don't know.

On Wed, Jun 12, 2013 at 8:48 AM, Said Jackson <saidjack at aol.com> wrote:
> 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 0.99999xxxx seconds.
>
> I found that adding a phase delay (long cable) helps keep the numbers positive.
>
> Or trigger one on the rising, and one on the falling edge to add 50ns delay ( for signals with good 50% duty cycle).
>
> Bye,
> Said
>
> On Jun 11, 2013, at 21:13, Jim Palfreyman <jim77742 at gmail.com> wrote:
>
>> 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 to 999.999... ms. It can't seem to make up its mind which to use.
>>
>> Why is this inconsistent?
>>
>> If I flip it to + TI and make sure the leading clock is on Start - all
>> works well.
>>
>> Thoughts?
>>
>> Jim Palfreyman
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


More information about the time-nuts mailing list