[time-nuts] Lost Calibration on CNT-81/PM-6681

Ed Palmer ed_palmer at sasktel.net
Thu Feb 2 13:08:06 EST 2017

Azelio, you're correct.  That's why I put 'single' and 'normal' in 
single quotes - to highlight the fact that the terms weren't really 
correct.  I see now that just saying that single mode on or off might 
have been less confusing.


On 2017-02-02 11:00 AM, Azelio Boriani <azelio.boriani at gmail.com> wrote:
> It seems that "normal mode" is not a mode: from the operator's manual:
> When on, the result from each measurement is displayed.
> When off, the counter averages all data captured during the set
> measurement time.
> No normal mode but single mode on or off. The measurments look better
> when averages are on...
> On Wed, Feb 1, 2017 at 8:46 PM, Ed Palmer<ed_palmer at sasktel.net>  wrote:
>> >Hi Magnus,
>> >
>> >When you did your measurements, did you use 'single' mode or 'normal' mode?
>> >
>> >When I got my PM6681, I wanted to check the interpolater to make sure that
>> >it was healthy.  I couldn't generate pulses over the whole range, but over
>> >the range of 50ns to 28 ns, my StdDev readings in 'single' mode were in the
>> >range of 2.6 - 3.6 e-11, i.e. similar to the example in the manual.  In
>> >normal mode, my readings were significantly better.  So I'm assuming that
>> >'single' mode was the correct mode to use.
>> >
>> >FYI, my unit was factory calibrated with a 4.05 ns pulse according to the
>> >PUD command, so I guess that's what gave the best results.  I also see that
>> >the example in the manual was for a 4.29 ns pulse. Does that suggest that
>> >shorter, harder to generate, pulses are important for this calibration?
>> >
>> >Ed

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