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. Ed On 2017-02-02 11:00 AM, Azelio Boriani <azelio.boriani@gmail.com> wrote: > It seems that "normal mode" is not a mode: from the operator's manual: > > SINGLE > 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@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