Hi Since most mixers also have DC offset issues, it is pretty common to high pass filter the signal before you try to hit a limiter. Yes, this can bring in other issues, but the net result is commonly a “win”.
Bob > On Feb 23, 2020, at 2:10 PM, Attila Kinali via time-nuts > <[email protected]> wrote: > > Good evening! > > I'm going through some old stuff... > > > On Wed, 27 Nov 2019 00:29:19 +0100 > Jan-Derk Bakker <[email protected]> wrote: > >> This has yielded a combined "simple" signal >> processing path of a differentiator, a double comb filter and the offset >> estimator, which is getting very close in performance to the "ideal" band >> pass filter (OADEV of 3.77e-13@tau=1s versus 3.25e-13@tau=1s for the BPF; >> full plot: >> http://www.lartmaker.nl/time-nuts/DMTD%20self-noise%20OADEV%20with%20PLL%20and%20various%20filters.pdf >> for this 600000-second recording: >> http://www.lartmaker.nl/time-nuts/600ksec%20run%20with%20PLL,%2010811%20through%20splitter.png >> . OADEV past ~1000sec is severely compromised by the fact that the >> measurement setup is in my home lab which sees temperature swings of up to >> 20 degrees C and which does get bumped from time to time. Longer runs in a >> more controlled setting forthcoming). > > > I can offer an explanation for the large effect of the zero correction seen > here. The LTC2140 is specified to have a +/-10µV/°C drift (at 1Vpp setting). > Converted into phase error due to zero crossing shift, this turns into > a phase shift of +/-1ps/°C @ 10MHz. Note, the shift is given as +/- and > per channel, which means, it could very well be that the channels are > not matched in their temperature characteristics and thus the total phase > shift could be +/-2ps/°C ... though total shift being closer to 0.5ps/°C is > more likely. > > Summa sumarum: DC offset correction is important if a zero crossing > detector is used. > > Attila Kinali > > -- > <JaberWorky> The bad part of Zurich is where the degenerates > throw DARK chocolate at you. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
