OK I do ASAPMay I ask you to measure without weighting ?
It's a detail for sure, but this kind of measure is always unweighted here.
OK I do ASAPMay I ask you to measure without weighting ?
It's a detail for sure, but this kind of measure is always unweighted here.
It enought only correlationMay I ask you to measure without weighting ?
It's a detail for sure, but this kind of measure is always unweighted here.
Which DAC is it ?I didn't have the recording from yesterday, but this should be similar: https://we.tl/t-KzWymSK46j
for me with E1DA cosmos ADC give exactly -15db with 1000 correlationSeems to work for me. Effect is most easily seen with open inputs, eliminating most common mode content. Measurement titles below show total input rms level for the various tests, starting with an rms average as a reference.
View attachment 385128
It's SMSL DO300. Just the right channel output, no summing.Which DAC is it ?
D50 III in mono mode (both outputs summed) ?
'cause I have similar results in that case with notch.
Just to compare....
Longer FFs provide narrower bin widths, so the noise floor will drop, but the RMS value we are comparing will not change.what would you get with longer fft's comparable with the number of samples processed in total?
I like it. Bought a used one for about half the price.I need to try one ;-)
My expectation is that the correlation gives negative values for these signal components and the FFT will consider this as an amplitude and it will thus have a non zero rms value.In simpler terms, what happens to the CC averaging output if the ADC channel input signals are identical except for polarity? Does it (partially) cancel?
Averaging re1*re2 + im1*im2 for each FFT bin, the average being a proxy for the squared magnitude at that bin frequency with the proviso that it could be negative.What equation did you take
(a+Jb)*conj(a+Jb) = (a+jb)*(a-Jb) =a^2+b^2Averaging re1*re2 + im1*im2 for each FFT bin, the average being a proxy for the squared magnitude at that bin frequency with the proviso that it could be negative.
OK, finally simple enough for me to understand.In simpler terms, what happens to the CC averaging output if the ADC channel input signals are identical except for polarity? Does it (partially) cancel?
Once the sets of re1*re2 + im1*im2 have been summed and divided by the number of cross correlations plot 10*log10 of their absolute values, since it is possible for them to be negative at frequencies where there is no input.after, i don't understand
sqrt(SUM(a^2+b^2)/nb-correl) right for you .
The virtual balanced input uses the FS voltage calibration values for each input to adjust the level before the sum/difference operation. The same will apply for the inversion option.Thinking that to the end, a gain fine-trim (for one channel would be handy to get deepest null there.
Ok, now I'm bit puzzled ...Yes, that works.
Both.Is the improvement observed really due to cross-correlation, or is it in the end rather a subtraction of the common-mode signal present on the two inputs?
for me is not good , look simulation , i have exactly attenuation = 5*log(N) for these levels with 2noise uncorrelated ~ 134dBFSOnce the sets of re1*re2 + im1*im2 have been summed and divided by the number of cross correlations plot 10*log10 of their absolute values, since it is possible for them to be negative at frequencies where there is no input.
For your DAC output measure use E1DA ADC ???I like it. Bought a used one for about half the price.