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..continuous from the previous message

With ARTA I have a very clean graph with Frequency Response and FFT-131072. A clean -60db falling.
I have done overlay the ADC Ch.2 on the ADC Ch.1 and I took this capture, very clean and I could export the one channel (csv, txt)

I try a lot to take an approximately graph like ARTA, at the Mi-Pro ...

2) At the last if I use as compensation file "Spectrum Analyzer Generate Frequency Compensation File (flat)" that from FRwhite then I have a totally different values of THD...the differences on compensation file is bigger!
Which method is right (1) or (2), probably the (2) is too very good to be ...

Nice Information, well expained but:

Actually, in the above discussion, the compensation factor at the fundamental frequency is assumed to be 0 dB... No UDDP calculation is required .

Is it meaning that UDPP THD calculation isn't required and the DDP THD_A is adequate? Look at my next answer ...

Thank you again for the help.

The compensation file is right, now. I make it for two channel as seems at the attachment capture.

I don't know if the compensation file must include the values before harmonics (10Hz-900Hz),

I have done the compensation file from the Frequency Response with White ...

Let's see what happens if I applied a compensation notch file.

I create a .fcf file with the values as I show at the attachment and then I loading it via [Spectrum Analyzer Processing]>"Compensation 1".

All the band under 2K has gone, I see at the manual that all frequencies that falls outside ...

Probably the issue with FR cutoff when I applied a compensation file, was due that I haven't restart the software Mi-Pro.

I changed the values of compensation file with positive values ​​instead of negative ones that I had.
But I seem that this applied of both channels and not only to Ch.A, at the ...

Let's see what happens if I applied a compensation notch file.

I create a .fcf file with the values as I show at the attachment and then I loading it via [Spectrum Analyzer Processing]>"Compensation 1".

All the band under 2K has gone, I see at the manual that all frequencies that falls outside the ...

I am come back :lol:

As you can see, the method-1 described as THD Notch 1 and the method-2 as THD Notch 2.
THD 20-20K, without compensation , I have
Method-1, 0.0000099% (-142.18dB)
Method-2, 0.0000079% (-141.79dB)

THD 8 harmonics order, without compensation , I have
Method-1, 0.0000078% (-142 ...

Congrats!
Tommorow, I will try your way!