Hi Arpiben,

1: It's an alias caused by the 100kHz signal. The 100kHz signal is sampled at 48kHz for the chart with no anti-aliasing filter applied

2: The latest version (v.15) appears correct to me

The transfer function is being computed from the harmonic values you specify and should reflect only those harmonics you entered with a simple sine test signal. Try the same with a two-tone test signal to see the IMD products.

3: Harmonic distortion is created by the non-linear transfer function of the device. A signal at level A being fed into the device will not come out at level A on the other side, but at some other level, B. Output B = f(A) where f is some non-linear transformation. This is what DISTORT does when you enter harmonics into the custom table: it computes the nonlinear transfer function that would correspond to the entered harmonic content. Once you enter more than one, the amplitude of the first harmonic will be affected by the additional non-linearities introduced by the new ones. This is what the transfer function looks like with the two harmonics you entered. A far cry from a straight line! Pick a value on the X axis (input) and find the corresponding value on the Y axis (output). At -0.5, for example the output will be less than -0.2, more than 6dB greater.

View attachment 42836
Amplitudes of signals will be altered depending on their magnitude. The larger the harmonics that you add and the more that you add, the larger the non-linearity of the transformation that will be generated by DISTORT. With the more 'realistic' harmonic distortions, the transformation is much closer to a straight line, and so the magnitude differences between what you enter and measure will be much smaller.

4: Good point. I sometimes find that it gets in the way, also

Realize that you can also move and zoom in/out the content of the chart by dragging it or using the mouse wheel (same controls as in DeltaWave).