A triangle window in frequency will suppress the sinc(t) sidelobes a lot, so I suggest trying that. Squaring the sidelobes makes them rather small. All window functions have side effects. At the moment, I prefer a triangular aka Bartlett window as being the best compromise, at least for TDR work.
This is comparison for Rectangular, Triangular, Blackman and Blackman-Harris-7 window functions:
This picture shows complex components with Blackman window
It seems that the Blackman window is the best choice here, because all other window function have high side lobe distortions.
Note: all these pictures are the same reflections from connectors and adapters between different pieces of cables connected together in a line with 50 Ohm load on the end (taken from the last test, see my previous post).
I'd also suggest preserving the sign of the time domain amplitude so that it's easy to tell capacitive and inductive discontinuities apart.
If I understand correctly, in time domain we have reflection coefficient Γ in complex representation. So, I just calculated VSWR in the following way:
VSWR = (1 + |Γ|) / (1 - |Γ|)
And it works pretty good. But I'm not sure, is it correct?
If you're talking about |Γ| it is always have positive sign. So I'm not sure what did you mean with "time domain amplitude"?
I want to get a chart with absolute impedance along the transmission line. Something like this:
Is it possible?