[time-nuts] A simple sampling DMTD

[Magnus Danielson]

Hi,

On 2019-11-28 21:18, Joseph Gwinn wrote:
> JD,
>
> I'll have to think about it, but I will mention that with batch 
> processing using window functions, it's common to precede the FFT using 
> a simple FIR filter to eliminate the low-frequency energy (due to 
> clutter, DC leakage/offset et al), the problem being that the FFT alone 
> may not have sufficient rejection to prevent low-frequency energy 
> breakthrough.
>
> An alternate approach is to compute the mean of the windowed data and 
> subtract that mean from all samples in the window before computing the 
> FFT.  In analog terms, this is like a big coupling capacitor blocking 
> DC.

You also wants to remove the slope between the two sample end-points, or
else that slope represents an in-phase sawtooth function. A
window-function tends to do that.

Cheers,
Magnus