[comp.dsp] 180-deg phase-shift -- A study in Usenet tech

SRGPMAP@grace.dsir.govt.nz (06/13/91)

Here is another theoretical breakthrough. It has been stated that a perfect
reconstruction filter for sampled audio has an infinite impulse response,
due to the infinitely sharp cut-off required at the Nyquist frequency. However,
a finite duration reconstruction filter with an impulse response which is a
half sine pulse (at a frequency of fs/2) gives exact reconstruction at the
Nyquist frequency.