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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: classic sample theory and FFT assumes steady state sinewaves - music is all but such (NT)... posted by Thorsten on June 26, 2001 at 13:19:06:
It implies a suitably band-limited input signal.And from this all else follows. A non-steady-state 20kHz
sine can be deconvolved into a steady-state sine and any number
of window functions to describe its transient nature. The latter
will imply frequency components above fs/2 (take a 44.1k system),
and as such a transient 20kHz sine is an illegal input signal
and hence should not be considered here.Likewise the triangular wave, which is a priori illegal as its
low-order harmonics exceed fs/2.So the argument is NOT against sampling, not against PCM or whatever,
but only against an fs/2 chosen too low in frequency.
The ringing in brickwall digital filters is there because of the
phase-linear high-order low-pass filters employed. Right. Phase-linear. High-order analog filters have severe phase-shift in
the passband, and guess what, they lack the pre-ringing.With this I am not saying that I advocate the use of any digital
filtering: after all, tinkering with the signal is tinkering
with the signal, be it in the analog domain or in the Z-domain.
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Follow Ups
- not quite - Werner 06/27/0103:43:31 06/27/01 (0)
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