Posted by akhilesh [ 204.97.214.168 ] on June 27, 2005 at 21:49:27:

In Reply to: Fiter response - frequency domain and time domain posted by Wayne Parham on June 27, 2005 at 15:53:06:

THanks, Wayne.
So it seems that the bidat uses an algorithm to interpolate that uses the accelaration of prior signal pulses in some way, as opposed to mean magnitudes of past pulses. I know Norm of audiocrafers guild has done some work on dacs too. No one seems to know how the bidat works (other than Ed Meitner & John Wright!) I know the stuff was proprietary, but does anyone know?
I alsoknow,based on my readings that Wadia for example tries to get get the phase anomalies out by optimizing for the time domain, with a rolloff at higher frequencies. For some reason, the bidat (and the IDAT before it) seem to be able to optimize for time and frequency becuase of its interpolation approach. I know it uses FIR filters, and varies the upsampling rate. My best guess is that the upsampling rate variabilty along with the interpolation values predicted on acelration of earlier signals leads somehow to a superior filter.
ANyone else care to throw in their comments! I am curious!
-akhilesh

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