Sounds like an interesting problem, but one above my paygrade. I think this is Julius O. Smith territory...or one of the other true gurus here. :)
Aaron Krister Johnson Music, etc.: https://soundcloud.com/aaron-krister-johnson https://soundcloud.com/filtercreed https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg https://aaronkristerjohnson.bandcamp.com/ http://www.untwelve.org Code: https://github.com/akjmicro <http://www.untwelve.org> On Wed, Jan 14, 2026 at 1:34 PM Daz Man <[email protected]> wrote: > Hi All, > > Does anyone know of a way to write an adaptive allpass filter in Faust? I > need to be able to adaptively phase shift a pair of signals (perhaps use > one as a reference and adapt the other) so they never phase cancel at any > frequency. > > I recently wrote some code for an adaptive NLMS FIR filter, and it works > well for noise reduction, but I have an application where I need to adapt > phase but not change amplitude. > > The purpose is to improve AM demodulation on a signal with multipath > fading, so the demodulated audio from the two sidebands is always combined > in-phase so there is never any cancellation. Previously I have tested a > multiband phase shifter approach for this, but it is not ideal, and it adds > a lot of group delay. > > An alternative might be to attempt to suppress the multipath fading > notches on the IQ signal before demodulation, but this is far more complex, > and since the signal modulation is audio and not data there is no training > signal to base the channel estimate on. > > Daz > _______________________________________________ > Faudiostream-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/faudiostream-users >
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