[PD] frequency-shifter

Frank Barknecht fbar at footils.org
Fri Dec 20 15:36:01 CET 2002

Hi Orm,

Orm Finnendahl schrieb:
> did anybody implement a frequency shifter using single-sideband
> modulation with Hilbert-Transform in pd?
> If so, I'd be very much interested in it.

If I remember correctly, you're on Linux, right? Then maybe this LADSPA
plugin (use with plugin~) by Steve Harris might do what you want, and it
shouldn't be too hard to port to PD native:

[Quoting http://plugin.org.uk]

  Bode frequency shifter (bodeShifter, 1431)
  A Bode/Moog Frequency Shifter is a popular analogue synth module, it
  works by shifting all the frequencies of an input signal up or down by a
  specified frequency. This version shifts in both directions at the same
  time as its almost no extra work and its often useful to have both
  directions.It doesn't actually work in the same way as an analogue
  Bode/Moog, which use Dome filters as the core, it uses a Hilbert
  Transformer, which is much simpler to implemtent in digital systems. The
  output is very similar though, and people are familiar with the name
  Bode.The theory of operation is pretty simple, and uses some clever maths
  to cancel out the upper or lower sidebands of a ringmodulator applied to
  the input signal. Read the source if you want more information. The
  Hilbert Transformet coefficents came from mkfilter, the excellent filter
  calculator, available at

Frank Barknecht <barknecht at dradio-online.de>
           -= www.dradio.de =-
DeutschlandRadio-Online * Redaktion Köln
tel 0221 - 345 1851 * fax 0221 - 345 1869

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