[sdiy] Weaver frequency shifter

David G Dixon dixon at mail.ubc.ca
Wed Apr 27 19:26:44 CEST 2022


Hi Richie,

My first attempt at a frequency shifter was via the Weaver method.  It was a
total fail.

My second (and final attempt) was with the Bode method, and it works like a
charm.  As part of that effort, I researched exactly how to calculate the
RCs of a Dome filter for any frequency range and any number of stages, and
that mathematical model is at the heart of my Freak Shift module, which has
two Dome filters (one 12-stage filter from 15 to 15000 Hz, and one 18-stage
filter from 0.1 to 10000 Hz).

For me, Weaver remains an interesting theory that is difficult or impossible
to realize in practice.

 

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
rburnett at richieburnett.co.uk
Sent: Wednesday, April 27, 2022 3:00 AM
To: synth-diy at synth-diy.org
Subject: [sdiy] Weaver frequency shifter

[CAUTION: Non-UBC Email]

Has anyone tried building a Frequency shifter using Weaver's method?  
Either analogue or digital.

I'm asking out of interest, rather than any immediate intention to build
anything.

All of the synth related designs I've seen seem to be based around the
phasing method, using either an analogue dome filter or digital Hilbert
transform to impart the 90 degree phase difference.  I was looking at
Weaver's or "the third method" of SSB generation relating to an SDR
discussion at work the other day, and it looks like a good candidate for a
modern DSP implementation.

-Richie,
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