[sdiy] Frequency shifters, again

[Magnus Danielson]

From: Don Tillman <don at till.com>
Subject: Re: [sdiy] Frequency shifters, again
Date: 20 Sep 2003 00:56:53 -0700

> Hey JH,
> 
> I forgot to speak up before when you first mentioned this topic...
> 
> I've seen this before.  (!!!)  It was an old issue of the Journal of
> the Audio Engineering Society, roughly around 1974.  
> 
> It was a voltage controlled filter built with two balanced modulators,
> a fixed filter between them, and a VCO.  At least two pages long, with
> a block diagram.
> 
> Unfortunately that's all my feeble memory can provide.  It probably
> wouldn't be difficult to hunt this down at a university library.

If you are interested in frequency shifting, I recommend to read Dr. Gingells
PhD Thesis. I've put the PDFs at

http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/00index.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/01chptr.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/02chptr.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/03chptr.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/04chptr.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/05chptr.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/06chptr.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/07refs.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/08elipt.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/01chptr.pdf

and you can also peak into these articles:
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/1969itt.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/1973itt.pdf
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/1975iee.pdf

and the UK patent:
http://www.takeonetech.de/buchi/magnus/synths/friends/gingell/UK69_1.pdf

In there you will learn quite alot about the frequency shifting techniques with
good references. However, the main result here is a much better way of
designing the filter and I think this is what you should make use of.

I haven't made a webpage with the above links, so I guess this email is your
first hint of these files, but please do look at them!

Dr. Gingell is into other stuff these days, but he wants his work to get spread
after all these years, and he went over quite some effort to hand it to me for
put up on the web!

Maybe you've seen the strange four-phase filter in The Art of Electronics?
It comes out of this work!

Cheers,
Magnus