[sdiy] SV: Re: Saw phase shifter used in frequence shifting.

[karl dalen]

--- Magnus Danielson <cfmd at bredband.net> skrev:

> From: karl dalen <dalenkarl at yahoo.se>
> Subject: Saw phase shifter used in frequence shifting.
> Date: Sat, 17 Sep 2005 03:29:25 +0200 (CEST)
> Message-ID: <20050917012925.6623.qmail at web25502.mail.ukl.yahoo.com>
> 
> > Harry, Magnus and the rest who migh be interested!
> > 
> > I came onto a idea here, can it be so that one could 
> > use the phased saw as a angle wrecker for an frequency shifter?
> > SSB, DSB type of shifter? (asuming the saw goes to the basic
> > saw to tri and then diode or saturated OTA sine shaper).
> > 
> > If a PW width of 50 declare 0 degres (saw phase will then start
> > at 90deg and end at 270 so the variable range would be 180 deg)
> > and anything above 50 gives positive direction of frequency 
> > shifts and anything below 50 gives negative frequency shift?
> > 
> > You still have the straight saw available as phase reference
> > 
> > Many types of quadratues could easily
> > be made out from one saw phase VCO!
> > 
> > Bad idea?
> 
> No, I don't see any problem with this. It should work well to get the
> quadrant
> variant from the same oscillator core. What is an issue, is the overtones of
> the shaped sine which I think is more of a concern for a frequency shifter
> than
> for normal musical useage. However, beyond that I can't see any problem.

I figured that to!
> 
> So, for the carrier oscillator it is clearly a go, the phase-shifting network
> for the signal remains an issue, but the polyphase filter is fairly simple
> and
> should work well.

I was talking about the SSB DSB shifters, dont they use just a simple
LPF filter between each multiplyer! Maybe the allpass type sound better 
then the SSB? I have no idea since i have never built a Frequency shifter unit!

KD

> 
> Go for it! ;O)
> 
> Cheers,
> Magnus
>