[PD] Negative frequency of modulating sinusouid in FT

Miller Puckette msp at ucsd.edu
Mon Jul 27 19:40:27 CEST 2020

Hi Maxi -

When you modulate a complex sinusoid with another one you only get one
sideband, not both.  The sideband's frequency is the sum of the two
original frequencies - so if they're exact opposites you only get the
result at frequency zero.

This is one reason for using complex sinusoids instead of "normal", real-valued


On Sat, Jul 25, 2020 at 05:44:37PM +0200, Maximiliano Estudies wrote:
> Hey peeps,
> I have another question regarding "The Theory and Technique of Electronic
> Music". It is not directly related to pd, but I guess that many of you will
> know this stuff and might be able to help me. I hope it is ok.
> In the last paragraph of 9.1 (
> http://msp.ucsd.edu/techniques/latest/book-html/node164.html) the frequency
> of the modulating signal is defined as having negative frequency (in the
> book -*k??)*, why is that the case? wouldn't a sinusoid with positive
> frequency *k??* also give us two partials at 0 and 2*k??*?
> Cheers,
> Maxi
> -- 
> Maximiliano Estudies
> *VDT Referat Beschallung*
> +49 176 36784771
> omslo.com
> maxiestudies.com

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