envelope follower

[CGS2510.SEP.STUDENT.UCA at CUB.UCA.EDU]

> > Unfortunately not! I had thought about this my self, but recent investigation
> > shows, that when you square a signal like a1*sin (w1*t)+ a2*sin(w2+t) you get 
> > a1^2*sin^2(w1*t)+2*a1*sin(w1*t)*a2*sin(w2*t)+a2^2 sin^2(w2*t)
> > since (a+b)^2 = a^2+2ab+b^2  :-< (the old binomial pitfall)
 
 
> Hang on a moment, 
> you have squared the amplitude, but what about the frequency components. This 
> is mathematically a 2D problem which requires complex multiplication.
 
> There will be sum and difference components of the frequencies.


Wait up! I cannot hear complex tones, only real ones.  This surely is 
a real valued problem that can be performed by basic trig identities, 
though I agree that it probably is much faster using complex 
representation arithmetic.