[sdiy] what is the amplitude envelope of a signal

[Czech Martin]

> If you're getting signal breakthrough it means either there's 
> some signal 
> breakthrough in the circuit due to a design or construction 
> fault, or the 
> filtering isn't working properly, or both. The output should 
> be a slow *DC* 
> variation. There should be no effective signal content above 
> 100Hz at the 
> very maximum, and 10Hz would be more typical for many applications.

That is a good question. A lowpass with 100Hz or even 10Hz
gives problems with signals that have a short attack.

> 
> The only way to create a perfect envelope follower is to do 
> it digitally in 
> non-real time, where you can go forward and backtrack with an 
> adaptive 
> time-constant and some clever logic. 

This is what I tryed, now I found that I can not write down
a formal description of "envelope", because I do not know
what it really is.

Like I said, I thought I knew exactly what it is about, but
when it comes to a formal description (algorithm) I know
nothing about.


m.c.