I should read your books more carefully :-)

Dieter

> -----Ursprungliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von Florian Anwander
> Gesendet: Freitag, 1. August 2008 11:17
> An: Doepfer_a100@yahoogroups.com
> Betreff: Re: AW: AW: 1 discontinuation of all modules with
> CEM3320, CEM3340 and CEM3381/PA381
>
>
> Hi
>
> > Is it What's the difference between the effect of having different
> > cores
> The theoretically resulting waveform of FM is only "real" for the core
> wave form. All other waveforms will be that, what the waveform converter
> produces from the fm'ed core-waveform.
>
>
> I uploaded two graphic files to the files section:
> http://launch.groups.yahoo.com/group/Doepfer_a100/files/analog-fm/
> These are excerpts from my book.
>
> I some months ago wrote the following text in private mail to Bakis,
> which explains the images:
> -----------------------snip------------------
>
> The most relevant thing is: FM with analogue VCOs has nothing to do with
> the theoretical FM, because everything depends on the working principle
> of the core oscillator (saw or triangle), and what the waveformconvertes
> make out of the fm'ed core wave form.
>
> I'll attach two excerpts from my book:
> analogue_fm.png explains what really happens in a saw based VCO. Left is
> an log FM, right is the linear FM:
>
> * the first row (rectangle) is the modulator with an amount of +1V to -1V
>
> * the second row (400Hz saw) is the carrier
>
> * the third row shows the two saws which would be created by a CV of +1V
> and -1V. In log FM this will be 1V up/down => 1 Octave up/down, =>
> 800Hz/200Hz. In lin FM this will be 1V a certain frequency up/down, =>
> lets say 200 HZ => 600Hz/200Hz. The higher result(800Hz or 600Hz) is
> light grey; the lower result (200Hz) is dark grey. The two frequencies
> look like two ramps with different steepness.
>
>
> * Now the fourth line shows what really happens in the VCO: There is a
> thin horizontal line, which is the threshold at which the Capacitor in
> the core-oscillator is unloaded.
> The rectangle switches between the two steepnesses. With the bigger
> steepness of the 800Hz at the log FM the resulting wave form will reach
> the threshold faster than with the "600Hz-steepness". As you can see the
> threshold will be reached at the same time as with the original
> carrier signal.
>
> Thats the one graphic.
>
>
> The second graphic shows, the same FM, but this time not the core saw
> oscillator, but the output of different wave forms from the waveform
> converter. The Modulator still is the known rectangle.
> Line a shows what we would expect for a triangle carrier.
> Line b shows what we would expect for a rectangle carrier.
> Line c shows what we really will get at the triangle output.
> Line d shows what we really will get at the rectangle output.
>
> The latter two show, what the waveform converter will create from the
> originally FM'ed saw from the core-oscillator. Here you can see that
> this has nothing to do with real FM
> -----------------------snip------------------
>
> ------------------------------------