[sdiy] Generating acyclic waveforms?

[cheater cheater]

On Mon, Mar 22, 2010 at 03:18, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> Ian Fritz wrote:
>>
>> At 07:06 PM 3/21/2010, Magnus Danielson wrote:
>>
>>>> You wouldn't see a significant effect like this in winds because the
>>>> waves are longitudinal waves in air and therefore have negligible
>>>> dispersion.  Additionally, driven systems such as winds excite coherent
>>>> waves, so there can be no speeding up of specific harmonics over many
>>>> cycles.
>>>
>>> However, the end-impedance would allow for a similar effect, such that
>>> the resonance frequency of the overtones would not match up exactly with the
>>> integer multiples frequency-wise form the base frequency. To illustrate the
>>> impedance effect on a wind instrument...
>>
>>
>> No. The played notes have harmonic spectra, because they are periodic.
>>  (In mathematical terms this is known as "Fourier's theorem").  You are
>> perhaps thinking of the resonances of the impedance curves, which are
>> affected by a number of parameters, including the shape of the bore and end
>> effects.  The art of making instruments is to try to get the two spectra to
>> match reasonably well.  This is *extensively* discussed in Benade's book
>> "Fundamentals of Musical Acoustics", chapters 20-23.
>>
>> Ian
>>
> I think you entirely missed my knowledge of both Fourier transforms and
> acoustical impedances and related resonances. I also think you might have
> missed the finer details that occurs in acoustical resonators such as used
> in crystal oscillators, where fundamental frequency and overtones is known
> to be non-harmonic due to among other things impedances, and that also many
> modes of oscillation occurs.

Magnus,
How does the effect you describe work? Does it have a name? Do you
think that it can be used for audio-rate oscillators, even if not
necessarily with voltage controlled frequency?

Thanks
D.