Re: Secondary Harmonics
"Raimund Specht" <>
Wed, 04 Jun 2003 18:27:13 -0000
> > Dear Experts,
> > Does anyone know if CoolEdit Pro's spectrogram would add
I still have not seen any spurious harmonics in CoolEdit. In fact, I
can not remember of any other major program having such problems.
However, theoretically it would be possible.
A simple test would be to generate a synthetic sine signal, that
does not have any harmonics. When your spectrogram software does not
show harmonics on that signal, your software would be ok.
Filtering would not be a reliable test for that. The reason is, that
there is no ideal low-pass filter, that would remove the signals
from the stop-band (the frequency range above the cutoff frequency)
completely to 100 percent. The stop-band attenuation of common
filters is limited to something like 60 or 90 dB (or even higher),
depending on the type of filter. So, larger signals may remain in
the filtered file (at much lower amplitudes of course). These
remaining signals (or harmonics) visible on a spectrogram were not
produced by the specrogram algorithm. They are really present in the
The University of NSW School of Computer and Engineering
takes no responsibility for the contents of this archive. It is purely
a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way.
If you wish to get material removed from the archive or
have other queries about the archive e-mail
Andrew Taylor at this address: