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Re: artifact in spectrogram created using Raven

Subject: Re: artifact in spectrogram created using Raven
From: "John Crockett" naturalcontemplative
Date: Mon Jul 16, 2012 11:08 am ((PDT))
Hi Laura,

Do all of your artifacts correspond to clipped signals? I just tried a litt=
le experiment with an ME66 and both the PMD-670 CF and MZRH1 MD recorders. =
I turned on a fan to create some good background noise, and then whistled l=
oudly. First I had the record gain low enough so the whistle signal did not=
 clip. Then I turned up the gain so it did clip. In the resulting sonogram,=
 a white (low volume) "shadow" appears in the frequencies below the whistle=
 signal wherever it is clipped, eclipsing the fan noise, just as it appears=
 in your sonogram. The worse the clipping, the more pronounced the "shadow.=
"

In the unclipped samples, the fan noise continues uneclipsed.

Is there something about clipping that overloads the preamp so it cuts out =
other frequencies besides the signal that is causing the clipping?

John Crockett

--- In  "laura.hilberg" <=
> wrote:
>
> I was using a PMD 680 recorder and a Telinga microphone with a parabola. =
I was using manual gain (no automatic), but I had some difficulty getting c=
lose enough to the birds for a clear signal and then having them shift posi=
tions so they were facing me more and being blasted away. And this is my fi=
rst time really recording, so inexperience definitely plays a role (and tha=
nkfully, they get better as they go along).
>
> Can you say what you mean by the gain needing to be set at a fixed level =
so that the sound doesn't clip? It was fixed, so I don't think that would b=
e an issue.
>
> And sorry about the sound sample - it wouldn't let me post it (464kb) bec=
ause it said there wasn't room.
>
> Thank you so much!
>








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