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Thread Subject:
pwelch

Subject: pwelch

From: Dave Brackett

Date: 7 Jan, 2009 17:37:02

Message: 1 of 3

I'm using pwelch to get a Power Spectral Density estimate of a wav file. The output is in dB/Hz. How can I get the output in just dB?

Is it as simple as multiplying each magnitude by its corresponding frequency?

Thanks.

Subject: pwelch

From: NZTideMan

Date: 7 Jan, 2009 19:37:01

Message: 2 of 3

On Jan 8, 6:37=A0am, "Dave Brackett" <davebrack...@hotmail.com> wrote:
> I'm using pwelch to get a Power Spectral Density estimate of a wav file. =
The output is in dB/Hz. How can I get the output in just dB?
>
> Is it as simple as multiplying each magnitude by its corresponding freque=
ncy?
>
> Thanks.

No. You must multiply by the interval in frequency.
PSD is in dB/Hz so that when you take the area under spectrum, you get
the variance - Parseval's Theorem.

Subject: pwelch

From: Dave Brackett

Date: 8 Jan, 2009 10:23:01

Message: 3 of 3

NZTideMan <mulgor@gmail.com> wrote in message <9decc7ae-6e5d-4818-8864-f6afc9b6ee67@d36g2000prf.googlegroups.com>...
> On Jan 8, 6:37=A0am, "Dave Brackett" <davebrack...@hotmail.com> wrote:
> > I'm using pwelch to get a Power Spectral Density estimate of a wav file. =
> The output is in dB/Hz. How can I get the output in just dB?
> >
> > Is it as simple as multiplying each magnitude by its corresponding freque=
> ncy?
> >
> > Thanks.
>
> No. You must multiply by the interval in frequency.
> PSD is in dB/Hz so that when you take the area under spectrum, you get
> the variance - Parseval's Theorem.

Ah ok, thanks!

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