Spectrogram for custom frequency region

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Spectrogram for custom frequency region

Vladan Divljak
Hi,

Lets say I would like to plot a spectrogram from 2 kHz to 8 kHz out of 20 kHz signal
Spectrogram documentation doesn't list such option, so I thought to ask if there is perhaps some other way of doing it, rather then plotting huge spectrogram and cropping custom region.

TIA

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Re: Spectrogram for custom frequency region

Antonio Peixoto
Hi,

I think that you can resample you file to 16KHz so the spectrogram will range in 0KHz to 8KHz.
sox audio.ogg -r 16k -n rate spectrogram

To increase the frequency resolution without increasing the height of the spectrogram, the rate effect may be invoked to reduce the sampling rate of the signal before invoking spectrogram; e.g.
sox audio.ogg -r 4k -n rate spectrogram
allows detailed analysis of frequencies up to 2kHz (half the sampling rate).

I hope it help



De: Vladan Divljak <[hidden email]>
Para: [hidden email]
Enviadas: Sexta-feira, 5 de Outubro de 2012 16:19
Assunto: [SoX-users] Spectrogram for custom frequency region

Hi,

Lets say I would like to plot a spectrogram from 2 kHz to 8 kHz out of 20 kHz signal
Spectrogram documentation doesn't list such option, so I thought to ask if there is perhaps some other way of doing it, rather then plotting huge spectrogram and cropping custom region.

TIA

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Re: Spectrogram for custom frequency region

Vladan Divljak
Thanks Antonio for your reply

Those numbers were mentioned as an example.
Re-sampling can lower upper boundary, but not low frequency, even if I accept changing of original signal. I guess bandpass or sinc can focus frequency region, but then again I would like a regional plot of original signal if possible.

I guess there is no such option, and was curious enough to ask.
I can always produce higher resolution plot then crop the image.


Cheers


On Fri, Oct 5, 2012 at 11:10 PM, Antonio Peixoto <[hidden email]> wrote:
Hi,

I think that you can resample you file to 16KHz so the spectrogram will range in 0KHz to 8KHz.
sox audio.ogg -r 16k -n rate spectrogram

To increase the frequency resolution without increasing the height of the spectrogram, the rate effect may be invoked to reduce the sampling rate of the signal before invoking spectrogram; e.g.
sox audio.ogg -r 4k -n rate spectrogram
allows detailed analysis of frequencies up to 2kHz (half the sampling rate).

I hope it help



De: Vladan Divljak <[hidden email]>
Para: [hidden email]
Enviadas: Sexta-feira, 5 de Outubro de 2012 16:19
Assunto: [SoX-users] Spectrogram for custom frequency region

Hi,

Lets say I would like to plot a spectrogram from 2 kHz to 8 kHz out of 20 kHz signal
Spectrogram documentation doesn't list such option, so I thought to ask if there is perhaps some other way of doing it, rather then plotting huge spectrogram and cropping custom region.

TIA

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