Re: [Discuss-gnuradio] Resample block for audio signal

[Murray Thomson]

Hi Andy,

Thanks a lot, I wasn't expecting so much help. I will read the flowgraph and I will try to understand it.

I've added an extra sine with double the frequency to simulate the first harmonic and when I transpose it I find lots of frequencies. Is this expected?

I will try to find a solution for it once I understand more how it works. Thank you so much, I hope you've enjoyed with it :)

Cheers,

Murray

On 13 March 2016 at 19:36, Andy Walls <address@hidden> wrote:

On Sun, 2016-03-13 at 12:00 -0400, address@hidden
wrote:
> Message: 10
> Date: Sun, 13 Mar 2016 12:29:07 +0000
> From: Murray Thomson

Hi Murray,

>
> Hi,
>
> This is probably an easy one but I'm stuck and i could do with some help.
> My goal is to get a musical note from the microphone and shift its
> frequency to transform the note to a different scale. For this to happen, I
> need to multiply all the frequencies for e.g. 1.5.
>
> I can achieve an octave of the signal multiplying it by itself (doubling
> the frequencies). I thought I could do this resampling the signal but now
> I'm not too sure. Do I need to use an FFT block for this?
>
> I would appreciate if someone can suggest the best way to go or point me in
> the right direction.

Since I was recording my daughter's violin audition video today, I was
in the mood to play around with this one.

Try the attached *grc file.  Note that you need headphones, or just keep
the speakers away from the microphone, or the feedback will ruin
everything.

Run the flowgraph and select "Up 5th" from the "Transpose" GUI widget to
multiply by 1.5.

Double check my variables for A3, B3, C4, D4, etc. and the QT GUI
chooser widget to make sure I got all the ratios right.

> Thanks,
> Murray

Regards,
Andy

transpose2.grc
Description: application/gnuradio-grc