How to double the freqency of an audio input?

[InstaAxEToast]

Hi I am working on a project for school. I am using a speedy 33 dsp and lab view. I am taking an audio signal (guitar) and I want to double the frequency (ie bump it up an octive). I have tried mixing the signal with itself and removing the dc. This works perfectly fine with a sin wave but it does not work with anything complex. Does anybody have an ideas on how I could do this?

[Mellobuck]

Hello InstaAX,

Perhaps a quick fix, if you are only concerned with how it sounds, would be to change the dt of the time between points. If your data is in a waveform, than this is pretty straightforward, Get Waveform Property>dt; dt/2> Build waveform[dt]. However, this would also be twice as fast (like a sped up tape).

If you want to keep the same speed, but higher pitch, you will need to modulate, then demodulate the signal with twice the frequency. This is the trick that all the "chipmunks" albums use. I have to admit that I have only done this is MATLAB, but the corresponding functions certainly exist in LabVIEW, and I will do a little searching to find the exact ones.

-Mello

[InstaAxEToast]

Thanks, I will give that a try.