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Numerics FFT

Jun 9, 2011 at 9:39 PM


I'm just staritng to get to grips with some DSP and have started using the Mathnet Numerics for my FFT. I am little confused on how to get the result I want.

Essentially I am taking some Audio data and pushing it through the FFT, I am plotting this output to simple single color spectrum analyser, it looks ok to me but its only giving me the one side of audio. Not sure if that makes sense, but the audio contains left and right signals so I thought I would see this plotted evenly. I am actually using ultrasound data so I was expecting to see negative freq for the one side.

My code is basically load an array with 512 samples of complex data (created from Real/Imag values) then do an in place transform.

I've read somewhere that some FFT's have power of 2's so you can extract the two sides of audio?

I may not be using the right terminology but would appreciate any help you can give.