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NI-USB 9233: audio frequency spectrum using C/C++

Hello all,

I'm a bit of a beginner in data acquisition and signal processing, so I hope my question is not too poorly formulated.

I am supposed to work with multiple audio signals (coming, from instance, from a CD player, navigation system, and so on) which will be (for testing purposes) all plugged in to a NI USB 9233 as "input channels".
I have to work with these audio channels through the NI USB card, for detecting volume and frequency spectrum, saving mp3 samples and various other things (programatically, by using the NIDAQmx C++ library).

My question: using a DAQmxCreateAIVoltageChan(), the card gives me voltages (which correspond to amplitudes, as far as I understand) -- so do I have to use the Fast Fourier Transform in order to get component frequencies for the audio spectrum? And do I need to code it by hand or is there some (NIDAQmx) C++ library that offers me the same thing as the FFT LabView VI?

Thank you very much for any hint!
--ACG.
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Hello,


the DAQmx API (Application Programming Interface) is used to communicate with NI-Hardware.
The DAQmx driver doesn’t provide any signal processing functions.
If you want to perform a signal processing function like a FFT-function, you have to use a tool which provides this functionality.

If you want to program in a text based language you can use for example LabWindows/CVI or Measurement Studio.
Attached you’ll find a link to these tools:

 

NI LabWindows™/CVI
http://www.ni.com/lwcvi/

NI Measurement Studio
http://www.ni.com/mstudio/

 

Regards
Ulrich
AE-NICER

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