Frequency Response VS FFT for measring frequency response of a audio ouput signal.

[rcard53762]

We have purchased the Sound and Vibration Toolkit and I have some questions.

From the frequency response example I looked at you measure the input then the ouput and the Vi gives you the difference.

I want to measure the audio frequency response a radio. 

So all I have is the output I dont have the audio input  to use as a reference. 

How would I measure frequency response with the frequency rasponse VI with only the output audio signal?

I was also looking at the FFT example to measure the audio signal frequency response.

But from what I can tell so far this only does 1 channel I want to do both channles at the same time.

Is there a way to do FFT on 2 channels at once and have them output on the same graph?

Thanks for any help you can provide.

[MickeyD]

Hi,

I was looking through the examples and If you look at the SVXMPL_Multichannel FFT (simulated) examples, this shows how to take an FFT with multiple signals. You just pass in an array of the waveforms.  If you need to put your signals together you can use the merge signals VI, which is located in the Express»SignalManipulation Pallette.  Let me know if you need any further help with this issue.

Have a great day,

Michael D
Applications Engineering
National Instruments