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Taking a fft of a audio signal

Hey Dennis

 

Is the rest of the code right because I added the VI in but it still doesn't give a good graph. I also have to log the y range if that makes any difference

 

Thnxs again..you're been really helpful

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Message 11 of 31
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I posted a VI here. http://forums.ni.com/ni/board/message?board.id=170&thread.id=163587 It is crude but i may give you a jump start

 



Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
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Message 12 of 31
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thanks for replying t06afre but mine is way simplier than this. I have mine posted  if you could have a look at it and see what is missing

 

Thanks in advance

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Message 13 of 31
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Maybe but my VI is actualy giving some usefull output....................Your vi is just some functions tossed out on a diagram. You have no understanding of what you are doing. And you are no interest in learning something.I guess you are just fishing for an easy way out, for your homework


Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
Message 14 of 31
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the audio signal is coming from the mic so i put in a acquire sound vi but where do I connect it to in your program
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Message 15 of 31
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Hi Moe

I have to admit that converting a dynamic data into something useful is not straight forward for a beginner. The Express VI concept is just flimflams glued into labview with cheap glue. It is also poor documented. None of my students are allowed to use Express VIs in their lab reports. I want them to learn Labview. You can not learn labview by tossing in some functionality into a block diagram. Since how to convert dynamic data to waveform data is not documented. I have made a small sample VI showing how to do it. Remember also that my FFT VI need some work to fit your need. You have to connect the delta t control to a terminal on the VI connector block. But it works. I have tested it

 

 



Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
Message 16 of 31
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Thnxs a lot for replying

 

I'm still having problems. The output that I have is just not the same as the DSA. Where do you connect the dt into? and honestly if you have time if you don't mind explaining wut the dt portion of it does?

 

Thnxs again

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Message 17 of 31
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When you read from a sound card your output is not in volts but in raw A/D steps that equal the resolution of the A/D in the sound card.  For example, a 16-bit A/D would range from -32768 to 32767 for a total of 65536 discrete steps.  These numbers have to be scaled to the voltage range the A/D is wired for.  If your mic input is wired for a voltage range of +/- 10 mV then you would have to use a scaling factor to scale the raw numbers to this voltage range (20mV/65536 = 0.3051757 uV per step).
Randall Pursley
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Message 18 of 31
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what kind of scaling factor would you recommend for volts?

 

thnxs in advance

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Message 19 of 31
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Hi Moe

You will find all information you need here http://zone.ni.com/devzone/cda/tut/p/id/4541 and http://zone.ni.com/devzone/cda/tut/p/id/4541. The dt value is the reciprocal of the sample frequency(1/x) The unit is second, and it will give you the time interval between two samples. Now the rest are up to you. I feel I can not give you more help unless you show me some progress in your learning curve



Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
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Message 20 of 31
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