04-29-2009 10:47 AM
Hi all,
This is probably a ridiculous question for you folks but I would like to detect the fundamental frequency of a signal coming in off a NI USB-9233. Most of the development I do is automation, but since I'm the only one that knows our NI software I had a semi-urgent request to add this feature to some existing software we have. Was looking around for a VI that already does this but I don't see any unless its built into another VI as a side function?
Any pointers on this?
PS. I have sound & vibration toolkit as well.
Thanks for the input!
04-30-2009 01:21 PM
Hello,
So there is no Specific VI that will extract the fundamental frequency directly, meaning that you cannot search for a VI called "Fundamental frequency...". However if you assume that the fundamental frequency has the largest amplitude (usually the case for most applications) you can use the Extract Tone.VI or the Extract Tones.vi These are found under: Functions >> Signal Processing >> Waveform Measurements .
Try this, I believe this should help you get started with your application.
06-09-2015 11:57 AM
It's an old thread, but similar to my search, please let me know how can I do the same work in FPGA level ?
06-10-2015 09:04 AM
Hello meBaga,
This is will much more difficult in the FPGA. Your best bet, however, would be to use the FFT function. That will allow you to view the spectrum of the signal. You'll have to figure out a way of determining the fundamental, though.
06-17-2015 06:27 AM
If you know the frequency of the fundamental have a look at the goertzel algorithm.
If you have the FPGA power to make a complete FFT: Here I posted a NI presentation on how the tone detection vi works, and how it performs
http://forums.ni.com/t5/Signal-Conditioning/frequency-of-sine-waveform-VI/m-p/2638895#M7428