measure frequency of a wrapped analog signal

[UniSA]

I am going to use LabVIEW to analyse an analog signal to obtain the frequency. The real signal is wrapped by another lower frequency signal outside. When I use "Extract Single Tone" vi to measure the frequency, it gives me the freq. of the outside signal. Please see the attached two figs. The first fig. shows the signal changing trend in a long period, while the second fig. shows the signal in a short period. Is there any good way to get both frequencies. Thanks in advance!
Jane

[hoffiz]

Hi,

What I would suggest is to do an fft on the signal, the result of the fft would give you all the frequency components of your signal so in your case the magnitude vs. frequency plot should show two peaks one for each frequency.

The extract single tone VI: Takes a signal in, finds the single tone with the highest amplitude or searches a specified frequency range, and returns the single tone frequency, amplitude, and phase.  So you can modified the range of frequencies you want to view.

See code attach.

I hope it helps

[sunu]

How to do FFT of the analog signal in labview FPGA to get the freq info?

[sunu]

How to do FFT of the analog signal in labview FPGA to get the freq info?

[Deagle]

sunu,

There is an FFT Express VI. More information is provided here. For further questions, please create a new thread for this under the FPGA software board.