To find frequency value

Priyanka_N

Hi,

 

Need help in finding the frequency value of the signal samples in a text file.(attached) 

In the text file, the first column represents the time and the second column represent the output value.System properties setup is shown below.

I tried few examples available in embed to find the frequency value.

• In a plot block by selecting the “Frequency Domain” option located in the  “plot/Options” tab.
• Another way by using FFT block

I am not sure whether its showing correct frequency value for the set of samples and is this the way to find frequency value or any other way.

Please help me out in finding the frequency value for this example.

 

Thank you,

Regards,

Priyanka

 

<?xml version="1.0" encoding="UTF-8"?>

Unable to find an attachment - read this blog

Ric_22025

Hi Priyanka,

The most direct way to identify the frequency content of a signal is using the FFT option in the plot block.  This technique will identify power at different frequencies over a frequency range starting at 0 Hz and going up to 1/(2*timeStep).  In the example you used above, the timeStep is .01 seconds so the maximum frequency you'd be able to see in the data is 50Hz. You can test this by applying a 20Hz sinwave to a plot with timeStep = .01, select FFT, and you'll see a spike at 20 Hz only and the frequency range will begin at 0 and go to 50 Hz.  

Ric