Author 
Message 
angel61606
Joined: Jul 8, 2020 Posts: 34

Posted: Oct 27, 2020 5:41 AM Post subject: Dominant Frequency problem 

Hi Jarek I am using Dominant frequency element to find the peak frequency between 0.04 to 0.26 Hz. i have passed my data from a band pass filter with those cut offs. But the dominant frequency elemnt doesn't work correctly. it sometimes shows frequency above 0.4. I even changed the low and high frequency properties in Dominant frequency elemnt but still it didnt work. i tried to change fft bin count and input sample bins and also overlap bins nothing worked . please help me out. thanks 


jarek
Joined: Oct 22, 2007 Posts: 848

Posted: Oct 27, 2020 11:57 AM Post subject: 

You may have to reconfigure it. The dominant frequency is based on FFT (Fast Fourier) transform, which has limitations. 


angel61606
Joined: Jul 8, 2020 Posts: 34

Posted: Oct 28, 2020 9:41 AM Post subject: 

Jarek, how do you calculate the resolution? I mean the frequency resolution I expect is less than 0.1 Hz , considering the fact that my sampling rate is 250, i chose 4096 or 16384 for FFT bin count. but I see another parameter to be set here "input sample count", what do u mean by it? and how does it affect the resolution. 


jarek
Joined: Oct 22, 2007 Posts: 848

Posted: Oct 28, 2020 5:20 PM Post subject: 

The "Input sample count" can be lower than FFT bin count. In such case the reminder is filled with 0 (zero) value. That can help with faster response time (when this is lower). Resolution is controlled by the number of FFT bins. 
