回應： peak detection in certain frequency

[ohla]

Hello everyone.

I am a rookie of labview, and I want to realize a program.

The program reads in data and then do FFT transform.

After getting FFT waveform, I want to search the waveform for peak in certain frequency, say 0.4~0.6Hz,

and then output its magnitude.

I have done the FFT part, but I have no idea about peak detection in certain frequency.

Please help me! Thanks!

[JÞB]

Since youve managed to move the signal into the frequency domain this becomes rather easy.  use the Array subset function to get an array of powerleves starting at the low cutoff freq and containing R samples (R = highest freq - lowest freq / Freq resolution)

Then use Array min max to return the largest power and calculate the frequency from its index!

[ohla]

i can understand your way.

if there are 1024 samples in the original signal, then after FFT, there are still 1024 samples in FFT waveform.

But how can I know the index certain frequency starts and ends?

[pine]

I guess you want to extract the frequency, amplitude and phase of a single-tone signal. You can use “Extract Single Tone Information.vi" directly. 

[Asad_Tirmizi]

Isnt this what you want ?