fft , power, rms , spectrum

[aswin p ajayan]

hi
i am an electronics student. i trying to do a project on power spectrum analysis . i think if i could sample the ac mains using inbuilt adc of pic18f4550
and perform a fourier transform,it might work . But the problem is that i cant understand fft algorithm .can anyone suggest some pdf's for my needs.


also what should be the acquisition rate


i am just a beginner . any threads might be helpful

 

[alec_t]

This should get you on your way:
https://www.dspguide.com/

 

[misterT]

But the problem is that i cant understand fft algorithm .

Fast Fourier Transform algorithms are not easy to understand because they are highly optimized.. they are not "intuitive". You need to work through all the theory from the beginning and then study computer science etc. to fully get into it.

 

[misterT]

also what should be the acquisition rate

The famous "Nyquist rate" states that you should sample at least twice the highest frequency to prevent aliasing. In practice you need to sample about 10 times the highest frequency if you want to have some chance to reproduce (or analyze) the signal.

 

[MrAl]

Hi,

I ran across this site:
**broken link removed**

That attempts to explain the butterfly algorithm which breaks down the problem into smaller problems and so speeds up the computation.
I did not read the whole reference so i cant say how accurate or complete it is, but it looked decent at first glance.
There are bound to be tons of other references too just look for the butterfly algorithm(s).