Hello everyone, I want to calculate true rms from samples and wonder if the window size must be an integer of the period of the signal. (I'm very lazy to measure the frequency of signal )

If there is an error with using non integer window size, how can be calculated?
Ah, the formula I saw in internet is
w
Vrms= sqrt(sum(V[n]*V[n])/Window)
n=1
Thanks in advance

 

If there is an error with using non integer window size, how can be calculated?

That would require knowing the frequency.

And welcome to the forums!

 

By 'non-integer' presumably you mean not an integral multiple of the signal period?

 

Yes not integral multiple of signal period, for example if signal is 20 ms then I use a window of 205 ms (20 *10.25). Is it the same as using 200 ms ??

Thanks

 

if signal is 20 ms then I use a window of 205 ms (20 *10.25). Is it the same as using 200 ms ??

No, it isn't.

 

Do you know any literature that describes this in detail...
Thanks

 

Do you know any literature that describes this in detail...
Thanks

Yes.

Google is your friend.