How can I calculate the period of this signal?

[m_eh_62]

yea that's right
I consider it in this manner:
Signal Energy≡FFT(signal²)
i konw squaring a signal will be double the bandwith of the signal
My question is by using the Signal Energy plot can we find it's period or not?
the signal energy plot show that the main content of signal be concentrated at indext 41 of energy plot.

 

[echo47]

I think you and I hit the "submit" buttons simultaneously.

You should apply your energy squaring calculation to the FFT's output points, not to the input waveform (that just creates distortion and harmonics).

Don't forget that the FFT outputs complex numbers.

 

[salam2000]

I don't understand you;
but these relation may help you:
cos^2 (x)=(1+cos(2x))/2
sin^2 (x)=(1-cos(2x))/2
therefore the power two equivalent to twice frequency.

 

[m_eh_62]

I think you and I hit the "submit" buttons simultaneously.

You should apply your energy squaring calculation to the FFT's output points, not to the input waveform (that just creates distortion and harmonics).

Don't forget that the FFT outputs complex numbers.

thanks for your help
yea that's right
I should assume (FFT(x))² not FFT(x²)