Total energy in Time and Frequency Dimain

I truly appreciated if somebody can direct me how to measure total energy in a certain frequency band?

I have a signal and use this code to measure total enery and the result is reasonable.

E1_timedomain=sum(abs(x.^2))

but it measuers total energy of whole signal. I just want to measure it between [0-100] Hz. Appreciared!

Answer 1

[Star Strider]

If you have R2018a or later, and the Signal Processing Toolbox, use the bandpass function to selectively filter the frequencies-of-interest. Then do whatever calculations you want to do on the output. If you have an earlier version, it is easy to design filters in MATLAB. I will help you with that, if necessary.

[Maria Amr]

Star Strider Thank you so much.

As usual, the best and the fast way.BIG like!

[Star Strider]

As always, my pleasure!

Answer 2

[Maria Amr]

Star Strider I have applied a bandpass filter and get a reasonable result. Would you please direct me how may I retrive the filtered signal? Appreciated!

that is my code:

bandpass(amp1,[1 78],fs);

[Star Strider]

You need to use an output:

filtered_signal = bandpass(amp1,[1 78],fs);

Answer 3

[Maria Amr]

Star Strider Appreciated!

[Star Strider]

As always, my pleaure!

(Also, in the future please post comments as Comments, not Answers.)