#### Coper

##### Member level 4

ADC I sample the signal, using digital filters I select one frequency from it.

For example, I have 128 signal samples and I need to decide whether there is a signal in this section or not.

Maybe RMS

XRMS=Sqert( (x1^2+x2^2+x3^2+xn^2)/n)

but maybe it's even easier somehow

simpler, I mean with faster math than 128 square rooting and addition

Or can you recommend a book that doesn't deal so much with theory, but with practical examples of digital signal processing?