Estimation of the amplitude of a signal

Hello,

What is the best way to estimate the amplitude of a signal?

I've recorded a value that is quite periodic (looks like a sinus wave) and I would like to estimate its amplitude. Any ideas?

Thanks.

Answer 1

[Star Strider]

It depends on what you want. There are two commonly-used measures of ‘amplitude’, peak-to-peak and root-mean-square:

t = 0:0.001:5;
y = sin(2*pi*t);

PeakToPeak_Amplitude = max(abs(y))*2
RMS_Amplitude = sqrt(mean(y.^2))

For this signal:

PeakToPeak_Amplitude =
     2

RMS_Amplitude =
      0.70704

[Nicolas Le Roy]

Is the peak to peak amplitude only valid for signal that are symmetric about the x axis?

[Star Strider]

No.

Generally, the peak-to-peak amplitude is just (max(y)-min(y)).

The RMS value is also calculated similarly, regardless of the waveform.

The movmax, movmin and movmean functions can be used to window these, although that’s not commonly done.