The small amplitude oscillation may be studied using data taken with sonar.
The plots x(t), v(t), a(t) appear sinusoidal. Measurements of the period T vs. amplitude a indicate that the motion is isochronous. It may be shown that T does not depend on the value of the mass while it does depend on its distance L from the center of oscillation.The value predicted by the model (T=2p*L/g) can be compared with the one measured from the plots x(t), v(t), a(t).

The large amplitude oscillation may be studied using data taken with the potentiometric sensor (after converting voltages into angles a.

Here the distortion of the plots of v_ang(t) and of a_ang(t) with respect to damped sinusoidal funtions is clearly evident. Also the plot of a_ang vs. a is no more linear.

Instead a_ang is linear with sina (as predicted by the model a_ang = —g/Lsina.

Also a plot of the period T vs. a will show that the pendulum is far from being isochronous.