Stochastic resonance

I am trying to look for a stochastic resonance in a system described by Langevin equation and a periodic forcing. While I can simulate an SDE numerically I have no idea how to calculate the ‘signal to noise
ratio’ which quantifies the stochastic resonance. I use python for my computations. Thank you very much in advance.

The equation is of the form
$$frac{dx}{dt}=-U'(x)+Acos Omega t+xi(t)$$