  A general method is presented to explicitly compute autocovariance functions
for non-Poisson dichotomous noise based on renewal theory. The method is
specialized to a random telegraph signal of Mittag-Leffler type. Analytical
predictions are compared to Monte Carlo simulations. Non-Poisson dichotomous
noise is non-stationary and standard spectral methods fail to describe it
properly as they assume stationarity.
