  We consider a class of skew product maps of interval diffeomorphisms over the
doubling map. The interval maps fix the end points of the interval. It is
assumed that the system has zero fiber Lyapunov exponent at one endpoint and
zero or positive fiber Lyapunov exponent at the other endpoint. We prove the
appearance of on-off intermittency. This is done using the equivalent
description of chaotic walks: random walks driven by the doubling map. The
analysis further relies on approximating the chaotic walks by Markov random
walks, that are constructed using Markov partitions for the doubling map.
