A new type of intermittency from a ring of four coupled phase-locked loops

This paper investigates a new type of intermittency from a ring of four coupled phase-locked loops (PLL's). This system can be represented by a six-dimensional nonlinear autonomous differential equation that has a four-dimensional invariant manifold named H. With a quasi-attractive property, this invariant manifold causes a type of intermittency. Namely, long laminar phases in H and short bursts out of H alternate irregularly. Different from the well-known on-off intermittency, the core of this intermittency is not a chaotic set in H, but two kinds of semistable periodic orbits in H called the entrance set and the exit set. We try to clarify the mechanism of this intermittency by using bifurcation analysis of these periodic orbits.