Parametric feedback resonance in chaotic systems.

If one changes the control parameter of a chaotic system proportionally to the distance between an arbitrary point on the strange attractor and the actual trajectory, the lifetime t of the most stable unstable periodic orbit in the vicinity of this point starts to diverge with a power law. The volume in parameter space where t becomes infinite is finite and from its nonfractal boundaries one can determine directly the local Liapunov exponents. The experimental applicability of the method is demonstrated for two coupled diode resonators.