  Nonlinear oscillators can mutually synchronize when they are driven by common
external impulses. Two important scenarios are (i) synchronization resulting
from phase locking of each oscillator to regular periodic impulses and (ii)
noise-induced synchronization caused by Poisson random impulses, but their
difference has not been fully quantified. Here we analyze a pair of uncoupled
oscillators subject to common random impulses with gamma-distributed intervals,
which can be smoothly interpolated between regular periodic and random Poisson
impulses. Their dynamics are charac- terized by phase distributions, frequency
detuning, Lyapunov exponents, and information-theoretic measures, which clearly
reveal the differences between the two synchronization scenarios.
