  Gravitational waves are a potential direct probe for the multi-dimensional
flow during the first second of core-collapse supernova explosions. Here we
outline the structure of the predicted gravitational wave signal from
neutrino-driven supernovae of non-rotating progenitors from recent 2D and 3D
simulations. We sketch some quantitative dependencies that govern the
amplitudes of this signal and its evolution in the time-frequency domain.
