We establish novel uniqueness results for the Gabor phase retrieval problem: if $\mathcal{ G} : L^2(\mathbb{ R}) \to L^2(\mathbb{ R}^2)$ denotes the Gabor transform then every $f \in L^4[-\tfrac{ c}{ 2},\tfrac{ c}{ 2}]$ is determined up to a global phase by the values $|\mathcal{ G}f(x,\omega)|$ where $(x,\omega)$ are points on the lattice $b^{ -1}\mathbb{ Z} \times (2c)^{ -1}\mathbb{ Z}$ and $b>0$ is an arbitrary positive constant. This for the first time shows that compactly-supported, complex-valued functions can be uniquely reconstructed from lattice samples of their spectrogram. Moreover, by making use of recent developments related to sampling in shift-invariant spaces by Gr\"ochenig, Romero and St\"ockler, we prove analogous uniqueness results for functions in shift-invariant spaces with Gaussian generator. Generalizations to nonuniform sampling are also presented. Finally, we compare our results to the situation where the considered signals are assumed to be real-valued.
Categories: math.FA