33Anguita, JaimeCisternas, Jaime05-01-202605-01-2026333333We propose a method for identifying orbital angular momentum (OAM) states within a vortex superposition using a Shack-Hartmann (SH) sensor as a spatial-diversity detector. We define a local OAM at every pixel of the SH image, from which we construct an OAM spectrum. The topological charges are determined fromtheOAMspectrum using a low-complexity algorithm, resulting in estimates that are robust to beam wandering. Data from a 200 m experimental transmission are successfully tested using the proposed technique.33info:eu-repo/semantics/closedAccessLow complexity algorithmOptical vorticesOrbital angular momentumShack-Hartmann sensorSignal modulationsSpatial diversityTopological charges33