A signal switch comprises a switch arrangement for selectively passing optical wireless communication, OWC, signals received from a plurality of photodetectors for output to an external device. A signal strength detector is arranged to measure a signal strength of OWC signals as passed by the switch arrangement. While an OWC signal received from a first one of the photodetectors with a signal strength is being passed by the switch arrangement, a selection unit controls the switch arrangement to pass a combination of the OWC signal from the first photodetector and the OWC signal from another photodetector, determines a signal strength of the combination of OWC signals, and estimates the signal strength of the OWC signal from the other photodetector based on the signal strength of the OWC signal from the first photodetector and the signal strength of the combination of OWC signals.