Apparatus and associated methods relate to pairing a receiver with an emitter based on a presence of an amplitude of a spectral profile at at least one predetermined frequency. In an illustrative example, a receiver may receive, from the emitter, an emitted optical signal modulated by the at least one predetermined frequency. A receiver may, for example, generate a digital signal corresponding to the optical signal received. A controller may, for example, generate the spectral profile from the digital signal. The controller may, for example, apply a predetermined threshold to the spectral profile. The controller may, for example, generate an output signal based on the presence of the amplitude of the spectral profile above the first predetermined threshold at the at least one predetermined frequency. Various embodiments may advantageously discriminate a corresponding emitter to establish an optical source-to-detector-link, for example, in the presence of other emitters and/or optically noisy environments.
