Real-time combining of optical array signals

The results of field experiments designed to demonstrate key enabling concepts of optical array receivers are presented, in a field environment similar to actual operating conditions. The theoretical framework and analytical evaluation of optical array receivers have been developed and documented in previous articles. This article describes the implementation and field evaluation of a two-element optical array receiver incorporating photon-counting, signal conditioning, high-speed digital sample distribution, adaptive delay compensation and sample combining operations required for array reception of intensity-modulated optical pulse-position modulated (PPM) signals. Data collected in the field was processed offline to determine communications performance of a two-element optical array, and demonstrate the inherent advantages of optical array reception.