FIELD: laser communications engineering; atmospheric laser communication lines receiving messages under varying background conditions. SUBSTANCE: device has newly introduced optical receiving system, holographic reflecting filter, light filter, all arranged in tandem on optical axis, and also first and second photodetectors, processing unit, and their interconnections; it enables direct estimation of background noise in the course of message reception . Optical receiving system passes received beam to holographic reflecting filter placed at angle α to optical axis. Holographic reflecting filter functions to spatially separate beam components into those not containing signal which are confined within light filter and converted into electric signal before entering photodetector and components containing signal which are converted by second photodetector. Upon receiving information about power of transmitted optical signal from first photodetector and information from second photodetector used to estimate background power, processing unit decides which of two signals, 0 or 1, reached optical receiver during time space under discussion. EFFECT: reduced average probability of abnormal discrimination of symbols. 1 dwg
