The beam operates primarily on the principle of sunshine obscuration employing infrared. The OSI-RI detector is actually a mixed transmitter/receiver which might be specifically connected to an intelligent detector circuit in LiteSpeed® or CLIP manner. Undesired alarms mainly because of the beam getting fully obscured for a brief time frame https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/