The beam operates totally on the basic principle of sunshine obscuration making use of infrared. The OSI-RI detector is actually a mixed transmitter/receiver that can be directly linked to an smart detector circuit in LiteSpeed® or CLIP mode. Power and connectivity occur in the imager only and the OSID-R only https://www.firesense.co.uk/type/addressable-fire-system/addressable-beam-detectors/