Linear detection smoke barrier for conventional systems. Includes independent transmitte, receiver and a control unit with LCD display. Ideal for protecting large surface places and spaces with high ceilings in which the structure can have reflecting surfaces. Possibility of adding a transmitter+receiver combination to be monitored from the control unit. Incorporates automatic dirt compensation circuit, relay alarm and breakdown output circuit and indicator of state led. Requires a power supply of 12/24VDC from a supply according to EN54-4.