Abstract: An anti-intruder system which sets up an alarm when being breached, the system comprises of plurality of posts deployed apart forming a peripheral fence, each post carries at least a master optical array and a slave optical array, each optical array has a multiplicity of infra-red transceivers, each transceiver includes a light source and a light detector, the master array is mounted oppositely to and facing the slave array of an adjacent post, wherein the light detector of each transceiver of each optical array is illuminated by more than a single light source of the transceivers of the opposite optical array and the intensity of illumination of the light sources of the transceivers of the master optical array are automatically adjusted according to the light intensity arriving to the light detectors of the transceivers of the slave optical array.

Abstract: An anti-intruder system which sets up an alarm when being breached, the system comprises of plurality of posts deployed apart forming a peripheral fence, each post carries at least a master optical array and a slave optical array, each optical array has a multiplicity of infra-red transceivers, each transceiver includes a light source and a light detector, the master array is mounted oppositely to and facing the slave array of an adjacent post, wherein the light detector of each transceiver of each optical array is illuminated by more than a single light source of the transceivers of the opposite optical array and the intensity of illumination of the light sources of the transceivers of the master optical array are automatically adjusted according to the light intensity arriving to the light detectors of the transceivers of the slave optical array.