PRIVATE BRANCH INFORMATION COMMUNICATION SYSTEM

摘要

PURPOSE:To prevent the collision phenomenon of plural slave units with each other at the time of mutually communicating optical information signals transmitted to space with light as a transmission medium by optical radio waves between a master unit and the plural slave units. CONSTITUTION:In this private branch information communication system 1, at the time of radio-communicating the optical information signals between the master unit 10 and the plural slave units 30, the master unit 10 intermittently generates timing signals for permitting transmission from the slave units 30 when no carrier of the optical information signals from the slave units 30 is present and originates the timing signals towards the slave units 30. In the meantime, the slave units 30 detect the presence of the timing signals from the master unit 10, generate a random number when the transmission to the master unit 10 is desired and originate the optical information signals from the slave units 30 only when the number of the timing signals and the random number after the timing signals are detected coincide.