Abstract: Disclosed herein is a building equipment managing method using a history database for recording the conditions of building equipment, a display device installed in public spaces of a building, and an input device installed in the public spaces of the building for inputting a request for the indication of necessary information, the method comprising the steps of: recording a change in a condition of the building equipment in the history database; and in response to receiving a request for indicating a content which is recorded in the history database from the input device, indicating on the display device the content which is recorded in the history database.

Abstract: A system for communicating between mobile units and an exchange station, with a radio frequency signal, in which an electric signal from a telephone exchange of the telephone station is converted into an optical signal with an electricity-to-light converter. The optical signal is carried via an optical fiber cable to a transmission communication antenna for emission, with amplification of the optical signal if necessary. The emitted signal is received by a receiving communication antenna, amplified with an optical amplifier if necessary, and converted to an electric signal with a light-to-electricity converter.