| 摘要 |
PURPOSE:To make an optical axis of luminous flux for beacon coincident with that of luminous flux for signal completely by providing an optical transmitter applying modulation of different frequency band from beacon and signal to a ray irradiated from a single light source and an optical receiver extracting selectively a modulation signal. CONSTITUTION:The beacon luminous flux irradiated from an opposite optical communication equipment, e.g., a luminous flux having a wavelength lambda2 turned on/off by a 5MHz clock signal is made incident in a photodiode 25 of the reception system, and converted into a 5MHz electric signal, and the beacon is amplified by a preamplifier 24 at a variable band and fed to a beacon output terminal 22 and a direction controller 40. The direction controller 40 controls the direction of luminous flux irradiated from an antenna 31 so that the electric field strength of the reception beacon is maximized. When the direction control is finished, switches 13, 23 are changed over and the transmission/reception of a PCM signal in faster speed is started. Thus, in irradiating the luminous flux for beacon as well as signal, the optical path from a laser diode 15 to the antenna 31 is made coincident completely. |
