| 摘要 |
PURPOSE:To obtain an optical interphone inexpensive and immune from noise, and has a long transmission distance, even if conventional analog electrooptic conversion E/O and analog photoelectric conversion O/E are used, by executing only ON/OFF as for electrooptic conversion, and executing electric (analog- frequency specific waveform number) conversion prior to said conversion. CONSTITUTION:A sound signal which is inputted from a microphone 1 is brought to an amplification/addition processing by an amplifier/adding circuit 2, and converted to a square wave having a frequency F by which a voltage from the amplifying/adding circuit 2 becomes F=alpha.V, in a voltage/frequency converter (V/F). In this regard, F, V, and alpha denote a frequency, an input voltage to the voltage/frequency converter (V/F), and a voltage/frequency conversion rate, respectively. The signal which is converted to the square wave is converted to an ON/OFF signal of light by a digital electrooptic converter E/O, inputted to a digital photoelectric converter O/E through an optical transmission line 3, and converted again to the square wave having the frequency F. The signal which is converted therein is inputted to a frequency/voltage converter (F/V) and converted to a voltage signal. |
