| 摘要 |
PURPOSE:To obtain an optical communication system where a superior communication is possible even for a high-speed and low-S//N weak light, by adopting a system strong against S//N which is a merit of frequency shift to raise outputs in the light transmitting side and the light receiving side. CONSTITUTION:1 and 0 of the digital signal are received by a line receiver 1, and the voltage of a frequency shift oscillator 2 is controlled to oscillate two high frequencies corresponding to 1 and 0, and these frequencies are applied to a double balanced mixer 3, and a low frequency of the difference between the output of the mixer 3 and the output of a local oscillator 6 is taken out by an LPF4 to cause a light emitting diode to emit the light through an output amplifier 5, thus transmitting the signal to optical fibers. The digital signal transmitted to optical fibers is received by the receiving device in the receiving side, and thus, outputs in the transmission side and the receiving side are raised to perform a superior communication by a high-speed and low-S//N weak light. |
