| 摘要 |
PURPOSE:To realize multiplex with high density by comprising equipment so that the frequency of a semiconductor laser beam for local oscillation can be located at the intermediate position of the frequencies of two beams sent from a transmitter. CONSTITUTION:An input signal 10 that is a digital signal with binary values is inputted a semiconductor laser in the transmitter 100, and the frequency of the semiconductor laser is deviated to nu0, nu1, respectively corresponding to the binary signals '0', '1'. The frequency nuL of the beam of the semiconductor laser 2 for local oscillation is arranged between the intermediate of the frequencies nu1 and nu0 of the two beams sent from the transmitter 100. In such a case, the frequency f1 in the signal '1' is set equally to the frequency f0 in the signal '0'. At a frequency discrimination circuit 220, an output voltage is varied corresponding to the frequency of an input signal, and a pulse signal is generated. The pulse signal is inputted to a digital signal reproduction circuit 230. |
