| 摘要 |
PURPOSE:To provide an optical communication system which can receive a tracking signal with high sensitivity without deteriorating the bit error ratio of a main signal. CONSTITUTION:A multilevel PPM modulation circuit 1 of a transmitter circuit 10 converts a main signal Sm into a multilevel PPM signal Sp and selects the signal Sp or an inverted PPM signal Spi received from an inverting circuit 2 by a switch 4 in response to the logical level of a tracking signal Ss. Then the circuit 1 tuns the signals Sp and Spi into a transmission signal St by the E/O conversion. A receiver circuit 20 reproduces a reception tracking signal Ssr out of the signal Sr received from an O/E 18 through an LPF 17. A timing reproducer circuit 11 and a switch control circuit 12 select either one of signals Sr and Sri received from a delay circuit 16 and an inverting circuit 15 to apply the switching control of a switch 13 based on the signal Sar and returns the signal Sr to a non-inverted PPM signal Spr. |
