| 摘要 |
PROBLEM TO BE SOLVED: To easily transmit optical signal of a high-speed signal over a long distance by generating the encoding signal of three levels, which is obtained by encoding a binary signal and have two outer levels showing the first state of the binary signal and an intermediate level showing the second state of the binary signal. SOLUTION: An encoder 10 converts a binary input signal on a line 12 into a signal of three levels, namely a tertiary signal. The signal constitutes an encoded electric signal on a line 14. The encoded electric signal of the three levels on the line 14 has two outer levels (positive and negative voltages of equal sizes, for example) and one intermediate, namely, inner level (zero voltage, for a example). To former ones show the first state ('1' of binary, for example) of the binary input signal and the latter the second state (zero of binary, for example) of the binary input signal. Then, an optical signal which is frequency- modulated is generated in accordance with the encoding signal of three levels is generated, it is optically converted, and the optical signal which shows the two states and which is amplitude-modulated is generated. |
