| 摘要 |
PROBLEM TO BE SOLVED: To reduce the influence of waveform distortion of a modulator drive signal due to the low band cutoff characteristic of a modulator drive circuit and to raise the limit for the distance of transmission by converting the binary data signal into a deformed duo-bianry signal that is suppressed to a DC component and using this duo-binary signal as the modulator drive signal to drive a light intensity modulator. SOLUTION: A binary data signal is converted into a deformed duo-binary signal that is suppressed to a DC component and used as a modulator drive signal which drives a light intensity modulator. A deformed duo-binary coding circuit 10 converts 0 and 1 of the binary data signal into 0 and +1 or -1 respectively and also converts the binary data signal into a ternary deformed duo-binary signal of -1, 0 and +1 whose +1 and -1 are never continuous over 2 bits respectively. The ternary deformed duo-binary signal is turned into a non-inverse deformed duo-binary signal and an inverse deformed duo-binary signal whose phases are inverted to each other by an inverter circuit 75 and then applied to the electrodes 84a and 84b of an MZ type light intensity modulator 80 via the modulator drive circuits 76a and 76b respectively. |
