| 摘要 |
PURPOSE:To convert an RZ code into an NRZ code without deteriorating the S/N converting an electric RZ code signal into an NRZ code signal with an OR signal between a signal resulting from retarding the said electric signal by a half of one time slot period and the RZ code signal. CONSTITUTION:A reception signal A received by a photodetector 1 and amplified by a preamplifier 2 and a gain variable amplifier 3 is a unipolar optical signal (RZ code) in which logical '1' is alternation of a high level and a low level in one time slot (pulse duty factor of 50%) and the signal is retarded at a delay element 7 by a half the time of one time slot. Thus, an output signal C of an OR gate 8 is an NRZ signal in which logical '1' shows a high level (100% pulse duty factor) and logical '0' depicts a low level in one time slot. Thus, the level of the signal converted into the NRZ code is not decreased, and the RZ code is converted into the NRZ code without deteriorating the S/N. |
