| 摘要 |
PROBLEM TO BE SOLVED: To provide a device which never cause buffer overflow or buffer underflow, in the amplitude phase modulator of an OLT(optical line terminator) consisting of an inside PSK and an outside PSK, performing phase modulation of a signal, subjected to amplitude modulation, in second bit sequence.SOLUTION: The buffer amount of an OLT buffer 11 is observed in a buffer amount observation unit 31, and when the inside PSKs of low transmission rate continue to increase the buffer amount, a transmission rate adjustment unit 32 reduces the transmission rate of a second bit sequence (data#2) input to the OLT buffer 11, or stops input thus reducing the buffer amount and preventing buffer overflow. When the outside PSKs of high transmission rate continue to decrease the buffer amount, the transmission rate adjustment unit 32 inserts dummy data into the OLT buffer, thus increasing the buffer amount and preventing buffer underflow. |
