The CATV system of the optical transmitter and FTTH system

摘要

PROBLEM TO BE SOLVED: To implement a CATV system using a FTTH method capable of communication even when OBI occurs in the case of operating high speed two-way communication service and low speed two-way communication service.;SOLUTION: An optical transmitter performs control so that a level of an uplink optical signal to be output is lower than a specified value, when only an uplink electric signal on the low speed two-way communication service side is input to the optical transmitter as shown in a state 3 in a figure 3(a). Thereby, a noise level of OBI can be reduced even when the OBI occurs. With respect to the low speed two-way communication service side, a reception level of an uplink electric signal on the center side can be maintained at a normal level, because light modulation degree increases even when decreasing a level of an uplink optical signal by decreasing bias current of a LD 110. With respect to the high speed two-way communication service side, normal communication is possible, because a level of the noise caused by the OBI is reduced by maintaining the normal level without decreasing a level of an uplink optical signal.;COPYRIGHT: (C)2013,JPO&INPIT