Patent ID: 7174108
Filing Date: 2007-02-06
Classification: H04B

Abstract:
1. A transmission system performing optical transmission, comprising: a first repeater and a second repeater, wherein the first repeater includes a first light source, a first modulation control part, a first splitter, a first optical amplifier amplifying a first optical main signal, a first Raman amplifier and a first fault occurrence recognizing part, wherein the second repeater includes a second light source, a second modulation control part, a second splitter, a second optical amplifier amplifying a second optical main signal, a second Raman amplifier and a second fault occurrence recognizing part, wherein the first and second repeaters are optically connected by a first optical transmission line transmitting the first optical main signal and a first optical supervisory channel signal from the first repeater to the second repeater, the first optical supervisory channel signal being produced by modulating a first light signal of a wavelength emitted from the first light source, wherein the first and second repeaters are optically connected by a second optical transmission line transmitting a second optical main signal and a second optical supervisory channel signal from the second repeater to the first repeater, the second optical supervisory channel signal being produced by modulating a second light signal of a wavelength emitted from the second light source, wherein the first Raman amplifier emits a first Raman pump light into the second optical transmission line in the opposite direction to that of the second optical main signal and the second optical supervisory channel signal, so that the second optical main signal and the second optical supervisory channel signal are amplified, wherein the second Raman amplifier emits a second Raman pump light into the first optical transmission line in the opposite direction to that of the first optical main signal and the first optical supervisory channel signal, so that the first optical main signal and the first optical supervisory channel signal are amplified, wherein the first light signal is separated into a first optical supervisory signal by the first splitter which is provided between the first light source and the first modulation control part, wherein the second light signal is separated into a second optical supervisory signal by the second splitter which is provided between a second light source and the second modulation control part, wherein the first repeater transmits the first optical supervisory signal to the second repeater along the second optical transmission line, wherein the second repeater transmits the second optical supervisory signal to the first repeater along the first optical transmission line, wherein, when the first fault occurrence recognizing part recognizes a level of the second Raman pump light below a predetermined threshold level of the second Raman pump light, the first fault occurrence recognizing part prevents only the first amplifier from amplifying the first optical main signal, wherein, if the second Raman amplifier becomes faulty, and the first fault occurrence recognizing part recognizes a level of the second optical supervisory signal below a predetermined threshold level of the second optical supervisory signal, the fault occurrence recognizing part prevents only the first amplifier from amplifying the first optical main signal, wherein, when the second fault occurrence recognizing part recognize a level of the first Raman pump light below a predetermined threshold level of the first Raman pump light, the second fault occurrence recognizing part prevents only the second amplifier from amplifying the second optical main signal, and wherein, if the first Raman amplifier becomes faulty, and the second fault occurrence recognizing part recognizes a level of the first optical supervisory signal below a predetermined threshold level of the first optical supervisory signal, the second fault occurrence recognizing part prevents only the second amplifier from amplifying the second optical main signal.