Abstract: An optical communication system and method for starting up and shutting down the system to ensure safety during repair of a fiber break are disclosed. A technique for shutting down an optical communication system having spans of optical transmission fiber interspersed serially between optical transformation sites and a plurality of amplifier sites includes shutting down both amplifiers on either side of a fiber disruption and both amplifiers in the same amplifier sites serving transmission in an opposite direction, followed by deactivation of all amplifiers within the same optical line between optical transformation sites. During startup, amplifiers enter an operating mode to ignore a system shutdown signal, an amplifier at a terminal site is forced on, and then successive amplifiers step through an intermediate safe power level before reaching full operating power.

Abstract: An optical communication system and method for starting up and shutting down the system to ensure safety during repair of a fiber break are disclosed. A technique for shutting down an optical communication system having spans of optical transmission fiber interspersed serially between optical transformation sites and a plurality of amplifier sites includes shutting down both amplifiers on either side of a fiber disruption and both amplifiers in the same amplifier sites serving transmission in an opposite direction, followed by deactivation of all amplifiers within the same optical line between optical transformation sites. During startup, amplifiers enter an operating mode to ignore a system shutdown signal, an amplifier at a terminal site is forced on, and then successive amplifiers step through an intermediate safe power level before reaching full operating power.

Abstract: An optical communication system and method for starting up and shutting down the system to ensure safety during repair of a fiber break are disclosed. A technique for shutting down an optical communication system having spans of optical transmission fiber interspersed serially between optical transformation sites and a plurality of amplifier sites includes shutting down both amplifiers on either side of a fiber disruption and both amplifiers in the same amplifier sites serving transmission in an opposite direction, followed by deactivation of all amplifiers within the same optical line between optical transformation sites. During startup, amplifiers enter an operating mode to ignore a system shutdown signal, an amplifier at a terminal site is forced on, and then successive amplifiers step through an intermediate safe power level before reaching full operating power.

Abstract: A digital optical telecommunication method including the steps of: generating a digital modulated optical signal in an optical transmitting station, which signal corresponds to a first electric input signal carrying a piece of information; feeding the modulated optical signal to an optical-fibre line; receiving the modulated optical signal transmitted from the optical-fibre line at an optical receiving station, converting it to an electric form and thereat generating a second digital electric signal; wherein the modulated optical signal is coded in a sequence of elementary information units at a first frequency and wherein the step of generating a second digital electric signal comprises detecting in said converted signal, an electric signal having a second frequency higher than the first frequency and recognizing in said detected signal, the phase of an electric signal at the first frequency by comparing a received sequence of elementary information units with at least one reference sequence and verifying th

Abstract: A digital optical telecommunication method including the steps of: generating a digital modulated optical signal in an optical transmitting station, which signal corresponds to a first electric input signal carrying a piece of information; feeding the modulated optical signal to an optical-fiber line; receiving the modulated optical signal transmitted from the optical-fiber line at an optical receiving station, converting it to an electric form and thereat generating a second digital electric signal; wherein the modulated optical signal is coded in a sequence of elementary information units at a first frequency and wherein the step of generating a second digital electric signal comprises detecting in said converted signal, an electric signal having a second frequency higher than the first frequency and recognizing in said detected signal, the phase of an electric signal at the first frequency by comparing a received sequence of elementary information units with at least one reference sequence and verifying th