Abstract: A method of determining a power correction factor for an optical power of an optical channel of a wavelength division multiplexed communications network. The method comprises configuring an optical source of the communications network to generate an unmodulated optical carrier signal for the optical channel. The method further comprises determining the optical power of the unmodulated optical carrier signal (PHIGH). The method further comprises configuring the optical source to apply a test modulation pattern to the optical carrier signal, to generate a modulated optical carrier signal. The method further comprises determining the optical power of the modulated optical carrier signal (PMOD). The method further comprises determining a power correction factor for the optical channel by determining the difference between the optical powers of the unmodulated optical carrier signal and the modulated optical carrier signal.

Abstract: A telecommunications network comprising first and second access equipment on one side of the network and third and fourth access equipment on another side of the network, a respective communication link is provided between the first and the third access equipment and between the second and fourth access equipment, and further, a communication link is provided between the first and the second access equipment, and between the third and fourth access equipment, each access equipment providing an interface for communication with the network, and each access equipment is configured to be capable of causing a change in the path followed by at least some of the traffic conveyed over the communication links.

Abstract: A method of determining a power correction factor for an optical power of an optical channel of a wavelength division multiplexed communications network. The method comprises configuring an optical source of the communications network to generate an unmodulated optical carrier signal for the optical channel. The method further comprises determining the optical power of the unmodulated optical carrier signal (PHIGH). The method further comprises configuring the optical source to apply a test modulation pattern to the optical carrier signal, to generate a modulated optical carrier signal. The method further comprises determining the optical power of the modulated optical carrier signal (PMOD). The method further comprises determining a power correction factor for the optical channel by determining the difference between the optical powers of the unmodulated optical carrier signal and the modulated optical carrier signal.

Abstract: A method of compensating for spectral tilt in an optical transmission system. The system comprises at least one span of optical waveguide for transmission of an optical signal and at least one optical amplifier for amplifying a power of the optical signal. The method comprises applying a predetermined spectral tilt to the optical signal to offset a spectral tilt effect dependent upon a property of the span(s) and independent of the optical signal power, and controlling the optical amplifier(s) to provide a gain tilt to offset a spectral tilt effect dependent upon a property of the optical signal.

Abstract: A telecommunications network (1) comprising first (A1) and second (A2) access equipment on one side of the network and third (B1) and fourth (B2) access equipment on another side of the network, a respective communication link (7, 8) is provided between the first and the third access equipment and between the second and fourth access equipment, and further, a communication link (9, 10) is provided between the first and the second access equipment, and between the third and fourth access equipment, each access equipment providing an interface for communication with the network, and each access equipment is configured to be capable of causing a change in the path followed by at least some of the traffic conveyed over the communication links.

Abstract: Data transmitted on optical fiber over long distances is subject to the introduction of errors at the receiving end, caused by distortions and alterations of the original data. Raising the transmission power to increase the level of signals at the receiving end also increases errors due to non-linear characteristics of the fiber. The invention optimizes launch power by assessing error rates due to amplified spontaneous emissions and due to four wave mixing, so that signal to noise ratios due to these causes exceed threshold levels while enabling launch power to be maximized.

Abstract: Data transmitted on optical fiber over long distances is subject to the introduction of errors at the receiving end, caused by distortions and alterations of the original data. Raising the transmission power to increase the level of signals at the receiving end also increases errors due to non-linear characteristics of the fiber. The invention optimizes launch power by assessing error rates due to amplified spontaneous emissions and due to four wave mixing, so that signal to noise ratios due to these causes exceed threshold levels while enabling launch power to be maximized.