Abstract: Channel power management may be achieved in a branched optical communication system such that uniform loading is provided across branch channels on a branch drop path without passing information signals that are not intended for the branch terminal to the branch drop path. In general, a system and method consistent with the present disclosure reuses one or more loading signals (e.g., noise bands) from the branch add path to maintain uniform loading in the branch drop path of the same branch. The system and method thus prevents trunk channels from being dropped to a branch terminal when those trunk channels are not intended for the branch terminal.

Abstract: An armored optical fiber cable may include a core cable portion and an armored cable portion surrounding the core cable portion. The core cable portion may include, among other layers, a steel tape layer wrapped around an insulation layer surrounding a conductive sheath. The steel tape layer improves armored resistance to dragging and abrasion caused by fishing gear by protecting the insulation layer surrounding the sheath.

Abstract: A method and system for distributed fault sensing and recovery in a communication system. A master controller is provided in each cable station of the system. Each master controller receives local alarms, e.g. aggregated alarms from associated shelf controllers, and may receive remote alarms from other master controllers. Local and remote alarms are compared to a profile provisioned in the master controllers for determining whether to perform a fault recovery function.

Abstract: Communication from a component in an optical communication system may be effected by modulating a system power voltage across the component to generate voltage signals representing the information to be communicated. The voltage signals generated by the component are detectable in the power feed equipment (PFE) in the optical communication system. Signature analysis may be performed on the system voltage data to identify the voltage signals and determine the information being communicated.

Abstract: A method and system for remotely upgrading a remote device may be used to upgrade application programs in devices that are difficult to access physically, such as undersea optical devices in an optical communication system. The method and system uses a Non-Erasable Application (NEA) to manage the upgrade of an application program, to determine if the application program is valid, and to provide default application functions if the application program is not valid. The NEA may be stored on a memory that is not remotely erasable and the application program may be stored on a memory that is non-volatile and programmable. Code status indicators may be used to indicate if the application program is valid, for example, to indicate that the code is present and functional.

Abstract: Polarization multiplexing with different differential phase shift keying (DPSK) schemes generally uses DPSK modulated signals modulated using different DPSK modulation schemes and combined with orthogonal polarizations relative to each other. The different DPSK modulation schemes may use different DPSK phase shifts to represent data, such as a regular DPSK modulation scheme and a ?/2 DPSK modulation scheme. By using different DPSK modulation schemes to represent data on the orthogonally polarized signals, the DPSK demodulators may effectively separate the orthogonally polarized signals using the property of the DPSK receivers. To optimize performance, the DPSK modulated signals may also be bit-interleaved when combined with orthogonal polarization.

Abstract: A system and method for managing toggling events in a network management system. The event is monitored and if the event maintains one of first and second states for a predetermined amount of time it is reported through the network management system. In one embodiment, if the event is a toggling alarm it is reported as active immediately and if it remains cleared for a predetermined amount of time it is reported as cleared.

Abstract: A method of managing gain tilt in an optical transmission segment including providing an optical transmission segment having a plurality of fiber optic cable spans and a plurality of repeaters coupled to the fiber optic cable spans. Gain tilt in the optical transmission segment is monitored. If negative gain tilt is accumulated at a repeater location in the transmission segment, the repeater at the repeater location is replaced with a higher gain repeater having a higher nominal gain value than the nominal gain value of the repeater being replaced.

Abstract: An apparatus, system and method wherein a polarization multiplexed differential phase shift keying format (POLMUX-DPSK) is provided with offset and bit-interleaved frequency channels and demodulated using a DPSK demodulator.

Abstract: An optical communication system supporting detection and communication networks. A communication network transmission path and the detection network transmission path are provided as separate paths established by separate fibers or fiber pairs of the same optical fiber cable. All of the elements coupled to the communication network transmission path and the detection network transmission path may be powered by the same power feed equipment through the same optical fiber cable power conductor.

Abstract: An optical add/drop multiplexer (OADM) and system incorporating the same for maintaining loading of WDM channels with loading signals or information signals when signals are added or dropped. The OADM may include reconfigurable band pass filters having a transmittance characteristic controllable using a command signal. Selective filtering of loading signals and/or information signals received from branch and trunk paths allows an output WDM signal including information signals on utilized channels and loading signals on all unutilized channels.

Abstract: An apparatus and method directed to testing and optimizing performance of an optical transmission system is disclosed, including at least one broadband dispersion compensation unit (DCU) or at least one depolarization device. The depolarization device may be used alone or in combination with the at least one broadband DCU. A method for optimizing performance of data channels in initial loading (IL) and full loading (FL) configurations of the optical transmission system is also disclosed.

Abstract: Various high loss loop back (HLLB) repeater architectures are disclosed that enable selectively monitoring (e.g., measuring, analyzing, etc) of Rayleigh signals from both inbound and outbound directions of an optical communication system. In one such embodiment, first and second optical test signal frequencies (or ranges) are used, in conjunction with selective filtering, for monitoring the outbound and inbound paths, respectively. The repeater architectures allow optical time domain reflectometry (OTDR) monitoring techniques to be employed, for example, in particularly long repeater spans, such as those in excess of 90 km in length.

Abstract: A system and method for mitigating dispersion slope is capable of reducing the performance impact on an optical communication system caused by dispersion slope. The system and method receives an optical signal, demultiplexes the optical signal and optically filters the demultiplexed optical signals. The optical filters may have a bandwidth that is wide with respect to the demultiplexed optical signals and narrow with respect to the original optical signal.

Abstract: A soft decision threshold control system and method may be used with a forward error correction (FEC) scheme to adjust or tune one or more soft decision thresholds in response to one or more bit value averages for the threshold(s) and in response to a bit error rate (BER). The bit value average for a soft decision threshold generally refers to an average number of binary values (e.g., logic ones and/or zeros) occurring in a bit stream detected using the soft decision threshold. For different BER levels in a particular system, for example, one or more of the soft decision thresholds may have a predetermined bit value average, which has been determined to provide a certain level of performance (e.g., an optimum performance). Thus, one or more of the soft decision thresholds may be adjusted such that the bit value averages for the soft decision thresholds are adjusted as a function of the BER.

Abstract: An optical fiber bend limiting device may be used in a movable optical connection system to transition optical fibers between at least first and second optical fiber connecting structures that move relative to each other. The optical fiber bend limiting device may be coupled between the optical fiber connecting structures such that the bend limiting device moves with the connecting structures. The optical fiber bend limiting device allows movement of the optical fibers within the movable optical fiber connection system while preventing the optical fibers from bending beyond a bend radius limit.

Abstract: An optical fiber bend limiting device may be used in a movable optical connection system to transition optical fibers between at least first and second optical fiber connecting structures that move relative to each other. The optical fiber bend limiting device may be coupled between the optical fiber connecting structures such that the bend limiting device moves with the connecting structures. The optical fiber bend limiting device allows movement of the optical fibers within the movable optical fiber connection system while preventing the optical fibers from bending beyond a bend radius limit.

Abstract: A system and method for loading unutilized channels of a WDM system with noise to improve system performance. A transmitter amplifier may impart noise to unutilized channels by reducing amplifier input or providing feedback of the amplifier output. Noise signals may also be looped back to the transmitter from received signals.

Abstract: A system and method for fault identification in optical communication networks. One or more repeaters in the system includes a loop back path that couples an output a first amplifier for amplifying signals carried in a first direction through a repeater to an input of a second amplifier for amplifying signals carried in a second direction through said repeater. Fault analysis is conducted using loop gain data associated with test signals transmitted on the first or second paths and returned on the opposite path through the loop back paths.

Abstract: A communication system including a repeatered trunk path and one or more unrepeatered branch segments coupled to the trunk path through associated submarine branching units. Each of the branch segments may be configured to carry at least the same channel capacity as the trunk path and may have a length greater than the average repeater spacing in the trunk path.