Abstract: A method of protection switching between first and second transceivers where dispersion compensation is effected electrically in the transmitters. The method includes detecting, at the second transceiver, a signal failure of a signal transmitted from the first transceiver and, upon detecting the signal failure, signalling the first transceiver to change its compensation function. The signalling can be done by encoding overhead bits in a signal transmitted from the second to the first transceiver. Another method of protection switching includes both transceivers toggling alternate reception paths upon detecting a signal failure and changing their dispersion compensation function to that of their respective alternate path.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: An optical communications system includes a hub modem and a set of two or more remote modems. Each remote modem includes a transmitter stage for transmitting a respective uplink data stream within a selected one of a set of two or more sub-channels. The hub modem optically communicates with the set of remote modems. The hub modem includes a receiver stage having an optical front-end for receiving an uplink optical channel signal within a spectral range that encompasses the set of two or more spectral sub-bands; a photodetector for detecting modulation components of the received uplink optical channel signal and for generating a corresponding high bandwidth analog signal; and a digital signal processor for processing the high bandwidth analog signal to recover the respective uplink data stream transmitted by each remote modem.

Abstract: An optical network system having a global controller capable of controlling all the elements of the network. The controller receives performance data from each optical network element and calculates a performance value for each channel transmitting through the system. The controller then isolates the channel with the minimum performance value and tests possible changes in network element parameters to find a change which would increase this performance value. Once such a change is found, it is implemented and the system is reoptimized.

Abstract: Bit-transparent muxing of an input signal for transport through an optical communications network. A fixed length container of the optical communications network is defined, which includes an overhead and a payload. A stuffing ratio (?) is based based on a line rate of the input signal and a data rate of the container. A number (NFS) of fixed stuffs is computed based on the stuffing ratio (?). The input signal and NFS fixed stuffs are inserted into the payload of the container, and the computed number NFS stored in the container's overhead. In some embodiments, the container is an overclocked OTU-3 (OTU3+) frame having a line rate of 44.6 Gb/s. This enables bit-transparent mux/demux of four nominal 10-Gig signals having line rates within a range of between 7.6 Gb/s and 10.4 Gb/s, or a single nominal 40-Gig signal having a line rate within a range of between 38.8 Gb/s and 41.6 Gb/s.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: Bit-transparent muxing of an input signal for transport through an optical communications network is provided. A fixed length container of the optical communications network is defined, which includes an overhead and a payload. A stuffing ratio (?) is based on a line rate of the input signal and a data rate of the container. A number (NFS) of fixed stuffs is computed based on the stuffing ratio (?). The input signal and NFS fixed stuffs are inserted into the payload of the container, and the computed number NFS stored in the container's overhead.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: An instrument panel system includes box sections that increase the stiffness, rigidity, and natural frequency of the instrument panel system. A two-piece instrument panel system provides a two-tone appearance with differing die draws and grains.

Abstract: Methods and techniques are disclosed for correcting the effect of cycle slips in a coherent communications system. A signal comprising SYNC bursts having a predetermined periodicity and a plurality of known symbols at predetermined locations between successive SYNC bursts is received. The received signal is partitioned into data blocks. Each data block encompasses at least data symbols and a set of check symbols corresponding to the plurality of known symbols at predetermined locations between a respective pair of successive SYNC bursts in the signal. Each data block is processed to detect a cycle slip. When a cycle slip is detected, the set of check symbols of the data block are examined to identify a first slipped check symbol, and a phase correction applied to data symbols of the data block lying between the first slipped check symbol and an end of the data block.

Abstract: In a method of synthesizing an optical signal, a multi-bit digital representation of a desired optical E-field is generated. The multi-bit digital representation has a resolution of N1-bits, where N1 is an integer greater than 2. At least two analog drive signals are synthesized based on the multi-bit digital representation. Each analog drive signal exhibits excursions between 2M discrete states (i.e. has a resolution of M-bits), where M is an integer greater than 2. An electrical-to-optical (E/O) converter is driven using the analog drive signals to generate an output optical E-field at an output of the E/O converter. An error is detected between the output optical E-field and the desired complex E-field waveform, and at least one parameter adjusted so as to minimize the detected error.

Abstract: In a decoder implementing a belief propagation algorithm for iteratively decoding a Low Density Parity Check (LDPC) encoded data block, a method of computing messages to be sent by a first node of the decoder to at least one neighbour node of the decoder. The method comprises: processing messages received by the first node to remove an echo of a previous message sent by the first node to the at least one neighbour node in a previous iteration, to yield corresponding modified messages; computing a message for a current iteration using the modified messages; and broadcasting the computed message for the current iteration to each of the at least one neighbour nodes.

Abstract: Described are an optical communications system and a method that allow for compensation of chromatic dispersion and polarization mode dispersion imparted to a communications signal propagating through an optical link. The system is based on a cost-effective optical transport architecture that accommodates baud rates exceeding 15 Gbaud and eliminates the need for costly optical dispersion compensators. Compensation for polarization mode dispersion is performed at the receiver using nonlinear processing. Advantageously, direct detection modulation using inexpensive electro-optic system components can be used in place of more costly and complex coherent and differential modulation formats. Digital filtering can be performed at the transmitter and the input signal can be inverted based on the nonlinearity of the transmitter electro-optic components. Consequently, the bandwidth and linearity requirements for the transmitter electro-optic components are relaxed, and cost reductions are realized.

Abstract: A method of carrier recovery from a high speed optical signal received through an optical communications network. A stream of multi-bit digital samples of the optical signal is processed to generate a multi-bit estimate X?(n) of each one of a plurality of transmitted symbols. A phase of each symbol estimate X?(n) is rotated, and a respective symbol phase error ??(n) of the rotated symbol estimate determined.

Abstract: A method of initializing an optical communication link between nodes. Optical transmitters adapted to pre-compensate link impairments based upon an optical compensation parameters are utilized to establish an optical communications link. Pre-compensation parameter values are selected at a node for generating an optical signal. The value is selected until confirmation from the remote node is received that the optical signal transmission has been successful. The successful pre-compensation parameter value is then used to generate the optical signal for the communications link.

Abstract: A method of minimizing jitter in a system for rate adapting a data signal for transport through a synchronous network. A phase difference is measured between a data clock synchronous with the data signal and a local clock of the synchronous network. A timing reference (F) indicative of a frequency difference between the asynchronous data signal and the local clock is measured using the measured phase difference. Calculation of the timing reference includes compensating ambiguity in the measured phase difference.

Abstract: A method and system for controlling optical signal to noise ratio (OSNR) of an optical signal at a receiver end of an optical link. A multi-bit sample stream is generated using a compensation function adapted to compensate impairments of the optical link A digital noise signal is generated and added to the multi-bit sample stream, and the resulting signal used to generate a degraded optical signal, which is then transmitted through the optical link.

Abstract: A method of controlling optical signal traffic in an optical network between a transmitter and a plurality of receivers, where the transmitter is adapted to compensate optical impairments based on at least one optical parameter, includes steps of identifying each path between the transmitter and the plurality of receivers, determining a respective optical parameter for each path, selecting one of the receivers for receiving an optical signal from the transmitter, and enabling the transmitter to generate the optical signal using the respective optical parameter of the path between the transmitter and the selected receiver. By preconfiguring compensation parameters for the various paths in the network, an all-optical network can be implemented wherein optical signals can be switched, added or dropped without having to match dispersion maps or perform optical-electrical-optical regeneration.

Abstract: An instrument panel system includes box sections that increase the stiffness, rigidity, and natural frequency of the instrument panel system. A two-piece instrument panel system provides a two-tone appearance with differing die draws and grains.

Abstract: In a method of estimating a bit rate (f1) of a digital signal conveyed through a SONET network between an originating node and a terminating node, the digital signal received by the originating node is processed to determine a result of a first function of the signal bit rate (f1) and a respective Tx local reference frequency (f2) of the originating node. A result of a second function of the Tx local reference frequency (f2) and a respective Rx local reference frequency (f3) of the terminating node is calculated. Finally, a result of a third function of the respective first and second function results is calculated, to derive an estimate of the signal bit rate (f4) relative to the Rx local reference frequency (f3).