Patent application number | Description | Published |
20090027656 | System and Method for Optical Time Domain Reflectometry Using Multi-Resolution Code Sequences - A system and method for time domain reflectometry (OTDR) using multi-resolution code sequences. One or more subsets of a set of predefined complementary code sequences may be transmitted as an OTDR signal to provide multi-resolution capability. | 01-29-2009 |
20090028549 | System and Method for Suppressing Beat Noise in Line Monitoring Equipment - A system and method for suppressing beat noise in line monitoring equipment. A wavelength dither generator wavelength modulates a carrier wavelength of a test signal laser transmitter. A test code is modulated on the dithered carrier wavelength to provide a test signal output of the line monitoring equipment. | 01-29-2009 |
20090028550 | System and Method Using Differential Loop Gain for Fault Identification in Line Monitoring Equipment - A system and method using differential loop gain for fault analysis in line monitoring equipment. Differential loop gain data is calculated from loop gain data, and fault analysis is conducted using differential loop gain data, e.g. by comparing the differential loop gain data to predefined fault signatures. | 01-29-2009 |
20090028552 | System and Method for Wavelength Monitoring and Control - A system and method using for wavelength monitoring and control in a WDM optical communication system. An aggregate channel monitor detects crosstalk between channels in the aggregate signal. Channel spacing may be modified by an element management system in response to the output of the aggregate channel monitor. | 01-29-2009 |
20090202237 | System and Method for Fault Identification in Optical Communication Systems - 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. | 08-13-2009 |
20090324249 | High Loss Loop Back For Long Repeater Span - 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. | 12-31-2009 |
20100034537 | FREQUENCY OFFSET POLARIZATION MULTIPLEXING MODULATION FORMAT AND SYSTEM INCORPORATING THE SAME - 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. | 02-11-2010 |
20100196016 | Polarization Multiplexing with Different DPSK Modulation Schemes and System Incorporating the Same - 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 π/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. | 08-05-2010 |
20110274442 | PILOT SYMBOL AIDED CARRIER PHASE ESTIMATION - Methods and systems for processing an optical signal in a communication system are disclosed. The disclosed methods yield benefits for estimation and tracking of carrier phase of received signals at a digital coherent receiver. Specifically, phase ambiguity is removed by the insertion of pilot symbols into a transmitted data stream. Pilot symbols are detected from a received signal, and carrier phase is estimated for the detected pilot symbols. If carrier phase track of received data symbols was lost, a correction is applied to recover the track. Coherent symbol decoding may be used which has not been possible with prior art techniques due to the possibility of phase tracking loss. | 11-10-2011 |
20120093510 | CORRELATION -CONTROL QPSK TRANSMITTER - An optical transmitter utilizing a multi-level data modulator to produce a PDM-QPSK signal, a one-bit delay interferometer configured to correlate the multi-level data modulated signal and an optical filter configured to combine the correlated multi-level data modulated signal with one or more neighboring signals prior to transmitting over one of a plurality of optical channels. The PDM-QPSK correlated signal is configured to reduce the signal spectrum thereby increasing spectral efficiency of the transmitted signal. | 04-19-2012 |
20120177362 | System and Method for Monitoring a Branched Optical Communication System - A system and method for monitoring an optical communication system. The system may include trunk terminals coupled through a trunk path and a branch terminal coupled the trunk path. A monitoring signal routing device within the branch terminal routes a monitoring signal from a branch-drop path to a branch-add path. | 07-12-2012 |
20120213521 | VESTIGIAL PHASE SHIFT KEYING MODULATION AND SYSTEMS AND METHODS INCORPORATING SAME - In general, optical communication systems and methods may implement a vestigial phase shift keying (PSK) modulation format to enable relatively high transmission rates with closer channel spacing and improved signal detection in a WDM optical communication system. A PSK modulated signal may be correlated with a phase shift, for example, using a delay line interferometer (DLI), to generate a vestigial PSK signal, which may be pre-filtered, combined, and transmitted in the WDM system. The correlation with a phase shift compresses and shifts the signal spectrum such that intersymbol interference (ISI) length may be reduced with minimal increase in the bit error rate (BER) when the vestigial PSK signal is detected. | 08-23-2012 |
20120213522 | GENERATING HIGHER-LEVEL QUADRATURE AMPLITUDE MODULATION (QAM) USING A DELAY LINE INTERFEROMETER AND SYSTEMS AND METHODS INCORPORATING SAME - In general, optical communication systems and methods may generate higher-level n | 08-23-2012 |
20130202021 | System and Method for Polarization De-Multiplexing in a Coherent Optical Receiver - A system and method for polarization de-multiplexing in a coherent optical receiver. De-multiplexing is achieved using a modified constant modulus algorithm (CMA) wherein filter coefficients are determined as a function of a coupling coefficient to avoid convergence of the CMA outputs. | 08-08-2013 |
20130216221 | System and Method Including Modified Bit-Interleaved Coded Modulation - A system and method with a modified bit-interleaved coded modulation with iterative decoding (BICM-ID). Coded and interleaved bits are combined and coded with a second FEC code that is then mapped to a modulation format. The second FEC code may be a single parity check (SPC) and the scheme may be referred to as a SPC-BICM-ID scheme. | 08-22-2013 |
20130216239 | System and Method for Blind Equalization and Carrier Phase Recovery in a Quadrature Amplitude Modulated System - A system and method for blind equalization of a QAM signal. Equalization is achieved using an algorithm characterized by cost function that is a function the Euclidian distance, e.g. the minimum Euclidian distance, between points of the constellation associated with the QAM signal, i.e. the distance between symbols. | 08-22-2013 |
20140010532 | PILOT SYMBOL AIDED CARRIER PHASE ESTIMATION - Methods and systems for processing an optical signal in a communication system are disclosed. The disclosed methods yield benefits for estimation and tracking of carrier phase of received signals at a digital coherent receiver. Specifically, phase ambiguity is removed by the insertion of pilot symbols into a transmitted data stream. Pilot symbols are detected from a received signal, and carrier phase is estimated for the detected pilot symbols. If carrier phase track of received data symbols was lost, a correction is applied to recover the track. Coherent symbol decoding may be used which has not been possible with prior art techniques due to the possibility of phase tracking loss. | 01-09-2014 |
20140068385 | System and Method Including Modified Bit-Interleaved Coded Modulation with Fractional Secondary Coding - A system and method with a modified bit-interleaved coded modulation with iterative decoding (BICM-ID). A first group of coded and interleaved bits are coded with a second FEC code and a second group of coded and interleaved bits are not coded with the second FEC code. The first and second groups are then mapped to a modulation format. The second FEC code may be a single parity check (SPC) and the scheme may be referred to as a BICM-ID scheme with a fractional secondary coding. | 03-06-2014 |
20140212131 | System and Method for Fault Identification in Optical Communication Systems - A repeater that enables both bi-directional optical time domain reflectometry (OTDR) and loop gain monitoring techniques that may be employed, for example, in particularly long repeater spans. In one embodiment, the repeater includes high loss loopback (HLLB) paths configured to couple test signals between incoming and outgoing fiber paths. The HLLB paths are coupled from the outputs to the inputs of amplifiers within the repeater and couple both OTDR and loopback signals from an outgoing fiber path to an incoming fiber path so that may be returned to line monitoring equipment that transmitted the test signals. | 07-31-2014 |
20140281832 | SYSTEM AND METHOD FOR CYCLE SLIP CORRECTION - A system and method including a parity bit encoder for encoding each n bits of data to be transmitted with a parity check bit to produce blocks of n+1 bits (n information bits plus one parity bit associated with the n information bits). Each of the blocks of n+1 bits are Gray mapped to a plurality of associated QAM symbols that are modulated onto an optical wavelength and transmitted to a receiver. A maximum a posteriori (MAP) decoder is used at the receiver to correct for cycle slip. Phase errors of 180 degrees may be detected by independently encoding odd and even bits prior to Gray mapping, and identifying errors in decoding odd numbered bits at the receiver. | 09-18-2014 |
20150071312 | SYSTEM AND METHOD USING CASCADED SINGLE PARTITY CHECK CODING - A system and method including a parity bit encoder for encoding each n−3 bits of data to be transmitted with three parity check bits to produce blocks of n bits (n−3 information bits plus three parity bits associated with the n information bits). Each of the blocks of n bits are Gray mapped to three QAM symbols that are modulated onto an optical wavelength and transmitted to a receiver. A maximum a posteriori (MAP) decoder is used at the receiver to correct for cycle slip. | 03-12-2015 |
20150071640 | Coded Modulation for Small Step-Size Variable Spectral Efficiency - A system and method involving a coded modulation scheme whereby different spectral efficiencies can be achieved for different transmitters in a WDM system using the same M | 03-12-2015 |