Entries |
Document | Title | Date |
20080226300 | OPTICAL DIFFERENTIAL-PHASE-SHIFT-KEYED DEMODULATOR APPARATUS AND METHOD - A system and method for demodulating an optical differential-phase-shift-keyed (DPSK) input signal using a Fabray-Perot etalon filter. In one embodiment the system receives a transmitted wavefront from the etalon filter and uses a detector to generate an electrical waveform from the transmitted wavefront. A comparator is used to receive an output from the detector and to generate a signal in accordance with each phase shift (i.e., bit transition) in the optical DPSK input signal. A latching flip-flop receives an output from the comparator and generates a digital signal representative of the bit pattern of the DPSK input signal. The system and method does not require the precisely matched dual optical paths of a Mach-Zehnder interferometer, and therefore is substantially less susceptible to thermal effects that could influence the operation of a conventional Mach-Zehnder interferometer in DPSK demodulation operations. | 09-18-2008 |
20080226301 | System and Method For Increasing Spectral Efficiency, Capacity and/or Dispersion-Limited Reach of Modulated Signals in Communication Links - A system and method for increasing spectral efficiency, capacity and/or extending dispersion-limited reach in a communication link employs narrow filtering of a baseband signal to reduce the original bandwidth to a substantially smaller bandwidth for transmission across a transmission medium such as an optical fiber. By restricting the bandwidth, the rate of spreading is reduced significantly. The receiver at the other end of the transmission medium includes an equalizer for returning the received signal to its original bandwidth for retrieval of information contained in the signal. | 09-18-2008 |
20080279565 | Apparatus And Method For Selfadapting Dispersion Compensation - The present invention discloses an apparatus and method for adaptive dispersion compensation, the apparatus comprising: a coarse-grain tunable dispersion compensator, a receiver with electric adaptive dispersion compensator, and a control logic unit. In the method, firstly it is to perform optical dispersion compensation for the input optical signals; then to perform electric dispersion compensation for the optical signals for which the optical dispersion compensation is performed; it is to detect the performance parameters of the receiving of the optical signals for which the electric dispersion compensation has been performed, and based on the performance parameters, it is to perform optical dispersion compensation adjustment for said input optical signals. With an optical de-multiplexer further, said apparatus can perform adaptive dispersion compensation for the multi-channel system. By using the apparatus and method for adaptive dispersion compensation of the present invention, it significantly reduces the number of adjustments as well as decreases the dispersion compensation time and can fast and accurately realize a wide range of adaptive dispersion compensation for either single channel or multi-channel. | 11-13-2008 |
20080310858 | APPARATUS AND METHOD OF OPTICAL COMPENSATION FOR SUBMARINE OPTICAL CABLE - The present invention provides optical compensation for a submarine optical cable optical. A dummy light module generates a dummy light signal according to a continuous spectrum in a predetermined range and a combining module combines a service signal with the dummy light signal. When the dummy light is used for the compensation, conventional problems are solved, including complicated control, difficult realization of the pre-equalization function and inflexible configuration. When service signals are increased, the adjustment for the power of the dummy light signal is avoided; therefore, the control for the dummy light is simplified. In the pre-equalization operation, power control is only performed on the dummy light signal in the single channel or the continuous dummy light signal; therefore, the realization of the pre-equalization function is easy. | 12-18-2008 |
20090003837 | END-TO-END CHROMATIC DISPERSION CHARACTERIZATION OF OPTICALLY AMPLIFIED LINK - An economic way of determining the chromatic dispersion along a link of a DWDM network is provided. A transmitter modulates the output signals of two lasers operating at two different wavelengths and the modulated output signals are sent into the link. Detectors at each one of a plurality of detection sites along the link determine a phase difference in modulation between the output signals of the two lasers. The chromatic dispersion for each detection site can be calculated from the modulation frequency and determined phase differences at that site. | 01-01-2009 |
20090010656 | Optical waveform measurement system and optical waveform measurement method - In an optical waveform measurement system, a phase comparator compares phases between an electric signal output from a PD and an electric signal output from a mixer, and outputs a signal having an amplitude proportional to the phase difference of the two electric signals to a VCO via an LPF, as an error signal. A BPF removes a jitter from the electric signal output from the VCO, and a sampling pulse light source outputs sampling light based on the electric signal with the jitter removed. An optical sampling gate samples signal light to be measured with sampling light output from a sampling pulse light source, and the sampled signal light to be measured is measured by an oscilloscope. | 01-08-2009 |
20090016739 | PATTERN EFFECT REDUCTION OF OPTICAL SIGNALS - A passive optical equalizer and a predistortion technique are employed to reduce pattern effect in optical signals which result from narrow filtering. | 01-15-2009 |
20090016740 | METHOD AND APPARATUS FOR COMPENSATING FOR FIBER NONLINEARITY IN A TRANSMISSION SYSTEM - A transmitter includes a frequency modulated laser. An optical spectrum reshaper (OSR) is positioned to receive the frequency modulated signal and has a transmission function effective to convert the frequency modulation to amplitude modulation. An optical fiber channel has a first end positioned to receive the filtered signal and a second end proximate a receiver. A filter is positioned between the second end and the receiver and has a peak transmission frequency thereof located on a transmission edge of the OSR, such as at a peak logarithmic derivative value of the transmission function of the optical spectrum reshaper. In some embodiments a first OSR is positioned to receive the frequency modulated signal and configure to output a filtered signal wherein high frequency portions are more attenuated than low frequency portions. A second OSR at the receiver attenuates the low frequency portions substantially more than the high frequency portions. | 01-15-2009 |
20090016741 | OPTICAL COMMUNICATION - The present invention relates to a method of optical communication, in particular optical communication involving spectral filtering in a passive optical network. The method includes the steps of: (i) performing a first spectral filtering function on a source signal having a spectral width so as to generate a plurality of feeder signals that are spectrally spaced apart from one another; (ii) performing a respective noise reduction function on the feeder signals; (iii) combining the feeder signals over a common waveguide of the optical link; (iv) receiving the feeder signals carried over the optical link and modulating the received feeder signals so as to impose data thereon; and, (v) returning the modulated feeder signals over the optical link so as to communicate the imposed data. Because noise is reduced centrally, a simpler passive optical network can be achieved. | 01-15-2009 |
20090022499 | OPTICAL SIGNAL TO NOISE RATIO SYSTEM - The present invention provides a system for improving Optical Signal to Noise Ratio “OSNR” ( | 01-22-2009 |
20090080901 | Dispersion compensating apparatus and dispersion compensating method - In a dispersion compensating apparatus, a reference identifying unit identifies a reference (X dB down) that makes a penalty lower than a predetermined value in accordance with optical signal information and a reference identifying table, and a VIPA plate temperature adjusting unit adjusts a refractive index of a VIPA plate by modifying a temperature of the VIPA plate so that a transmission center wavelength derived from the reference matches the wavelength defined by an ITU-T Grid. If a dispersion compensation value setting unit performs an optimal residual dispersion value search, the VIPA plate temperature adjusting unit determines if a filtering penalty is lower than a predetermined value in accordance with a penalty management table. If the filtering penalty is lower than the predetermined value, temperature adjustment of the VIPA plate is not performed. | 03-26-2009 |
20090087194 | Optical transmission system and optical transmission method - An optical transmission system, where in an optical transmitter a detection bit having a specific pattern set according to the number of bits to be transmitted within one symbol time, is imparted with respect to a transmission signal in which transmission information has been encoded according to a preset format, and an optical signal generated by modulating light according to the transmission signal is transmitted to a transmission line. In an optical receiver, logic inversion or bit swap of received data is detected and compensated by using the detection bit included in the received signal, a decoding process of the compensated received signal is executed. As a result, when an optical signal capable of transmitting multi-bit information within one symbol time is transferred, it is possible to realize excellent transmission characteristics, by reliably compensating an error in received data caused by the modulation format or the multiplex system of the optical signal. | 04-02-2009 |
20090154938 | IN-CHANNEL RESIDUAL CHROMATIC DISPERSION MEASUREMENT - A system generates optical pulses, that include two frequencies within one optical channel, at a first end of an optical link, and receives the optical pulses at a second end of the optical link. The system also sets a frequency difference for the two frequencies of the optical pulses, calculates a relative group delay difference for the two frequencies of the optical pulses, and calculates a residual chromatic dispersion of the channel based on the frequency difference and the calculated relative group delay difference. | 06-18-2009 |
20090162074 | WAVELENGTH DISPERSION COMPENSATION CONTROL METHOD AND WAVELENGTH DISPERSION COMPENSATION CONTROL DEVICE - A wavelength dispersion compensation control method determining whether a clock component is contained in an optical signal received from an optical transmission path and, if a clock component if contained in the optical signal, extracting the clock component, and stopping control of a variable wavelength dispersion compensator when no clock component is extracted. | 06-25-2009 |
20090263142 | TUNABLE OPTICAL FILTER - A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The MZ interferometers, having free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. The PLC chip, including a zero-dispersion lattice-filter interleaver stage, a switchable fine-resolution stage and, or a retroreflector for double passing the filter, is packaged into a hot-pluggable XFP transceiver package. A compensation heater is used to keep constant the amount of heat applied to the PLC chip inside the XFP package, so as to lessen temperature variations upon tuning of the PLC optical filter. | 10-22-2009 |
20090324246 | Method of Limiting the Non-Linear Phase Noise of a Phase-Modulated Optical Signal of Constant Amplitude, and an Associated Device - A non-linear phase noise limiter device limits the non-linear phase noise that affects a phase-modulated input optical signal of constant mean amplitude conveyed over a transmission line. The device is placed at a zero dispersion point of the transmission line, and it is suitable for suppressing amplitude fluctuations about a mean value in said optical signal. | 12-31-2009 |
20100008678 | Multi-Channel Optical Transport Network Training Signal Wrapper - Systems and methods are provided for multi-channel ITU G.709 optical transport network (OTN) transmission and receiving. The transmission method accepts a canonical ITU G.709 OTN frame including an OTU overhead (OH) section, an ODU section, and a forward error correction (FEC) parity section. A training signal wrapper is added to the ITU G.709 OTN frame, and at least a portion of a training-enhanced (TE) OTN frame is buffered in a tangible memory medium in preparation for striping. The method stripes the training-enhanced OTN frame into n parallel streams to supply n TE_OTN-PFs (Parallel Frames) at an output. | 01-14-2010 |
20100014872 | Method and apparatus for generating a dispersion compensation signal - An apparatus for generating a dispersion compensation signal includes a splitting module for splitting a data signal to be transmitted into N channels of data signals; N pre-processing modules for adjusting in frequency domain the phases and amplitudes of the N channels of data signals and outputting N channels of pre-warped electrical signals; an optical carrier generating module for generating N channels of coherent optical carriers; N electro-optic modulators for modulating the N channels of coherent optical carriers based on the N channels of pre-warped electrical signals and generating N channels of pre-warped optical signals; an optical coupling module for coupling the N channels of pre-warped optical signals into a dispersion compensation optical signal. By pre-processing the data signals, the present disclosure may allow the use of existing devices to generate a dispersion compensation signal so that the bandwidth requirement set by prior art on the electrical device is reduced. | 01-21-2010 |
20100034542 | METHODS AND APPARATUS FOR GENERATION AND TRANSMISSION OF OPTICAL SIGNALS - Methods and apparatus ( | 02-11-2010 |
20100040380 | OPTICAL CORRELATION APPARATUS - An optical correlation apparatus is described which forms first and second parallel optical signals in response to a serial input data stream. The first parallel optical signal is arranged to have bright pulses represent binary 1 and the second parallel optical signal is arranged to have bright pulses represent binary 0. A channel select means, such as an optical switch or amplitude modulators deselects or blocks channels in the first parallel optical signal which correspond to binary 1 in a reference data string and also deselects or blocks channels in the second parallel optical signal which correspond to binary 0 in the reference data string. The remaining optical signals are combined at one or more detectors. Where the input data matches the reference data string each bright pulse in the first and second parallel optical signals is deselected and the detector registers zero intensity. However when there is any mismatch at least one channel will pass a bright pulse to the detector. An instance of zero intensity can therefore be used as an indication of pattern match. | 02-18-2010 |
20100067918 | ULTRA-MINIATURIZED THZ COMMUNICATION DEVICE AND SYSTEM - Ultra-miniaturized THz spectrometer/multi-channel receiver devices are provided. THz communication devices employ a THz transmitter, a THz receiver and a modulator, wherein the THz transmitter is configured to introduce a THz signal to the modulator and the THz receiver is configured to receive the THz signal from the modulator and demodulate the signal. Communication systems and methods employing the THz spectrometer/multi-channel receiver devices enable secure communications. Portable THz emitter devices are provided employing semiconductor lasers and a nonlinear birefringent waveguide monolithically integrated on the same substrate. | 03-18-2010 |
20100074627 | Interference-Rejection Coding Method For An Optical Wireless Communication System And The Optical Wireless Communication System Thereof - An interference-rejection coding method for an optical wireless communication system and such an optical wireless communication system are provided. The coding method uses delay modulation, block code techniques and filtering to reduce the low frequency interference from light sources. A plurality of codewords from the block codes are reserved for performing digital data recovery. The invention removes the need of analog clock data recovery circuit, and does not require complex hardware for realization. Therefore, it can be applied to a wide range of applications, such as optical WLAN, data transmission of medical facilities, wireless communication in the aircraft, encrypted data transmission network, and low-priced transmission interfaces. | 03-25-2010 |
20100135670 | PHASE-MODULATING COMMUNICATION DEVICE - A system, method, and communication device are disclosed. The system can include an optical interrogator and a phase-modulating communication device. The communication device can include a retro-optimized lens, a phase modulator, and a processor. The retro-optimized lens can be a non-imaging optical arrangement configured to minimize deviation between an incoming signal and a reflected signal used for return link communications. The processor can be configured to calibrate a modulation path length of the communication device based on a wavelength of the communication signal and can control an operation of the phase-modulator to send phase-coded messages to the interrogator. Optionally, the processor can perform a real-time phase calibration of the communication device using feedback from the interrogator. | 06-03-2010 |
20100142972 | OPTICAL RECEIVER HAVING AN AUTOMATIC FIBER OPTIC SIGNAL ADJUSTMENT CIRCUIT - A fiber optic communication system includes a first fiber optic device configured to transmit a fiber optic signal. A second fiber optic device is in fiber optic communication with and configured to receive the fiber optic signal from the first fiber optic device. The second fiber optic device includes an adjustment circuit configured to automatically adjust the fiber optic signal if the fiber optic signal is transmitted outside of a predetermined signal strength range. | 06-10-2010 |
20100166435 | DISPERSION COMPENSATION METHOD AND DEVICE IN OPTICAL COMMUNICATION SYSTEM - A dispersion compensation method and a dispersion compensation device in an optical communication system are provided. The method mainly includes the following steps. A dispersion compensation value transmitted through a working path at a second wavelength is received through a non-working path at a first wavelength in an optical communication system. The non-working path at the first wavelength and the working path at the second wavelength use the same service channel. Dispersion in the non-working path at the first wavelength is compensated according to the dispersion compensation value. Therefore, no matter the working path is a main path or a backup path, the dispersion compensation value on the non-working path can be accurately regulated in time, such that the dispersion of the working path reaches an optimal status each time after the protection switching occurs to the service, thereby ensuring the fast switching of the service. | 07-01-2010 |
20100215378 | Apparatus and method for interference mitigation and channel selection for visible light communication - A device and method for device association, interference mitigation and channel selection for use in a visible light communication (VLC) network. The method includes transmitting on every one of a plurality of supported color channels of a first device to estimate an ambient interference on each supported color channel. The method also includes receiving a transmission on at least some of the supported color channels, where the number of receiving color channels is less than or equal to the number of supported color channels of the transmitter. The method further includes calculating a channel quality index for each of the receiving color channels. The method still further includes selecting at least one of the receiving color channels of the first device to be used as a communication channel. The method also includes reporting the at least one communication channel to a second device in the VLC network. In certain embodiments, the method includes establishing guard color channels for each of the supported color channels. | 08-26-2010 |
20100232805 | Local Oscillator Frequency Offset Compensation in a Coherent Optical Signal Receiver - A system and method implementing dual stage carrier frequency offset compensation (FOC) in a coherent receiver for an optical communication system. In the first stage, a feed forward FOC function compensates for relatively slowly drifting frequency offsets. In a second stage, a decision-feedback FOC function compensates for relatively quickly drifting frequency offsets. The feed forward frequency offset compensation may be implemented with a feed forward carrier phase estimation function and the decision-feedback frequency offset compensation may be implemented with a decision-feedback carrier phase estimation function. | 09-16-2010 |
20100247110 | OPTICAL DISPERSION COMPENSATOR, OPTICAL TRANSMISSION APPARATUS, OPTICAL TRANSMISSION SYSTEM, AND METHOD THEREOF - An optical dispersion compensator including a first optical device in which light inputted from a first port is outputted from a second port and light inputted from the second port is outputted from a third port, an optical filter type dispersion compensation device that receives light from the second port of the first optical device and compensates wavelength dispersion with respect to the received light, and a second optical device that includes a fourth port to which light is inputted from the optical filter type dispersion compensation device, and in which the light inputted from the fourth port is outputted from a fifth port and light inputted from a sixth port is outputted from the fourth port. | 09-30-2010 |
20100296819 | Optical Receivers and Communication Systems - Optical communications systems and methods transmit signals through an optical medium at a rate associated with a symbol interval. Receivers are communicatively coupled to the optical medium, and receive the signals. The received signals are processed using a plurality of filters. Each filter is used sequentially, one per symbol interval, during a sequence of consecutive symbol intervals. In certain exemplary embodiments, the tap spacing is K/M times the symbol interval, where K is the number of filters used, and M is an integer greater than K. | 11-25-2010 |
20100322637 | Optical Communication System Having Enhanced Spectral Efficiency Using Electronic Signal Processing - An optical communication system combines strong electrical pre-filtering of data at the transmitter and digital feedback equalization (DFE) at the receiver to enhance spectral efficiency. The system can be applied to optical networking and digital communication systems, including binary modulated systems optical network systems. | 12-23-2010 |
20110013914 | METHOD AND APPARATUS FOR IMPROVING RECEPTION OF OPTICAL SIGNALS - A method and apparatus for receiving digital information transmitted via an optical signal over an optical channel wherein the optical signal includes an optical carrier ( | 01-20-2011 |
20110020010 | SPECTRAL TILT COMPENSATION - 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. | 01-27-2011 |
20110103804 | OPTICAL TRANSMISSION SYSTEM - An optical transmission system is provided with an optical transmission apparatus, an optical reception apparatus, an optical transmission line redundantly configured with an active system optical transmission line and an standby system optical transmission line, an optical switch that switches an optical transmission line between the active system optical transmission line and the standby system optical transmission line, a variable dispersion compensator placed between the optical switch and the optical reception apparatus, a dispersion amount measuring unit that measures the dispersion amount of the standby system optical transmission line when the active system optical transmission line is being selected by the optical switch, a dispersion compensation amount setting unit that sets the amount of dispersion compensation to be applied to the standby system optical transmission line based on the measured dispersion amount of the standby system optical transmission line, and a control unit that controls, when the optical transmission line is switched from the active system optical transmission line to the standby system optical transmission line by the optical switch, the variable dispersion compensator so that the amount of dispersion compensation becomes the set amount of dispersion compensation. | 05-05-2011 |
20110103805 | Methods for Accessing a Process Chamber Using a Dual Zone Gas Injector with Improved Optical Access - Methods for processing events occurring in a process chamber are provided. In one method, an operation includes carrying gas and receiving an optical signal from the process chamber to an analysis tool that operates in response to the optical signal having a signal-to-noise ratio (SNR) for process analysis. And, dividing the carried gas and optical signal into a plurality of separate gas and optical signals between the process chamber and the analysis tool. The dividing is configured through separate apertures so that the apertures collectively maintain the SNR of the optical signal received at the tool. Methods provide a septum in a second bore dividing the second bore into apertures configured to reduce etching of and deposition on the optical access window and to maintain the desired SNR at the diagnostic end point. | 05-05-2011 |
20110116806 | High-Speed Adaptive Decision Feedback Equalizer - A decision-feedback equalizer (DFE) can be operated at higher frequencies when parallelization and pre-computation techniques are employed. Disclosed herein is a DFE design that operates at frequencies above 10 GHz, making it feasible to employ decision feedback equalization in optical transceiver modules. An adaptation technique is also disclosed to maximize communications reliability. The adaptation module can be treated as a straightforward extension of the pre-computation unit. At least some method embodiments include, in each time interval: sampling a signal that is partially compensated by a feedback signal; comparing the sampled signal to a set of thresholds to determine multiple speculative decisions; selecting and outputting one of the speculative decisions based on preceding decisions; and updating a counter if the sampled signal falls within a window proximate to a given threshold. Once a predetermined interval has elapsed, the value accumulated by the counter is used to adjust the given threshold. | 05-19-2011 |
20110158654 | DIFFERENTIAL QUADRATURE PHASE SHIFT KEYING SYSTEM, METHOD, AND DEVICE - A differential quadrature phase shift keying (DQPSK) system, method, and device are disclosed. The DQPSK system includes: a transmitter, configured to: pre-code an input first signal and second signal, and generate an in-phase signal and a quadrature signal; modulate the in-phase signal to generate a first differential phase shift keying (DPSK) signal, and modulate the quadrature signal to generate a second DPSK signal; perform a 90 degree phase shift on the first DPSK signal or the second DPSK signal, and interfere with the other DPSK signal to obtain a DQPSK signal; and send the DQPSK signal to a receiver; the receiver, configured to: demodulate the DQPSK signal sent from the transmitter in detuned filter mode, and restore the first signal and the second signal through optical/electrical (o/E) conversion. With the present invention, the accurate control on the phase difference between two arms of an Asymmetric Mach-Zehnder Interferometer (AMZI) is avoided, thus facilitating the signal control and adjustment, and greatly lowering the system cost. | 06-30-2011 |
20110200338 | VISIBLE-LIGHT COMMUNICATION SYSTEM SYSTEM AND METHOD - Disclosed is a visible light communication system including a transmission device, including multiple light emitting units emitting light of different colors and mapping transmission data to a chromaticity point, calculating luminescence of each of the light emitting units, generating a preamble signal for channel matrix estimation, and emitting light based on the preamble signal and calculated luminescence amount. A reception device of the visible light communication system includes multiple light receiving units and estimates a channel matrix based on a corresponding optical signal when an optical signal corresponding to the preamble signal is received in each light receiving unit, compensates the optical signal corresponding to the chromaticity point for a propagation path based on the estimated channel matrix, detects a chromaticity point on the chromaticity coordinates based on a signal after the propagation path compensation, and demodulates the transmission data. | 08-18-2011 |
20110222864 | METHOD AND SYSTEM FOR COMPENSATING FOR OPTICAL DISPERSION IN AN OPTICAL SIGNAL - A method for compensating for optical dispersion includes receiving an optical signal at a first node of an optical network that includes a first set of channels and a second set of channels that are each configured to be received using coherent digital receivers at a second node of the optical network. Each coherent digital receiver provides electronic dispersion compensation for the received channel at the second node. The method also includes forwarding the first set of channels from the first node without performing optical dispersion compensation on those channels. Furthermore, the method includes compensating for optical dispersion in the second set of channels at the first optical node and forwarding those channels from the first node. The optical dispersion compensation on the second set of channels at the first node provides dispersion compensation in addition to the compensation provided by the associated coherent digital receivers at the second node. | 09-15-2011 |
20110274439 | COMMUNICATION SYSTEM COMPRISING A TUNABLE LASER - A communication system includes a communication unit with a first part and a number of a second part, where the second part is arranged to be placed at the location of an end user, and where the first part is common for a number of second parts. The first part and the second part respectively include a laser, and each second part is connected with the first part by a fibre optic cable and a frequency filter, the first part and the relevant second part being arranged to exchange information by laser light. Each second part includes a tunable laser, the first part is arranged to analyze light received from a second part, and to transmit information to the second part while the first part is receiving light from the second part, and the information contains information for the second part that it should adjust, where required, its frequency or wavelength, and the second part thus is arranged to change its frequency or wavelength. | 11-10-2011 |
20110293289 | METHOD, SYSTEM, AND APPARATUS FOR BLIND EQUALIZATION OF BPSK SIGNALS - A system, method, and apparatus is disclosed for enabling a constant modulus algorithm (CMA) to be reliably used for blind equalization training of an equalizer. According to one embodiment, received signals in a binary phase shift keying (BPSK) format are converted to a quadrature phase shift keying (QPSK) format, to which CMA processing can be reliably applied for equalization. According to another aspect of this embodiment, the equalized QPSK signals are rotated to convert the signals to an equalized BPSK format for output. | 12-01-2011 |
20110305462 | Power Manageable Optical OFDM Transponder - The invention relates to the field of optical transmission systems. In particular, the invention relates to a system and a method for adjusting an optical OFDM transmission system in a power optimized manner An optical OFDM transmitter ( | 12-15-2011 |
20120014698 | TRANSMISSION OF PATHOLOGICAL DATA PATTERNS - A method and apparatus is presented for reducing or eliminating pathological data patterns from signals for transmission over optical communications systems. One embodiment includes a decoder/deserializer configured to receive an encoded serial digital signal, a ditherer configured to dither a least significant bit of each digital data word, and a reserializer/encoder configured to serialize digital data and encode it, for example according to an applicable communication standard such as SMPTE 259M. The improvements may be provided in a single removable unit, such as a small form-factor pluggable (SFP) module compatible with existing optical communications equipment. | 01-19-2012 |
20120027418 | Equalizer for an Optical Transmission System - An equaliser ( | 02-02-2012 |
20120027419 | FRAME/SYMBOL SYNCHRONIZATION IN COHERENT OPTICAL OFDM - One aspect provides an optical communication system. The system includes an optical-to-digital converter, a frequency estimator and a symbol synchronizer. The optical-to-digital converter is configured to receive an optical OFDM bit stream including an OFDM symbol bearing payload data and a symbol header preceding the OFDM payload data. The frequency estimator is configured to determine a carrier frequency offset of the payload data from the symbol header. The symbol synchronizer is configured to determine a starting location of the payload data within the bit stream by cross-correlating a synchronization pattern within the symbol header with a model synchronization pattern stored by the symbol synchronizer. | 02-02-2012 |
20120082465 | OPTICAL TRANSMITTING APPARATUS, OPTICAL RECEIVING APPARATUS, AND OPTICAL COMMUNICATION SYSTEM COMPRISING THEM - A phase shift unit provides a prescribed phase difference (π/2, for example) between a pair of optical signals transmitted via a pair of arms constituting a data modulation unit. A low-frequency signal f | 04-05-2012 |
20120128373 | METHOD AND APPARATUS OF PERFORMING ONT WAVELENGTH TUNING VIA A HEAT SOURCE - A method and apparatus of tuning a signal received from a first network terminal at a second network terminal is disclosed. The method may include receiving the signal at the second network terminal. The signal may be operating at a first wavelength. The method may also include determining a port used to receive the signal at the second network terminal, and identifying a predetermined port wavelength used as a basis to shift the first wavelength to the predetermined port wavelength for subsequent signals received. The method may also include transmitting the predetermined port wavelength information to the first network terminal to inform the first network terminal to tune subsequent signals to the desired wavelength for the port. | 05-24-2012 |
20120141138 | System, Devices and Methods for Subcarrier Recovery at Local Oscillator Frequency in Optical OFDM System - The invention provides methods, devices and a system for recovering the corrupted subcarrier at the local oscillator (LO) frequency in coherent optical OFDM transmission. The method includes performing advanced coding on a data signal to obtain an encoded signal; performing high order modulation on the encoded signal to obtain a high-order-modulated signal; performing OFDM modulation on the high-order-modulated signal to obtain an electrical OFDM signal; and performing up-conversion on the electrical OFDM signal to obtain an optical OFDM signal to be output. The inventive technique of employing advanced coding with low rate combining with higher order modulation can be used to reduce the decoding bit error ratio (bit error rate) level, so that the LO subcarrier can be fully recovered while the bandwidth of the transmitted signal may be substantially the same as the existing optical OFDM system, and there is no need to add any feedback control module or feedback loop support or the like to the existing optical OFDM system, so that the complexity of the receiving side can be reduced. | 06-07-2012 |
20120141139 | System and Method for Optical-Electrical-Optical Reach Extension in a Passive Optical Network - A system and method are disclosed in which an optical network may include an optical-electrical converter module within an OEO (Optical Electrical Optical) reach extension system (OEO RE system), the OEO RE system having an OEO port and including a downstream frame regeneration block; and a downstream control data extraction block including a GPON operating parameter extraction module (GOPEM), wherein the GOPEM is operable to extract at least one OEO-port operating parameter from data frames arriving at the GOPEM module. | 06-07-2012 |
20120177383 | OPTICAL RECEIVER AND OPTICAL TRANSMISSION SYSTEM - An optical receiver includes: a first generator to generate, from an optical signal to which a reference signal is inserted, a first digital signal representing a signal component of a first partial band including the reference signal, using a first local oscillation light of a first frequency; a second generator to generate, from the optical signal, a second digital signal representing a signal component of a second partial band including the reference signal, using a second local oscillation light of a second frequency being different from the first frequency; a frequency compensator to adjust a frequency of the signal component of the first partial band and a frequency of the signal component of the second partial band according to a frequency of the reference signal; and a combiner to combine the first and second partial bands adjusted by the frequency compensator. | 07-12-2012 |
20120189320 | SKEW COMPENSATION AND TRACKING IN COMMUNICATIONS SYSTEMS - Compensation for in-phase (I) and quadrature (Q) timing skew and offset in an optical signal may be achieved based on the correlation between derivatives of I and Q samples in the optical signal. The magnitude of the correlation between derivatives is measured to determine the presence of skew. Correlation between derivatives may be coupled with frequency offset information and/or with trials having additional positive and negative skew to determine presence of skew. Correlations are determined according to pre-defined time periods to provide for continued tracking and compensation for timing skew that may result from, for example, thermal drift. | 07-26-2012 |
20120224863 | MULTIPATH CHANNEL FOR OPTICAL SUBCARRIER MODULATION - In a representative embodiment, a multipath channel and an optical subcarrier modulation scheme are designed in concert to cause different modulated subcarriers of the optical communication signal to become substantially uncorrelated over the aggregate signal bandwidth. Provided that the employed FEC code has sufficient error-correcting capability for average channel conditions, breakdowns in the operation of the FEC decoder and the corresponding system outages can substantially be avoided. | 09-06-2012 |
20120224864 | METHOD AND ARRANGEMENT FOR STABILIZING A COLOR CODING METHOD AND OPTICALLY TRANSFERRING DATA - A method is provide for optically transferring data between a transmitter and a receiver employs a color coding method based on a plurality of elementary colors for encoding and transferring the data. Each elementary color is transmitted by one optical radiation source each on the transmitter side, and is received on the receiver side by one optical radiation receiver each. A control loop is formed between the transmitter and the receiver, wherein calibration messages are sent by the transmitter to the receiver, and wherein compensation information is determined by means of comparing at least one channel property of at least one received calibration message to a corresponding channel property of at least one previously transmitted calibration message, and wherein an adjustment of at least one transmitting parameter is made in the transmitter on the basis of the compensation information. | 09-06-2012 |
20120237225 | COMMUNICATION SYSTEM - According to an aspect of an embodiment, a communication system includes a transmission apparatus with a coding section that generates multi-level-coded signals and transmits the multi-level-coded signals; and a deskew signal generation section that generates and transmits a deskew signal related to the multi-level-coded signals. The communication system also includes a receiving apparatus with a decoding section that decodes the multi-level-coded signals to generate decoded signals, and a deskew processing section that performs deskew processing for compensating skew among the decoded signals of the multiple channels. The deskew signal generation section generates the deskew signal that has been framed by extracting a part of the data from each of the channels of the input signals, adding framing data for enabling a receiving apparatus to recognize which channel the extracted data has been extracted from, and performing rate conversion. | 09-20-2012 |
20130108276 | OPTICAL RECEIVER AND OPTICAL TRANSMISSION SYSTEM | 05-02-2013 |
20140099128 | Inter-band cross-phase modulation compensation for the mitigation of intra-channel nonlinear impairments in optical fiber transmission - An optical communication system includes a digital signal processer coupled to the coherent receiver, said coherent receiver including a nonlinearity compensation module for compensating for nonlinear effects in fiber in the optical link for increasing capacity or transmission distance of the fiber, the nonlinearity compensation module includes a spectral slicing of the signal into bands, computing nonlinear interaction between the bands with parameters opposite to those of the fiber to reverse the non-linear effects in the fiber, and only certain nonlinear interactions between bands are considered thereby reducing complexity of the nonlinearity compensation. | 04-10-2014 |
20140119739 | Opto-Isolator With Correction Circuit - An opto-isolator with a correction circuit is disclosed. The correction circuit is configured to make adjustments for degradation of the light source of the opto-isolator. The correction circuit may comprise a photodetector for detecting degradation of the light source of the opto-isolator. When the light source degrades below a predetermined level, the correction circuit may be configured to make adjustments. | 05-01-2014 |
20140119740 | Opto-Isolator With Compensation Circuit - An opto-isolator with a compensation circuit is disclosed. The compensation circuit may be configured to compensate degradation of the light source of the opto-isolator. The compensation circuit may comprise a circuit for counting an extended use of the isolator. When the count value exceeds a predetermined count value, the compensation circuit may be configured to compensate the degradation of the light source by adjusting the driver of the light source. In another embodiment, an electrical control system having such opto-isolator is illustrated. | 05-01-2014 |
20150071652 | METHODS AND SYSTEMS FOR REDUCED COMPLEXITY NONLINEAR COMPENSATION - Aspects of the present invention provide techniques for compensating nonlinear impairments of a signal traversing an optical communications system. A parallel array of linear convolutional filters are configured to process a selected set of samples of the signal to generate an estimate of a nonlinear interference field. The predetermined set of samples comprises a first sample and a plurality of second samples. A processor applies the estimated nonlinear interference field to the first sample to least partially compensate the nonlinear impairment. | 03-12-2015 |