Abstract: A clock recovery method and apparatus is provided. The high-order demultiplexing-demapping unit (102) demultiplexes and demaps the high-order OTN frame (101) into N low-order ODTUjk frames (103), and transmits the N low-order ODTUjk frames (103) to the low-order demapping unit (104); the low-order demapping unit (104) respectively demaps the N ODTUjk frames (103) into N ODUj frames (105), and writes the ODUj frames from memory unit 1 (106) to memory unit n (108) into memory unit n+1 (109) to memory unit 2n (111) by using the clock signal whose gaps are uniformly distributed; and the ODUj frame clock generating unit (113) adjusts the read out clock in memory unit n+1 (109) to memory unit 2n (111), i.e. ODUj frame clock (114), according to the data volume stored in memory unit n+1 (109) to memory unit 2n (111).

Abstract: Aspects of the invention provide a method and system for synchronizing a transceiver and a framer in an optical transmission network. Subsequent to achieving synchronization of an inbound data stream, an internal framer may be adapted to inform a downstream device such as a full framer, that synchronization has already been attained. Accordingly, the downstream device may not need to perform resynchronization of the inbound data and can immediately start processing the inbound data. Advantageously, the internal framer may provide expedited error checking, handling and reporting prior to receipt of the data by the downstream device.

Abstract: A waveform converting unit gives a change to a clock signal as a periodic voltage fluctuation that drives a pulse carver unit carrying out shaping into an RZ waveform. The pulse carver unit receives a bias voltage applied thereto from a bias voltage applying unit, is driven by the clock signal that is given a change by the waveform converting unit and that is amplified by an amplifying unit, and outputs an RZ pulse whose duty has been changed.

Abstract: A topology for optical transceiver components comprises an electrical signal interface stage, a data timing and signal reformatting stage, and an optical fiber interface stage. Unlike transceiver components known in the art, functions having signals with the most jitter are partitioned into the electrical signal interface stage. Data timing functions, for example retiming or clock and data recovery, are included in the data timing and reformatting stage. Output jitter from the data timing and signal reformatting stage is approximately equal to jitter in a clock signal, enabling use of semiconductor components having jitter greater than SONET limits and thereby increasing a value of production yield. Embodiments of the invention are well suited for 40 G transmitters and receivers in nonconnectorized surface mount packages. 40 G transceivers built in accord with the invention are expected to have lower cost, smaller size, and higher production yield than 40 G transceivers known in the art.

Abstract: To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus.

Abstract: An optical transmission apparatus includes a first transceiver unit coupled to a first node, a second transceiver unit coupled to a second node, an electrical signal processing unit provided between the transceiver units, a first transmission clock generating unit configured to generate a clock used by the second transceiver unit based on a clock of a signal arriving through the first node, a second transmission clock generating unit configured to generate a clock used by the first transceiver unit based on a clock of a signal arriving through the second node, a selector configured to select an output clock of the first transmission clock generating unit at a time of optical input interruption at the second node, and a frequency dividing unit configured to produce a frequency-divided clock obtained by dividing frequency of the output clock selected by the selector for provision to the second transmission clock generating unit.

Abstract: In a coherent optical receiver of an optical communications network, a method of recovering a clock signal from a high speed optical signal received through an optical link. A set of compensation vectors are adaptively computed for compensating Inter-symbol Interference (ISI) due to at least polarization impairments of the optical signal. A channel delay is estimated based on the computed compensation vectors. The estimated channel delay is subtracted from the computed compensation vectors to generate corresponding modified compensation vectors. Finally, the modified compensation vectors are used to derive a recovered clock signal.

Abstract: An optical transmission system for performing frequency synchronization even with a client signal with low frequency accuracy, and for transmitting thereof by accommodating/multiplexing without causing a bit slip. A new overhead is added to the entire client signal, and the signal including the new overhead being stuffed is transmitted in conjunction with a plurality of stuffing bits as an optical signal wherein a data storing bit for a negative stuffing, a stuffing information notification bit, and a stuff bits inserting bit for a positive stuffing in the payload are defined in plurality as stuffing bits for adjusting clock frequencies of the client signal in this new overhead.

Abstract: An apparatus for performing an optical line analysis of continuous data signals. The apparatus comprise a phase position processor for computing a phase early/late indicator; a phase control code processor for computing a difference phase indicator; a frequency extractor for computing a low frequency jitter indicator; and a statistical calculator for computing a plurality of statistical measures regarding frequency and amplitude components of a jitter of an input continuous data signal, wherein the statistical measures are computed based on one of the phase early/late information indicator, the difference phase indicator, or the low frequency jitter indicator.

Abstract: An electroabsorption optical modulator used as a sampling element has two optical terminals and a power supply terminal, the two optical terminals are used to input and output light, and the power supply terminal imparts an electric field to an optical path connecting the two optical terminals. The electroabsorption optical modulator has a characteristic in which an absorption index is changed with respect to the light beam propagating through the optical path according to a level of the electric field. A monitoring (synchronization sampling) object optical signal is input into one of the two optical terminals of the electroabsorption optical modulator. A predetermined direct-current voltage exhibiting a high absorption index for the monitoring (synchronization sampling) object optical signal is imparted to the power supply terminal of the electroabsorption optical modulator.

Abstract: A process for transmitting data on an optical fiber including multiplexing in wavelength signals coming from a plurality of monochrome transmitters, each of which has its own wavelength, and modulating information to be transmitted by a carrier realized per channel, wherein timing (clocking) of each transmitter is controlled by a common clock.

Abstract: The invention pertains to a method for determining the assignment of subsignals (S1, S2, S3, S4) transmitted by inverse multiplexing, particularly via an Optical Transport Network (OTN), to the transmission links (5a, 5b, 5c, 5d) carrying said subsignals with the following steps: a digital transmission signal (S) to be transmitted is divided into a certain number M of subsignals (S1, S2, S3, S4), wherein each subsignal of a transmitting end of a transmission link (5a, 5b, 5c, 5d) that is assigned exclusively to this subsignal is transmitted to a receiving end of the assigned transmission link; the subsignals (S1, S2, S3, S4) are once again assembled into a digital reception signal (E) on the receiving ends of the transmission links (5a, 5b, 5c, 5d); after a synchronization for the correct assembly of the subsignals (S1, S2, S3, S4) into the digital reception signal (E) has been carried out on the receiving end, the signal transmission via at least one transmission link (5a, 5b, 5c, 5d) is interrupted for a de

Abstract: Consistent with the present disclosure, optical signals are modulated in accordance with a higher order QAM modulation format, such as 8-QAM, to carry customer data, for example. The optical signals are converted to corresponding electrical signals, which are then subject to further processing. In particular, phase data associated with the higher order QAM constellation is processed, such that the outer points of the constellation are rotated to have the same phase as the inner points. As a result, both the inner and outer points resemble a constellation, and both may be more readily processed using feedforward or feedback carrier recovery. After such carrier recovery, the phase data is further processed so that the outer points are rotated back and the customer data can be extracted from the phase data.

Abstract: An economical optical network is constituted by effectively using network resources by using the minimum number of, or minimum capacity of 3R repeaters. 3R section information corresponding to topology information on the optical network to which an optical node device itself belongs is stored, and the 3R section information stored is referred so as to autonomously determine whether or not the optical node device itself is an optical node device for implementing the 3R relay when setting an optical path passing through the optical node device itself. Alternatively, when the optical node device itself is a source node, another optical node device for implementing the 3R relay among the other optical node devices through which the optical path from the optical node device itself to the destination node passes is identified, and this identified optical node device is requested to implement the 3R relay when setting an optical path in which the optical node device itself is a source node.

Abstract: Femtosecond pump/probe experiments using short X-Ray and optical pulses require precise synchronization between 100 meter-10 km separated lasers in a various experiments. For stabilization in the hundred femtosecond range a CW laser is amplitude modulated at 1-10 GHz, the signal retroreflected from the far end, and the relative phase used to correct the transit time with various implementations. For the sub-10 fsec range the laser frequency itself is upshifted 55 MHz with an acousto-optical modulator, retroreflected, upshifted again and phase compared at the sending end to a 110 MHz reference. Initial experiments indicate less than 1 fsec timing jitter. To lock lasers in the sub-10 fs range two single-frequency lasers separated by several teraHertz will be lock to a master modelocked fiber laser, transmit the two frequencies over fiber, and lock two comb lines of a slave laser to these frequencies, thus synchronizing the two modelocked laser envelopes.

Abstract: In conventional technology, if a frame itself is discarded as being invalid when a sync header has an error, an error correction cannot be performed on a frame that does not fall out of synchronization even at such a low error rate that an error correction can satisfactorily be performed. According to the present invention, each of an optical line terminal and an optical network unit includes a synchronization detection part for detecting whether or not received data converted into frame form falls out of synchronization, and an error correction part for performing an error correction on a frame of the received data that has been detected not falling out of synchronization by the synchronization detection means, irrespective of existence of an error in a sync header of that frame.

Abstract: An optoelectronic timing system includes an adaptive frequency generator system in which optical pulses are developed by a semiconductor laser. The pulses are directed into a number of time-quantifiable optical paths. Time quantification for a pulse is based upon the time required for a pulse to travel a particular length at the speed of light. Pulses are recombined at a nodal point and exhibit a numerical relationship with the periodicity of the issued pulse train equal to the numerical relationship between the lengths of the number of optical waveguides. A pulse detector and a regenerator are coupled to the semiconductor laser. A regeneration waveguide having a length equal to the longest of the optical paths is coupled to receive pulses from the laser.

Abstract: A method is provided in one example embodiment and includes providing a time protocol assistant associated with a time-synchronized domain (TSD). The TSD includes a set of nodes that are synchronized to a same time source. The TSD has defined egress and ingress edge points where bidirectional measurements can be made and the egress and ingress edge points are coupled to the time protocol assistant. The method also includes synchronizing one or more packets flowing through a network that includes the TSD through the same time source. In more specific embodiments, the nodes are synchronized to the same time source via the network and the same time source is a grandmaster clock that synchronizes one or more transparent clocks. In yet other embodiments, the transparent clocks manipulate precision time protocol (PTP) packets sent by the grandmaster clock.

Abstract: A method and apparatus for producing a series of amplified optical pulses from a series of input optical pulses. The method includes creating a set of local optical pulses from a series of input optical pulses, the set of local optical pulses being applied to the input of an optical amplifier and having different amplitudes arranged in a graded order. The set of local optical pulses are amplified by an optical amplifier to have a significantly amplified first local optical pulse that is removed from the set of local optical pulses and output as a part of the series of amplified optical pulses. After removing the significantly amplified first local optical pulse, the set of local optical pulses is recreated by adding a new optical pulse from the series of input optical pulses to the end of the set of local optical pulses; and the recreated set of local optical pulses is routed back to be applied to the input of the optical amplifier to continue producing the series of amplified optical pulses.

Abstract: System and methods are provided, in an Optical Transport Network (OTN), for communicating asynchronous Tributary Slots (TSs) via a synchronous Optical Payload Transport Unit of level k (OTUk) interface. The transmission method accepts a plurality of TSs at a corresponding plurality of asynchronous data rates. The TSs are mapped, using a tangible memory medium, into pseudo-Optical channel Data Tributary Unit (ODTU) frames synchronized to a common clock. Then, the synchronized pseudo-ODTU frames can be interleaved into an OTUk frame, without the need of a phase-locked loop (PLL) or buffering.

Abstract: A method for transmission of multiple, independent data packages across a single optical fiber utilizing both time division multiplexing and wavelength division multiplexing is described. The method includes transmitting a first data package across the single optical fiber at a first wavelength and transmitting a second data package across the same optical fiber at a second wavelength, in either the same direction or in a direction opposite as the first data package, wherein the second data package transmission may be concurrent with the first data package transmission. the method further includes separating the data package transmissions into two optical paths, filtering the second wavelength from a first of the two optical paths, detecting the first data package at the first wavelength, filtering the first wavelength from a second of the two optical paths, and detecting the second data package data at the second wavelength.

Abstract: A method and apparatus for producing a series of amplified optical pulses from a series of input optical pulses including creating a set of local optical pulses from a series of input optical pulses, the set of local optical pulses having different amplitudes arranged in a graded order. The set of local optical pulses are amplified by an optical amplifier to form a significantly amplified first local optical pulse that is removed from the set of local optical pulses and output. The method successively removes the significantly amplified first local optical pulse, re-creates the set of local optical pulses by adding a new optical pulse to the end of the set of local optical pulses; and routes the recreated set of local optical pulses back to the input of the optical amplifier to continue producing the series of amplified optical pulses.

Abstract: An optical interconnect includes a transmitter circuit, a receiver circuit and an optical signal transmission route. The transmitter circuit includes a control circuit and an electrical/optical converter circuit. The control circuit receives an input electrical signal and outputs a drive signal. The electrical/optical converter circuit includes a light emitting element and converts the drive signal to an optical signal. The receiver circuit includes an optical/electrical converter circuit and a data recovery circuit. The data recovery circuit includes a second trigger signal generator and a latch circuit. The optical/electrical converter circuit includes a light receiving element and a received-signal amplifying circuit. The light receiving element converts the optical signal from the light emitting element to an output current signal. The received-signal amplifying circuit converts the output current signal to a required digital voltage signal.

Abstract: An optical transmission system capable of time difference correction without increasing guard times, thereby improving optical packet transmission efficiency. An optical switching processor sets identical switching timing for input ports thereof such that optical signals input from the input ports are switched at the same timing. During initialization, a time difference corrector transmits an optical dummy packet to an optical switch node, and detects synchroneity of the optical dummy packet returned thereto after being switched by the optical switch node. If synchronization error is detected, the time difference corrector adjusts the output timing of the optical dummy packet so that the timing of arrival of the optical dummy packet at the optical switching processor may coincide with the switching timing of the optical switching processor, to thereby correct the time difference between the switching timing and the arrival timing.

Abstract: A method and apparatus for receiving a digital signal having a plurality of significant bits of resolution. The apparatus includes a mode locked laser comprising a single output. The apparatus also includes a beam divider operable to receive the single output. The apparatus also includes a plurality of optical modulators operable to communicate with said beam divider and operable to receive a respective plurality of signals corresponding to a plurality of significant bits of resolution. Optionally, the apparatus also includes a source operable to output a digital waveform with the plurality of signals corresponding to the plurality of significant bits of resolution of the digital waveform, the plurality of signals operable to drive the plurality of optical modulators.

Abstract: An economical optical network is constituted by effectively using network resources by using the minimum number of, or minimum capacity of 3R repeaters. 3R section information corresponding to topology information on the optical network to which an optical node device itself belongs is stored, and the 3R section information stored is referred so as to autonomously determine whether or not the optical node device itself is an optical node device for implementing the 3R relay when setting an optical path passing through the optical node device itself. Alternatively, when the optical node device itself is a source node, another optical node device for implementing the 3R relay among the other optical node devices through which the optical path from the optical node device itself to the destination node passes is identified, and this identified optical node device is requested to implement the 3R relay when setting an optical path in which the optical node device itself is a source node.

Abstract: A highly precise clock synchronization apparatus in a real-time locating system (RTLS), includes an optical transmitting/receiving unit for receiving a clock information frame from a clock synchronization server, converting the received clock information frame in series-parallel, and transmitting/receiving the clock information data and the clock information; an offset estimation unit for detecting a preamble signal and a clock information signal from the series-parallel converted clock information frame, calculating a phase difference value by comparing the detected preamble signal with the detected clock information signal, and outputting an offset value based on the calculated phase difference value; and a clock synchronization unit for updating a local clock value to a time of the clock synchronization server based on the offset value and the clock information frame.

Abstract: An optical signal reception device that receives and demodulates an optical signal modulated by DQPSK and performs logical inversion and other controls to transit to the object reception state.

Abstract: According to one embodiment, an optically coupled insulating device includes an optical transmitter and an optical receiver. The optical transmitter includes an analog-to-digital converter, an encoder, a transmitting controller, and an electrooptical transducer. The encoder is configured to generate a transmitting signal by superimposing an output of the analog-to-digital converter onto a signal based on a clock signal. The transmitting signal is encoded to have an average duty ratio of more than zero and less than one. The transmitting controller is configured to output one of the transmitting signal and the output of the analog-to-digital converter depending on an input level of the analog signal. The electrooptical transducer is configured to convert an output of the transmitting controller into an optical signal. The optical receiver includes an optoelectrical transducer, a decoder, and a receiving controller.

Abstract: A circuit and method to synchronize with a data transmission having a plurality of data transmission frames each with a start boundary identified by a predetermined synchronization pattern, includes comparing sets of data within the data transmission to a predetermined synchronization pattern. A frame tracking signal is assigned to each one of the plurality of comparison results that indicates a match between a data pattern within one of the plurality of sets of data and the predetermined synchronization pattern, including matches that occur multiple times within a known duration of the data transmission frame duration. Based on each frame tracking signal assigned to a comparison result, the start boundary of the data transmission frames is searched. The start boundary may be search by monitoring successive occurrences of the predetermined synchronization pattern in the data transmission at intervals of the known data transmission frame duration for each data matching data pattern.

Abstract: A circuit to synchronize with a data transmission includes a comparator to read a set of data within a serialized data transmission, compare the set of data to a predetermined data pattern and output a comparison result. For a serialized data transmission, the comparator receives the serialized transmission and a shift register serially coupled to the comparator to hold the data pattern. A synchronization detector receives a comparison hit vector based on the comparison result from the comparator and aligns a boundary of a data frame according to the comparison hit vector if the comparison hit vector indicates a match between the data pattern in the set of data and the predetermined data pattern. For a deserialized data transmission, each stage of a multistage shift register read a set of data from the deserialized data transmission and selectively outputs the set of data to a comparator which compares each set to a predetermined data pattern and output a comparison result.

Abstract: A system and method for management of bandwidth in a fiber optic, ethernet-based, TDMA communications system. A request/grant process is used to control the use of upstream bandwidth. A sense of time must therefore be shared by a headend and remote end-user devices. The invention provides for a gigabit media-independent interface in a media access controller to detect start-of-frame delimiters in incoming data. This allows for synchronization of a headend and end-user devices. The invention also allows for phase locking a transmit bit rate, at a headend, to the headend's clock. Transmitted data can the be used downstream to derive a local clock. Synchronization can also be maintained by the use of synchronization bytes in MPEG frames and/or variable length frames. Efficient bandwidth usage can also be facilitated by the use of maximum data units in allocating bandwidth in unsolicited grants, and by allowing flexible fragmentation and/or prioritization of internet protocol (IP) packets.

Abstract: A system and method are provided for calibrating temporal skew in a multichannel optical transport network (OTN) transmission device. The method accepts a pair of 2n-phase shift keying (2n-PSK) modulated signals, as well as a pair of 2p-PSK modulated signals. The 2n-PSK and 2p-PSK signals are converted to 2n-PSK and 2p-PSK optical signals, respectively. The 2n-PSK and 2p-PSK optical signals are orthogonally polarized and transmitted. A timing voltage is generated that is responsive to the intensity of the orthogonally polarized signals. The timing voltage is correlated to a reference frame calibration pattern associated with a preamble/header portion of an OTN frame. Then, the timing voltages associated with the Ix, Qx, Iy, and Qy signal paths are compared, and the misalignment between the timing voltages and the reference frame calibration pattern is minimized in response to adjusting time delay modules in the Ix, Qx, Iy, and Qy signal paths.

Abstract: A system, method, and computer program product for synchronizing time between a centralized controller device and at least one subscriber device on a fiber access network. The control layer of a network device is expanded, and additional messaging control is added via the transmission of data frames. The expansion prevents reliance on a physical layer signal. The time synchronization also allows a time stamp to be incorporated into a message. Thus, bandwidth is not wasted by simply transmitting a time stamp by itself. In an embodiment, the centralized controller device measures the time difference between the time at which a particular ranging request is transmitted and the time at which the particular ranging request is received. The time difference represents the time adjustment value for the particular subscriber device and allows the device to synchronize its time with that of the centralized controller device.

Abstract: A system and method are provided for calibrating skew in a multichannel optical transport network (OTN) transmission device. The method accepts a pair of 2n-phase shift keying (2nPSK) modulated signals via Ix and Qx electrical signal paths, where n>1. Likewise, a pair of 2p-PSK modulated signals are accepted via Iy and Qy electrical signal paths where p>1. The Ix, Qx, Iy, and Qy signals are correlated to a preamble/header portion of an OTN frame. A voltage on the Ix signal path is compared with Qx, and VO12 voltage is generated. A voltage on the Iy signal path is compared with Qy, and VO34 is generated. One of the Ix or Qx voltages is compared with one of Iy or Qy voltages to generate VOxy. Then, the VO voltages are minimized in response to adjusting time delay modules in the Ix, Qx, Iy, and Qy signals paths.

Abstract: A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal.

Abstract: Photonic signals are tagged with a pre-selected modification, such as a polarization signature to carry data across an obstructed path between sender and receiver. Communication authentication through polarization variation allows for Yuen-Kumar or entangled photon quantum communication protocols to propagate through environmental scattering media such as air, smoke, fog, rain, and water. While ultraviolet light photons are well suited as a carrier for quantum communication signals scattered in air, it is appreciated that visible wavelengths have longer propagation paths in water to convey non-line-of-sight data. A secure signal is scattered by the media and simultaneously communicated to a single recipient or multiple recipients exposed to scattered signal portions. A process of solving the scattering processes through a random scattering media is provided to reconstruct a quantum keyed message at a receiver.

Abstract: In a clock signal extraction system, an optical modulator modulates an input optical signal having its clock frequency equal to a first or second frequency with a modulation electrical signal having its frequency equal to the average of the first and second frequencies to output a modulated optical pulse signal to a phase comparator, which receives a reference electrical signal generated by a reference signal generator and having its frequency half as high as a difference between the first and second frequencies to compare in phase the modulated optical pulse signal with the reference electrical signal to output a resultant phase comparison signal to a modulation electrical signal generator, which in turn outputs a modulation electrical signal to the optical modulator and clock signal generator, which generates a signal with the modulation and reference electrical signals mixed, and outputs the signal at first or second frequency as a clock signal.

Abstract: A node, a data processing system, and a data processing method are provided. The node includes a control module, adapted to generate synchronization information and Optical Burst (OB) configuration information; at least one synchronization processing module, adapted to perform a synchronization process on OB paths at a plurality of wavelengths according to the synchronization information; and a cross-connection module, adapted to perform, a cross-connection process on the OB paths, on which the synchronization process has been performed. The data processing system includes at least two nodes, where the nodes are connected through OB paths at one or more wavelengths, and the nodes are adapted to transfer service data through the OB paths. The technical solutions can reduce volume, power consumption, and costs of the nodes, and avoid a problem of generation of data conflict on an optical layer due to lack of optical buffers in all optical switching.

Abstract: For use in visible light communication (VLC), methods for synchronization with multiple topology support and for transmitting an extended preamble. The method for synchronization includes transmitting a two-part preamble sequence. The preamble sequence includes one or more repetitions of a fast locking pattern (FLP) configured to be used for clock synchronization, and one or more repetitions of a topology dependent pattern (TDP) configured to be used to distinguish a plurality of VLC topologies. The method for transmitting an extended preamble includes generating an extended preamble and transmitting the extended preamble during a receive or idle mode for maintaining visibility support and for better synchronization performance.

Abstract: The present invention relates to optical communications and discloses a master clock time synchronization method, slave clock time synchronization method, system and optical network device in a Passive Optical Network (PON) for the purpose of resolving time synchronization in Ethernet over Gigabit PON Encapsulation Method (GEM) mode. The PON master clock time synchronization method includes: predefining a rule for matching packet time stamp generating points; sending a first clock packet carried in a first downstream frame; acquiring time at a packet time stamp generating point that matches the frame data of the first downstream frame at the PON Media Access Control (MAC) layer and regarding the acquired time as the time the first clock packet is sent; and sending a second clock packet in a second downstream frame, where the second clock packet carries the time the first clock packet is sent.

Abstract: On an optical access network, transmission at different bit rates is realized without modifying subscriber units. A low-speed signal generating part generates a low-speed signal having a low bit rate. A high-speed signal generating part generates a high-speed signal having a high bit rate. A recovery signal generating part generates a recovery signal. A multiplex part generates and sends a multiplexed signal obtained by multiplexing the low-speed signal, the high-speed signal, and the recovery signal. A reception processing part performs processing for receiving the multiplexed signal by extracting clocks from the low-bit-rate signal. When the reception processing part enters a free running state in response to receiving the high-speed signal, the recovery signal generating part generates the recovery signal at a low bit rate in order to recover clock synchronization from the free running state.

Abstract: A device may include a first network module to capture network data at a first location in a network and a second network module to capture network data at a second location in the network different from the first location in the network. The device may include a control module to receive control commands relating to the first network module and the second network module. The control module may forwarded the control commands to the first network module and the second network module. The control module may receive the captured network data from the first network module and the second network module.

Abstract: A method and a device are provided for phase recovery of at least two channels comprising the steps of (i) a phase is estimated for each channel; (ii) the phase estimated of each channel is superimposed by a coupling factor with at least one other phase estimated. Further, a communication system is suggested comprising such a device.

Abstract: A head-end circuit comprises first and second continuous light sources, first and second modulators. The first and the second continuous light sources provide first and second optical signals respectively corresponding to first wavelength and second wavelength, which is different from the first wavelength. The first modulator modulates the first optical signal based on first clock signal to generate an optical clock signal. The second modulator modulates the second optical signal based on downlink data to generate optical downlink data with the carrier of the second optical signal. The optical clock signal and the optical down link data are outputted to a remote antenna unit via first fiber path.

Abstract: A ranging signal R1 generated by a signal generator and reaches to a signal checker via a working system transmission line, a loop circuit, and an auxiliary system transmission line. The signal checker measures a delay time from the generation to the arrival of the signal R1. A ranging signal R2 generated by the signal generator and reaches to a signal checker via an auxiliary system transmission line, a loop circuit, and an auxiliary system transmission line. The signal checker measures a delay time from the generation to the arrival of the signal R12. A delay time of the working system transmission line is calculated from the delay times of the signals R1 and R2. Disruption of the services provided by the other ONUs can be prevented since the working system transmission line is not used for upstream communication of the ranging signals R1 and R2.

Abstract: An optical packet processor includes one or more optical packet inputs that receive asynchronous optical packets. An optical packet interconnect directs the optical packets from the different optical packet inputs to different optical packet outputs. The optical packets are buffered either before or after being directed from the inputs to the different outputs. Problems associated with optical buffering are overcome by synchronizing the asynchronous optical packets with the optical packet buffers. The novel optical buffer architectures described also reduce or eliminate the use of certain high cost optical components.

Abstract: An optoelectronic device implements a serializer array circuit or multi-channel CDR circuit to reduce the cost and size of the circuit. An efficient serializer array circuit includes a plurality of serializer blocks sharing the functionality of a single CMU to clock a plurality of serial signals out of the final stages of the serializer blocks. An efficient multi-channel CDR circuit includes a single CDR for acquiring the clock for one of a plurality of data signals and a plurality of DLLs using the recovered clock to acquire the data for the plurality of data signals. Alternately, an efficient multi-channel CDR circuit includes a single frequency acquisition loop and a plurality of data acquisition loops.

Abstract: Asynchronous optical data is aligned with synchronous convergence points in an optical packet switching system. The convergence points can be any place where data enters an optical packet switching element, buffer stage, switch fabric, etc. The arrival time for data approaching the convergence point is compared with a reference signal associated with the upcoming convergence point. The comparison is used to identify the amount of time-shift required to align the approaching data with the reference signal. Control information is derived according to the comparison and used to control an optical data aligner that synchronizes the data with the convergence point.

Abstract: In one embodiment, detecting an initialization of a synchronization phase of a network device in a fiber channel fabric, performing synchronization phase optimization of the network device to select a predetermined number of interfaces, and transmitting a synchronization request on the predetermined number of interfaces, are provided.