Clock Recovery Patents (Class 398/155)
  • Patent number: 10326533
    Abstract: A method and structure for equalization in coherent optical receivers. Block-based LMS (BLMS) algorithm is one of the many efficient adaptive equalization algorithms used to (i) increase convergence speed and (ii) reduce implementation complexity. Since the computation of the equalizer output and the gradient of the error are obtained using a linear convolution, BLMS can be efficiently implemented in the frequency domain with the constrained frequency-domain BLMS (FBLMS) adaptive algorithm. The present invention introduces a novel reduced complexity constrained FBLMS algorithm. This new approach replaces the two discrete Fourier transform (DFT) stages required to evaluate the DFT of the gradient error, by a simple frequency domain filtering. Implementation complexity can be drastically reduced in comparison to the standard constrained FBLMS. Furthermore, the new approach achieves better performance than that obtained with the unconstrained FBLMS in ultra-high speed coherent optical receivers.
    Type: Grant
    Filed: October 24, 2017
    Date of Patent: June 18, 2019
    Assignee: INPHI CORPORATION
    Inventors: Mario R. Hueda, Néstor D. Campos
  • Patent number: 10205524
    Abstract: A method and an apparatus for setting a quiet window in a passive optical network system are provided. A first response time from a time after an optical line terminal (OLT) transmits a serial number request up to a time in which the OLT receives a first response signal to the serial number request is measured, and a second response time up to a time in which the OLT receives a final response signal to the serial number request is measured. In addition, distance information of an optical network unit (ONU) including the first response time and the second response time is acquired.
    Type: Grant
    Filed: March 16, 2017
    Date of Patent: February 12, 2019
    Assignee: ELECTRONICS & TELECOMMUNICATIONS RESEARCH INSTITUTE
    Inventors: Geun Yong Kim, Hark Yoo, Sung Chang Kim, Dongsoo Lee
  • Patent number: 10177871
    Abstract: A method of fragmented packet transmission in a multiple-channel passive optical network (PON), comprising fragmenting, by a Gigabit-PON encapsulation method (GEM)/next generation-PON encapsulation method (XGEM) engine of a network element, data into a plurality of packet fragments; encapsulating, by the GEM/XGEM engine, the plurality of packet fragments into frames; scheduling, by a bonding block of the network element, transmission of the frames on a plurality of channels, wherein an order for transmitting the frames is based in part on channel availability; and transmitting, by a transmitter of the network element, the frames to a receiver on the plurality of channels according to the scheduling.
    Type: Grant
    Filed: July 8, 2016
    Date of Patent: January 8, 2019
    Assignee: Futurewei Technologies, Inc.
    Inventors: Yuanqiu Luo, Frank Effenberger, Duane Remein
  • Patent number: 10110304
    Abstract: A communication device includes: an optical-communication circuit that is capable of performing optical communication with a different communication device and transmits a first electric signal to the different communication device at a startup time of the communication device; an electro-communication circuit that is capable of performing electro communication with the different communication device and receives a second electric signal transmitted from the different communication device in response to the first electric signal; and a control circuit that transmits error information indicating an error in the optical communication to a device after the second electric signal is received by the electro-communication circuit.
    Type: Grant
    Filed: May 30, 2017
    Date of Patent: October 23, 2018
    Assignee: FUJITSU LIMITED
    Inventor: Atsushi Miki
  • Patent number: 10097279
    Abstract: An heterodyne apparatus and method for measuring performance parameters of a coherent optical receiver at RF frequencies is disclosed. Two coherent lights are launched into signal and LO ports of the receiver with an optical frequency offset f. One of the lights is modulated in amplitude at two phase-locked modulation frequencies F1 and F2. COR performance parameters are determined by comparing two frequency components of the COR output. The group delay variation (GDV) information is obtained by comparing phases of two time-domain traces corresponding to frequency components of the COR output signal at the two modulation frequencies shifted by the optical frequency offset f.
    Type: Grant
    Filed: October 4, 2017
    Date of Patent: October 9, 2018
    Assignee: Elenion Technologies, LLC
    Inventors: Bernd-Harald Horst Jurgen Rohde, Erich Gottwald
  • Patent number: 9871583
    Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.
    Type: Grant
    Filed: March 3, 2017
    Date of Patent: January 16, 2018
    Assignee: INPHI CORPORATION
    Inventors: Shih Cheng Wang, Seyedmohammadreza Motaghiannezam, Matthew C. Bashaw
  • Patent number: 9696412
    Abstract: A system and method for measuring the temporal delay an optical signal experiences along a path is provided it uses single photon sensitive detectors and multiple optical pulse rates. The multiple optical pulse rates are chosen to allow each to be isolated in post-processing even if only a single detector is employed. The detectors can be time-gated at a repetition rate synchronized but different from the optical pulse rates, including the use of a pulsed-pump up-conversion detector. The pulse rate choice allows improved performance, including an extension of the unambiguous temporal delay range. The ability to isolate the pulse rates can also be used for measuring multiple path delays simultaneously or for spectrally resolving path characteristics without requiring the use of spectral filtering. The post-processing function can be segmented to include an initial signal quality estimation step so further processing can be aborted if it is unlikely to succeed.
    Type: Grant
    Filed: January 20, 2015
    Date of Patent: July 4, 2017
    Assignee: Nucript LLC
    Inventors: Gregory S. Kanter, Daniel R. Reilly
  • Patent number: 9686019
    Abstract: The disclosed coherent optical receiver includes a local light source; a 90-degree hybrid circuit; an optoelectronic converter; an analog-to-digital converter; a skew addition unit; and a FFT operation unit. The 90-degree hybrid circuit makes multiplexed signal light interfere with local light from the local light source, and outputs multiple optical signals separated into a plurality of signal components. The optoelectronic converter detects the optical signal and outputs a detected electrical signal. The analog-to-digital converter digitizes the detected electrical signal and outputs a detected digital signal. The skew addition unit adds to the detected digital signal an additional skew amount whose absolute value is equal to, whose sign is opposite to a skew amount of a difference in propagation delay in each lane connected to each output channel of the 90-degree hybrid circuit. The FFT operation unit performs a fast Fourier transform on the output from the skew addition unit.
    Type: Grant
    Filed: December 16, 2011
    Date of Patent: June 20, 2017
    Assignee: NEC CORPORATION
    Inventors: Kiyoshi Fukuchi, Junichi Abe, Wakako Yasuda
  • Patent number: 9625505
    Abstract: A line frequency detector receives an input signal representing a power source and detects a line frequency of the power source based on the input signal. The line frequency detector includes a first band pass filter having a pass band centered at an upper end of an expected frequency range of the power source and a second band pass filter having a pass band centered at a lower end of the expected frequency range. The input signal is filtered by the first and second band pass filters, generating a first characteristic signal and a second characteristic signal. The line frequency detector determines a characteristic ratio between the first characteristic signal and the second characteristic signal, and maps the characteristic ratio to the line frequency of the power source.
    Type: Grant
    Filed: February 24, 2014
    Date of Patent: April 18, 2017
    Assignee: Dialog Semiconductor Inc.
    Inventor: John W. Kesterson
  • Patent number: 9602116
    Abstract: In an example, the present invention provides an analog to digital converter device for a high speed data transmission from 1 GS-s to 100 GS-s, although there can be other variations. In an example, the device has an input receiver device coupled to a transimpedance amplifier. In an example, the transimpedance amplifier is coupled to an input stream of data at 10 GHz to 100 GHz, or other variations.
    Type: Grant
    Filed: January 7, 2016
    Date of Patent: March 21, 2017
    Assignee: INPHI CORPORATION
    Inventors: Michael Le, James Gorecki, Jamal Riani, Jorge Pernillo, Amber Tan, Karthik Gopalakrishnan, Belal Helal, Chang-Feng Loi, Irene Quek, Guojun Ren
  • Patent number: 9578074
    Abstract: Techniques for adaptive content transmission are described herein. During transmission of a content item, a network connection may be monitored to collect data corresponding to one or more network conditions associated with the transmission of the content item. Such network conditions may include, for example, network throughput, available network bandwidth, network latency and others. The collected data may be used to dynamically adjust one or more transmission attributes in connection with the transmitted content item. The one or more transmission attributes may be determined for adjustment at any desired transmission interval.
    Type: Grant
    Filed: November 11, 2013
    Date of Patent: February 21, 2017
    Assignee: Amazon Technologies, Inc.
    Inventors: Mark Kalman, Scott Wright Heath, Gerard Joseph Heinz, II, Keith Emery Belovay, Vinod Murli Mamtani, Bin Wang
  • Patent number: 9549008
    Abstract: Techniques for adaptive content transmission are described herein. During transmission of a content item, a network connection may be monitored to collect data corresponding to one or more network conditions associated with the transmission of the content item. Such network conditions may include, for example, network throughput, available network bandwidth, network latency and others. The collected data may be used to dynamically adjust one or more transmission attributes in connection with the transmitted content item. The one or more transmission attributes may be determined for adjustment at any desired transmission interval.
    Type: Grant
    Filed: November 11, 2013
    Date of Patent: January 17, 2017
    Assignee: Amazon Technologies, Inc.
    Inventors: Mark Kalman, Scott Wright Heath, Gerard Joseph Heinz, II, Keith Emery Belovay, Vinod Murli Mamtani, Bin Wang
  • Patent number: 9252559
    Abstract: An optical-fiber filter system to narrow a linewidth and to reduce noise fluctuations of an optical beam is provided. The optical-fiber filter system includes an optical fiber having a first end-face and an opposing second end-face, the first end-face and the second end-face setting a fiber length; a fiber Bragg grating having a first reflectivity positioned at the first end-face; and a reflector having a second reflectivity positioned at the second end-face. When the optical beam at a first frequency is coupled from a laser into one of the first end-face or the second end-face, a resonant cavity is established at the first frequency between the fiber Bragg grating and the reflector while Brillouin scattered light shifted from the first frequency within the optical fiber is transmitted through the fiber Bragg grating.
    Type: Grant
    Filed: July 10, 2012
    Date of Patent: February 2, 2016
    Assignee: Honeywell International Inc.
    Inventors: Chellappan Narayanan, Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu
  • Patent number: 9094122
    Abstract: A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments.
    Type: Grant
    Filed: January 23, 2013
    Date of Patent: July 28, 2015
    Assignee: CIENA CORPORATION
    Inventors: Kim B. Roberts, Han Sun
  • Patent number: 9042737
    Abstract: In the present invention, wasted power consumption caused when a clock and data recovery unit in an optical network unit in a PON system is activated from a power-saving state is reduced and rapid, secure communication is performed. A clock and data recovery unit includes a phase-locked loop that can be set to normal mode or power-saving mode and that includes a voltage-controlled oscillator and recovers a clock signal and a data signal from input signals. The clock and data recovery unit includes a reference clock multiplier circuit that multiplies a reference clock signal and outputs the multiplied reference clock signal; and a frequency training loop that includes the same voltage-controlled oscillator and performs synchronous oscillation training by the voltage-controlled oscillator using the reference clock multiplier circuit before the phase-locked loop transitions from power-saving mode to normal mode.
    Type: Grant
    Filed: February 21, 2012
    Date of Patent: May 26, 2015
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventor: Naruto Tanaka
  • Patent number: 9025965
    Abstract: Disclosed are a phase locked loop (PLL) of a digital scheme and a method thereof. More specifically, disclosed are a digital phase locked loop having a time-to-digital converter (TDC), a digital loop filter (DLF), and a digitally controlled oscillator (DCO), and that is designed to have a constant jitter characteristic at all times even though an operating condition of a circuit varies according to a process, voltage, temperature (PVT) change, and a method thereof.
    Type: Grant
    Filed: December 22, 2011
    Date of Patent: May 5, 2015
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Seung Woo Lee, Kwang Chun Choi, Woo Young Choi, Bhum Cheol Lee
  • Patent number: 9020086
    Abstract: A clock data recovery circuit module including a clock recovery circuit, a frequency comparison circuit and a signal detecting circuit is provided. The clock recovery circuit is configured to output a data recovery stream and a data recovery clock based on an input signal and a clock signal. The frequency comparison circuit is coupled to the clock recovery circuit. The frequency comparison circuit is configured to compare a frequency difference between the data recovery clock and the clock signal to adjust the frequency of the clock signal based on a comparison result. The signal detecting circuit is coupled to the frequency comparison circuit. The signal detecting circuit is configured to receive and detect the input signal, and the signal detecting circuit determines whether to enable the frequency comparison circuit according to the detection result. Furthermore, a method for generating a data recovery clock is also provided.
    Type: Grant
    Filed: March 28, 2013
    Date of Patent: April 28, 2015
    Assignee: Phison Electronics Corp.
    Inventors: Chih-Ming Chen, An-Chung Chen
  • Patent number: 9020341
    Abstract: An optical transmission system includes at least a first optical link to transmit a first data signal as a part of a multi-lane signal and a second optical link to transmit a second data signal as another part of the multi-lane signal; on the transmission side, a reference clock is constantly applied to the first data signal of the first optical link, and a delay clock is applied to the second data signal responsive to a control signal on the second optical link; on the receiving side, the phase of a first clock signal detected from the first data signal received on the first optical link and the phase of a second clock signal detected from the second data signal received on the second optical link are compared, and the control signal is detected from the comparison result.
    Type: Grant
    Filed: January 4, 2013
    Date of Patent: April 28, 2015
    Assignee: Fujitsu Limited
    Inventor: Tsuyoshi Yamamoto
  • Publication number: 20150110501
    Abstract: An optical modulator device directly-coupled to a driver circuit device. The optical modulator device can include a transmission line electrically coupled to an internal VDD, a first electrode electrically coupled to the transmission line, a second electrode electrically coupled to the first electrode and the transmission line. A wave guide can be operably coupled to the first and second electrodes, and a driver circuit device can be directly coupled to the transmission line and the first and second electrodes. This optical modulator and the driver circuit device can be configured without back termination.
    Type: Application
    Filed: December 26, 2014
    Publication date: April 23, 2015
    Inventor: Carl POBANZ
  • Patent number: 9002212
    Abstract: Provided is an optical line terminator (OLT) to recover packet data and a clock from an optical signal including a silent interval. The OLT may receive packet data and a clock from at least one optical network unit (ONU). Even in a silent interval in which the at least one ONU does not transmit packet data, the OLT may successfully recover the clock.
    Type: Grant
    Filed: August 19, 2011
    Date of Patent: April 7, 2015
    Assignee: Intellectual Discovery Co., Ltd.
    Inventors: Mun Seob Lee, Dong Soo Lee, Geun Yong Kim, Hark Yoo, Young Suk Lee, Sung Chang Kim, Jai Sang Koh, Jong Deog Kim
  • Patent number: 8989593
    Abstract: Consistent with an aspect of the present disclosure, an optical signal carrying data or information is supplied to photodetector circuitry that generates a corresponding analog signal. The analog signal may be amplified or otherwise processed and supplied to analog-to-digital conversion (ADC) circuitry, which samples the analog signal to provide a plurality of digital signals or samples. The timing of such sampling is in accordance with a clock signal supplied to the ADC circuitry. A phase detector is provided that detects and adjust the clock signal to have a desired phase based on frequency domain data that is output from a Fast Fourier transform (FFT) circuit that receives the digital samples. Preferably, the phase detector circuit is configured such that it need not receive all the frequency domain data output from the FFT at any given time in order to determine the clock phase.
    Type: Grant
    Filed: December 6, 2010
    Date of Patent: March 24, 2015
    Assignee: Infinera Corporation
    Inventors: Han Henry Sun, Kuang-Tsan Wu
  • Patent number: 8971718
    Abstract: A clock and data recovery (CDR) circuit, a method of recovering a clock and data from a received raw data stream and a BI-PON optical network transceiver (ONT) receiver front-end incorporating the CDR circuit. In one embodiment, the CDR circuit includes: (1) a line rate CDR circuit having a voltage controlled oscillator, the line rate CDR circuit configured to recover a raw data stream at a receiving line rate, (2) a fixed-rate down-sampler coupled to the line rate CDR circuit and configured to down-sample the raw data stream based on a fixed-rate and (3) a variable-rate down-sampler coupled to the fixed-rate down-sampler and configured further to down-sample the raw data sample based on a variable-rate.
    Type: Grant
    Filed: June 1, 2012
    Date of Patent: March 3, 2015
    Assignee: Alcatel Lucent
    Inventors: Hungkei Chow, Dusan Suvakovic, Christophe Van Praet, Guy Torfs, Xin Yin, Zhisheng Li
  • Patent number: 8971703
    Abstract: A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path.
    Type: Grant
    Filed: February 1, 2012
    Date of Patent: March 3, 2015
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Etsushi Yamazaki, Takayuki Kobayashi, Masahito Tomizawa, Riichi Kudo, Koichi Ishihara, Tadao Nakagawa, Mitsuteru Ishikawa
  • Patent number: 8971701
    Abstract: A universal optical receiver may include an optical channel monitor configured to acquire spectral data for an optical signal on at least one selected optical channel, a tunable local oscillator configured to be tuned to a center frequency of the optical signal on the at least one selected optical channel, a storage device configured to store data associated with the optical signal responsive to acquisition of the spectral data and tuning of the tunable local oscillator, and processing circuitry configured to execute an algorithm that employs a plurality of binary distinctions based on physical characteristics of the optical signal and employs at least one calculation of figure of merit associated with a series of parameter values of the optical signal to identify a format of the optical signal.
    Type: Grant
    Filed: September 4, 2012
    Date of Patent: March 3, 2015
    Assignee: The Johns Hopkins University
    Inventors: Eric J. Adles, Michael L. Dennis, Raymond M. Sova, Joseph E. Sluz, Michael G. Taylor, Curtis R. Menyuk, John W. Zweck
  • Patent number: 8964722
    Abstract: A method for synchronizing a plurality of clocks arranged within a plurality of nodes of a packet-switching network comprises comparing parameters that relate to the plurality of clocks in order to determine master-slave relationships between the plurality of clocks, and exchanging time-stamped messages over the packet-switching network each time between a master clock and an associated slave clock to make the associated slave clock subservient to the master clock. A node of the packet-switching network comprises a frequency source controlled by a synchronous physical layer technology. The parameters that relate to a clock of the node comprise a parameter that relates to the frequency source to determine the master slave relationships based on one property of the frequency source.
    Type: Grant
    Filed: December 7, 2009
    Date of Patent: February 24, 2015
    Assignee: Alcatel Lucant
    Inventors: Michel Le Pallec, Dinh Thai Bui
  • Patent number: 8942561
    Abstract: One embodiment provides an Ethernet Passive Optical Network (EPON) system for clock transport. The system includes a reference clock configured to generate a frequency-reference signal, an optical line terminal (OLT) coupled to the reference clock, and an optical network unit (ONU). The OLT includes a clock generator configured to generate an OLT clock based on at least the frequency-reference signal. The ONU includes an optical transceiver, a clock recovery module, and a clock output mechanism. The optical transceiver is configured to transmit optical signals to and receive optical signals from the OLT. The clock-recovery module is configured to recover the frequency-reference signal from the received optical signals. The clock output mechanism is configured to output the recovered frequency-reference signal, thus facilitating transport of the frequency-reference signal over the EPON.
    Type: Grant
    Filed: October 6, 2009
    Date of Patent: January 27, 2015
    Assignee: Broadcom Corporation
    Inventors: Edward W. Boyd, Hidehiko Shibuya
  • Publication number: 20150010312
    Abstract: Apparatuses and methods for an optical data interface with electrical forwarded clock are provided. One example optical data interface (220, 320) can include a transmitter (224, 324) having a data input (232, 332) and a clock input (242, 342), and a receiver (226, 326) having a data output (271, 339) and a forwarded clock signal path (254, 376). An optical communication path (248, 348) is coupled between the data input (232, 332) and the data output (271, 339) and configured to communicate a data signal. An electrical communication path (236, 336) is coupled between the clock input (242, 342) and the forwarded clock signal path (254, 376). The electrical communication path (236, 336) is arranged to forward a clock signal used by the receiver (226, 326) as a reference for the optical data signal.
    Type: Application
    Filed: April 24, 2012
    Publication date: January 8, 2015
    Inventors: Daniel A. Berkram, Dacheng Zhou
  • Publication number: 20150003842
    Abstract: The present invention discloses a clock recovery circuit, an optical receiver, and a passive optical network device. In the clock recovery circuit provided by the embodiment of the present invention, a first signal indicating whether a data loss abnormality occurs in initial serial data is introduced at a side of a phase detector, and a phase adjustment control signal is output to a phase adjustor according to a state of the first signal; and the phase adjustor performs different types of phase adjustment according to a state of the initial serial data, so that a data sampler can recover an accurate clock when the initial serial data is normal and can implement smooth switching of output clock information in special cases such as initial serial data clock loss or recovery, and no great abrupt phase change occurs, thereby ensuring stable and reliable working of a system.
    Type: Application
    Filed: May 22, 2014
    Publication date: January 1, 2015
    Applicant: Huawei Technologies Co., Ltd.
    Inventor: Deqiang Chen
  • Patent number: 8917194
    Abstract: Methods and apparatus intelligently switching between line coding schemes based on context. In one exemplary embodiment, an High Definition Multimedia Interface (HDMI) system is configured to transmit control and video data according to an 8B/10B line coding protocol, and data island data according to TERC4 (TMDS (Transition Minimized Differential Signaling) Error Reduction Coding 4-bit). Various elements of the disclosed HDMI devices are configured to determine when a context switch occurs, and thereafter seamlessly transition between the appropriate line code protocol.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: December 23, 2014
    Assignee: Apple, Inc.
    Inventor: Colin Whitby-Strevens
  • Patent number: 8913895
    Abstract: In a method for controlling timing of a transmission signal from a network termination device having a receiver and a transmitter, a signal is received at the receiver of the network termination device, the signal having been transmitted in accordance with a predetermined bit rate. A core clock signal for the receiver is determined based on the predetermined bit rate at which the signal was transmitted, and the core clock signal is communicated to the transmitter of the network termination device. At the transmitter of the network termination device, a phase adjusted clock signal is generated, and the phase adjusted clock signal is set as the transmitter clock signal. The transmitter clock signal is offset from the core clock signal, and the transmission signal is transmitted from the transmitter of the network termination device based on the transmitter clock signal.
    Type: Grant
    Filed: June 14, 2012
    Date of Patent: December 16, 2014
    Assignee: Marvell International Ltd.
    Inventors: John M. Chiang, Cesar A. Johnston
  • Patent number: 8891960
    Abstract: A method of communicating data between a network device and a data network to which the device is connected via an optical fiber data link in which the device is connected to the optical fiber data link and the connection is monitored to detect data communication at a first standard. If data communication is detected at the first standard, data communication is established using the first standard. If not, the connection is monitored at the second standard. If data communication is detected at the second standard, data communication is established using the second standard.
    Type: Grant
    Filed: October 10, 2008
    Date of Patent: November 18, 2014
    Assignee: PacketFront Systems AB
    Inventor: Charles Foster
  • Patent number: 8891973
    Abstract: A receiving unit using a voltage-controlled oscillator is allowed to compensate for the frequency characteristics of the voltage-controlled oscillator resulting from temperature change, without adding a capacitive element for temperature compensation. A receiving unit and an optical line terminal include a clock and data recovery circuit that extracts a clock signal and a data signal from a received signal, and have: a calibrator that calibrates an oscillation frequency of a voltage-controlled oscillator included in the clock and data recovery circuit; and a managing unit having a function of managing a schedule for receiving signals, the managing unit selecting a time where a duration of a certain state meets a time required for calibration by the calibrator to thereby output a reset signal (calibration instruction signal) to the calibrator, the state having no received signal (upstream signal) from which a clock signal and a data signal are to be extracted.
    Type: Grant
    Filed: July 6, 2010
    Date of Patent: November 18, 2014
    Assignees: Sumitomo Electric Industries, Ltd., Ensphere Solutions, Inc.
    Inventor: Naruto Tanaka
  • Patent number: 8873689
    Abstract: A phase interpolator for a CDR circuit produces an output clock having level transitions between the level transitions on two input clocks. The input clocks drive cross-coupled differential amplifiers with an output that can be varied in phase by variable current throttling or steering, according to an input control value. The differential amplifiers produce an output signal with a transition spanning a time between the start of a transition on the leading input clock up to the end of the transition on the lagging input clock. The output clock is linear so long as the transitions on the two input clocks overlap. Active integrators each having an amplifier with a series resistance and capacitive feedback path are coupled to each input to the cross-coupled differential amplifiers, which enhances overlap of the input clock rise times and improves the linearity of the interpolated output signal.
    Type: Grant
    Filed: August 2, 2012
    Date of Patent: October 28, 2014
    Assignee: Taiwan Semiconductor Manufacturing Co., Ltd.
    Inventors: Tao Wen Chung, Chan-Hong Chern, Ming-Chieh Huang, Chih-Chang Lin, Yuwen Swei
  • Patent number: 8855496
    Abstract: A method and apparatus conduct an optical clock rate negotiation to support asymmetric clock rates for visible light communication (VLC) in a VLC device. A first frame that includes a receiver clock rate supported by a first VLC device is transmitted at a predetermined clock rate. A response frame that includes a receiver clock rate supported by a second VLC device is received from the second VLC device. A transmission clock rate of the first VLC device is selected based on the response frame from the second VLC device. Subsequent frames for data communication are transmitted to the second VLC device at the selected transmission clock rate of the first device. Alternatively, when conducting optical clock negotiation in the PHY layer, multiple clock rates are supported within a single frame.
    Type: Grant
    Filed: December 21, 2010
    Date of Patent: October 7, 2014
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Sridhar Rajagopal, Eran Pisek, Farooq Khan, Ying Li
  • Patent number: 8842994
    Abstract: A method and system of distributing clock synchronization information within an optical communications network including a plurality of network elements, in which a first network element receives an ingress clock synchronization message, the ingress clock synchronization message including a clock synchronization message identifier and a correction field. The first network element inserts the clock synchronization message identifier into an optical channel frame overhead and inserts the ingress clock synchronization message into an optical channel frame payload. The first network element transmits the optical channel frame overhead and the optical channel frame payload to a second network element, and determines a transit time of the clock synchronization message identifier across each of the network elements. The second network element updates the correction field of the ingress clock synchronization message with said transit times to form an egress clock synchronization message.
    Type: Grant
    Filed: August 22, 2012
    Date of Patent: September 23, 2014
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventors: Sergio Lanzone, Orazio Toscano, Stefano Ruffini
  • Publication number: 20140270802
    Abstract: A quantum mechanical synchronization system for a classical distributed computing system. Einstein-Podolsky-Rosen links are established providing entangled photons to provide the quantum synchronization. In one embodiment, the system includes a laser oscillator pump, a spontaneous parametric down-conversion element coupled to the laser oscillator pump, the spontaneous parametric down-conversion element having a first optical output and a second optical output, a first photodetector coupled to the first optical output, a first clock coupled to the first photodetector, a second photodetector coupled to the second optical output by an optical link, and a second clock coupled to the second photodetector.
    Type: Application
    Filed: May 21, 2013
    Publication date: September 18, 2014
    Applicant: RAYTHEON COMPANY
    Inventors: Steven J. Silverman, Nils Paz, John R. Harmon
  • Publication number: 20140270805
    Abstract: A clock at a first network element that is connected to a second network element over an optical fiber link is aligned in time/phase using packet protocols such as PTP. The invention discloses how to correct the asymmetry error inherent in traditional packet-based time-transfer methods.
    Type: Application
    Filed: March 13, 2013
    Publication date: September 18, 2014
    Inventor: Sanjay Mani
  • Patent number: 8831435
    Abstract: A system and method for synchronizing a clock signal. Data traffic is received through a first channel of a fiber optic. A clock signal is received through a second channel of the fiber optic. A clock at a node is disciplined with the clock signal. The clock signal is sent from the clock to one or more interfaces within a node.
    Type: Grant
    Filed: October 13, 2008
    Date of Patent: September 9, 2014
    Assignee: CenturyLink Intellectual Property LLC
    Inventor: Michael Bugenhagen
  • Patent number: 8811555
    Abstract: An integrated circuit (“IC”) may include clock and data recovery (“CDR”) circuitry for recovering data information from an input serial data signal. The CDR circuitry may include a reference clock loop and a data loop. A retimed (recovered) data signal output by the CDR circuitry is monitored by other control circuitry on the IC for a communication change request contained in that signal. Responsive to such a request, the control circuitry can change an operating parameter of the CDR circuitry (e.g., a frequency division factor used in either of the above-mentioned loops).
    Type: Grant
    Filed: February 4, 2010
    Date of Patent: August 19, 2014
    Assignee: Altera Corporation
    Inventors: Kazi Asaduzzaman, Tim Tri Hoang, Tin H. Lai, Shou-Po Shih, Sergey Shumarayev
  • Publication number: 20140226992
    Abstract: An object of the present invention is to provide a subscriber-side device, which can generate accurate time information and can synchronize a time with other device even if a power supply of a portion that receives a downlink signal is in an OFF state, and to provide an optical transmission system including the same. The subscriber-side device of the present invention corrects and outputs free-running time information, which is generated based on a free-running clock signal, by a time correction value generated based on a frequency deviation between a synchronization clock signal and the free-running clock signal. When the downlink signal sent from the station-side device is in a signal interruption state of being incapable of recognizing or receiving the downlink signal, the subscriber-side device corrects and outputs the free-running time information by a time correction value generated before the downlink signal turns to the signal interruption state.
    Type: Application
    Filed: December 12, 2011
    Publication date: August 14, 2014
    Applicant: Mitsubishi Electric Corporation
    Inventor: Koji Takahashi
  • Patent number: 8805201
    Abstract: A time synchronization method and a time synchronization device in a passive optical network (PON), and a PON are provided. The method includes receiving a synchronization packet sent after time synchronization of an optical line terminal (OLT) with a master clock (MC) is achieved, wherein the synchronization packet carries a timestamp TMt1i determined after the time synchronization of the OLT is achieved, adjusting a local clock according to the timestamp to achieve time synchronization of an optical network unit/optical network terminal (ONU/ONT) with the OLT, and after the time synchronization of the OLT is achieved, instructing an slave clock (SC) to perform time synchronization. A time synchronization device and a time synchronization system for implementing the method in a PON are further provided.
    Type: Grant
    Filed: July 30, 2012
    Date of Patent: August 12, 2014
    Assignee: Huawei Technologies Co., Ltd.
    Inventors: Jun Zhao, Sanzhong Li, Meng Sui
  • Patent number: 8781333
    Abstract: The invention relates to a clock recovery apparatus being configured to recover clock information from an input signal. The clock recovery apparatus comprises Fourier transforming means (201) being configured to transform the input signal into a frequency domain signal upon the basis of a Fourier transform, correlating means (215) being configured to correlate the frequency domain signal to obtain a correlation value associated with a certain frequency, and clock recovery means (217) being configured to determine whether the certain frequency corresponds to a clock frequency in order to recover the clock information.
    Type: Grant
    Filed: February 3, 2012
    Date of Patent: July 15, 2014
    Assignee: Huwei Technologies Co., Ltd.
    Inventors: Fabian Nikolaus Hauske, Chan Zhao
  • Patent number: 8774621
    Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.
    Type: Grant
    Filed: November 25, 2010
    Date of Patent: July 8, 2014
    Assignee: Mitsubishi Electric Corporation
    Inventor: Hiroaki Mukai
  • Patent number: 8761609
    Abstract: A receiver for fiber optic communications.
    Type: Grant
    Filed: November 2, 2010
    Date of Patent: June 24, 2014
    Assignee: ClariPhy Communications, Inc.
    Inventors: Oscar E. Agazzi, Diego E. Crivelli, Hugo S. Carrer, Mario R. Hueda, Martin I. del Barco, Pablo Gianni, Ariel Pola, Elvio Serrano, Alfredo Taddei, Alejandro Castrillon, Martin Serra, Ramiro Matteoda
  • Patent number: 8755695
    Abstract: A burst transmission method and a receiver resetting method and apparatus in a Passive Optical Network (PON) are provided. A burst receiver resetting method in a PON includes: receiving a preamble sequence and synchronizing data; after synchronizing the data, continuing to receive the data, and matching a Burst Terminator (BT); and resetting a receiver after successfully matching the BT. Meanwhile, an apparatus for implementing the method and a corresponding burst data transmission method are provided. By using the burst receiver resetting method and apparatus in the PON and the corresponding burst transmission method at an Optical Network Unit (ONU) burst transmission end, a Reach Extender (RE) does not need to unpack upstream burst bandwidth allocation information carried in downstream data.
    Type: Grant
    Filed: September 25, 2013
    Date of Patent: June 17, 2014
    Assignee: Huawei Technologies Co., Ltd.
    Inventors: Jing Li, Dongning Feng, Dongyu Geng, Frank Effenberger
  • Patent number: 8755687
    Abstract: A communication system comprising an emitter of weak light pulses, a detector which is capable of detecting single photons, and a source of a clock signal, wherein said emitter and detector are synchronized using said clock signal, the system further comprising a frequency divider for said clock signal to produce a reduced frequency clock signal and a clock regenerator for regenerating the original clock signal from the reduced frequency clock signal, the system further comprising a communication channel configured to communicate the clock signal between the emitter and detector, the clock signal being reduced before sending through said channel and reconstructed after it has exited said channel.
    Type: Grant
    Filed: May 21, 2012
    Date of Patent: June 17, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: James Dynes, Zhiliang Yuan, Andrew W. Sharpe, Andrew James Shields
  • Patent number: 8737833
    Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.
    Type: Grant
    Filed: November 25, 2010
    Date of Patent: May 27, 2014
    Assignee: Mitsubishi Electric Corporation
    Inventor: Hiroaki Mukai
  • Patent number: 8731198
    Abstract: In general, techniques are described for protecting optical networks from consecutive identical digit (CID) errors. An optical network device comprising a control unit and an interface may implement the techniques described in this disclosure. The control unit determines whether a data packet will result in a CID error prior to encapsulating at least a portion of the data packet to form a passive optical network (PON) frame and then, in response to the determination that the data packet will result in the CID error, modifies the data packet to form a modified data packet so that the modified data packet will not result in the CID error. The control unit encapsulates the modified data packet to form a PON frame. The control unit applies a scrambling polynomial to the PON frame to form a scrambled PON frame. The interface transmits the scrambled PON frame.
    Type: Grant
    Filed: February 2, 2012
    Date of Patent: May 20, 2014
    Assignee: Calix, Inc.
    Inventors: Christopher T. Bernard, Charles J. Eddleston
  • Patent number: 8724995
    Abstract: Provided is a passive optical network system for operating a mixture of PONs with differing transmission speeds and is capable of reducing power consumption on the basis of the amount of signals being transmitted. The master station of the passive optical network system, which determines the amount and timing of signals sent thereto by each of a plurality of slave stations on the basis of the requests of the plurality of slave stations and receives signals from the plurality of slave stations via an optical fiber network, is equipped with a control unit that determines in each set cycle the amount, transmission timing, and transmission speed of the signals that each slave station is permitted to transmit to said master station on the basis of the amount of signals that each of the plurality of slave stations has requested to transmit, and that notifies such to each slave station.
    Type: Grant
    Filed: November 9, 2009
    Date of Patent: May 13, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Tohru Kazawa, Akihiko Tsuchiya, Norihiro Sakamoto, Yusuke Yajima, Masatoshi Takihiro
  • Patent number: RE45193
    Abstract: An apparatus and method for extracting an optical clock signal are provided. The apparatus includes a first reflection filter selecting and reflecting only a first frequency component in an input optical signal; a first Fabry-Perot laser diode matching the first frequency component reflected by the first reflection filter with a predetermined output mode and outputting the first frequency component in the predetermined output mode; a second Fabry-Perot laser diode selecting a second frequency component in an input optical signal that has not been reflected but has been transmitted by the first reflection filter, matching the second frequency component with a predetermined output mode, and outputting the second frequency component in the predetermined output mode; and a photodetector receiving the first frequency component from the first Fabry-Perot laser diode and the second frequency component from the second Fabry-Perot laser diode and beating them to extract a clock signal.
    Type: Grant
    Filed: August 18, 2011
    Date of Patent: October 14, 2014
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Jaemyoung Lee, Je Soo Ko