Equalizers Patents (Class 375/229)
  • Patent number: 9071477
    Abstract: A method and associated processing module for an interconnection system, providing a pre-tap tuning directing and a post-tap tuning directing. The interconnection system includes a transmitter filter and a receiver equalizer; the transmitter filter performs filtering according to a pre-tap and a post-tap, and the receiver equalizer performs equalization according to an equalizer tap. The pre-tap tuning directing includes: forming an indicative pattern with a plurality of data samples and a transition sample from an equalized signal, comparing if the indicative pattern matches predetermined pattern(s), and accordingly directing whether the pre-tap is incremented/decremented. The post-tap tuning directing selects whether the post-tap is incremented/decremented according to a positive/negative sign of the equalizer tap.
    Type: Grant
    Filed: October 9, 2013
    Date of Patent: June 30, 2015
    Assignees: GLOBAL UNICHIP CORPORATION, TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD.
    Inventors: Wen-Juh Kang, Chen-Yang Pan, Jung-Chi Huang
  • Patent number: 9054412
    Abstract: Disclosed are various embodiments providing processing circuitry for selecting a channel estimation filter from a plurality of channel estimation filters based on a channel quality metric, the selected channel estimation filter being associated with an intrinsic coefficient. The processing circuitry may then determine a scaled coefficient, the scale coefficient being based on scaling the intrinsic coefficient with respect to a bit size constraint, the bit size constraint being determined by a bit length of a multiplication circuitry operand. Moreover, the processing circuitry may generate an output based on the scaled coefficient and an input signal.
    Type: Grant
    Filed: June 26, 2012
    Date of Patent: June 9, 2015
    Assignee: Broadcom Corporation
    Inventors: Hari Moorthy, Wei Luo
  • Patent number: 9054907
    Abstract: A multi-phase partial response equalizer circuit includes sampler circuits that sample an input signal to generate sampled signals in response to sampling clock signals having different phases. A first multiplexer circuit selects one of the sampled signals as a first sampled bit to represent the input signal. A first storage circuit coupled to an output of the first multiplexer circuit stores the first sampled bit in response to a first clock signal. A second multiplexer circuit selects one of the sampled signals as a second sampled bit to represent the input signal based on the first sampled bit. A second storage circuit stores a sampled bit selected from the sampled signals in response to a second clock signal. A time period between the second storage circuit storing a sampled bit and the first storage circuit storing the first sampled bit is substantially greater than a unit interval in the input signal.
    Type: Grant
    Filed: January 6, 2014
    Date of Patent: June 9, 2015
    Assignee: Rambus Inc.
    Inventor: Aliazam Abbasfar
  • Patent number: 9049068
    Abstract: An equalizer includes a first module and a second module. The first module is configured to receive a differential input signal, perform low pass filtering on the differential input signal to generate a low pass differential input signal, and perform high pass filtering on the differential input signal to generate a high pass differential input signal. The second module is configured to receive the low pass differential input signal and the high pass differential input signal and generate a differential output signal based on a combination of the low pass differential input signal and the high pass differential input signal.
    Type: Grant
    Filed: August 14, 2013
    Date of Patent: June 2, 2015
    Assignee: MARVELL INTERNATIONAL LTD.
    Inventor: Sasan Cyrusian
  • Patent number: 9048957
    Abstract: A signal processing circuit includes: a first compensator configured to compensate for waveform distortion corresponding to chromatic dispersion of a received optical signal by using digital electrical signals obtained by sampling analog electrical signals by using a sampling signal, the analog electrical signals being obtained by opto-electric conversion of multiple optical signals that include an intensity of the received optical signal and phase information thereon; and a chromatic dispersion compensation controller configured to control a compensation value for the chromatic dispersion in the first compensation from the digital electrical signals in which the chromatic dispersion has been compensated for on the basis of a detected phase offset between the sampling signal and a modulation frequency of the received optical signal.
    Type: Grant
    Filed: June 24, 2010
    Date of Patent: June 2, 2015
    Assignee: FUJITSU LIMITED
    Inventor: Hisao Nakashima
  • Patent number: 9042468
    Abstract: A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over the communication channel. The method further includes determining a sequence of second coefficient estimates of the communication channel based on a decomposition of the first coefficient estimates in a dictionary matrix and a sparse vector of the second coefficient estimates, the dictionary matrix including filter characteristics of at least one known transceiver filter arranged in the communication channel.
    Type: Grant
    Filed: June 27, 2013
    Date of Patent: May 26, 2015
    Assignee: Intel Mobile Communications GmbH
    Inventors: Oana-Elena Barbu, Guillaume Damien Andre Monghal, Christian Rom, Bernhard H. Fleury, Niels Lovmand Pedersen, Carles Navarro Manchon
  • Patent number: 9042488
    Abstract: A phase offset compensator for compensating a phase offset is provided. The phase offset includes a first phase sub-offset and a second phase sub-offset. The phase offset compensator includes a feedback loop comprising a first loop filter, the feedback loop being configured to compensate the first phase sub-offset of the phase offset, and a feed forward loop comprising a second loop filter, the feed forward loop being configured to compensate the second phase sub-offset of the phase offset.
    Type: Grant
    Filed: August 24, 2012
    Date of Patent: May 26, 2015
    Assignee: Huawei Technologies Co., Ltd.
    Inventor: Changsong Xie
  • Patent number: 9042497
    Abstract: A system that incorporates the subject disclosure may include, for example, a process that includes adjusting a filter in electrical communication between an input terminal and a demodulator. The filter is applied to an information bearing signal, e.g., to mitigate interference, received at the input terminal, resulting in a filtered signal. An error signal is received, indicative of errors detected within information obtained by demodulation of a modulated carrier of the filtered signal. A modified filter state is determined in response to the error signal and the filter is adjusted according to the modified filter state, e.g., to improve mitigation of the interference. Other embodiments are disclosed.
    Type: Grant
    Filed: August 9, 2013
    Date of Patent: May 26, 2015
    Assignee: ISCO International, LLC
    Inventors: Amr Abdelmonem, Mikhail Galeev, Sean S. Cordone, Howard Wong
  • Patent number: 9042429
    Abstract: A radio receiver apparatus includes a serving cell detector configured to generate a detected serving cell signal based on a serving cell detector input signal. The radio receiver apparatus further includes a first interfering cell detector configured to generate a detected first interfering cell signal based on a first interfering cell detector input signal and a first interfering cell synthesizer configured to generate synthesized first interfering cell signal based on the detected first interfering cell signal. A serving cell interference removing unit is configured to remove the synthesized first interfering cell signal from a serving cell signal to generate the serving cell detector input signal.
    Type: Grant
    Filed: June 27, 2013
    Date of Patent: May 26, 2015
    Assignee: Intel Mobile Communications GmbH
    Inventors: Christian Faber, Andreas Senst, Manfred Zimmermann, Lothar Winkler
  • Patent number: 9042434
    Abstract: Method and filter for filtering a signal, in which the signal is applied to a delay line having a plurality of taps. Respective weighting coefficients of a windowing function are applied to outputs from the plurality of taps to thereby generate a plurality of weighted outputs. The method comprises repeatedly selecting, for output, whichever of the weighted outputs has the highest value.
    Type: Grant
    Filed: April 4, 2012
    Date of Patent: May 26, 2015
    Assignee: Intel Corporation
    Inventor: Christopher Brian Smart
  • Patent number: 9042435
    Abstract: A transmitter and/or receiver for performing frequency domain equalization is provided. A transmitter includes a pilot position determination unit for determining positions for inserting pilots in a frequency domain based on frequency spectrums of data, and a pilot insertion unit for inserting the pilots between the frequency spectrums of the data according to the determined positions for inserting the pilots.
    Type: Grant
    Filed: March 25, 2013
    Date of Patent: May 26, 2015
    Assignees: Samsung Electronics Co., Ltd., Postech Academy-Industry Foundation
    Inventors: Dong Sik Kim, Ui Kun Kwon, Gi Hong Im, Chang Yong Shin
  • Patent number: 9042436
    Abstract: An apparatus is disclosed to compensate for non-linear effects resulting from the transmitter, the receiver, and/or the communication channel in a communication system. A receiver of the communication system contains an image cancellation module that compensates for images generated during the modulation and/or demodulation process. The image cancellation module includes a fine carrier correction loop to correct for frequency offsets between the transmitter and receiver. The image cancellation module includes a coarse acquisition mode and a decision directed mode. The decision directed mode allows for a larger signal-to-noise ratio for the receiver when compared against the coarse acquisition mode.
    Type: Grant
    Filed: March 26, 2013
    Date of Patent: May 26, 2015
    Assignee: Broadcom Corporation
    Inventors: Bruce J. Currivan, Loke Tan, Thomas Kolze, Hanli Zou, Lin He
  • Patent number: 9036724
    Abstract: A data signal correction circuit includes a channel characteristic calculator unit configured to calculate a channel characteristic estimate value of a received data signal on the basis of a pilot signal, a path detector unit configured to determine a delay quantity of multipath propagation of the received data signal on the basis of the calculated channel characteristic estimate value, and an adaptive filter configured to receive the delay quantity and the channel characteristic estimate value as input items, adjust an input interval of the channel characteristic estimate value along a carrier frequency axis in accordance with the delay quantity, and perform adaptive equalization on the channel characteristic estimate value inputted to the adaptive filter at the adjusted input interval.
    Type: Grant
    Filed: February 12, 2014
    Date of Patent: May 19, 2015
    Assignees: FUJITSU SEMICONDUCTOR LIMITED, FUJITSU LIMITED
    Inventors: Hiroaki Takagi, Masataka Umeda, Naoto Adachi
  • Patent number: 9031124
    Abstract: A method of generating a hypothesis and estimating a CFO includes receiving a signal including a set of radio frames, dividing each received radio frame of the set into a set of received sub-sequences, dividing, each of reference radio frames from a reference signal stored in the receiver into a set of reference sub-sequences, correlating the set of received sub-sequences with the set of reference sub-sequences to obtain a set of correlation values, generating, a first value set and a second value set of hypothesis based on the correlation values, generating a first and a second hypothesis based on the first value and the second value set, and averaging the first and the second hypothesis to obtain an averaged hypothesis, performing a DFT on the averaged hypothesis to obtain a DFT sequence, determining a peak position of the DFT sequence, and estimating the CFO based on the peak position.
    Type: Grant
    Filed: February 21, 2014
    Date of Patent: May 12, 2015
    Inventors: Shrinivas Bhat, Niranjan Mylarappa Gowda
  • Patent number: 9031123
    Abstract: A receiver performs interference mitigation under blind or semi-blind conditions using diversity present in the signal of interest or in the interferer. A first path interference mitigation procedure extracts training information from received signals, performs interference mitigation on the training information and estimates the channel. The second path interference mitigation procedure uses data extracted from the received signal and the channel estimate to perform interference mitigation. Each interference mitigation process can take the form of a lossy compression followed by decompression.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: May 12, 2015
    Assignee: Acorn Technologies, Inc.
    Inventor: Fernando Lopez de Victoria
  • Patent number: 9025651
    Abstract: Methods, systems, and devices are described for equalizing data from an optical signal. Samples are filtered with at least one filter to compensate for polarization mode dispersion in an optical path. The filtered samples may be used to determine errors based on a difference between a radius of a recovered symbol and a target radius. A parameter may be assigned to one or more of the errors and properties of the at least one filter may be updated based on the assigned parameters. The parameter may be assigned from a small set of parameters based on at least one threshold value. Outputs generated from the filtered samples may also be assigned a parameter from a different set of parameters. The parameter assigned to the output may be used to update the particular set of taps of the at least one filter from which the output was generated.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: May 5, 2015
    Assignee: ViaSat, Inc.
    Inventors: Sameep Dave, Fan Mo
  • Patent number: 9025678
    Abstract: A signaling system is described. The signaling system comprises a transmit device, a receive device including a partial response receive circuit, and a signaling path coupling the transmit device and the receive device. The receive device observes an equalized signal from the signaling path, and includes circuitry to use feedback from the most recent previously resolved symbol to sample a currently incoming symbol. The transmit device equalizes transmit data to transmit the equalized signal, by applying weighting based on one or more data values not associated with the most recent previously resolved symbol value.
    Type: Grant
    Filed: April 30, 2012
    Date of Patent: May 5, 2015
    Assignee: Rambus Inc.
    Inventors: Vladimir M. Stojanovic, Mark A. Horowitz, Jared L. Zerbe, Anthony Bessios, Andrew C. C. Ho, Jason C. Wei, Grace Tsang, Bruno W. Garlepp
  • Patent number: 9020024
    Abstract: A rate-adaptive equalizer automatically initializes its tap coefficients to values. During an initialization process, a linear search algorithm is performed that sweeps the tap coefficients through different combinations of tap coefficients while assessing information about an eye associated with an input signal received over a communications channel. When the eye information indicates that the eye is open, the current tap coefficients are selected as the initial tap coefficients to be used at the beginning of the main adaptation algorithm.
    Type: Grant
    Filed: October 31, 2013
    Date of Patent: April 28, 2015
    Assignee: Avego Technologies General IP (Singapore) Pte. Ltd.
    Inventors: Faouzi Chaahoub, Georgios Asmanis, Sriramkumar Sundararaman, Samir Aboulhouda
  • Patent number: 9020021
    Abstract: An apparatus for encoding data signals includes a transmitter configured to encode and transmit a data signal over a communication channel, the transmitter including a precoder; a signal shaper configured to adjust the data signal by applying an equalization setting to the data signal, the equalization setting including an amplitude and offset and transmit the adjusted data signal to the precoder; and a processing unit. The processing unit is configured to perform: receiving channel coefficients associated with the communication channel; for each of a plurality of amplitude settings and a plurality of offset settings, calculating whether a modulo amplitude level would occur at a receiver using a modulo operation; selecting the equalization setting from the plurality of amplitude settings and the plurality of offset settings based on the calculation; and transmitting a control signal specifying the equalization setting to the signal shaper.
    Type: Grant
    Filed: July 29, 2013
    Date of Patent: April 28, 2015
    Assignee: International Business Machines Corporation
    Inventors: Marcel A. Kossel, Daihyun Lim, Pradeep Thiagarajan
  • Patent number: 9020020
    Abstract: Disclosed are various embodiments for a symbol level Krylov method equalizer implemented in a wireless communications device. An HSDPA or WCDMA signal is input to the wireless communications device. A conjugate gradient method is applied to symbol-level samples of the signal until a termination condition is met. The termination condition may comprise having zero residual error, residual error below a threshold, or a specified number of iterations. Additionally, a preconditioning matrix may be applied to the inputs of the conjugate gradient method.
    Type: Grant
    Filed: November 19, 2012
    Date of Patent: April 28, 2015
    Assignee: Broadcom Corporation
    Inventor: Chun-Hsuan Kuo
  • Patent number: 9020082
    Abstract: A method includes, by a detector, receiving from a low frequency equalizer a data signal and an error signal, matching a tail portion of the data signal to a tail portion of an extended filter-pattern, and, based upon the error signal at a given location of the data signal and upon the imbalance, producing an output signal indicating whether a long-term residual intersymbol interference of the data signal in the error signal has a positive sign or a negative sign. The tail portion of the extended filter-pattern includes an imbalance between a count of each of the possible values and an unfixed sequence. The data signal includes data points with one of at least two possible values.
    Type: Grant
    Filed: September 4, 2012
    Date of Patent: April 28, 2015
    Assignee: Fujitsu Limited
    Inventor: Yasuo Hidaka
  • Patent number: 9020023
    Abstract: The present technique relates to a reception device and a reception method which can improve equalization performance. An equalization processing unit has a time domain equalization unit which equalizes a received signal in a time domain and a frequency domain equalization unit which is provided in parallel to the time domain equalization unit and which equalizes the received signal in a frequency domain, and performs control of switching between the time domain equalization unit and the frequency domain equalization unit. The present technique can be applied to, for example, equalize a signal of data transmitted by way of single carrier transmission or data transmitted by way of multicarrier transmission.
    Type: Grant
    Filed: May 15, 2012
    Date of Patent: April 28, 2015
    Assignee: Sony Corporation
    Inventors: Katsumi Takaoka, Naoki Yoshimochi, Hidetoshi Kawauchi, Ryo Hasegawa, Hirofumi Maruyama
  • Patent number: 9014250
    Abstract: A channel in a multiple carrier communication system is equalized by computing a desired spectral response, shortening the impulse response of the channel so that a significant part of an energy of the impulse response is confined to a region that is shorter than a target length and filtering the signal based on the desired spectral response. A multiple carrier communication system may include a primary impulse shortening filter that receives an output signal of an analog to digital converter and accepts coefficients. A secondary impulse shortening filter may receive the output signal of the analog to digital converter, output an output signal, and pass coefficients to the primary impulse shortening filter. A reference signal generator may output a reference signal. A comparator may compare the output signal and the reference signal and output a resulting error signal. An adaptive processor may compute coefficients for the secondary impulse shortening filter based on the error signal.
    Type: Grant
    Filed: December 28, 2012
    Date of Patent: April 21, 2015
    Assignee: Tellabs Operations, Inc.
    Inventors: Gopal Harikumar, Daniel J. Marchok, Kenneth J. Rudofski
  • Patent number: 9014313
    Abstract: Described embodiments recover timing and data information from a signal received via a communication channel. An analog-to-digital converter (ADC) operating at a baud rate of the communication channel generates an actual ADC value corresponding to each bit sample of the received signal. A fast symbol estimation module estimates, based on the actual ADC value, a bit value corresponding to each bit sample. The fast symbol estimation module operates at a digital clock rate. The estimated bit values are provided to a timing recovery module. An ADC reconstruction module, based on a first number of pre-cursor estimated bit values, an estimated cursor bit value, and a second number of post-cursor estimated bit values, generates a reconstructed ADC value corresponding to each bit sample. Based on the reconstructed ADC values, the estimated bit values, and the actual ADC values, a corrected bit value is generated for each bit sample.
    Type: Grant
    Filed: February 7, 2012
    Date of Patent: April 21, 2015
    Assignee: LSI Corporation
    Inventor: Erik V. Chmelar
  • Patent number: 9014254
    Abstract: Testing a Decision Feedback Equalizer (‘DFE’), the DFE including a summing amplifier operatively coupled to a plurality of latches and an input signal line for receiving a data signal, including: preventing a differential data signal from being received by the summing amplifier; and iteratively for each tap to be tested: setting a tap coefficient for each tap to zero; setting an output of the plurality of latches to a predetermined value; setting a tap coefficient for the tap to be tested to a full scale value; and determining whether a resultant output signal from the DFE matches a predetermined expected output signal.
    Type: Grant
    Filed: June 19, 2013
    Date of Patent: April 21, 2015
    Assignee: International Business Machines Corporation
    Inventors: Eugene R. Atwood, Matthew B. Baecher, Minhan Chen, Hayden C. Cranford, Jr., William R. Kelly, Todd M. Rasmus
  • Patent number: 9014252
    Abstract: A channel equalization scheme is provided. A linear equalizer using a continuous-time linear equalization and a decision feedback equalizer using a discrete-time decision feedback equalization are integrated together from a hybrid receiver equalizer. The continuous-time linear equalization scheme and the discrete-time decision feedback equalization scheme are blended using a joint adaptation algorithm to form an equalization scheme for inter-symbol interference cancellation in the hybrid receiver equalizer. The hybrid receiver equalizer controls crosstalk while maintaining signal bandwidth and linearity of a signal by the high-order high frequency roll-off of the linear equalizer used. Using this configuration, the hybrid receiver equalizer eliminates the need for adaptive bandwidth controller used in conventional low-pass receiver equalization schemes. The hybrid receiver equalizer can be used in receivers for dual-speed simultaneous transmission on the same physical link.
    Type: Grant
    Filed: December 6, 2006
    Date of Patent: April 21, 2015
    Assignee: LSI Corporation
    Inventors: Yikui (Jen) Dong, Cathy Ye Liu, Freeman Yingquan Zhong
  • Patent number: 9008169
    Abstract: A 1/n-rate decision feedback equalizer (DFE) and method include a plurality of branches. Each branch includes a summer circuit configured to add a feedback signal to a received input, and a latch configured to receive an output of the summer circuit in accordance with a clock signal. A feedback circuit includes a multiplexer configured to receive as input, an output of each branch, the multiplexer having a clocked select input and configured to multiplex the output of each branch to assemble a full rate bit sequence, and a filter configured to provide cancellation of intersymbol interference (ISI) from the received input to be provided to the summer circuit of each branch.
    Type: Grant
    Filed: June 28, 2013
    Date of Patent: April 14, 2015
    Assignee: International Business Machines
    Inventors: John F. Bulzacchelli, Byungsub Kim
  • Patent number: 9008165
    Abstract: An apparatus of automatic power control for burst mode laser transmitter and method are provided. In one implementation a method includes: pushing a first multi-bit data into a data memory; modifying the data memory to remove a condition of frequent transition in the data memory, if the condition of frequent transition is found; establishing a list of indices pointing to data transition of the data memory; and sequentially examining a respective run length of the data indexed by each entry in the list, modifying the associated data to lengthen the respective run length if the respective run length is too short, modifying the associated data to shorten the respective run length if the respective run length is too long, and outputting a second multi-bit data by taking data from the data memory.
    Type: Grant
    Filed: January 11, 2012
    Date of Patent: April 14, 2015
    Assignee: Realtek Semiconductor Corp.
    Inventor: Chi-Liang Lin
  • Patent number: 9008166
    Abstract: A filter calculating device includes a first equalization filter calculating section that generates at least a first conversion matrix and a first triangular matrix based on a channel state of a first channel; a first quasi-orthogonalization section that calculates a first unimodular matrix based on the first triangular matrix; and a second equalization filter calculating section that generates at least a second conversion matrix and a second triangular matrix based on a channel state of a second channel and the first unimodular matrix.
    Type: Grant
    Filed: April 2, 2012
    Date of Patent: April 14, 2015
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroshi Nakano, Hiromichi Tomeba, Takashi Onodera, Alvaro Ruiz Delgado
  • Patent number: 9008159
    Abstract: In some embodiments, a method includes receiving, at a receiver of a first device via a channel of a communication medium, multiple data transmissions. Each data transmission of the multiple data transmissions has a guard interval of multiple guard intervals, wherein the multiple guard intervals have different lengths. The method includes determining, based on signal characteristics of the multiple data transmissions, the data transmission from among the multiple data transmissions having a preferred physical data rate. The method includes setting a length of an adjusted guard interval for the channel for data communication from a transmitter of a second device to the receiver of the first device via the communication medium, to a length of the guard interval for the data transmission having the preferred physical data rate.
    Type: Grant
    Filed: January 10, 2013
    Date of Patent: April 14, 2015
    Assignee: QUALCOMM Incorporated
    Inventors: Hassan Afkhami, Purva R. Rajkotia, Manjunath Anandarama Krishnam
  • Patent number: 9008164
    Abstract: An HDMI signal adjusting method is provided. A method for adjusting an HDMI signal of a high definition multimedia interface (HDMI) signal receiving apparatus includes: setting an equalizer gain for an HDMI signal, receiving an HDMI signal which is adjusted according to signal adjustment information set by an HDMI signal transmitting apparatus from the HDMI signal transmitting apparatus, signal-processing the received HDMI signal according to the set equalizer gain, detecting an error rate of the signal-processed HDMI signal, and transmitting signal adjustment information corresponding to an HDMI signal having a lowest error rate from among a plurality of the signal-processed HDMI signals corresponding to a plurality of different combinations of the equalizer gain and the signal adjustment information to the HDMI signal transmitting apparatus.
    Type: Grant
    Filed: July 10, 2013
    Date of Patent: April 14, 2015
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Seung-se Hong, Young-jo Seo, Sung-bo Oh, Jun-ho Lim, Hyoung-woo Jeon, Ki-sung Cha
  • Patent number: 9008094
    Abstract: A data transmission and reception apparatus is used for a high efficiency satellite transmission. The apparatus includes an initial phase calculation unit to calculate initial phase information using a preamble and a postamble of a data packet applied thereto, a symbol transition calculation unit to perform forward and backward metric operations using the initial phase information calculated by the initial phase calculation unit and a pilot symbol in the data packet to calculate a symbol transition of the data packet, and a phase error estimation unit to calculating a phase error using the pilot symbol in a spot where the pilot symbol is positioned, the calculated phase error being provided to the symbol transition calculation unit.
    Type: Grant
    Filed: September 13, 2012
    Date of Patent: April 14, 2015
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Pansoo Kim, Deock Gil Oh
  • Patent number: 9001919
    Abstract: A communications system includes a receiver unit connected with a transmission channel. The receiver unit determines a signal power of a first communications signal received over the transmission channel. A transmitter unit is connected with the transmission channel and transmits a second communications signal, wherein a gain of the communications signal being output by the transmitter unit is controllable. A control unit controls the gain of the transmitter unit in response to the determined signal power. At the receiver unit, detection of broadcast signal ingress during data communication is improved and methods for avoiding disturbances between coexisting communications systems may become more reliable. Different distances between successive training symbols suitable for channel estimation may be provided to enhance the noise measurement.
    Type: Grant
    Filed: July 1, 2010
    Date of Patent: April 7, 2015
    Assignee: SONY Corporation
    Inventors: Andreas Schwager, Gerd Spalink
  • Patent number: 9001880
    Abstract: Disclosed are devices and methods for identification and cancellation of interfering signals, especially far-end crosstalk (FEXT), in a communication system with at least two pairs of wires of a balanced line bundle. The devices include at least a cancellation circuit, which is connected downstream to dead time elements, an interference characteristic detection device and a cancellation control unit, which controls a setting of filter coefficients of an adaptive filter and the cancellation signal source. The adaptive filter is configured as a digital cancellation filter having filter coefficients separated in time by a first delay element having the delay time T, and having an adjustable additional delay time t, whereby the setting of the additional delay time ? takes place together with the setting of filter coefficients.
    Type: Grant
    Filed: January 5, 2011
    Date of Patent: April 7, 2015
    Assignees: Broadband United GmbH, iAd Gesellschaft fĂ¼r Informatik, Automatisierung und Datenverarbeitung mbH
    Inventors: Georg Herrmann, Hermann Hampel, Ulrich Berold, Manfred Deinzer, Roman Tzschoppe, Johannes B. Huber
  • Patent number: 8995519
    Abstract: Generating updated coefficients for an adaptive equalizer involves generating phase tracking information using asynchronous detection strategy (ADS) based on resolved data, and equalized signals, and estimating a phase corrected error based on the equalized signals, the phase tracking information and the resolved data. An inhibit signal is generated to inhibit updating of the equalization coefficients, the inhibit signal representing a likelihood of the phase corrected error being accurate, determined according to the phase corrected error, and the equalized signals. The equalization coefficients for the equalizer are adapted based on the received signals, and on the phase corrected error, and the adapting is inhibited according to the inhibit signal. Compared to conventional ADS, the new combination with the inhibit signal can enable improved convergence of coefficient adaptation. This is particularly useful for coherent receivers for optical systems.
    Type: Grant
    Filed: October 15, 2010
    Date of Patent: March 31, 2015
    Assignee: Telefonaktiebolaget L M Ericsson (Publ)
    Inventors: Tommaso Foggi, Giulio Colavolpe
  • Patent number: 8989251
    Abstract: A compensator generating a compensation signal to compensate for nonlinear echo in an output of a current source. The nonlinear echo is a result of transitioning the current source between an ON state and an OFF state. The compensator includes driving, weighting, function, and compensating circuits. The driving circuit receives a first signal that is based on the output of the current source. The weighting circuit is configured to generate a second signal based on weighted versions of the first signal. The function circuit, based on the second signal, (i) updates each of multiple functions, and (ii) selects a first function. The driving circuit generates a driving signal based on the first function selected by the function circuit. The compensating circuit generates the compensation signal based on the driving signal to compensate for the nonlinear echo provided by the output of the current source.
    Type: Grant
    Filed: May 29, 2014
    Date of Patent: March 24, 2015
    Assignee: Marvell International Ltd.
    Inventors: Xiaopeng Chen, Runsheng He, Shuran Wei
  • Patent number: 8989588
    Abstract: An optical transceiver includes an optical IC coupled to a processor IC. For transmit, the optical IC can be understood as a transmitter IC including a laser device or array. For receive, the optical IC can be understood as a receiver IC including a photodetector/photodiode device or array. For a transmitter IC, the processor IC includes a driver for a laser of the transmitter IC. The driver includes an equalizer that applies high frequency gain to a signal transmitted with the laser device. For a receiver IC, the processor IC includes a front end circuit to interface with a photodetector of the receiver IC. The front end circuit includes an equalizer that applies high frequency gain to a signal received by the receiver IC. The driver can be configurable to receive a laser having either orientation: ground termination or supply termination.
    Type: Grant
    Filed: January 22, 2013
    Date of Patent: March 24, 2015
    Assignee: Intel Corporation
    Inventors: Gil Afriat, Lior Horwitz, Dror Lazar, Assaf Issachar, Alexander Pogrebinsky, Adee O. Ran, Ehud Shoor, Roi Bar, Rushdy A. Saba
  • Patent number: 8989323
    Abstract: An outdoor radio communication system comprises a first radio unit, a second radio unit, and a single cable coupling the first radio unit to the second radio unit. Each radio unit includes a downconverter, a radio processor that is communicatively coupled to the downconverter, and a XPIC module. The cable further includes a first twisted-pair of wires for communicatively coupling the first downconverter to the second XPIC module and a second twisted-pair of wires for communicatively coupling the second downconverter to the first XPIC module. The first XPIC module generates a first reference signal using a signal from the second downconverter to cancel cross-polarization interference in an output signal of the first radio processor. Similarly, the second XPIC module generates a second reference signal using a signal from the first downconverter to cancel cross-polarization interference in an output signal of the second radio processor.
    Type: Grant
    Filed: September 21, 2012
    Date of Patent: March 24, 2015
    Assignee: ZTE (USA) Inc.
    Inventors: Dong Hong Yom, Ying Shen
  • Patent number: 8989253
    Abstract: A technique for a reconditioning equalizer filter for non-constant envelope signals is described. The input to a transmitter chain is modified by a reconditioning equalizer filter, prior to being applied to the transmitter. The reconditioning equalizer filter modifies and smoothens the amplitude of the signal. The modified and smoothened signal has its peaks reduced which results in lower Crest Factor. The input to the reconditioning equalizer filter could be a baseband, intermediate frequency (IF) or radio frequency (RF) signal. When the signal is an IF or RF signal, it needs to be down-converted to baseband before being applied to the reconditioning equalizer filter. The reconditioning equalizer filter could be performed in a digital or analog domain.
    Type: Grant
    Filed: June 17, 2014
    Date of Patent: March 24, 2015
    Assignee: Altera Corporation
    Inventor: Kiomars Anvari
  • Patent number: 8989303
    Abstract: An equalizer provided in a digital transmitter compensates for attenuation in a signal channel to a digital receiver. The equalizer generates signal levels as a logical function of bit history to emphasize transition signal levels relative to repeated signal levels. The preferred equalizer includes an FIR transition filter using a look-up table. Parallel circuits including FIR filters and digital-to-analog converters provide a high speed equalizer with lower speed circuitry. The equalizer is particularly suited to in-cabinet and local area network transmissions where feedback circuitry facilitates adaptive training of the equalizer.
    Type: Grant
    Filed: January 31, 2014
    Date of Patent: March 24, 2015
    Assignee: Massachusetts Institute of Technology
    Inventor: William J. Dally
  • Patent number: 8989249
    Abstract: A signaling system includes a pre-emphasizing transmitter and an equalizing receiver coupled to one another via a high-speed signal path. The receiver measures the quality of data conveyed from the transmitter. A controller uses this information and other information to adaptively establish appropriate transmit pre-emphasis and receive equalization settings, e.g. to select the lowest power setting for which the signaling system provides some minimum communication bandwidth without exceeding a desired bit-error rate.
    Type: Grant
    Filed: August 23, 2011
    Date of Patent: March 24, 2015
    Assignee: Rambus Inc.
    Inventors: Jared L. Zerbe, Fred F. Chen, Andrew Ho, Ramin Farjad-Rad, John W. Poulton, Kevin S. Donnelly, Brian S. Leibowitz
  • Patent number: 8989250
    Abstract: Methods and circuits for equalizing a linear response in an observation path of a digital pre-distorter. A method comprises generating observed signals in an observation path based on observing a transmit signal; down-converting the observed signals into intermediate frequencies using different LO frequencies; calculating a ratio using the intermediate frequencies; and equalizing the linear response of the observation path on the observed signals using the ratio. An apparatus comprises a directional coupler for observing a transmit signal and generating observed signals; a down-converter for converting the observed signals into intermediate frequencies using different LO frequencies; and an adaptive estimator for calculating a ratio using the intermediate frequencies and using the ratio to equalize a linear response from the observation path on the observed signals.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: March 24, 2015
    Assignee: PMC-Sierra US, Inc.
    Inventors: William D. Warner, Andrew S. Wright, Bartholomeus T. W. Klijsen, Derek J. W. Ho
  • Publication number: 20150078427
    Abstract: A clock data recovery circuit including a recovery unit and a loop control unit is provided. The recovery unit generates a recovery clock signal according to an original data signal. The recovery unit locks a frequency of the recovery clock signal to a correction frequency through a first loop, and locks the frequency of the recovery clock signal to a sampling frequency through a second loop. The correction frequency is smaller than the sampling frequency. The recovery unit adjusts the frequency of the recovery clock signal according to a reference clock signal and a first dividing signal in the first loop. The loop control unit switches the recovery unit to the first loop or the second loop according to a frequency difference between the reference clock signal and a second dividing signal.
    Type: Application
    Filed: September 16, 2013
    Publication date: March 19, 2015
    Applicant: HIMAX TECHNOLOGIES LIMITED
    Inventor: Shih-Chun Lin
  • Patent number: 8982939
    Abstract: Described herein is an apparatus, method and system corresponding to relate to a low power digital phase interpolator (PI). The apparatus comprises: a digital mixer unit to generate phase signals from a series of input signals, the phase signals having phases which are digitally controlled; a poly-phase filter, coupled to the digital mixer unit, to generate a filtered signal by reducing phase error in the phase signals; and an output buffer, coupled to the poly-phase filter, to generate an output signal by buffering the filtered signal. The low power digital PI consumes less power compared to traditional current-mode PIs operating on the same power supply levels because the digital PI is independent of any bias circuit which are needed for current mode PIs.
    Type: Grant
    Filed: December 21, 2011
    Date of Patent: March 17, 2015
    Assignee: Intel Corporation
    Inventor: Hongjiang Song
  • Patent number: 8983010
    Abstract: Briefly, in accordance with one or more embodiments, in response to receiving a single carrier signal that is not phase locked, channel equalization may be applied to the signal via a channel equalizer. The equalized signal may be phase averaged to provide a signal that is at least partially phase stabilized. The channel equalizer may then be trained by feeding back the at least partially phase stabilized phase reference to the channel equalizer. The resulting signal may then be decoded via coherent or quasi-coherent detection.
    Type: Grant
    Filed: March 25, 2014
    Date of Patent: March 17, 2015
    Assignee: Anchor Hill Communications, LLC
    Inventor: Eric Jacobsen
  • Patent number: 8976852
    Abstract: The present disclosure relates to a receiving node, and to a related method for determining when to apply a turbo equalization mode to compensate for Inter-Symbol Interference in a radio signal received over a radio channel from a transmitting node. The method comprises decoding the received radio signal into a decoded signal, determining a current error level in the decoded signal, predicting a turbo equalization gain based on instantaneous channel information of the radio channel and deciding whether to apply the turbo equalization mode depending on the predicted turbo equalization gain and the determined current error level in the decoded signal.
    Type: Grant
    Filed: May 19, 2011
    Date of Patent: March 10, 2015
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventors: Jinliang Huang, Tore Mikael André
  • Patent number: 8976909
    Abstract: A non-linear detector for detecting signals with signal-dependent noise is disclosed. The detector may choose a data sequence that maximizes the conditional probability of detecting the channel data. Since the channel may be time-varying and the precise channel characteristics may be unknown, the detector may adapt one or more branch metric parameters before sending the parameters to a loading block. In the loading block, the branch metric parameters may be normalized and part of the branch metric may be pre-computed to reduce the complexity of the detector. The loading block may then provide the branch metric parameters and any pre-computation to the detector. The detector may then calculate the branch metric associated with the input signal and output the channel data.
    Type: Grant
    Filed: May 23, 2013
    Date of Patent: March 10, 2015
    Assignee: Marvell International Ltd.
    Inventors: Hongxin Song, Seo-How Low, Panu Chaichanavong, Zining Wu
  • Patent number: 8976851
    Abstract: A method which includes receiving a first modulated signal from a first user device, the first modulated signal being generated based upon a time-frequency transformation of first user data. The method further includes receiving a second modulated signal from a second user device, the second modulated signal being generated based upon a time-frequency transformation of second user data. The first modulated signal and the second modulated signal are then processed.
    Type: Grant
    Filed: June 25, 2013
    Date of Patent: March 10, 2015
    Assignee: Cohere Technologies, Inc.
    Inventors: Ronny Hadani, Salim Shlomo Rakib
  • Patent number: 8976853
    Abstract: A receiver may receive a signal that was generated by passage of symbols through a non-linear circuit. An equalizer of the receiver may equalize the received signal based on a first non-linearity compensated, inter-symbol correlated (ISC) feedback signal to generate an equalized signal. The receiver may correct a phase error of the equalized signal to generate a phase-corrected equalized signal. The phase correction may be based on a second, non-linearity compensated, inter-symbol correlated (ISC) feedback signal.
    Type: Grant
    Filed: October 14, 2013
    Date of Patent: March 10, 2015
    Assignee: MagnaCom Ltd.
    Inventor: Amir Eliaz
  • Patent number: RE45506
    Abstract: An enhanced VSB receiver includes a tuner which tunes an RF signal and converts it into an IF signal, an IF mixer which converts the IF signal into a baseband signal, and a demodulator which demodulates the baseband signal into a VSB signal. The enhanced VSB receiver further includes a map recovery unit which recovers VSB map information of the VSB signal, an enhanced equalizer for compensating channel distortion of the VSB signal and outputting an equalized symbol, and an enhanced Viterbi decoder for estimating whether polarity inversion occurred during a symbol period of the equalized symbol and Viterbi-decoding the equalized symbol based on the polarity estimation.
    Type: Grant
    Filed: March 12, 2014
    Date of Patent: May 5, 2015
    Assignee: LG Electronics Inc.
    Inventors: In Hwan Choi, Kyong Won Kang