Equalizers Patents (Class 375/229)
  • Patent number: 8483318
    Abstract: A split-band system for processing a broadband input signal is disclosed. A signal divider divides the input signal into at least a higher frequency band and a lower frequency band. The lower frequency band is processed in a lower frequency circuit path. The higher frequency band is processed in a higher frequency circuit path. The higher frequency circuit path has a group delay equal to the lower frequency circuit path. A signal combiner combines the processed lower frequency band and the processed higher frequency band into an output signal.
    Type: Grant
    Filed: November 4, 2008
    Date of Patent: July 9, 2013
    Assignee: Agilent Technologies, Inc.
    Inventor: Richard K Karlquist
  • Publication number: 20130170534
    Abstract: A method and system for receiving and decoding horizontally encoded MIMO-OFDM transmissions with improved efficiency. In one embodiment, MIMO decoding is performed on each of the extracted separate tones of a MIMO-OFDM signal to extract and demodulate frequency domain symbols of the first layer corresponding to one or more code blocks. For each code block of the first layer that passes an error check, corresponding portions of the second layer are decoded using SIMO decoding.
    Type: Application
    Filed: December 29, 2011
    Publication date: July 4, 2013
    Inventors: Tzahi Weisman, Tom Harel, Ayelet Doron
  • Publication number: 20130170535
    Abstract: A receiver recovers local service data symbols from first Orthogonal Frequency Division Multiplexed (OFDM) symbols in the presence of second OFDM symbols. The second OFDM symbols carry national broadcast data symbols and modulated on to the sub-carriers of the second OFDM symbols using a first modulation scheme. The first OFDM symbols carry the national broadcast data symbols and the local service data symbols from a local insertion pipe and modulated on to the sub-carriers of the first OFDM symbols using a second modulation scheme. The receiver comprises an OFDM detector which includes an equalizer to recover local service modulated sub-carriers of the second modulation scheme.
    Type: Application
    Filed: January 23, 2013
    Publication date: July 4, 2013
    Applicant: Sony Corporation
    Inventor: Sony Corporation
  • Patent number: 8472513
    Abstract: Disclosed is a method and system that adapts coefficients of taps of a Finite Impulse Response (FIR) filter to increase elimination of Inter-Symbol Interference (ISI) introduced into a digital communications signal due to distortion characteristics caused by a real-world communications channel. In the communications system there is a Finite Impulse Response (FIR) filter. The FIR filter has at least one pre and/or post cursor tap that removes pre and/or post cursor ISI from the signal, respectively. The pre/post cursor taps each have pre/post cursor coefficients, respectively, that adjusts the effect of the pre/post cursor portion of the FIR filter. The FIR filtered signal is transmitted over the channel which distorts the signal due to the changing and/or static distortion characteristics of the channel. The channel distorted signal is received at a receiver that may pass the channel distorted signal through a quantifier/decision system (e.g.
    Type: Grant
    Filed: January 14, 2009
    Date of Patent: June 25, 2013
    Assignee: LSI Corporation
    Inventors: Amaresh Malipatil, Lizhi Zhong, Wenyi Jin, Ye Liu
  • Publication number: 20130156085
    Abstract: The calibration method, performed on a phased array device including channel elements coupled in parallel by a transmission line, has the steps of: obtaining channel responses corresponding to the channel elements through the transmission line, and each of the channel responses is obtained when one of the channel elements is turned on, and the rest of the channel elements are turned off; calculating a characteristic value corresponding to the transmission line based on the obtained channel responses of the channel elements; and adjusting a channel parameter of one of the channel elements based on the characteristic value of the transmission line.
    Type: Application
    Filed: September 12, 2012
    Publication date: June 20, 2013
    Applicant: MEDIATEK SINGAPORE PTE. LTD.
    Inventors: Sean Timothy NICOLSON, ChuanKang LIANG, Jing-Hong Conan ZHAN
  • Patent number: 8467437
    Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.
    Type: Grant
    Filed: November 12, 2008
    Date of Patent: June 18, 2013
    Assignee: Rambus Inc.
    Inventors: Jared L Zerbe, Vladimir M Stojanovic, Fred F Chen
  • Patent number: 8467438
    Abstract: A receiver is provided that can receive a first signal transmitted on a first carrier and a second signal transmitted on a second carrier. The receiver includes a channel estimation portion, a multicarrier nonlinear equalizer, a first log likelihood computing portion and a second log likelihood computing portion. The channel estimation portion can output a first estimation. The multicarrier nonlinear equalizer can output a first equalized signal and a second equalized signal. The first log likelihood ratio computing portion can output a first log likelihood ratio signal based on the first equalized signal. The second log likelihood ratio computing portion can output a second log likelihood ratio signal based on the second equalized signal. The multicarrier nonlinear equalizer can further output a third equalized signal and a fourth equalized signal. The third equalized signal is based on the first signal, the second signal and the first estimation.
    Type: Grant
    Filed: December 9, 2010
    Date of Patent: June 18, 2013
    Inventor: Bassel F. Beidas
  • Publication number: 20130148233
    Abstract: Various embodiments of the present invention provide systems and methods for data processing. For example, a data processing system is discussed that includes: an equalizer circuit, a signal to noise ratio calculation circuit, and a parameter adjustment circuit. The equalizer circuit is operable to equalize a data input to yield an equalized output. The signal to noise ratio calculation circuit is operable to calculate a signal to noise ratio of the equalized output based at least in part on a noise power derived from the equalized output. The parameter adjustment circuit is operable to adjust a parameter based at least in part on the signal to noise ratio.
    Type: Application
    Filed: December 12, 2011
    Publication date: June 13, 2013
    Inventors: Haitao Xia, Ming Jin, Dahua Qin, Shaohua Yang
  • Patent number: 8462897
    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: March 8, 2012
    Date of Patent: June 11, 2013
    Assignee: Marvell International Ltd.
    Inventors: Hongxin Song, Seo-How Low, Panu Chaichanavong, Zining Wu
  • Patent number: 8462838
    Abstract: Various example embodiments are disclosed. According to one example embodiment, a small form factor pluggable (SFP or SFP+) module may include an equalizer and a logic controller. The equalizer may be configured to receive data, provide signal information to a logic controller based on the received data, equalize the data based on equalization instructions received from the logic controller, and transmit the equalized data. The logic controller may be configured to transmit the signal information received from the equalizer receive programming instructions provide the equalization instructions to the equalizer based on the programming instructions, receive control inputs associated with the data, and provide status outputs based on the control inputs and the programming instructions. The SFP or SFP+ module may be configured to plug into a small form factor (SFF) host connector.
    Type: Grant
    Filed: December 4, 2009
    Date of Patent: June 11, 2013
    Assignee: Cisco Technology, Inc.
    Inventors: Qinghua Chen, Maurilio De Nicolo, Stephen Ong, Richard Brooks, Liming Yin
  • Patent number: 8457224
    Abstract: The present invention provides a channel estimation apparatus in which channel estimation may be made higher than heretofore in accuracy and may be used for calculating the weight for an equalization filter to achieve an optimum equalizing performance. A subcarrier copying unit 20 copies K items of end-side subcarriers, using the channel estimation obtained by a correlation processing unit 14 and K which is a subcarrier copy number. An IDFT unit 15 transforms the channel estimation obtained at the subcarrier copying unit 20 into the time domain channel response. A noise path removing unit 16 removes noise paths from the channel response output from the IDFT unit 15. A DFT unit 17 performs DFT of the channel response, from which the noise paths are removed by the noise path removing unit 16, to output a noise-suppressed frequency domain channel estimation value. A weight calculation unit 5 inputs the frequency domain channel estimation value output from the DFT unit 17 to calculate an equalizing weight.
    Type: Grant
    Filed: February 6, 2008
    Date of Patent: June 4, 2013
    Assignee: NEC Corporation
    Inventor: Masayuki Kimata
  • Patent number: 8457258
    Abstract: The present invention relates to a method for minimizing means square estimation error (MSEE) and bit error rate during channel estimation and equalization between a transmitter and a receiver of an orthogonal frequency division multiplexing (OFDM) systems. The method comprises transmitting from said transmitter to said receiver a training sequence for channel estimation being superimposed onto data at specific pilot to data power ratio (PDPR), receiving the OFDM signals along with the training sequence as an input, cross-correlating said received signal to a specific lag determined by the rms delay spread of the channel, with a specific known training sequence stored in a register, and which is also the sequence that is added to the data at the transmitter in the time domain having a prescribed pilot to data power ratio.
    Type: Grant
    Filed: September 3, 2008
    Date of Patent: June 4, 2013
    Assignee: Indian Institute of Technology
    Inventors: Ratnam Varada Raja Kumar, Jinesh Parameshwaran Nair
  • Patent number: 8457191
    Abstract: An adaptive equalizer. Implementations of adaptive equalizers may include implementations of 8-QAM adaptive equalizers that may include a signal filter, an adaptive processor coupled to the signal filter and a slicer coupled to the signal filter and the adaptive processor. The slicer may be configured to utilize a plurality of desired signals corresponding to an 8-QAM signal constellation having four quadrants, four levels disposed along the I-axis, and three levels disposed along the Q-axis. The slicer may also be configured to output an error signal by receiving an equalized output signal, processing the equalized output signal by correlating the equalized output signal with a decision region within one of the four quadrants, selecting one of a plurality of desired signals corresponding to the decision region, and calculating the error signal using the desired signal and the equalized output signal.
    Type: Grant
    Filed: March 10, 2008
    Date of Patent: June 4, 2013
    Assignee: Comtech EF Data Corp.
    Inventors: Lazaro F. Cajegas, III, Cris M. Mamaril
  • Patent number: 8451966
    Abstract: Disclosed herein is an information processor, including: a receiving section configured to receive an OFDM signal transmitted in accordance with an OFDM system; a FFT arithmetically operating section configured to carry out FFT for a signal within a predetermined interval of the OFDM signal; a delay profile estimating section configured to estimate delay profiles from the OFDM signal received by the receiving section; an inter-symbol interference amount estimating section configured to estimate inter-symbol interference amounts for a plurality of candidates for the predetermined interval, respectively, by using the delay profiles estimated by the delay profile estimating section; and a searching section configured to search for the candidate having the minimum inter-symbol interference amount estimated by the inter-symbol interference amount estimating section from among the plurality of candidates in the predetermined interval, and supply data on the candidate thus searched for as the predetermined interval
    Type: Grant
    Filed: September 28, 2009
    Date of Patent: May 28, 2013
    Assignee: Sony Corporation
    Inventors: Hidetoshi Kawauchi, Toshiyuki Miyauchi, Takashi Yokokawa, Takuya Okamoto, Hiroyuki Kamata
  • Patent number: 8451884
    Abstract: An offset calibration method is provided. Two input terminals of an equalizer are switched to a common voltage at a first time point, wherein the equalizer generates a first equalized signal and a second equalized signal according to the common voltage. It is determined whether a first offset voltage is present in the equalizer according to the first and second equalized signals generated from the common voltage. If the first offset voltage is determined to be present in the equalizer, a first compensation voltage is provided to the equalizer.
    Type: Grant
    Filed: February 21, 2008
    Date of Patent: May 28, 2013
    Assignee: Mediatek Inc.
    Inventors: Chien-Ming Chen, Chih-Chien Huang, Shang-Yi Lin
  • Publication number: 20130128942
    Abstract: An interference cancellation receiver for a pre-coded orthogonal frequency division multiplexed (OFDM) based system combines temporal interference cancellation within the OFDM framework. Multi-path equalization and inter-symbol interference (ISI) cancellation are performed on a time domain channel estimate of a received signal. An output from the multi-path equalization is transformed to the frequency domain. Inter-channel interference (ICI) is performed in the frequency domain on an equalized signal from the multi-path equalization after transforming the equalized signal from the time domain to the frequency domain.
    Type: Application
    Filed: May 22, 2012
    Publication date: May 23, 2013
    Applicant: QUALCOMM Incorporated
    Inventors: Divaydeep Sikri, Farrokh Abrishamkar, Bahadir Canpolat
  • Patent number: 8446942
    Abstract: A waveform equalization circuit includes: a decision feedback equalization unit that feeds back and equalizes an input signal; a clock phase adjustment unit that adjusts a clock phase of a signal equalized by the decision feedback equalization unit based on a signal determined with a prescribed potential as a threshold; and a duo-binary decoder that encodes, into a duo-binary signal, the signal determined with the prescribed potential as a threshold based on a clock adjusted by the clock phase adjustment unit from the signal equalized by the decision feedback equalization unit; wherein the equalized signal is generated by adding the duo-binary signal encoded by the duo-binary decoder to the input signal. A first post-tap of the input signal is equalized by the clock phase adjustment unit without feedback equalization by the decision feedback equalization unit. Second and subsequent post-taps of the input signal are fed back and equalized by the decision feedback equalization unit.
    Type: Grant
    Filed: March 6, 2009
    Date of Patent: May 21, 2013
    Assignee: NEC Corporation
    Inventors: Hideyuki Hasegawa, Kazuhisa Sunaga, Kouichi Yamaguchi
  • Patent number: 8446998
    Abstract: A technique for processing received signals in multiple-antenna systems. Received signals from the different antennas may be amplified by a Low Noise Amplifier (LNA) and time-multiplexed by a switch to form a single analog signal. The time-multiplexed analog signal is down-converted and processed using a single RF chain for each signal component. This may result in an N-fold decrease in hardware in multiple antenna receiver systems.
    Type: Grant
    Filed: May 4, 2007
    Date of Patent: May 21, 2013
    Assignee: Quantenna Communications, Inc.
    Inventors: Behrooz Rezvani, Farrokh Farrokhi, Andrea Goldsmith
  • Patent number: 8446936
    Abstract: Disclosed is a co-channel feedback signal cancelling regenerative repeater of the Advanced Television Systems Committee (ATSC) that extracts a predetermined reference value of feedback signal to be able to cancel the feedback signal among received signals, including: a signal receiving unit; a signal demodulating unit that converts frequency of a received signal and demodulates it into a baseband signal; an interference equalizing unit that corrects characteristics of the demodulated signal and cancels feedback signal; a channel equalizing unit that compensates for channel distortion of an original signal from which the feedback signal is cancelled; a modulating unit that modulates the channel distortion-compensated original signal and converts it into an analog signal; and a signal transmitting unit that converts the frequency of the modulated signal, controls and amplifies its gain, and transmits a regenerative transmission signal.
    Type: Grant
    Filed: April 17, 2009
    Date of Patent: May 21, 2013
    Assignees: Darbs Co., Ltd., Korean Broadcasting System
    Inventors: Yong-Soek Kim, Sang-Gee Kang, Young-Woo Suh
  • Patent number: 8446941
    Abstract: Disclosed are an equalizer and an equalization method employing an adaptive algorithm for high speed data transmissions. The equalizer includes: a subtraction unit subtracting a feedback signal from an input signal to generate a subtraction signal; a timing signal generation unit generating a sampling timing signal; an equalization signal generation unit equalizing the subtraction signal according to the sampling timing signal to generate an equalization signal; and a feedback signal generation unit calculating a filter coefficient value by using the subtraction signal and the equalization signal, delaying the equalization signal, and weighting the delayed equalization signal according to the filter coefficient value to generate a feedback signal.
    Type: Grant
    Filed: September 14, 2010
    Date of Patent: May 21, 2013
    Assignee: Electronics and Telecommunications Research Institute
    Inventor: Choong Reol Yang
  • Patent number: 8442471
    Abstract: An agile RF tuner circuit capable of converting a wide portion of RF signal into an IF signal suitable for analog-to-digital conversion. The circuit up converts a received RF signal to a high IF signal and then down converts the high IF signal to a low IF signal. Embodiments of the RF circuit incorporate harmonic reject mixers to suppress harmonics and intermodulations typically associated with the frequency conversion process.
    Type: Grant
    Filed: December 29, 2011
    Date of Patent: May 14, 2013
    Assignee: CSR Technology Inc.
    Inventors: Carey Ritchey, Kim E. Beumer, Marius Pop
  • Patent number: 8442105
    Abstract: In an embodiment of an equalizer, a demodulator for MMSE-SIC receives a symbol vector to provide first information. A decoder receives the first information to provide second information to the demodulator. The decoder iteratively processes the first information to provide the second information. The demodulator and decoder are coupled in a loop for feeding back the second information for iteratively refining the first information. A detection-cancellation block of the demodulator receives the symbol vector to provide an equalized vector. A channel pre-processor block of the demodulator receives an initial vector output of the detection-cancellation block for the symbol vector for a demodulating-decoding iterative sequence to provide a weight vector. The channel pre-processor block provides an approximation using a fixed matrix to generate the weight vector. The detection-cancellation block receives the weight vector for equalization of the symbol vector in order to provide the equalized vector.
    Type: Grant
    Filed: November 2, 2011
    Date of Patent: May 14, 2013
    Assignee: Xilinx, Inc.
    Inventors: Christopher H. Dick, Raghavendar M. Rao
  • Patent number: 8442103
    Abstract: A method and transceiver for processing a signal in a communication system are provided. The method includes identifying a Channel Impulse Response (CIR) of the signal as of minimum phase, maximum phase, or mixed phase, processing the signal without performing prefiltering when the CIR is identified as minimum phase and performing all pass prefiltering of the signal when the CIR is identified as maximum phase or mixed phase. The transceiver includes a computation block and an all pass filter. The computation block identifies CIR of a signal as minimum phase, maximum phase, or mixed phase, performs root identification when the CIR of the signal is identified to be mixed phase and enables all pass filtering of the signal when the CIR of the signal is identified as mixed phase or maximum phase. The all pass filter transforms the signal to its minimum phase equivalent.
    Type: Grant
    Filed: August 10, 2009
    Date of Patent: May 14, 2013
    Assignee: Samsung Electronics Co., Ltd
    Inventor: Sundar Rajan Krishnamurthy
  • Patent number: 8442102
    Abstract: A chip equalization apparatus and method for selecting cluster signals from broadcast signals being continuously received in multi-path channels for extracting a plurality of cluster signals from among the received broadcast signals and using a plurality of chip equalizers each having a tap coefficient update part for updating the tap coefficients of the selected cluster signals when the equalization outputs are combined to compensate the broadcast signals and provide low power consumption and efficient equalization for use in a satellite broadcasting receiving system.
    Type: Grant
    Filed: December 27, 2007
    Date of Patent: May 14, 2013
    Assignee: SK Telecom Co., Ltd.
    Inventors: Goon Seop Lee, Sung Hoon Lee, Jong Tae Ihm, Jae Hwang Yu, Dong Hahk Lee, Ku Ik Chung, Jin Hee Han
  • Patent number: 8442170
    Abstract: A method is provided for equalizing OFDM symbol vectors received on AM in-band on-channel radio signal including a main carrier and first and second BPSK modulated subcarriers. The method comprises the steps of: computing a BPSK magnitude signal; filtering the BPSK magnitude signal; filtering complex samples received on the main carrier; using the filtered BPSK magnitude signal and the filtered complex samples received on the main carrier to compute a plurality of flat fade equalization coefficients; and multiplying the OFDM symbol vectors by the flat fade equalization coefficients. A receiver that includes an equalizer, which operates in accordance with the method is also provided.
    Type: Grant
    Filed: February 23, 2010
    Date of Patent: May 14, 2013
    Assignee: iBiquity Digital Corporation
    Inventors: Brian William Kroeger, Kun Wang
  • Publication number: 20130114661
    Abstract: A wireless communication receiver includes a first signal processing block, a phase noise compensation apparatus, and a second signal processing block. The first signal processing block is arranged for generating a first processed output by processing a reception signal, wherein the first signal processing block includes a channel estimation unit arranged for performing channel estimation. The phase noise compensation apparatus is arranged for receiving the first processed output and generating a second processed output by performing phase noise compensation according to the received first processed output. The second signal processing block is arranged for receiving the second processed output and processing the received second processed output.
    Type: Application
    Filed: November 9, 2011
    Publication date: May 9, 2013
    Inventors: Chia-Hsien Chiang, Ching-Shyang Maa, Chih-Hsiu Lin
  • Patent number: 8437387
    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: April 4, 2012
    Date of Patent: May 7, 2013
    Assignee: Broadcom Corporation
    Inventors: Bruce J. Currivan, Loke Kun Tan, Thomas Joseph Kolze, Hanli Zou, Lin He
  • Patent number: 8437415
    Abstract: A method and system of estimating frequency offset at a subscriber station is disclosed. The method includes the subscriber station receiving a composite signal, in which the composite signal includes multi-carrier signals transmitted from a plurality of base stations. The subscriber station selects a subset of the plurality of base stations. The subscriber station selects at least one pair of multi-carrier symbols of the composite signal, wherein each of the at least one pair of multi-carrier symbols include a plurality of pilot sub-carriers. The subscriber station selects a subset of the plurality of pilot sub-carriers of the at least one pair of multi-carrier symbols based on transmit pilot symbols of the pilot sub-carriers of the multi-carrier signals transmitted by the subset of the plurality of base stations.
    Type: Grant
    Filed: October 7, 2010
    Date of Patent: May 7, 2013
    Assignee: Broadcom Corporation
    Inventors: Sriram Mudulodu, Louay Jalloul
  • Publication number: 20130107932
    Abstract: A multi-user MIMO receiver of a UE in question for detecting a pre-coded signal includes a unit configured to blindly estimate information concerning a pre-coding vector for a paired UE, which is operated on the same resource as the multi-user MIMO receiver, based on received data. Further, the multi-user MIMO receiver comprises an equalizer configured to equalize the pre-coded signal based on the estimated information concerning the pre-coding vector for the paired UE.
    Type: Application
    Filed: October 25, 2012
    Publication date: May 2, 2013
    Inventors: Tobias Scholand, Biljana Badic, Rajarajan Balraj, Peter Jung, Guido Bruck, Zijian Bai, Stanislaus Iwelski
  • Patent number: 8433002
    Abstract: Methods and apparatus for initially decoding a frame control header (FCH) in an orthogonal frequency-division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) system in an effort to accurately determine the downlink frame prefix (DLFP) such that the remainder of an OFDM/A frame may be properly decoded are provided. Used, for example, when boosting factors applied in the transmitter to various elements of the OFDM/A frame and/or available pilots for the FCH are unknown, such methods may utilize a preamble channel estimate, the FCH pilots, or a combination thereof.
    Type: Grant
    Filed: September 28, 2011
    Date of Patent: April 30, 2013
    Assignee: QUALCOMM Incorporated
    Inventors: Jong Hyeon Park, Bok Tae Sim, Ju Won Park, Tae Ryun Chang
  • Patent number: 8428110
    Abstract: A system includes a memory hub chip including a Tomlinson-Harashima precoding (THP) equalizer portion operative to perform transmitter equalization at the memory hub chip and send data from to a memory chip.
    Type: Grant
    Filed: March 25, 2011
    Date of Patent: April 23, 2013
    Assignee: International Business Machines Corporation
    Inventors: Marcel A. Kossel, Thomas H. Toifl
  • Patent number: 8428112
    Abstract: An interface circuit inputting and outputting data and a clock that have multiple speeds is provided with an equalizer capable of changing a circuit parameter, a frequency detection part detecting a clock frequency, and a parameter calculation control part calculating an appropriate circuit parameter according to the clock frequency and controlling the equalizer. The frequency detection part detects at what frequency the interface circuit is operating presently and sends the frequency to the parameter calculation control part. The parameter calculation control part calculates the circuit parameter of the equalizer so that the interface circuit operates optimally at the detected frequency, and sets the circuit parameter to the equalizer. In this manner, since the circuit parameter of the equalizer in the interface circuit can be controlled appropriately according to the frequency of the input and output clock, optimum operation is always available.
    Type: Grant
    Filed: September 23, 2008
    Date of Patent: April 23, 2013
    Assignee: Fujitsu Limited
    Inventor: Shunichiro Masaki
  • Patent number: 8428196
    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: May 11, 2012
    Date of Patent: April 23, 2013
    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: 8428206
    Abstract: A method and system of fine timing synchronization for an OFDM signal. The OFDM signal is coarse timing synchronized, generating a synchronization sequence and a CFR (Channel Frequency Response). The synchronization sequence is removed. A correlation coefficient of the correlation between the CFR applied to a number of carriers and the number of carriers with different window shifts is calculated. The largest window shift corresponding to a downsampling factor is indicated by the lowest correlation coefficient greater than a threshold. The CFR is downsampled by the downsampling factor, and an inverse FFT is performed on the downsampled CFR with a reduced number of calculations reduced by the downsampling factor, transforming the CFR into a CIR. A fine timing synchronization position is determined from the CIR and is utilized by an FFT unit within an OFDM receiver to accurately receive OFDM symbols of the OFDM signal.
    Type: Grant
    Filed: March 5, 2009
    Date of Patent: April 23, 2013
    Assignee: NXP B.V.
    Inventor: Yan Li
  • Patent number: 8422542
    Abstract: A method of ameliorating channel effects present in a signal received through a channel, wherein the signal conveys at least first and second information streams and the method comprises the steps of determining from the first stream activation of the second stream and processing the signal to ameliorate channel effects, when the second stream is present, in a first manner comprising filtering the signal through filter means to ameliorate channel dispersion and then processing the signal through Rake receiver means or, when the second stream is absent, in a second manner comprising processing the signal through the Rake receiver means without prior amelioration of channel dispersion by the filter means.
    Type: Grant
    Filed: July 24, 2007
    Date of Patent: April 16, 2013
    Assignee: MStar Semiconductor, Inc.
    Inventor: Cyril Valadon
  • Patent number: 8422543
    Abstract: Communication signal compensation systems and methods are operable to compensate communication signals communicated to media devices using an agile equalizer over a coaxial cable communication system. An exemplary embodiment receives a first compensation control signal from a first media device, compensates a received first communication signal based upon the first compensation control signal, communicates the first compensated communication signal to the first media device over the first coaxial cable; receives a second compensation control signal from a second media device, compensates a received second communication signal based upon the second compensation control signal, and communicates the second compensated communication signal to the second media device over the second coaxial cable. The first compensation control signal defines compensation for communication signals communicated over a first coaxial cable.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: April 16, 2013
    Assignee: EchoStar Technologies L.L.C.
    Inventors: Phuc Nguyen, Pujitha Davuluri
  • Publication number: 20130089131
    Abstract: A system and method for wirelessly transmitting audiovisual information. Training information may be stored in a memory. A plurality of packets may be generated, including the training information. The plurality of packets may also include audiovisual information. The plurality of packets may include first information identifying a first training pattern of a plurality of possible training patterns. The first training pattern may specify one or more locations of the training information in the plurality of packets. The first information may be usable by a receiver to determine the first training pattern of the plurality of possible training patterns. The plurality of packets may be transmitted in a wireless manner.
    Type: Application
    Filed: November 30, 2012
    Publication date: April 11, 2013
    Applicant: COHERENT LOGIX INCORPORATED
    Inventor: Coherent Logix Incorporated
  • Patent number: 8416844
    Abstract: A synchronization section specifies a position of a guard interval correlation's center of gravity based on a guard interval correlation value, and calculates a carrier-direction shift amount Fshift. An equalization section shifts the passband of a carrier interpolation filter of a carrier interpolation section by the carrier-direction shift amount Fshift calculated by the synchronization section. This shift processing causes the delay profile to be kept in the center of the passband of the carrier interpolation filter, for any FFT window position. This enables transmission path estimation without limiting a range of an FFT window position even if the passband of the carrier interpolation filter is narrower than a guard interval of an OFDM signal.
    Type: Grant
    Filed: March 25, 2008
    Date of Patent: April 9, 2013
    Assignee: Panasonic Corporation
    Inventors: Mikihiro Ouchi, Kenichiro Hayashi, Tomohiro Kimura
  • Patent number: 8416846
    Abstract: A receiver is optimized by adapting the taps of a decision feedback equalizer component within the receiver. Data decisions and error decisions are generated. These data decision and error decisions are used to derive an error rate of data by measuring the number of margin hits that occur. A balance value is also calculated from the data decisions and the error decisions. The balance value is used to update a tap of the decision feedback equalizer. The updating of the tap continues until the number of margin hits has been minimized.
    Type: Grant
    Filed: December 20, 2010
    Date of Patent: April 9, 2013
    Assignee: NetLogic Microsystems, Inc.
    Inventors: Andrew Lin, Faramarz Bahmani
  • Patent number: 8416842
    Abstract: A channel estimation method and apparatus using a self-tracking algorithm is provided for improving channel estimation accuracy. The channel estimation apparatus of a mobile terminal includes a receiver for converting a received radio signal into a baseband signal, a match filter for converting the baseband signal into a digital signal including at least two samples, a channel estimator for buffering the samples, for analyzing multipath signals to predict a maximum power position and multipath energy, and for estimating a channel by selecting a multi-tap at the maximum power position through a slew control, an equalization controller for calculating an equalization tap gain using the multi-tap selected by the channel estimator, and an equalizer for compensating for distortion in the samples output by the channel estimator using the equalization tap gain calculated by the equalization controller.
    Type: Grant
    Filed: December 22, 2009
    Date of Patent: April 9, 2013
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Young Min Ki, Jae Hong Lee, Hun Kee Kim, Kyung Seung Ahn, Seong Wook Song, Min Sung Hur
  • Publication number: 20130083836
    Abstract: Systems and methods are provided for decoding signal vectors in multiple-input multiple-output (MIMO) systems, where the receiver has received one or more signal vectors from the same transmitted vector. The receiver combines the received vectors by vector concatenation The concatenated vector may then be decoded using, for example, maximum-likelihood decoding. In some embodiments, the combined signal vector is equalized before decoding.
    Type: Application
    Filed: November 21, 2012
    Publication date: April 4, 2013
    Applicant: MARVELL WORLD TRADE LTD.
    Inventor: Marvell World Trade Ltd.
  • Patent number: 8411731
    Abstract: In order to process a subband signal of a plurality of real subband signals which are a representation of a real discrete-time signal generated by an analysis filter bank, a weighter for weighting a subband signal by a weighting factor determined for the subband signal is provided to obtain a weighted subband signal. In addition, a correction term is calculated by a correction term determiner, the correction term determiner being implemented to calculate the correction term using at least one other subband signal and using another weighting factor provided for the other subband signal, the two weighting factors differing. The correction term is then combined with the weighted subband signal to obtain a corrected subband signal, resulting in reduced aliasing, even if subband signals are weighted to a different extent.
    Type: Grant
    Filed: June 26, 2007
    Date of Patent: April 2, 2013
    Assignee: Fraunhofer-Gesellschaft zur Foerderung der Angewandten Forschung E.V.
    Inventors: Bernd Edler, Harald Popp
  • Patent number: 8411733
    Abstract: In an RF signal transmission network such as the reverse channels of a coaxial cable network, there is provided at least one adaptive equalizer for pre- or post-filtering inter-symbol interference in the transmitted signals, the adaptive equalizer having a series of coefficients for which values are required. In order to improve the transmission efficiency the preamble used in these channels is shortened by coarsely estimating the channel using a short “unique word’ placed at the beginning of the equalizer training sequence. The coarse channel estimate is crudely inverted to produce a set of equalizer coefficients which partially equalize the channel. By initializing the adaptive equalizer with these approximate coefficients, it is possible to reduce the length of the training sequence needed for the equalizer to converge.
    Type: Grant
    Filed: June 15, 2010
    Date of Patent: April 2, 2013
    Assignee: Vecima Networks Inc
    Inventors: Brian Berscheid, Zohreh Andalibi, Eric Salt
  • Patent number: 8411725
    Abstract: Adaptive reconfiguration of a wireless receiver is enabled based on channel geometry. According to an embodiment, the wireless receiver includes a geometry factor processing module and signal processing modules, e.g. such as but not limited to an SIR estimation module, a power estimation module, a despreading module, a low-pass filter, a combing weight generation module, a coefficient estimation module, a synchronization control channel interference canceller module, etc. The geometry factor processing module determines a geometry factor for the channel over which signals are transmitted to the wireless receiver, the geometry factor being a measure of the ratio of total transmitted power received by the wireless receiver to total interference plus noise power at the wireless receiver. One or more of the receiver signal processing modules are reconfigurable based on the geometry factor.
    Type: Grant
    Filed: September 25, 2009
    Date of Patent: April 2, 2013
    Assignee: Telefonaktiebolaget LM Ericsson (Publ)
    Inventors: Douglas A. Cairns, Jaroslaw Niewczas, Yoshitaka Murata, Elias Jonsson
  • Patent number: 8406351
    Abstract: A method and device for compensating for undesirable signal characteristics such as baseline wander that includes a linear equalization filter responsive to receive an input, a combiner responsive to an output of the linear equalization filter, and a decision feedback equalization filter responsive to an output of the combiner, where the combiner is further responsive to an output of the decision feedback equalizer. Additionally, an error feedback circuit is responsive to the output of the combiner, and the combiner is further responsive to an output of the error feedback circuit to form a compensated signal having reduced distortion relative to the distorted signal.
    Type: Grant
    Filed: March 12, 2012
    Date of Patent: March 26, 2013
    Assignee: Marvell International, Ltd.
    Inventor: Shirish Altekar
  • Publication number: 20130070832
    Abstract: Various embodiments of the present invention relate to systems, devices and method of frequency synthesis that generate in-phase and quadrature-phase clock signals at a programmable frequency. The generated frequency, which can range from a fraction to multiples of the input reference frequency, is generated by dividers following a phase-locked loop, thus avoiding the use of a low input reference frequency as well as frequency doubling.
    Type: Application
    Filed: November 13, 2012
    Publication date: March 21, 2013
    Applicant: MAXIM INTEGRATED PRODUCTS, INC.
    Inventor: Maxim Integrated Products, Inc.
  • Patent number: 8401061
    Abstract: A system and method for testing a modem of a digital subscriber line access multiplexer (DSLAM) includes a pair of modems communicatively coupled to each other by way of a communications path that includes a first DSL communication medium connected to one modem, a second DSL communication medium connected to the other modem, which is part of the DSLAM, and an Ethernet medium connected between the first and second DSL modems. DSL signals can be dispatched from the first (or second) modem via the first (or second) DSL communication medium for receipt by the second (or first) DSL modem via the second (or first) DSL communication medium, whereupon, DSL signals passing from the first DSL communication medium to the second DSL communication medium, or vice versa, are converted into Ethernet packets for transmission over the Ethernet medium and then back into DSL signals.
    Type: Grant
    Filed: July 12, 2007
    Date of Patent: March 19, 2013
    Assignee: Tollgrade Communications, Inc.
    Inventors: Jeffrey A. Gibala, Matthew G. Cimbala, Thomas R. Schneider, Jr., Regis J. Nero, Jr., Gregory L. Quiggle
  • Patent number: 8401064
    Abstract: A receiver is optimized by adapting parameters of components within the receiver. Various component parameters are adapted by using either a least means squared algorithm or a steepest descent algorithm. The taps of a decision feedback equalizer can be adapted by using either a least means squared algorithm or a steepest descent algorithm. The gain value of a linear equalizer and the input of a digital to analog converter coupled to the linear equalizer are also adapted through the least means squared algorithm or a steepest descent algorithm. A variable gain amplifier is also capable of being adapted through the use of the least means squared algorithm. Clock offsets are also configured by use of a steepest descent algorithm.
    Type: Grant
    Filed: December 20, 2010
    Date of Patent: March 19, 2013
    Assignee: NetLogic Microsystems, Inc.
    Inventors: Andrew Lin, Faramarz Bahmani
  • Publication number: 20130064557
    Abstract: According to a first aspect of the present invention there is provided an apparatus for performing power equalisation and phase correction of two signals (400). The apparatus comprises a first hybrid coupler (401) configured to operate as a power combiner, and a second hybrid coupler (402) configured to operate as a power divider, wherein the apparatus is configured to provide an output (406) of the first hybrid coupler as an input (407) to the second hybrid coupler.
    Type: Application
    Filed: December 2, 2010
    Publication date: March 14, 2013
    Inventors: Wenfei Hu, Jonathan Stuart Drake
  • Patent number: 8396110
    Abstract: In one embodiment, a receiver circuit is provided. The receiver circuit includes a low-power equalization circuit having a first linear equalization circuit coupled to receive serial data. The receiver circuit includes a low-noise equalization circuit having a second linear equalization circuit coupled to receive the serial data, and a non-linear equalization circuit coupled to an output of the second linear equalization circuit. The receiver circuit includes a control circuit configured to enable the low-power equalization circuit and disable the low-noise equalization circuit in response to a first state of a control signal. The control circuit is configured to disable the low-power equalization circuit and enable the low-noise equalization circuit in response to a second state of the control signal.
    Type: Grant
    Filed: December 3, 2010
    Date of Patent: March 12, 2013
    Assignee: Xilinx, Inc.
    Inventor: Cheng-Hsiang Hsieh