Using A Transversal Filter Patents (Class 370/291)
  • Patent number: 10263669
    Abstract: In order to balance the power requirements of a MIMO receiver with the gains that may be achieved through its use, an apparatus determines whether a current configuration of the UE supports iterative MIMO reception. When it is determined that the current configuration of the UE supports iterative MIMO reception, the apparatus determines whether at least one parameter of the received signal is within a corresponding target condition, respectively, for each of the at least one parameters, e.g., including determining whether a scheduling percentage meets a scheduling threshold and whether an error rate is within an error rate range. When both the configuration supports iterative MIMO reception and the signal parameter(s) meet the corresponding target condition(s), the apparatus uses the iterative MIMO receiver. If not, the apparatus uses a serial receiver.
    Type: Grant
    Filed: August 23, 2017
    Date of Patent: April 16, 2019
    Assignee: QUALCOMM Incorporated
    Inventors: Chinmay Vaze, Prashant Udupa Sripathi, Supratik Bhattacharjee, Michael McCloud
  • Patent number: 10186280
    Abstract: The present invention relates to coding of audio signals, and in particular to high frequency reconstruction methods including a frequency domain harmonic transposer. A system and method for generating a high frequency component of a signal from a low frequency component of the signal is described.
    Type: Grant
    Filed: October 25, 2017
    Date of Patent: January 22, 2019
    Assignee: Dolby International AB
    Inventors: Lars Villemoes, Per Ekstrand
  • Patent number: 10061784
    Abstract: Provided is a method for fusing a plurality of data, this method comprising inputting a plurality of N-dimensional uncertain data where N is a natural number not being a zero, representing the inputted plurality of uncertain data in a first form of a data set in a 2N-dimensional extended space, generating a second form of a data set by applying whitening transform WT to the 2N-dimensional extended space, acquiring a first point or first vector through a linear projection to a transformed constraint manifold from the second form of the data set and generating a N-dimensional fused data by applying inverse-whitening transform to the first point or first vector.
    Type: Grant
    Filed: April 22, 2016
    Date of Patent: August 28, 2018
    Assignee: Research & Business Foundation Sungkyunkwan University
    Inventors: Suk Han Lee, Abu Bakr Muhammad
  • Patent number: 9972337
    Abstract: An echo cancellation method includes receiving an echo reference signal, receiving a microphone signal, decomposing, with a first filter bank, the echo reference signal into a series of subband echo reference signals, decomposing, with a second filter bank, the microphone signal into a series of subband microphone signals, estimating a group delay between the echo reference signal and the microphone signal using the series of subband echo reference signals and the series of subband microphone signals, estimating, using adaptive filters, acoustic echoes in the echo reference signal based at least in part on the group delay, subtracting the acoustic echoes from the series of subband microphone signals to obtain a series of acoustic echo removed subband signals, combining the series of acoustic echo removed subband signals into a single time domain echo removed signal, and sending the single time domain echo removed signal to a host operating system.
    Type: Grant
    Filed: June 22, 2016
    Date of Patent: May 15, 2018
    Assignee: Cisco Technology, Inc.
    Inventors: Xilin Li, Wei Li, Fuling Liu, Xinmin Yan
  • Patent number: 9961469
    Abstract: The present invention relates to a method and an apparatus for processing a signal, which are used for effectively reproducing an audio signal, and more particularly, to a method and an apparatus for processing a signal, which are used for implementing binaural rendering for reproducing multi-channel or multi-object audio signals in stereo with a low calculation amount.
    Type: Grant
    Filed: September 17, 2014
    Date of Patent: May 1, 2018
    Assignee: WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC.
    Inventors: Taegyu Lee, Hyunoh Oh
  • Patent number: 9947337
    Abstract: An echo canceller includes a fast Fourier transform (FFT) unit to provide frequency domain representation (FD) of an input. A multiband adaptive filter receives the FD of the input and provides an FD filter output, the adaptive filter is a finite input response (FIR) digital filter. Another FFT unit provides an FD of a microphone signal, and a summer adds the FD filter output to the FD of the microphone signal to provide echo-canceller FD output. A feedback subsystem uses the echo-canceller FD output to adjust filter coefficients of at least a first, a second, and a third frequency band of the multiband adaptive filter to minimize uncancelled output in the echo-canceller FD output. The feedback subsystem adjusts the filter coefficients of the second frequency band of the adaptive filter according to uncancelled output in the first, second, and third frequency bands of the echo-canceller FD output.
    Type: Grant
    Filed: March 21, 2017
    Date of Patent: April 17, 2018
    Assignee: OmniVision Technologies, Inc.
    Inventors: Chung-An Wang, Dong Shi
  • Patent number: 9928824
    Abstract: A noise control system may be configured to process one or more first noise inputs from one or more first acoustic sensors, the one or more first noise inputs representing external noise sensed at one or more respective noise sensing locations on an outer surface of a sheltering structure; to process one or more second noise inputs from one or more second acoustic sensors, the one or more second noise inputs representing residual noise at one or more respective residual noise sensing locations on an inner surface of the sheltering structure; to determine a noise control pattern based at least on the one or more first noise inputs and the one or more second noise inputs; and to generate one or more control signals to control acoustic signals generated by one or more acoustic transducers based on the noise control pattern.
    Type: Grant
    Filed: December 28, 2015
    Date of Patent: March 27, 2018
    Assignee: SILENTIUM LTD.
    Inventors: Jossef Barath, Daniel Cherkassky, Yaron Karo
  • Patent number: 9589575
    Abstract: An echo cancellation system that detects and compensates for differences in sample rates between the echo cancellation system and a set of wireless speakers based on a frequency-domain analysis. The system generates Fourier transforms for a microphone signal and a reference signal and determines a series of angles for individual frames. For each tone in the Fourier transforms, the system determines the angles and uses linear regression to determine an individual frequency offset associated with the tone. Using the individual frequency offsets associated with the tones, the system uses linear regression to determine an overall frequency offset between the audio sent to the speakers and the audio received from a microphone. Based on the overall frequency offset, samples of the audio are added or dropped when echo cancellation is performed, compensating for the frequency offset.
    Type: Grant
    Filed: December 2, 2015
    Date of Patent: March 7, 2017
    Assignee: AMAZON TECHNOLOGIES, INC.
    Inventors: Robert Ayrapetian, Philip Ryan Hilmes
  • Patent number: 9240878
    Abstract: Techniques and methods for performing asymmetric, full-duplex communication via a signal line. In an embodiment, a transceiver includes transmit circuitry to transmit a first signal via a node coupled to a signal line, where the first signal is transmitted concurrently with the transceiver receiving a second signal via the node at a substantially different data rate than that of the first signal. In another embodiment, signal processing circuitry of the transceiver detects a composite signal at the node, the composite signal including a combination of the first signal and the second signal. Based on the combination of the first signal and the second signal, the signal processing circuitry generates a processed signal, including the signal processing circuitry reducing a contribution by the first signal. The processed signal is provided to receiver circuitry of the transceiver.
    Type: Grant
    Filed: January 27, 2014
    Date of Patent: January 19, 2016
    Assignee: Lattice Semiconductor Corporation
    Inventors: Rahul Velitheri, Vinayak Agrawal, Namrta Sharma, Prashanth Tirunagari, Manjusha Manchikalapudi
  • Patent number: 9232071
    Abstract: Mobile communication devices, having multiple speakers and/or microphones to perform a number of audio functions, for use with mobile devices, are provided. The microphones may be housed within the communication device housing. To compensate for the unwanted signal feedback between the speakers and microphones, acoustic echo cancellation may be implemented to determine the proper distance and relative location between the speakers and microphones. Acoustic echo cancellation removes the echo from voice communications to improve the quality of the sound. The removal of the unwanted signals captured by the microphones may be accomplished by characterizing the audio signal paths from the speakers to the microphones (speaker-to-microphone path distance profile), including the distance and relative location between the speakers and microphones. The optimal distance and relative location between the speakers and microphones is provided to the user to optimize performance.
    Type: Grant
    Filed: October 31, 2012
    Date of Patent: January 5, 2016
    Assignee: QUALCOMM Incorporated
    Inventors: Erik Visser, Michael Joseph Contour, Eric S. Mattis, Joseph Robert Fitzgerald, Kwokleung Chan
  • Patent number: 9154187
    Abstract: Systems and methods for operating a filter for echo cancellation are described. In one embodiment, a method for operating a filter for echo cancellation involves monitoring at least one of a filter coefficient of the filter and an echo cancellation error to generate a monitoring result and, in response to the monitoring result, adjusting at least one of delay elements and filter taps of the filter to vary an impulse response of the filter. Other embodiments are also described.
    Type: Grant
    Filed: May 24, 2013
    Date of Patent: October 6, 2015
    Assignee: NXP B.V.
    Inventors: Sujan Pandey, Frits Steenhof
  • Patent number: 9143621
    Abstract: A canceller splits a signal, transmitted from a near end terminal (ET) to a far ET, into a sub-sampled signal corresponding to a higher frequency sub-band of the signal transmitted to the far ET, and a sub-sampled signal corresponding to a lower frequency sub-band of the signal transmitted to the far ET; and splits a signal received from a far ET into a sub-sampled signal corresponding to a higher frequency sub-band of the signal received from the far ET, and a sub-sampled signal corresponding to a lower frequency sub-band of the signal received from the far ET. The canceller includes a first adaptive filter for filtering the sub-sampled signal corresponding to the lower frequency sub-band, a second adaptive filter for filtering the sub-sampled signal corresponding to the higher frequency sub-band, and controls the adaptation of the first and second adaptive filters so that these two adaptations are never simultaneous.
    Type: Grant
    Filed: January 11, 2012
    Date of Patent: September 22, 2015
    Assignee: Alcatel Lucent
    Inventors: Moulay Fadili, François Pinier
  • Patent number: 9077363
    Abstract: A method and system for encoding an analog signal on a stochastic signal, the encoded signal then converted to a digital signal by an analog to digital converter, the analog to digital converter thereafter decoding from the encoded signal a digital signal, which corresponds to the analog signal. The stochastic signal may be a noise signal shaped to a Gaussian normal curve. An encoding process is performed by a multiplication circuit, which multiplies the stochastic signal by the analog signal, producing a product signal for an analog to digital conversion. During analog to digital conversion, the product signal is decoded. The decoding is performed using an arithmetic operation, which may be a Root Sum Square function or a Root Means Square function. The decoded signal is then mapped to account for offset error, gain error, and endpoint adjustment. The result is a decoded digital signal corresponding to the analog signal.
    Type: Grant
    Filed: December 3, 2013
    Date of Patent: July 7, 2015
    Assignee: ANALOG DEVICES, INC.
    Inventor: Thomas M. MacLeod
  • Patent number: 8976715
    Abstract: A packet voice transceiver adapted to reside at a first end of a communication network and to send an ingress communication signal comprising voice packets to, and receive an egress communication signal comprising voice packets from, a second packet voice transceiver residing at a second end of the communication network. The packet voice transceiver includes a far-end echo canceller that reduces echo that is present in the egress communication signal. The far-end communicates with other functional components of the transceiver system and adapts its behavior based on the activity of the other functional components.
    Type: Grant
    Filed: February 19, 2008
    Date of Patent: March 10, 2015
    Assignee: Broadcom Corporation
    Inventor: Wilfrid LeBlanc
  • Patent number: 8837651
    Abstract: An apparatus and a method for estimating a channel in a broadband wireless access system. A receiving apparatus includes a first channel estimation filter having a tap coefficient which is channel-adaptively variable, the first channel estimation filter acquiring a channel impulse response by filtering received pilot symbols, a second channel estimation filter having a fixed tap coefficient, the second channel estimation filter acquiring a channel impulse response by filtering received pilot symbols, and a selector which selects the operation of one of the first and the second channel estimation filters according to channel correlativity.
    Type: Grant
    Filed: August 23, 2007
    Date of Patent: September 16, 2014
    Assignee: Samsung Electronics Co., Ltd
    Inventor: Jae-Hoon Jeon
  • Patent number: 8797575
    Abstract: A communication control apparatus including: a count portion that counts the number of received data; and a discard portion that is provided at an upstream side of a control portion on a forwarding route of the received data, and discards received data according to a counted value by the count portion.
    Type: Grant
    Filed: August 17, 2010
    Date of Patent: August 5, 2014
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Yuichi Kawata, Yoshifumi Bando, Keita Sakakura, Hiroaki Yamamoto, Kenichi Takahashi, Masakazu Kawashita
  • Patent number: 8787861
    Abstract: In some implementations, an apparatus includes an echo canceller that generates an echo interference compensation signal that compensates for an echo interference signal in a communication signal, a crosstalk canceller that generates a crosstalk interference compensation signal that compensates for a crosstalk interference signal in the communication signal, and a combiner that generates a combined interference compensation signal based on the echo interference compensation signal and the crosstalk interference compensation signal.
    Type: Grant
    Filed: September 7, 2012
    Date of Patent: July 22, 2014
    Assignee: Marvell International Ltd.
    Inventors: Xiaopeng Chen, Runsheng He
  • Patent number: 8659986
    Abstract: A transceiver system is disclosed. The transceiver system comprises a first transceiver physical layer circuit (PHY) having a first plurality of channels and a second transceiver PHY disposed adjacent the first transceiver PHY and having a second plurality of channels. Filter circuitry is coupled between at least one of the plurality of first channels and at least one of the plurality of second channels.
    Type: Grant
    Filed: July 25, 2011
    Date of Patent: February 25, 2014
    Assignee: Aquantia Corporation
    Inventors: Jerry Martinson, Paul Langner, Hossein Sedarat
  • Patent number: 8605891
    Abstract: A system and method for provide a stable gain from an adaptive gain control device in a signal path. An echo canceller is also located in the signal path, and is used to provide performance information regarding losses in the signal. This performance information is fed to the automatic gain control device via a connection. The automatic gain control device thereafter uses the performance information to determine a maximum gain that might be provided based upon losses cause by echo conditions. The gain however is limited in order to provide for a stable system. The performance information includes a loss rate that includes a combination of the echo return loss and the echo return loss enhancement.
    Type: Grant
    Filed: June 21, 2011
    Date of Patent: December 10, 2013
    Assignee: Broadcom Corporation
    Inventor: Wilfrid LeBlanc
  • Patent number: 8559532
    Abstract: To assist with the detection of unfiltered device(s), a system observes how the received noise changes between two links as the transmit signal is changed. Harmful unfiltered nonlinear devices will generate significant noise that depends on the transmitted signals; therefore, this additional noise can be quantified to some extent by comparing the observed noise for two different transmit signals. The total noise can be determined from the SNR if the received signal is known. The received signal may be read directly in some non-standard systems, or it may be determined from the known transmit signal and channel attenuation, which is sometimes the case in standard-compliant links, but often with a relatively large error. To circumvent this problem, certain embodiments of this invention only consider the change in noise between two links with the same channel attenuation. This differential comparison makes it unnecessary to accurately know the channel attenuation.
    Type: Grant
    Filed: January 26, 2009
    Date of Patent: October 15, 2013
    Assignee: AWARE, Inc.
    Inventor: Christopher Cunningham
  • Patent number: 8411603
    Abstract: Methods and systems for dual digital microphone processing in an audio CODEC are disclosed and may include demultiplexing one or more received time-multiplexed digital audio signals from one or more digital microphones, and separately processing each of the demultiplexed digital audio signals. The digital microphones may include microelectromechanical (MEMS) microphones. The demultiplexed digital audio signals may be level-converted, downshifted, and/or filtered. The filtering may include a finite impulse response (FIR) filter. A sampling rate of the one or more demultiplexed digital audio signals may be converted by repeating the demultiplexed digital audio signals. Audio beamforming and/or diversity processing may be performed utilizing the digital microphones.
    Type: Grant
    Filed: August 28, 2008
    Date of Patent: April 2, 2013
    Assignee: Broadcom Corporation
    Inventor: Hongwei Kong
  • Patent number: 8364298
    Abstract: A system, method, and program product are provided for filtering sound from a selected application on a computer without interrupting voice communications on the computer. The method comprises: monitoring a selected program for an outgoing digital audio signal from a selected application; detecting said digital audio signal; and filtering an analog microphone input with the digital audio signal.
    Type: Grant
    Filed: July 29, 2009
    Date of Patent: January 29, 2013
    Assignee: International Business Machines Corporation
    Inventors: William Arthur Griffith, Indran Naick, Wing Sent
  • Patent number: 8270394
    Abstract: Methods and apparatus describe techniques for reducing interference signals in a communication signal. An apparatus includes, in at least one aspect, a transceiver circuit to receive a communication signal that includes one or more interference signals and a compensation circuit to generate a compensation signal to compensate for the one or more interference signals in the communication signal based on one or more cancellation coefficients and one or more data symbols.
    Type: Grant
    Filed: December 29, 2008
    Date of Patent: September 18, 2012
    Assignee: Marvell International Ltd.
    Inventors: Xiaopeng Chen, Runsheng He
  • Patent number: 8254490
    Abstract: Embodiments of a method and apparatus of reducing transmit signal components of a receive signal of a transceiver are disclosed. One embodiment of an apparatus includes a transceiver that simultaneously transmits a transmit signal and receives a receive signal. The transceiver includes a transmit DAC that generates the transmit signal based on a transmit digital signal stream. The transmit DAC includes a plurality of transmit DAC circuit elements, and a plurality of transmit DAC switches that control which of the plurality of transmit DAC circuit elements contribute to generating the transmit signal. The transceiver additionally includes an echo cancellation DAC that generates an echo cancellation signal based on the transmit digital signal stream.
    Type: Grant
    Filed: July 19, 2010
    Date of Patent: August 28, 2012
    Assignee: PLX Technology, Inc.
    Inventor: Gaurav Chandra
  • Patent number: 8190114
    Abstract: A method of transmitting information in a wireless communications system can be provided by selectively applying filtering to transmission of a carrier signal of a first band of frequencies of a wireless communications system based on a frequency separation distance between a frequency content of the carrier signal and a second band of frequencies allocated to a communications system other than the wireless communications system.
    Type: Grant
    Filed: July 17, 2006
    Date of Patent: May 29, 2012
    Assignee: ATC Technologies, LLC
    Inventors: Peter D. Karabinis, Santanu Dutta
  • Patent number: 8130941
    Abstract: An echo canceler 10 generates an echo elimination signal by filtering through adaptive filters 101 and 102 reference signals input from sound sources causing echoes. It includes a sound source number detecting unit 103 for detecting the number of the sound sources causing echoes from the reference signals, and a control unit 105 for making the number of taps of the adaptive filters 101 and 102 variable in accordance with the number of the sound sources detected by the sound source number detecting unit 103.
    Type: Grant
    Filed: April 10, 2009
    Date of Patent: March 6, 2012
    Assignee: Mitsubishi Electric Corporation
    Inventors: Takuya Taniguchi, Shin Kato, Noritaka Kokido
  • Patent number: 8077642
    Abstract: A method includes transmitting a first signal over a network from a first communication link to a second communication link. The method further includes receiving a second signal with the first communication link from the second communication link. The method further includes canceling signal echo from the first signal present in the second signal with a digital echo canceller. The method further includes providing correction data from a memory array to the digital echo canceller during the cancellation of the signal echo. An associated apparatus is also disclosed.
    Type: Grant
    Filed: December 28, 2007
    Date of Patent: December 13, 2011
    Assignee: Intel Corporation
    Inventor: Ehud Shoor
  • Patent number: 7483420
    Abstract: Digital signaling processing (DSP) circuitry that supports multiple channel or time division multiplexing (TDM) applications is provided. For example, the DSP circuitry can process one or more channels of data without mixing the data of one channel with data of another channel. DSP circuitry of the invention supports multiple channel or TDM applications by embedding a tap delay line structure within the DSP circuitry. Utilizing this embedded tap delay line structure enables the DSP circuitry to support multi-channel or TDM applications independent of any external circuitry such as logic resources, thereby freeing up those resources for other uses.
    Type: Grant
    Filed: March 8, 2004
    Date of Patent: January 27, 2009
    Assignee: Altera Corporation
    Inventor: Ben Esposito
  • Patent number: 7471670
    Abstract: Methods and apparatus describe techniques for reducing interference signals in a communication signal. A communication signal is received through a receiver. The communication signal contains an interference signal. A digital replica of the interference signal is generated, the digital replica is converted into a corresponding analog replica of the interference signal. The analog replica of the interference signal is subtracted from the communication signal.
    Type: Grant
    Filed: January 20, 2004
    Date of Patent: December 30, 2008
    Assignee: Marvell International Ltd.
    Inventors: Xiaopeng Chen, Runsheng He
  • Publication number: 20080151791
    Abstract: A packet voice transceiver adapted to reside at a first end of a communication network and to send an ingress communication signal comprising voice packets to, and receive an egress communication signal comprising voice packets from, a second packet voice transceiver residing at a second end of the communication network. The packet voice transceiver includes a far-end echo canceller that reduces echo that is present in the egress communication signal. The far-end communicates with other functional components of the transceiver system and adapts its behavior based on the activity of the other functional components.
    Type: Application
    Filed: February 19, 2008
    Publication date: June 26, 2008
    Inventor: Wilfrid LeBlanc
  • Publication number: 20070280388
    Abstract: A novel and useful mechanism for shutting down very small canceller taps that have little influence on the output of the canceller. Disabling or completely disabling these taps results in a significant reduction in power consumption of the circuit incorporating the canceller. Shutting down very low valued canceller taps also results in reduced least mean square (LMS) noise caused by the jittering of the smaller taps of the canceller. Several methods are provided that determine the number and location of the taps to be shutdown. The mechanism of the invention is operative to shut down canceller taps that are lower than a predetermined threshold. Methods include comparing each individual tap to a threshold, comparing an average of each tap to a threshold, comparing groups of taps to a threshold and comparing an average of groups of taps to a threshold. Taps or groups of taps are smaller than the threshold are shutdown thus reducing the power consumption of the canceller.
    Type: Application
    Filed: May 31, 2006
    Publication date: December 6, 2007
    Inventors: Rafi Dalla Torre, Itay Lusky, Nohik Semel, Oran Keren, Ariel Yagil
  • Patent number: 7065056
    Abstract: A circuit for transmitting and receiving communications. The circuit includes a transmit block, a receive block, and an echo canceller, coupled to the transmit block and to the receive block, for determining an echo signal and subtracting it from the received signal, the determination of the echo signal involving a predetermined number N of coefficients calculated at the beginning of each of the communications in an initialization phase. The circuit periodically updates during communication a restricted group of coefficients chosen from among the most significant coefficients. The present invention also relates to an echo cancellation method.
    Type: Grant
    Filed: June 29, 2001
    Date of Patent: June 20, 2006
    Assignee: STMicroelectronics S.A.
    Inventor: William Glass
  • Patent number: 6947395
    Abstract: An echo cancelling system for cancelling echoes in a communication path includes an echo locator and an echo canceller. The echo locator is coupled to the communication path and locates the positions of echo signals received from the communication path. The echo canceller is also coupled to the communication path and cancels echo signals received therefrom. During echo cancellation, the echo canceller becomes active in regions corresponding to the positions of echo signals in response to the echo locator.
    Type: Grant
    Filed: September 14, 2000
    Date of Patent: September 20, 2005
    Assignee: Mitel Networks Corporation
    Inventors: Mirjana Popovic, Dieter Schulz
  • Patent number: 6744887
    Abstract: A system and method of Acoustic Echo Cancellation includes a digital filter used to estimate the echo path is split into 2 filters: one fixed infinite impulse response (IIR) filter and one adaptive finite impulse response (FIR) filter. The fixed filter models the composite frequency response of the loudspeaker, its cabinet enclosure and the direct coupling path between the loudspeaker and the microphone(s). The adaptive filter models the time varying characteristics of the indirect coupling path between the loudspeaker and microphone.
    Type: Grant
    Filed: October 5, 1999
    Date of Patent: June 1, 2004
    Assignee: Zhone Technologies, Inc.
    Inventors: Alberto D. Berstein, Abraham Wei, Tom Wei
  • Patent number: 6694020
    Abstract: The invention is a multiple channel teleconferencing system employing a stereophonic acoustic echo canceler that exploits the coherence between multiple channels. In accordance with the invention a small non-linearity is incorporated into each channel path between the microphone and the speaker and an efficient frequency domain adaptive algorithm is implemented in the echo canceler circuit. The frequency domain algorithm converges to a solution much more quickly, than, for instance, a time domain, normalized least mean squares, solution.
    Type: Grant
    Filed: September 14, 1999
    Date of Patent: February 17, 2004
    Assignee: Agere Systems, Inc.
    Inventor: Jacob Benesty
  • Patent number: 6671374
    Abstract: An adaptive filter for echo cancellation includes a segmented sparse transversal filter having an input, the filter having an adjustable length, adjustable lengths for the segments and adjustable tap weights. The adaptive filter further includes an adaptive tap weight control mechanism providing a tap weight vector including tap weights and a tap weight vector length to the taps of the transversal filter, the adaptive tap weight control mechanism setting the tap weights and the tap weight vector length in response to comparison of estimated truncation error to a target truncation value and in response to a magnitude of integrated cross correlation coefficients between a reference signal and an error signal from the adaptive filter.
    Type: Grant
    Filed: August 3, 2000
    Date of Patent: December 30, 2003
    Assignee: Globespanvirata, Inc.
    Inventors: Omar A. Nemri, Sandeep Pombra
  • Patent number: 6661895
    Abstract: A zero-delay structure to be used in sub-band echo cancellation systems. In telecommunications, a delay is usually introduced in sub-band decomposition and/or sub-band reconstruction. This invention will help remove this. This structure not only removes the delay but does not sacrifice the performance of the echo canceller. It is to be used in combination with any sub-band-based echo canceller or wavelet echo canceller.
    Type: Grant
    Filed: October 7, 1999
    Date of Patent: December 9, 2003
    Assignee: Zarlink Semiconductor Inc.
    Inventors: Qu Jin, Kon Max Wong, Qiang Wu, Philippe Wu, Gordon J. Reesor
  • Patent number: 6498850
    Abstract: A compander circuit (20) for echo cancellation in telecommunications apparatus with an estimator module (21) for estimating an echo coupling and a delay of a line echo and a characteristic module (23) with an associated multiplier (24) for controlling the short-time output level of zout(k) as a function of the short-time input level of zin(k) is characterized in that at all inputs and outputs of the compander circuit (20), a plurality of N communications channels are applied and outputted, respectively, at an N-fold clock rate as compared with a single communications channel; that all memory units in the compander circuit (20) are designed as multiplexer-buffer-demultiplexer (MBD) units (30); and that a modulo-N counter (26) is provided which controls all MBD units (30) so that in each of the MBD units (30), always the same memory cell (351, 352, 35N) assigned to a particular communications channel is addressed.
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: December 24, 2002
    Assignee: Alcatel
    Inventors: Michael Walker, Hans Jürgen Matt, Armin Mann, Fritz Weinschenk, Holger Söhnle
  • Patent number: 6452967
    Abstract: A method for reducing disturbing effects of coupling between a first transmission/reception device and a second transmission/reception device that are each connected to a subscriber line. According to the method, a signal received on a reception path of the first device is delayed by a delay equal to p times the transmission period. A coupling signal relating to a transmission path of a second device and the reception path of the first device is estimated based on a signal transmitted over the transmission path of the second device, and the delayed signal is ridded of the estimated coupling signal. Additionally, a device for transmitting/receiving a signal is provided. The device includes a memory coupled to a reception path for temporarily storing p symbols, a subtraction circuit, and a coupling estimation block.
    Type: Grant
    Filed: February 17, 1999
    Date of Patent: September 17, 2002
    Assignee: STMicroelectronics S.A.
    Inventor: François Druilhe
  • Patent number: 6426979
    Abstract: The present invention addresses signal noise problems associated with telecommunications. In particular, echo cancellation is addressed by the present invention, which employs an inventive adaptive filtration scheme. In one aspect of the invention, a method is provided for controlling an adaptive balance filter. In another aspect of the invention, an apparatus is provided for controlling an adaptive balancing filter, comprising: a transmit path; an adaptive balance control circuit; and a receive path.
    Type: Grant
    Filed: April 29, 1999
    Date of Patent: July 30, 2002
    Assignee: Legerity, Inc.
    Inventors: Xun Yang, Yan Zhou
  • Publication number: 20020080865
    Abstract: A circuit having a hybrid to convert a bi-directional signal into an input signal and an output signal A signal subtractor to receive the input signal and subtract therefrom an estimated echo signal produced by an echo estimation unit which may derive the estimated echo signal from the output signal.
    Type: Application
    Filed: November 27, 2001
    Publication date: June 27, 2002
    Inventor: Ishai Schwarzband
  • Patent number: 6404809
    Abstract: An improved two-point equalizer training technique for use with V.90 modem systems utilizes a number of scaling parameters to enable the compensation of robbed bit signaling (RBS) effects in a manner that is decoupled from the compensation of analog impairments in the data communication channel. The preferred technique employs six scaling parameters corresponding to the six RBS phases typically associated with practical V.90 systems. One of the scaling parameters is fixed at a value of one to simplify the computational load associated with the adaptive training algorithms. The decision error is utilized to adaptively adjust the equalizer filter taps and the scaling parameters. The techniques of the present invention may be used to initially train the equalizer resident at the analog client modem and/or to initially train the echo canceler resident at the digital server modem.
    Type: Grant
    Filed: September 8, 1998
    Date of Patent: June 11, 2002
    Assignee: Conexant Systems, Inc.
    Inventor: Xuming Zhang
  • Patent number: 6381272
    Abstract: A multi-channel adaptive filter system for use, for example, in echo cancellation for generating an echo estimate for each channel is described. The system includes a forward and backward prediction filter parameter generator that in response to the multi-channel inputs generates a single forward prediction filter vector signal {right arrow over (&ohgr;)}p−1(n) and corresponding single forward error F(n) signal and a single backward prediction filter vector signal {right arrow over (&ngr;)}p−1(n) and corresponding single backward error signal B(n). The system further includes an error generator responsive to errors in the estimated signal for multiplying the errors by a 1-&mgr; where &mgr; is a constant for generating error vector signals {right arrow over (e)}i.p-{right arrow over (e)}J,p(n) for each channel.
    Type: Grant
    Filed: January 22, 1999
    Date of Patent: April 30, 2002
    Assignee: Texas Instruments Incorporated
    Inventor: Murtaza Ali
  • Patent number: 6256383
    Abstract: An automatic balance system for a transmit signal of a wireless local loop communication system. The automatic balance system includes a finite impulse response (FIR) filter system, the FIR filter system including at least one FIR tap for replicating at least one portion of an echo signal, the echo signal being an undesired component of the transmit signal. The system also includes a non-adaptive infinite impulse response (IIR) filter system operatively coupled to the FIR filter system, the non-adaptive IIR filter system including an IIR tap for replicating a long-tail portion of the echo signal. A first summer is operatively coupled to the FIR filter system and non-adaptive IIR filter system, the first summer combining the output replicated portions of the echo signal from the FIR filter system and the IIR filter system to generate a replicated echo signal.
    Type: Grant
    Filed: November 7, 1997
    Date of Patent: July 3, 2001
    Assignee: Legerity, Inc.
    Inventor: Herbert M. K. Chen
  • Patent number: 6246444
    Abstract: A digital/analog TV common-use receiver having a single ghost canceler, and a ghost cancellation method are provided. The single ghost canceler includes a first filter coefficient generator for generating first filter coefficients using a first reference signal included in the analog TV signal, a second filter coefficient generator for generating second filter coefficients using a second reference signal included in the digital TV signal, and a digital filter for filtering the analog TV signal using the first filter coefficients if the analog TV signal is received, and the digital TV signal using the second filter coefficients if the digital TV signal is received. Since an equalizer used when receiving a terrestrial digital TV broadcast is also used upon receiving a terrestrial analog TV broadcast, the single equalizer can correspond to both digital and analog TV signals.
    Type: Grant
    Filed: October 28, 1998
    Date of Patent: June 12, 2001
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Ki-bum Kim
  • Patent number: 6219334
    Abstract: A coherent detection type OFDM receiver is disclosed. The coherent detection type OFDM receiver demodulates a digital data sequence. The OFDM receiver obtains a channel frequency response with a frequency spectrum of a received signal and a frequency spectrum of a reference signal. The channel frequency response is filtered in the frequency domain by a filter. At this point, the OFDM receiver estimates delay time of a received delayed signal and designates the bandwidth of the filter with the estimated result. The OFDM receiver compensates the distortion of the waveform of the received signal with the channel frequency response that has been filtered by the filter and demodulates a digital data sequence with the received waveform that has been compensated.
    Type: Grant
    Filed: March 12, 1998
    Date of Patent: April 17, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kazumi Sato, Minoru Namekata
  • Patent number: 6181794
    Abstract: An echo canceler for canceling an echo signal mixed in an input signal received from a hybrid circuit. The echo canceler has a double filter structure comprised of an adaptive filter and a fixed filter. The adaptive filter receives the input signal to generate a first echo estimation signal according to a filter coefficient thereof, and the fixed filter receives the input signal to generate a second echo estimation signal according to a filter coefficient thereof. A first adder subtracts the first echo estimation signal from the input signal to generate a first echo-canceled signal, and a second adder subtracts the second echo estimation signal from the input signal to generate a second echo-canceled signal. A mode selector selectively outputs one of the first and second echo-canceled signals having a relatively more canceled echo component.
    Type: Grant
    Filed: October 7, 1997
    Date of Patent: January 30, 2001
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Ho-Chong Park, Young-Ky Kim
  • Patent number: 6130943
    Abstract: A method and an apparatus suppresses echo in telephone communication systems having a send path and a receive path. A first filter is coupled to the send path carrying a voice signal. The first filter removes a first set of frequencies but allows either fundamental frequencies or second harmonics in the voice signal to pass through. Thus, the first filter preserves the fundamental frequencies or the second harmonics in the voice signal. A complementary filter is coupled to the receive path carrying the echo. The complementary filter is used to remove the remaining frequencies that are present in the echo. By operating jointly in a complementary way, the first filter and the complementary filter removes the echo.
    Type: Grant
    Filed: December 23, 1996
    Date of Patent: October 10, 2000
    Assignee: MCI Communications Corporation
    Inventor: William Christopher Hardy
  • Patent number: 6028929
    Abstract: An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive non-linear echo path response detection. The echo canceller circuit comprises a first digital filter having non-adaptive tap coefficients to simulate an echo response occurring during a call. A second digital filter having adaptive tap coefficients to simulate an echo response occurring during the call is also used. The adaptive tap coefficients of the second digital filter are updated over the duration of the call. A coefficient transfer controller is disposed in the echo canceller circuit to transfer the adaptive tap coefficients of the second digital filter to replace the tap coefficients of the first digital filter when a set of one or more transfer conditions is met. A non-linear echo path response detector is provided. The non-linear echo path detector is responsive to one or more parameters of the first and second digital filters to detect a non-linear echo path condition.
    Type: Grant
    Filed: November 14, 1997
    Date of Patent: February 22, 2000
    Assignee: Tellabs Operations, Inc.
    Inventor: Kenneth P. Laberteaux
  • Patent number: 6009083
    Abstract: The problem of tracking rapid changes in the echo signals associated with modems is eliminated by using an echo canceler consisting of cascaded adaptive filters. Each filter in the structure contributes to the modeling of the overall echo path impulse response, with a longer filter providing the ability to model long echo path impulse responses and a shorter filter providing the ability to track changes in the echo path impulse response over time.
    Type: Grant
    Filed: February 12, 1998
    Date of Patent: December 28, 1999
    Assignee: Lucent Technologies, Inc.
    Inventors: Richard Thomas Flanagan, Jean-Jacques Werner