Entries |
Document | Title | Date |
20080205633 | Estimating delay of an echo path in a communication system - Methods and corresponding systems for reducing an echo signal include assigning a subsegment delay to each of a plurality of subsegment adaptive filters. A send signal and a delayed receive signal are coupled to each of the subsegment adaptive filters, wherein the delayed receive signal is delayed according to a respective subsegment delay. A set of filter coefficients in each of the subsegment adaptive filters are adapted, in parallel, to correspond to a respective subsegment impulse response of a connected system. Each set of filter coefficients is analyzed to produce a pure delay, and the pure delay is used to delay the receive signal for a main adaptive filter. An echo signal replica is produced using the main adaptive filter and an error signal. The echo signal replica is subtracted from the send signal to produce the error signal. | 08-28-2008 |
20080219434 | METHOD AND APPARATUS FOR VOICE COMMUNICATION - A voice communication device with an integrated framework structure for echo cancellation and noise reduction is disclosed. A microphone receives a local input signal while a speaker is outputting a local output signal. The local input signal and output signal are all decomposed into a plurality of subband signals by filter banks for conducting individual processing of echo cancellation and noise reduction per subband. The subband echo canceller is followed by a DFT unit to split the cancellation result into a plurality of narrow frequency bins whereby the noise reduction is performed. The noise reduction results are recombined by an IDFT unit for residual echo removal in a subband non-linear processor. The final output is obtained from a synthesis filter bank that synthesizes the subband signals after echo cancellation and noise reduction into a full-band signal. | 09-11-2008 |
20080240413 | CROSS-CORRELATION BASED ECHO CANCELLER CONTROLLERS - Cross-correlation based echo canceller controllers are described herein. By way of example, a system for controlling an echo canceller having one or more adaptive filters can include one or more adaptive filter controllers each corresponding to one of the one or more adaptive filters and each configured to halt adaptation of its corresponding adaptive filter according to the cross-correlation of its corresponding corrupted signal and its corresponding error signal of its corresponding adaptive filter. | 10-02-2008 |
20080240414 | HYBRID ECHO CANCELLER CONTROLLERS - Hybrid echo canceller controllers are described herein. By way of example, a system for controlling an echo canceller can include a signal indicator and an echo canceller controller. The signal indicator can be configured to indicate periods of near-end signal and to indicate periods of echo only with echo-path change in the corrupted signal based at least in part on cross-correlation between two signals associated with the echo canceller. The echo canceller controller can be configured to control the echo canceller according to indications from the signal indicator. | 10-02-2008 |
20080240415 | HYBRID ECHO CANCELLER CONTROLLERS - Hybrid echo canceller controllers are described herein. By way of example, a system for controlling an echo canceller can include a cross-correlator, a discriminator and an echo canceller controller. The cross-correlator can be configured to produce a cross-correlation based output that facilitates controlling the echo canceller by cross-correlating two signals associated with the echo canceller. The discriminator can be configured to produce a discriminator output that discriminates between near-end signal and echo in a corrupted signal. The echo canceller controller can be configured to control the echo canceller according to the cross-correlation based output and the discriminator output. | 10-02-2008 |
20080247535 | Method and apparatus for mitigating impact of nonlinear effects on the quality of audio echo cancellation - A method is provided for reducing the adverse impact of echo on audio quality in a two-communication system. The method includes two parts. The first part begins by detecting non-linear effects (e.g. clippings and audio glitches). If a non-linear effect is detected, the system temporarily disables adaptation of the adaptive filter. In this way, filter coefficients obtained before the non-linear effect happens will not be corrupted, so the AEC can quickly recover from the non-linear effects. The second part begins by monitoring a parameter reflecting signal quality (e.g., ERLE). If the signal quality parameter falls below a given value the system switches from a full-duplex mode of operation to a half-duplex mode of operation. In this way, when a non-linear effect that is undetectable or occurs repeatedly (e.g., speaker volume changes) and which can corrupt an acoustic echo canceller (AEC) for a relatively long period of time, the system switches from full-duplex operation to half-duplex operation. In half-duplex operation, communication can only happen in one direction at a time, and thus the echo path is broken, effectively eliminating echoes. When the non-linear effect is no longer present and the quality parameter rises to a normal level, communication returns to a full-duplex mode of operation and the AEC once again removes the echoes. | 10-09-2008 |
20080247536 | Spectral domain, non-linear echo cancellation method in a hands-free device - Disclosed is a non-linear echo canceller and method for cancelling echo during full duplex communication in a hands free communication system. An input signal from a far-end talker and an input signal from the output from an echo canceller are received. K spectral subbands are created for each input signal. The spectral echo residual power at each subband is estimated and compared to a clean signal power to calculate a signal to echo ratio. Gains are calculated based on each calculated ratio and non-linear echo is cancelled based on the calculated gains. | 10-09-2008 |
20080260141 | Method and apparatus for enhanced convergence of the normalized LMS algorithm - Adaptive filters employing a normalized time domain least mean square algorithm having enhanced convergence rates by virtue of the use of an update gain greater than | 10-23-2008 |
20080304653 | Acoustic echo cancellation solution for video conferencing - Echo cancellation for audio/video conferencing uses an inaudible tone added at an originating conference site to the transmitted voice signal, for echo cancellation. The tone, upon receipt with the voice signal at a remote conferencing site and retransmission back to the originating site, is used to determine both the round trip delay of the conferencing link and the acoustic characteristics of the remote site, so as generate an echo cancellation signal for better audio performance. | 12-11-2008 |
20080310617 | Transmission Links - A device is provided for measuring properties of transmission links by an adaptive filter. The device comprises a first output terminal adapted to provide a first signal to the transmission link. Further, the device includes a first input terminal for receiving an echo signal of the first signal. An adaptive filter forms a part of the device and is coupled to the first input terminal. The device includes a second output terminal for providing information identifying filter coefficient of the adaptive filter. | 12-18-2008 |
20090028321 | Echo Path Change Detection in a Network Echo Canceller - An echo canceller is proposed that has an echo path change detector ( | 01-29-2009 |
20090060167 | Adaptive filter for use in echo reduction - Methods and corresponding systems in an adaptive filter include calculating a signal estimator output using filter coefficients, and calculating an error signal. Next, a coefficient threshold is determined. Thereafter, for each filter coefficient, a first step size is assigned to filter coefficients with a magnitude less than the coefficient threshold, and a second step size is assigned to filter coefficients with a magnitude greater than or equal to the coefficient threshold. Finally, the filter coefficients are updated using the first and second step sizes and the error signal. The coefficient threshold can be selected as the average of the magnitudes of the filter coefficients. Alternatively, the coefficient threshold can be selected as the Mth largest of the filter coefficients ranked in order of magnitude. In one embodiment, the first step size can be less than one and the second step size can be greater than one. | 03-05-2009 |
20090136020 | METHOD AND APPARATUS FOR ECHO CANCELLATION - A method and apparatus for echo cancellation is disclosed. The apparatus includes an echo compensator and a double talk detector. The echo compensator compensates for associated feedback echo by filtering an echo component from a receiver input signal. The double talk detector provides a control signal based on comparisons of a receiver output signal to a threshold signal and to a transmit signal. The echo compensator also selectively updates filter parameters based on the control signal. | 05-28-2009 |
20090232297 | Echo canceler and echo canceling method - An echo canceler uses an adaptive filter to remove an echo of an incoming far-end signal from an outgoing near-end signal in the presence of ambient noise, updating the filter coefficients while the far-end signal is active and the near-end signal is inactive. The near-end and far-end signals are also sampled to obtain data vectors, which are averaged to generate simulated near-end and far-end signals, from which substitute filter coefficients are calculated and updated while the far-end signal is silent, the substitute filter coefficients being used when the far-end signal becomes active again. The number of data vectors averaged is varied according to the ratio of echo power to ambient near-end noise power, or according to the echo attenuation ratio, thereby speeding up convergence of the filter coefficients. Data sampled while the near-end and far-end signals are both active are excluded from the updating process. | 09-17-2009 |
20090245502 | ACOUSTIC ECHO CANCELER - An echo canceler is constituted of an adaptive filter for generating an echo replica simulating an echo occurring in an echo path lying between a speaker and a microphone, a subtracter for subtracting the echo replica from the sound received by the microphone, a double-talk detector which extracts a prescribed frequency band, in which the signal level is attenuated due to the echo path, from the output signal of the subtracter and which determines a double-talk event with respect to the extracted frequency band, and a controller for controlling the adaptive filter to update the echo replica in the double-talk event. | 10-01-2009 |
20090245503 | DEVICE FOR CANCELING CROSSTALK, SIGNAL PROCESSING SYSTEM AND METHOD FOR CANCELING CROSSTALK - A method for canceling crosstalk, the method includes the steps of: filtering the signal corresponding to a far end crosstalk source in the frequency domain according to adaptive filter parameter; combining the received signal corresponding to a far end sending signal and the filtered signal in frequency domain corresponding to the far end crosstalk source. A device for canceling crosstalk and a signal processing system. | 10-01-2009 |
20090257579 | Echo Canceller - An echo canceller is capable of reducing echo feeling in a conversation even if a tone signal is input. The echo canceller of this invention judges whether a far-end input signal is a calling control tone signal or not, and if that is the case, resets a coefficient of an adaptive filter. An echo canceller of another aspect judges whether a far-end input signal is a predetermined kind of a tone signal or not, and stops the update of the coefficient of the adaptive filter if the result is affirmative and an amount of echo cancellation is not larger than a threshold value. Further, when the tone signal ends, the echo canceller compares amounts of echo cancellation before and after the end of the tone signal, in accordance with a result of the comparison, restart the update of the coefficient of the adaptive filter after resetting the coefficient of the adaptive filter, or restarts the update of the coefficient of the adaptive filter without resetting the coefficient of the adaptive filter. Moreover, notch filters may be provided to eliminate a tone signal frequency component at input stages of the adaptive filter and the adder for echo cancellation. | 10-15-2009 |
20090304178 | Echo canceler - An echo canceller, in which an adder adds a pseudo echo generated by an adaptive filter to an echo, so that the echo and the pseudo echo are canceled to each other, includes: a subband filter ( | 12-10-2009 |
20100002867 | METHOD AND ARRANGEMENT FOR THE ADAPTIVE FILTERING OF SIGNALS - The invention relates to a method for adaptive filtering in which a level of a reference signal necessary for the adaptive filtering is determined in the context of an adaptation by estimation, using a quantity equivalent to the reference signal, wherein the filtering is dependent on the electrical power of at least one signal extracted from a transmission channel to be filtered, and the equivalent quantity is determined by means of a mathematical function based on the electrical power of at least the extracted signal. The invention further relates to an arrangement with means for carrying out the method. | 01-07-2010 |
20100054454 | Method and apparatus for the detection and suppression of echo in packet based communication networks using frame energy estimation - A method and apparatus for use in suppressing acoustic echo in a target speech signal being transmitted through a packet-based communications network uses frame energy estimation applied to the target speech signal and to a reference speech signal. The method or apparatus estimates one or more reference speech energy levels in one or more reference packets based on one or more of the speech parameters generated by the speech encoding of the reference signal; estimates a target speech energy level in a target packet based on one or more of the speech parameters generated by the speech encoding of the target signal; compares the target speech energy level to one or more reference speech energy levels; and detects an echo in the target speech signal based on the comparison of the target speech energy level to the one or more reference speech energy levels. | 03-04-2010 |
20100054455 | METHOD AND ARRANGEMENT FOR CONTROLLING ADAPTIVE FILTERS - The invention relates to methods for controlling adaptive filters, where a first step involves a first input signal, which has a narrowband frequency range and occurs at least intermittently during an adaptation phase in the filter, at the input of the filter prompting the adaptation phase to be continued until an echo signal which is conditional upon the first input signal and in the same frequency range is compensated for completely, a second step involves the adaptation phase being suspended when complete compensation for the echo signal has been achieved, and a third step involves the adaptation phase being continued if the first input signal is followed by a second input signal which has a narrowband frequency range and which differs from the frequency range of the first input signal at least by a frequency value, with the above steps being repeated starting at the first step, or with a fourth step involving a new adaptation phase being performed if the first input signal is followed by a third input signal having a wideband frequency range. The invention also relates to an arrangement for carrying out the method. | 03-04-2010 |
20100074432 | Double-talk detection - Within audio telecommunications for audio-visual conferencing a means of reliable double-talk detection is required for several reasons, including control of residual echo, and control of adaptive algorithms used to estimate the echo. Existing techniques tend to either fail when echo return loss is very low or require highly complex algorithms to increase the range of detecting whether double-talk is occurring. The invention is based upon a new method of estimating the power envelope of the double-talk signal. This estimation is then employed in conjunction with a slightly modified version of an echo return loss enhancement (ERLE) based statistic, to form a double-talk decision based on a combination of the two statistics. The resulting decision rule works for both low-ERLE and high-ERLE situations, which is useful when there can be large variations in the magnitude of the echo path seen by the algorithms, or where near-end noise prevents the achievement of high ERLE. | 03-25-2010 |
20100074433 | Multichannel Acoustic Echo Cancellation - A multi-party spatial audio conferencing system is configured to receive far end signals from remote participants. The system comprises a speaker array that outputs spatialized sound signals and one or more microphones that capture and relay a sound signal comprising an echo of the spatialized sound signal to a multichannel acoustic echo cancellation (MC-AEC) unit having a plurality of echo cancellers. Respective echo cancellers perform cancellation of an echo associated with a far end signal from one of the multiple participants according to an algorithm based upon echo cancellation coefficients. The echo cancellation coefficients are determined from the input channel signals, the spatialization parameters associated with each input channel, and the audio signals captured by the microphones. This allows respective echo cancellation filters to be updated simultaneously even though the corresponding remote participant is not talking. | 03-25-2010 |
20100074434 | Echo cancelling device, communication device, and echo cancelling method having the error signal generating circuit - Provided is an echo canceller capable of realizing an excellent echo cancellation performance even in a double talk state. An echo canceller ( | 03-25-2010 |
20100086122 | Echo canceller and echo cancelling method and program - An echo canceler uses an adaptive filter to remove an echo of a far-end input signal from a near-end input signal. Filter coefficients are calculated and updated while the far-end signal is active. While the far-end signal is silent, substitute filter coefficients are similarly calculated to be swapped in as initial values for the filter coefficients when the far-end signal changes from silent to active. The substitute filter coefficients are generated from a simulated far-end signal and a simulated near-end signal obtained by combining corresponding samples in different intervals of the far-end and near-end input signals. To facilitate convergence of the substitute filter coefficients, use of the simulated far-end and near-end signals is disabled when the corresponding samples cancel out. | 04-08-2010 |
20100104091 | ENHANCED ECHO CANCELLATION - The present invention provides for echo cancellation circuitry and variable rate encoding circuitry to cooperate with one another to effectively provide comfort noise in an effective and efficient manner. The echo cancellation circuitry will use far-end signals to generate estimated echo signals, which correspond to the actual echo signals appearing in near-end signals. The estimated echo signals are essentially subtracted from the near-end signals in an effort to remove the actual echo signals from the near-end signals. The echo cancellation circuitry will monitor any residual echo signals in the resulting processed near-end signals and provide residual echo control signals that are indicative of whether the residual echo signals should be replaced with comfort noise. The residual echo control signals are used at least in part by the variable rate encoding circuitry to determine the encoding rate to use for encoding different portions of the processed near-end signals. | 04-29-2010 |
20100135483 | SYSTEMS AND METHODS FOR DOUBLE-TALK DETECTION IN ACOUSTICALLY HARSH ENVIRONMENTS - A communications device that is configured to detect double talk is described. An echo canceller is configured to cancel an echo from an input signal using an adaptive filter. A double-talk detector provides a double-talk statistic. The double-talk statistic is proportional to the ratio of the remaining echo energy in the cancellation error signal and the total cancellation error energy. | 06-03-2010 |
20100177884 | ECHO PRESENCE DETERMINATION IN VOICE CONVERSATIONS - Presence of echo in a conversation is determined through a search performed in the sub-band domain using independent short length adaptive filters across a range of sub-band and maximum expected echo delay values. The adaptive filters attempt to predict and cancel the echo in the microphone signal based on the content in the speaker signal. If substantial cancelation is achieved in any of the sub-band filters, echo presence in the microphone signal is determined. | 07-15-2010 |
20100226492 | Echo canceller canceling an echo according to timings of producing and detecting an identified frequency component signal - An echo canceller includes an initial delay estimator producing a reference signal containing an identified frequency component masked by means of frequency masking effect to output the reference signal on an echo path, and detecting, from a sending voice signal, an echo component of the identified frequency component derived from the reference signal. The estimator finds an initial delay amount on the echo path on the basis of a forming timing of the reference signal containing the identified frequency component and a detection timing of the echo component in the identified frequency component in the sending voice signal. The echo canceller includes a delay circuit for delaying a received voice signal by the initial delay amount on the echo path obtained from the estimator to supply a resulting signal to a pseudo echo generator. | 09-09-2010 |
20100266118 | Method and System for Stereo Echo Cancellation for VOIP Communication Systems - An exemplary embodiment of the present invention is directed toward a method and system for cancelling line echo in the presence of a known secondary audio signal. Filter adaption is enabled in the presence of a known secondary audio source such as the sound of a computer game, a music signal or other secondary audio sources that would otherwise prevent echo cancellation due to an apparent double talk condition. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims. | 10-21-2010 |
20100272251 | ECHO REMOVING APPARATUS, ECHO REMOVING METHOD, AND COMMUNICATION APPARATUS - Disclosed herein is an echo removing apparatus including: a sound input terminal configured to input an external sound signal from external equipment; a first echo removing device configured to, after admitting as input signals the external sound signal coming from the external equipment and input through the sound input terminal and a receiver sound signal transmitted from a calling party, estimate a first pseudo echo component from the external sound signal in order to remove the first pseudo echo component from the receiver sound signal; and a second echo removing device configured to, after admitting as input signals the external sound signal coming from the external equipment and input through the sound input terminal and a transmitter sound signal input from a microphone, estimate a second pseudo echo component from the external sound signal in order to remove the second pseudo echo component from the transmitter sound signal. | 10-28-2010 |
20100290615 | Echo canceller operative in response to fluctuation on echo path - In a telephone device, a near-end signal processor delays each input near-end signal delivered from the respective microphones by a delay amount, and synthesizes the input near-end signals into a synthesized near-end signal. In an echo canceller, mounted on board the telephone device, a far-end signal is delayed by the same delay amounts as used in the near-end signal processor to form plural delayed far-end signals, which are synthesized into a synthesized far-end signal, with which the echo component in the synthesized near-end signal will be suppressed. | 11-18-2010 |
20100303228 | METHOD AND SYSTEM FOR A DUAL ECHO CANCELLER - Methods and systems for a dual echo canceller (EC) are disclosed and may include cancelling echo in utilizing a dual echo canceller, wherein said dual echo canceller includes an active echo canceller and an adaptive echo canceller. Filter coefficients may be copied from the adaptive echo canceller to the active echo canceller for the cancellation, based on whether said adaptive echo canceller has converged. The coefficients may be copied utilizing copy logic, which may comprise divergence detection and/or echo path change detection. The coefficients may be reset to default settings utilizing the copy logic. The coefficients may be calculated utilizing normalized block least mean squares (NBLMS), and may be calculated when the NBLMS is enabled by update logic. The coefficients may be calculated utilizing linear predictive coefficient (LPC) filtered uplink and downlink signals. | 12-02-2010 |
20110013766 | METHOD AND APPARATUS HAVING ECHO CANCELLATION AND TONE DETECTION FOR A VOICE/TONE COMPOSITE SIGNAL - A system includes receive and send inputs, an adaptive filter, a combiner, a non-linear processor, and a tone detector. The receive input receives a first signal having first voice and first tone information. The send input receives a second signal having echo information, second tone information, and second voice information. The adaptive filter has an input coupled to the receive input, and an output. The combiner has a first input coupled to the send input, a second input coupled to the output of the adaptive filter, and an output providing an intermediate signal. The nonlinear processor has an input coupled to the output of the combiner and an output for providing an output signal for obtaining the second voice. The tone detector is coupled to the output of the combiner and detects the second tone in the intermediate signal prior to the intermediate signal being processed by the nonlinear processor. | 01-20-2011 |
20110033037 | ADAPTIVE FILTERING WITH FLEXIBLE SELECTION OF ALGORITHM COMPLEXITY AND PERFORMANCE - An adaptive filter configured to use multiple algorithm species that differ in the quality of echo suppression and respective burdens imposed on the computational resources of the host communication device. Depending on the available computational budget, the adaptive filter selects an algorithm species that, while supporting a relatively high quality of echo suppression, involves a relatively low risk of overwhelming the computational resources. The adaptive filter monitors changes in the available computational budget and, if appropriate or necessary, can change the algorithm species to maintain a quality of echo suppression that is optimal for the current computational budget. If a change of the algorithm species is initiated, then at least a portion of internal algorithm data from the previously running algorithm species might be transferred for use in the subsequent algorithm species. | 02-10-2011 |
20110044448 | System for low complexity adaptive ECHO and NEXT cancellers - The present invention relates to design and implementation of low complexity adaptive echo and NEXT cancellers in multi-channel data transmission systems. In this invention, a highly efficient weight update scheme is proposed to reduce the computational cost of the weight update part in adaptive echo and NEXT cancellers. Based on the proposed scheme, the hardware complexity of the weight update part can be further reduced by applying the word-length reduction technique. The proposed scheme is general and suitable for real applications such as design of a low complexity transceiver in 10GBase-T. Different with prior work, this invention considers the complexity reduction in weight update part of the adaptive filters such that the overall complexity of these adaptive cancellers can be significantly reduced. | 02-24-2011 |
20110058667 | ECHO CANCELLER HAVING ITS EFFECTIVE FILTER TAPS ADAPTIVELY CONTROLLED WITH ECHO CANCELLATION AMOUNT MONITORED - In an echo canceller including an ADF and a cancellation adder, an ACANC calculator finds an average value of the amount of echo cancellation for a predetermined period to update the average value of the amount of echo cancellation, and detects a convergence state of the ADF to find the amount of echo cancellation in the convergence state of the ADF. A coefficient selector, when receiving a detection signal of the convergence state from the ACANC calculator, finds a power ratio of the sum total of power of all tap coefficients and the partial total of power of tap coefficients not to be assigned to taps to determine the effective number of taps useful for suppressing an echo component on the basis of the amount of echo cancellation and the power ratio. The ADF updates only the effective number of taps to disable the remaining taps. | 03-10-2011 |
20110064213 | Time Domain Adaptive Filter Bank for Network Echo Reduction or Cancellation - In one or more embodiments, an echo reduction system can include multiple adaptive filters operable to provide estimated echo replicas based on received signal information coupled to respective multiple adders that can combine a send signal and outputs of the respective adaptive filters and can provide respective output combinations to a filter selector. The filter selector can select from the outputs of the adders and provide a selected output as output for the echo reduction system. In one or more embodiments, the filter selector can control signal processing of the filters by providing control signal to the adaptive filters, where the control signals can indicate to ones of the adaptive filters to pause or continue signal processing. In one or more embodiments, the echo reduction system can include at least one delay unit that can delay receive signal information to at least one of the adaptive filters. | 03-17-2011 |
20110085656 | Method and System for Filtering a Signal and for Providing Echo Cancellation - The present invention provides for adaptive filters that have improved computational and memory bandwidth proprieties. When applied to telecommunication applications, the present invention additionally provides for improved methods and systems of canceling echoes. In one embodiment of the adaptive filter of the present invention, a filter, preferably an adaptive finite impulse response (FIR) filter, of an appropriate length, N, is chosen. Once the filter is chosen, convergence is achieved and the filter is converted to an infinite impulse response (IIR) filter. In the course of operation, data is received from an input source and used to adapt the zeroes of the IIR filter using the least means square (LMS) approach, keeping the poles fixed. The adaptation process generates a set of converged filter coefficients that are then applied to the input signal to create a modified signal used to filter the data. The novel adaptive filter method and system presented herein can be used to improve the calculation of the echo impulse response by, among other things, reducing the computational complexity and memory requirements of the coefficient calculation conducted within the adaptive filter. | 04-14-2011 |
20110091031 | ECHO CANCELER - An echo canceler | 04-21-2011 |
20110150210 | Distributed VAD control system for telephone - A telephone includes a transmit channel and a receive channel, each including a bank of sub-band filters having a VAD coupled one to each sub-band filter. Each VAD measures the spectral energy in a sub-band, compares the spectral energy to a first threshold, and produces an output signal representative of whether or not the first threshold is exceeded. The voice activity detector also includes a threshold circuit for calculating a dynamically adjustable noise threshold based upon averaged measured spectral energy. A wide band or system VAD monitors echo canceling circuitry to detect voice activity and double talk. | 06-23-2011 |
20110261948 | Techniques for Updating Filter Coefficients of an Adaptive Filter - A technique for updating filter coefficients of an adaptive filter includes filtering a signal with an adaptive filter, whose filter coefficients are grouped into filter blocks. In this case a number of the filter blocks is less than or equal to a number of the filter coefficients. During each update period, the filter coefficients for less than all of the filter blocks are updated based on a network echo path impulse response. | 10-27-2011 |
20110261949 | Techniques for Implementing Adaptation Control of an Echo Canceller to Facilitate Detection of In-Band Signals - A technique for detecting in-band signaling tones in a communication system includes performing a first adaptation of an adaptive filter of an echo canceller in response to detection of a far-end harmonic signal. In this case, the adaptive filter provides an echo estimation signal. The technique also includes subtracting the echo estimation signal from a near-end signal that includes one or more in-band signaling tones to provide an error signal. The technique further includes detecting, using a tone detector, the one or more in-band signaling tones in the error signal. | 10-27-2011 |
20110261950 | ADAPTIVE FILTER AND ECHO CANCELLER HAVING THIS ADAPTIVE FILTER - Disclosed is an adaptive filter that prevents adaptation error from increasing in a state of double talk, without providing a double-talk detection circuit. In this adaptive filter, using input signal x[n] and error signal e[n], a tap coefficient setting section ( | 10-27-2011 |
20120069989 | PERSONAL SPEAKERPHONE DEVICE - This disclosure describes a personal speakerphone device for teleconferencing a local participant with near side audio data and a far side participant with far side audio data. The device includes a controller that couples to a speaker and a microphone inside an enclosure that couples the speaker and the microphone within a coupling frequency range, and where the enclosure houses the speaker, the microphone, the controller, analog to digital conversion circuitry, digital to analog conversion circuitry, supporting circuitry, and one or more ports for data through which audio data is transferred. Additionally, the device includes a first frequency band decomposer, a second frequency band decomposer, one or more echo cancellers, and a converger. Further, the device includes a primary doubletalk detector and a secondary doubletalk detector. | 03-22-2012 |
20120099722 | ECHO CANCELER - An echo canceler | 04-26-2012 |
20120099723 | ECHO CANCELER - An echo canceler | 04-26-2012 |
20120140918 | SYSTEM AND METHOD FOR ECHO REDUCTION IN AUDIO AND VIDEO TELECOMMUNICATIONS OVER A NETWORK - A method and a system use an intermediate server to process the communication between two parties, so as to eliminate echoes between them. The server performs echo cancellation in a network-based voice communication system handling a large number of conversations. In one implementation, the server allocates two echo cancellation modules to each conversation, with each echo cancellation module including (a) a communication interface for communicating with a client program associated with the echo cancellation module; (b) a first buffer for storing audio data received from the client program for transmission to another echo cancellation module; (c) a second buffer for storing audio data received from the other echo cancellation module for transmitting to the associated client program; and (d) a set of filters using the audio data in both the first buffer and the second buffer to cancel echoes in the audio data in the second buffer. | 06-07-2012 |
20120224685 | Cross-Talk Coefficient Updating In Vector Transmission - Embodiments related to far-end cross-talk coefficient updating in vector transmission systems are depicted and described herein. | 09-06-2012 |
20120237018 | APPARATUS AND METHOD FOR CONVERGENCE CONTROL - Regardless of the presence of echo or uplink speech, a microphone signal is received at a small filter and this small filter is functionally and/or physically separate from an adaptive echo canceller filter. The signal is applied to the small filter and an error signal is determined from the signal utilizing the small filter. The small filter continuously adapts the received signals. A first adaptation factor is determined based at least upon the error signal and the microphone signal according to a first signal analysis approach and a second adaptation factor is determined based at least upon the microphone signal according to a second signal analysis approach. The first adaption factor is compared to the second adaptation factor and one of the first adaptation factor or the second adaptation factor is selected based upon at least one predetermined criteria. The selected adaptation factor is applied to the echo canceller filer to control the convergence of the echo canceller filter. | 09-20-2012 |
20120288084 | FAST ECHO GAIN CHANGE DETECTION - An apparatus generally having a first circuit and a second circuit is disclosed. The first circuit may be configured to synthesize a first vector by filtering a second vector based on a third vector. The second circuit may be configured to (i) generate a gain corresponding to a fourth vector, (ii) compare the gain to a plurality of thresholds and (iii) update the third vector as a function of the gain where the compare determines that the gain is not between the thresholds. The fourth vector may be received from a network as an echo of the second vector. | 11-15-2012 |
20130044872 | ECHO CANCELLER AND A METHOD THEREOF - The present invention relates to an echo canceller ( | 02-21-2013 |
20130077777 | INPUT/OUTPUT APPARATUS AND COMMUNICATION TERMINAL - An input/output apparatus includes a speaker, a microphone, an adaptive filter circuit and a control circuit. The speaker is configured to output audio based on a voice-receiving signal. The microphone is configured to produce a voice-transmitting signal based on gathered audio. The adaptive filter circuit is configured to produce a residual signal based on a pseudo echo signal and a amplified voice-transmitting signal. The pseudo echo signal is produced from the voice-receiving signal and a transfer coefficient which expresses audio transfer properties between the speaker and the microphone. The amplified voice-transmitting signal is produced by causing a microphone amplification circuit to amplify the voice-transmitting signal. The control circuit is configured to stop output of the residual signal from the adaptive filter circuit during at least one of the speaker and the microphone is muted. | 03-28-2013 |
20130129078 | ECHO CANCELLER - The proposed echo canceller comprises:—an adaptive filter for receiving a signal affected by an echo, and for supplying a filtered signal that is an estimate of the echo;—a subtractor for subtracting this estimate from the received signal and supplying a residual signal;—means for detecting ( | 05-23-2013 |
20130136254 | Method In A Communication System - Method and arrangement in a Vector Control Entity for efficient selection of which crosstalk to cancel when applying partial vectoring in a DSL communication system. The method comprises calculating a respective crosstalk effect indicator, CEI | 05-30-2013 |
20130163748 | SYSTEM FOR REDUCING SPEAKERPHONE ECHO - A telecommunication system including a speakerphone provides a coupled signal path, including a microphone, configured to sense an incoming audio signal and an echo signal and generate a coupled signal. The echo signal includes non-linear distortion generated by a speaker of the speakerphone. An echo signal path, including an amplifier, is configured to sense the echo signal and generate an echo reference signal. The echo reference signal includes the non-linear distortion. An acoustic echo canceller is configured to receive the coupled signal from the coupled signal path, to receive the echo reference signal from the echo signal path, and to cancel out the non-linear distortion included in the coupled signal based on the non-linear distortion included in the echo reference signal. | 06-27-2013 |
20130163749 | System and Method for the Application on an LMS Method to Updating an Echo Canceller in an ADSL Modem - An echo cancellation device relies on the known characteristics of the sync frame to monitor, update in an off-line fashion and determine the accuracy of an echo canceller in, for example, a modem, such as an ADSL modem. Specifically, time domain samples are read from the transmit (Tx) and receive (Rx) paths of the modem. These samples are stored in memory. When the sync frame has received a predetermined number of the same Tx samples and Rx samples, the samples are stored. Running averages, over the sync frames, of the TX and RX samples are maintained. These averages are subtracted from a sync frame of samples, to allow LMS updating of the echo canceller taps, free of extraneous signals. Updating, i.e., tracking of changes in the echo channel, is done for the echo canceller in an off-line fashion. The coefficients for the in-line version are updated, while the off-line version is updated over several sync frames. Periodically, the performance of the off-line version is compared with the in-line version. The coefficients of the in-line version are replaced by those of the off-line version only if it is determined the off-line version, which is tracking echo channel changes, has better performance. After replacement of the in-line coefficients, the off-line tracking is continued in the off-line version. | 06-27-2013 |
20130236004 | Method and System for Stereo Echo Cancellation for VOIP Communication Systems - An exemplary embodiment of the present invention is directed toward a method and system for cancelling line echo in the presence of a known secondary audio signal. Filter adaptation is enabled in the presence of a known secondary audio source such as the sound of a computer game, a music signal or other secondary audio sources that would otherwise prevent echo cancellation due to an apparent double talk condition. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims. | 09-12-2013 |
20130243184 | METHODS, APPARATUS AND ARTICLES OF MANUFACTURE TO CANCEL ECHO FOR COMMUNICATION PATHS HAVING LONG BULK DELAYS - Example methods, apparatus and articles of manufacture to cancel echo for a communication path having long bulk delays are disclosed. A disclosed example method includes determining a first location of a first coefficient having a largest magnitude of a first plurality of magnitudes associated with a first plurality of coefficients of a first phase; determining a second location of a second coefficient having a largest magnitude of a second plurality of magnitudes associated with a second plurality of coefficients of a second phase different than the first phase; comparing a difference between the first and second locations to a threshold; and, when the difference is less than the threshold, selecting a first offset based on a greater of the magnitude of the first coefficient and the magnitude of the second coefficient; and cancelling an echo contained in a signal using the first offset. | 09-19-2013 |
20130329882 | Half-Duplex Speakerphone Echo Canceler - A speakerphone having transmit path with a microphone and a first amplifier having a gain determined by a controller and an input coupled to the microphone, a receive path with a second amplifier having a gain determined by the controller and a speaker coupled to an output of the second amplifier, and operable in a half-duplex mode using an adaptive echo canceller to at least partially remove from the transmit path acoustically-coupled signals from the receive path. The controller increases the gain of the first amplifier and decreases the gain of the second amplifier when a level of signals in the transmit path exceed a level of signals in the receive path, and decreases the gain of the first amplifier and increases the gain of the second amplifier when the level of signals in the receive path exceed the level of signals in the transmit path. | 12-12-2013 |
20140023190 | MIMO Mechanism for Strong FEXT Mitigation - A digital subscriber line access multiplexer (DSLAM) configured to couple to a first subscriber line and a second subscriber line, wherein the DSLAM comprises at least one transmitter configured to transmit a first signal onto the first subscriber line in a first time slot, transmit a second signal onto the second subscriber line in the first time slot, wherein the first and second signals are linearly related and are intended for a first customer premise equipment (CPE), transmit a third signal onto the second subscriber line in a second time slot, and transmit a fourth signal onto the first subscriber line in the second time slot, wherein the third and fourth signals are linearly related and are intended for a second CPE. | 01-23-2014 |
20140056423 | ECHO CANCELLATION APPARATUS, ECHO CANCELLATION METHOD AND COMMUNICATIONS APPARATUS - An echo cancellation apparatus cancels an echo signal included in a second speech signal including the echo signal of a first speech signal, and includes: a first echo replica generating unit generating a first echo replica by processing the first speech signal through a filter whose characteristic is equalized with a acoustic transfer function of amplified sound; a first echo cancelling unit generating and providing a first echo-cancelled signal by subtracting from the second speech signal the first echo replica generated by the first echo replica generating unit; and a filter updating unit generating a nonlinear-converted echo-cancelled signal by performing nonlinear conversion on the first echo-cancelled signal generated by the first echo cancelling unit, and updating the filter characteristic thereby equalizing the filter characteristic with the acoustic transfer function, using the nonlinear-converted echo-cancelled signal, the first speech signal, and a norm of the first speech signal. | 02-27-2014 |
20140064476 | SYSTEMS AND METHODS OF ECHO & NOISE CANCELLATION IN VOICE COMMUNICATION - In an example, time and frequency domain speech enhancement is implemented on a platform having a programmable device, such a PC or a smartphone running an OS. Echo cancellation is done first in time domain to cancel a dominant portion of the echo. Residual echo is cancelled jointly with noise reduction during a subsequent frequency domain stage. The time domain block uses a dual band, shorter length Adaptive Filter for faster convergence. Non-linear residual echo is cancelled based on an echo estimate and an error signal from the adaptive filters. A controller locates regions that had residual echo suppressed and which do not have speech and injects comfort noise. The controller can be full-duplex and operate non-linearly. An AGC selectively amplifies the frequency bins, based on the Gain function used by the residual echo and noise canceller. | 03-06-2014 |
20140112467 | System and Method for Acoustic Echo Cancellation - A system and method are presented for acoustic echo cancellation. The echo canceller performs reduction of acoustic and hybrid echoes which may arise in a situation such as a long-distance conference call with multiple speakers in varying environments, for example. Echo cancellation, in at least one embodiment, may be based on similarity measurement, statistical determination of echo cancellation parameters from historical values, frequency domain operation, double talk detection, packet loss detection, signal detection, and noise subtraction. | 04-24-2014 |
20140133648 | METHOD AND APPARATUS FOR ACOUSTIC ECHO CANCELLATION IN VOIP TERMINAL - A method of acoustic echo cancellation in the VoIP terminal using processing of the far-end signal with the digital adaptive filter in order to obtain the echo estimate that is subtracted from the microphone signal in which the far-end signal, before is is converted to the analog from and passed to the loudspeaker ( | 05-15-2014 |
20140133649 | SYSTEMS AND METHODS FOR ECHO CANCELLATION AND ECHO SUPPRESSION - Traditionally, echo cancellation has employed linear adaptive filters to cancel echoes in a two way communication system. The rate of adaptation is often dynamic and varies over time. Disclosed are novel rates of adaptation that perform well in the presence of background noise, during double talk and with echo path changes. Additionally, the echo or residual echo can further be suppressed with non-linear processing performed using joint frequency-time domain processing. | 05-15-2014 |
20140146963 | Detecting Double Talk in Acoustic Echo Cancellation Using Zero-Crossing Rate - A method for acoustic echo cancellation in a communication device is provided that includes receiving a first near-end audio signal in the communication device, wherein the first near-end audio signal comprises acoustic echo of a far-end audio signal reproduced by the communication device, and performing echo cancellation on the first near-end audio signal to generate a second near-end audio signal with at least some of the acoustic echo removed, wherein the echo cancellation is performed responsive to presence or absence of double-talk (DT), and wherein a zero-crossing rate (ZCR) is used to detect the presence or absence of DT. | 05-29-2014 |
20140177822 | ECHO SUPPRESSION - Method, user device and computer program product for suppressing echo. An audio signal is output from a speaker. A microphone receives an audio signal, wherein the received audio signal includes an echo resulting from the outputted audio signal. A Finite Impulse Response filter estimate ĥ(n) is dynamically adapted in the time domain based on the outputted audio signal and the received audio signal to model an echo path h(n) related to the echo in the received audio signal. The filter estimate ĥ(n) is used in an estimate of the echo power in the received audio signal, and the estimated echo power is used to apply echo suppression to the received audio signal, thereby suppressing the echo in the received audio signal. | 06-26-2014 |
20140211935 | METHOD AND APPARATUS FOR REDUCING NOISE IN A COMMUNICATION SYSTEM - A system that incorporates teachings of the present disclosure may include, for example, a controller to: determine crosstalk coupling characteristics between a plurality of lines of a digital subscriber line system connected to a plurality of modems based on a transition between a full power mode and one or more other modes, and provide the determined crosstalk coupling characteristics to one or more of the plurality of modems for performance of at least one of pre-coding a transmitted signal and processing a received signal along a line of the plurality of lines, where the pre-coding and processing is performed based at least in part on the determined crosstalk coupling characteristics, and where the pre-coding of the transmitted signal and the processing of the received signal reduce effects of fluctuating crosstalk. Other embodiments are disclosed. | 07-31-2014 |
20140211936 | REDUCED MEMORY VECTORED DSL - A reduced-memory vectored DSL system includes methods and apparatus for reducing the bandwidth and memory storage demands on a vectored DSL system in which FEXT data is transmitted and stored. When test signal data, such as training and/or tracking data, is sent to determine FEXT characteristics of the DSL system, error signals are available for all or substantially all of the upstream and/or downstream frequency band DSL tones used in the system. Dividing a frequency band into sub-bands, only a subset of tones in each sub-band is used for deriving FEXT data. For tones in the sub-band subsets, full-precision FEXT data values can be derived. For other tones, approximations of the FEXT data can be derived. Memory is reduced in both the transmission of such FEXT data (between upstream and downstream ends of the DSL system) as well as within an upstream-end device such as a DSLAM that performs vectoring using a separate or internal vectoring processing apparatus. | 07-31-2014 |
20140233724 | DIGITAL SUBSCRIBER LINE MANAGEMENT USING VIRTUAL NOISE CALCULATION - A digital subscriber line management system is provided. It comprises a device for calculating a set of values specifying a virtual noise mask. The device includes a receiver for receiving or otherwise obtaining a set of measurements of noise levels experienced at a digital subscriber line transceiver at each of a plurality of frequencies at different times, and a processor for calculating, in respect or each frequency, a combined value based on a plurality of measurements taken at different times, and for generating the set of values specifying a virtual noise mask in dependence upon the combined values. | 08-21-2014 |
20140270148 | ACOUSTIC ECHO CANCELLATION USING A VARIABLE LENGTH ADAPTIVE FILTER - An audio conferencing system having a base station, a loud speaker and one or more microphones generally operates to receive a F.E. audio signal, play the signal, and to receive a N.E. audio signal at the microphone that includes the F.E. audio signal modified by an echo path and a N.E. audio signal. The base station includes an adaptive filter whose length is controlled to be variable depending upon activity detected at each of one or more filter elements comprising the adaptive filter. | 09-18-2014 |
20140270149 | Clipping Based on Cepstral Distance for Acoustic Echo Canceller - Echo cancellation is provided in a telephone device by calculating a metric value indicative of a similarity between a representation of an incoming signal from a far end talker and a representation of an outgoing signal from a near end talker. A threshold value is derived based on the metric value. A portion of the outgoing signal is removed by using the threshold value to determine an amount to remove from the outgoing signal with continuous, real-time updating of the threshold value. | 09-18-2014 |
20140270150 | Apparatus with Dynamic Audio Signal Pre-Conditioning and Methods Therefor - An apparatus includes an echo canceller having an audio signal input and an audio signal output and dynamic pre-conditioning logic. The dynamic pre-conditioning logic is operatively coupled to the echo canceller audio signal output as a feedback signal and has a dynamic pre-conditioning logic output operatively coupled to the echo canceller audio signal input. The dynamic pre-conditioning logic is also operative to receive an audio signal input from at least one microphone. The dynamic pre-conditioning logic is operative to analyze the feedback signal to obtain at least one characteristic, and pre-condition the audio signal input, based on the at least one characteristic of the feedback signal, and provide a pre-conditioned audio signal at the echo canceller audio signal input. The echo canceller audio signal output is then provided to a noise suppressor for the send path of a full duplex communication channel. | 09-18-2014 |
20140334620 | METHOD FOR PROCESSING AN AUDIO SIGNAL AND AUDIO RECEIVING CIRCUIT - A method for processing an audio signal is described comprising receiving a first audio signal via a first receiving path comprising a first microphone; receiving a second audio signal via a second receiving path comprising a second microphone; and performing echo suppression of the first audio signal based on the first audio signal and the second audio signal. | 11-13-2014 |
20150055774 | ECHO CANCELLATION WITH QUANTIZATION COMPENSATION - An apparatus having a first circuit and a second circuit is disclosed. The first circuit is configured to generate a first intermediate signal by expanding a first input signal subjected to a quantization. The second circuit is configured to generate a second intermediate signal based on a second input signal. The second intermediate signal approximates an echo in the first input signal caused by the second input signal. The second circuit is also configured to generate a third intermediate signal by companding the second intermediate signal to compensate the quantization of the first input signal. | 02-26-2015 |
20150078549 | CONTROLLING ECHO IN A WIDEBAND VOICE CONFERENCE - In one embodiment, an echo canceller configured to cancel echo in a wideband voice conference is provided. A double-talk condition may be when a plurality of users are speaking substantially simultaneously. When a double-talk condition is detected in the wideband conference, a high-frequency process is enabled and used to process signals in the high band to reduce echo. Accordingly, echo in the high band may not be produced by end devices being used by the users' speaking. Also, the users speaking have the echo cancelled in the low band and substantial echo does not result. This results in the users speaking experiencing the conference in the narrowband. The other users that are not speaking, however, continue to receive wideband signals. The users not speaking also continue to have echo cancellation performed for the high band and low band because these users are not speaking and thus attenuation of their voices is not a consideration. | 03-19-2015 |
20150117635 | NETWORK APPARATUS WITH MULTIPLE COMMUNICATION PORTS - This disclosure provides a network apparatus with communication ports, each connected to multiple channels, assigned a seed for eliminating the interference among the communication ports, and operable in a master or slave mode, each channel having a communication unit which comprises: an echo canceller, a near-end crosstalk (NEXT) canceller, a decision feedback equalizer, and a control unit configured for controlling the communication ports if the echo canceller and the decision feedback equalizer keep updating their filter coefficients according to the same symbol during a first pre-determined time-interval; wherein when more than two of the communication ports operate in the master mode, the control unit assigns different seeds to the more than two communication ports; and wherein when successive two of the communication ports operate in the slave mode, the control unit stops either the echo canceller or the NEXT canceller from updating their filter coefficients during a second pre-determined time-interval. | 04-30-2015 |
20150311949 | SIGNAL PROCESSING METHOD IN DSL SYSTEM, APPARATUS, AND SYSTEM - Embodiments of the present invention provide a signal processing method in a DSL system. The method includes: determining that there is no to-be-sent downstream signal on m subscriber lines in n subscriber lines; superimposing a signal X on the m subscriber lines, so that a signal output on the m subscriber lines after precoding processing is 0, where x | 10-29-2015 |
20160006540 | METHOD FOR ADJUSTING PARAMETERS OF SENDING DEVICE AND RECEIVING DEVICE, AND TERMINAL DEVICE - The present invention discloses a method for adjusting parameters of a sending device and a receiving device, and a terminal device. In the method, a new precoding parameter that needs to be used by a sending device on a line when a precoding matrix in a downlink direction of the line changes, and a new signal recovery parameter that needs to be used by a receiving device and matches the new precoding parameter are first acquired; and then the new precoding parameter, the new signal recovery parameter, and a set moment and/or symbol at which the sending device starts to use the new precoding parameter are sent to the sending device, and the new signal recovery parameter and the set moment and/or symbol are sent to the receiving device by using the sending device. | 01-07-2016 |
20160006880 | VARIABLE STEP SIZE ECHO CANCELLATION WITH ACCOUNTING FOR INSTANTANEOUS INTERFERENCE - Examples of the disclosure provide variable step size (VSS) adaptive echo cancellation in the presence of near-end noise such as dense double talk without using an explicit double talk detector and/or without using a dual-filter. During a conversation, the present value for an error signal is monitored. Based on the monitored present value for the error signal, a first function is determined. A second function is determined based on long-term statistics describing a reference signal, a near-end noise signal, and the error signal. An adaptation coefficient is calculated for the VSS adaptive filter based on the determined first function and the determined second function. The calculated adaptation coefficient is used in the VSS adaptive filter for echo cancellation against interference due to the near-end noise signal during the conversation. | 01-07-2016 |
20160014267 | Acoustic Echo Suppression | 01-14-2016 |
20160044159 | SYSTEM AND METHOD FOR ACOUSTIC ECHO CANCELLATION - A system and method for acoustic echo cancellation is provided. Embodiments may include receiving, at one or more microphones, an audio reference signal from an audio speaker. Embodiments may also include filtering the audio reference signal using one or more adaptive audio filters. Embodiments may further include analyzing a level of signal energy of the audio reference signal with regard to time, frequency and audio channel to identify at least one maximum error contribution point. Embodiments may also include updating the one or more adaptive audio filters based upon, at least in part, the analyzed audio reference signal. | 02-11-2016 |
20160127561 | Automatic Tuning of a Gain Controller - A gain control system for applying gain to a far-end signal, the system comprising: a signal identifier configured to detect an echo of the far-end signal in a microphone signal; and a path estimator configured to estimate a characteristic of an echo path of the detected echo, wherein: the signal identifier is further configured to detect a near-end signal from the microphone signal; and in response to detecting the near-end signal, the gain control system is configured to adjust the gain applied to the far-end signal in dependence on the estimated characteristic of the echo path. | 05-05-2016 |
20160134759 | Pure Delay Estimation - A system for estimating delay between a far-end signal and an echo of the far-end signal in a microphone signal, the system comprising: a buffer configured to store a time-series of far-end samples representing the far-end signal; a first delay estimator configured to form a first estimate of the delay in respect of a speech frame representing speech in the microphone signal; a second delay estimator configured to form a second estimate of the delay for the speech frame by operating a first set of one or more filters on far-end samples selected from the buffer in dependence on an operating delay; a second set of one or more filters for operation on far-end samples; and a controller configured to, in response to a determination that the first estimate of the delay for the speech frame differs from the operating delay for a previous frame by at least a predefined length of time, cause the one or more filters of the second set to operate on far-end samples selected from the buffer according to the first estimate of the delay and, if in respect of one or more speech frames a measure of convergence of the second set of filters exceeds a measure of convergence of the first set of filters by at least a first predefined threshold, update the operating delay using the first estimate of the delay. | 05-12-2016 |
20180027125 | ADAPTIVE FILTER UNIT FOR BEING USED AS AN ECHO CANCELLER | 01-25-2018 |