Abstract: Techniques for simultaneously and efficiently eliminating echo and noise mixed in voice are disclosed. According to one aspect of the present invention, an adaptive filter system for eliminating noises and echo mixed in voice signal comprises a first signal adaptive filter, a first subtractor, a second adaptive filter and a second subtractor. The first signal adaptive filter estimates the noise mixed in the voice signal according to a reference noise. The first subtractor subtracts the noise estimated by the first adaptive filter from the voice signal to obtain a voice signal without the mixed noise. The second adaptive filter estimates the echo mixed in the voice signal according to a remote voice signal. The second subtractor subtracts the echo estimated by the second adaptive filter from the voice signal without mixed noise to obtain a clean voice signal.

Abstract: An echo canceler circuit (10) and method attenuates at least post-echo canceler uplink data (90) to produce attenuated uplink data (100) in response to uplink echo return loss based attenuation data (40). The echo canceler circuit (10) includes an echo return loss based attenuation data generator (20) and at least an uplink data attenuator (30). The echo return loss based attenuation data generator (20) produces the uplink echo return loss based attenuation data (40) in response to echo return loss data (70). The echo return loss data (70) is based on at least one of: attenuated downlink data (50), pre-echo canceler uplink data (60), and/or amplifier gain data (80). The uplink data attenuator (30) attenuates the post-echo canceler uplink data (90) to produce attenuated uplink data (100) based on the uplink echo return loss based attenuation data (40).

Abstract: A signal processing system enhances communication. When an audio signal is detected, an echo component of the detected audio signal may be estimated. A near party communication device may receive an audio signal from a remote party communication device. A characteristic of the received audio signal may be adjusted based on the echo component of the detected audio signal.

Abstract: A system that incorporates teachings of the present disclosure may include, for example, an echo measurement device having a controller to transmit a test signal in a communication path which is looped back at an end point identified as having an echo problem. The test signal can be transmitted at a remote location from the end point. The test signal can be represented by a limited burst signal of one or more frequencies operating outside a range of an operating frequency of an echo canceller deactivation signal transmitted in the communication path. Additional embodiments are disclosed.

Abstract: Methods and apparatus for echo cancellation in a system having a speaker and a microphone are disclosed. The speaker receives a speaker signal x(t). The microphone receives a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t) that is dependent on the speaker signal x(t). The microphone signal d(t) is filtered in parallel with first and second adaptive filters having complementary echo cancellation properties relative to each other. A minimum echo output e3(t) is determined from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter. The minimum echo output has a smaller energy and less correlation to the speaker signal x(t). A microphone output is then generated using the minimum echo output e3(t).

Abstract: A method and apparatus for identifying echo sources in a communication path. A system that incorporates teachings of the present disclosure may include, for example, an echo measurement device (EMD) having a transmit module to transmit an echo canceller deactivation signal in a communication path of the communication system, wherein the echo canceller deactivation signal deactivates one or more echo cancellers in said communication path. The transmit module can also transmit a test signal in the communication path which is looped back at an end point identified as having an echo problem, wherein the test signal is transmitted at a remote location from the end point. The EMD can further include a detection module to detect one or more echo signals associated with the test signal. Additional embodiments are disclosed.

Abstract: A method and apparatus for adapting dual filters is disclosed. In one aspect, a method may include transforming a signal, adapting a first adaptive filter based on the transformed signal, estimating a delay of an impulse response based on the adaptation of the first filter, delaying a signal based on the estimated delay, and adapting a second adaptive filter based on the delayed signal. In one aspect, an echo or other unwanted signal may be reduced or cancelled based on the adaptation of the second filter.

Abstract: A non-linear processor for use in an echo canceller is set forth. The non-linear processor includes a center clipping digital filter receiving an echo compensated signal. The non-linear processor provides a center clipped output signal having non-linear thresholds at values of +TNLP and ?TNLP. The value of TNLP is dynamically dependent, at least in part, on echo return loss measurements. To limit the processor's susceptibility to corruption from double-talk conditions, the non-linear processor inhibits the dynamic setting of the TNLP value when a double-talk condition is present. Additionally, or in the alternative, the non-linear processor locks the value of the echo return loss measurement after a predetermined number of consecutive echo return loss measurements have values falling within a predetermined range of one another. Such locking further reduces the susceptibility of the non-linear processor to corruption from double-talk conditions.

Abstract: In one embodiment, the present invention includes an apparatus having an automatic gain control (AGC) stage to receive an input signal from a communication channel physical medium, a first local gain stage coupled to an output of the AGC stage, an equalizer coupled to an output of the first local gain stage, an echo canceler to receive local data to be transmitted along the communication channel physical medium, and a second local gain stage coupled to an output of the echo canceler. Other embodiments are described and claimed.

Abstract: A non-echo canceling voice band modem capable of detecting subscriber alerting signal (SAS) tones and customer premises equipment alerting signal (CAS) tones is provided. The modem includes a shaping filter, an analog-to-digital converter (ADC), a SAS tone detector, a CAS tone detector and an echo canceler. The shaping filter, which is located in a transmitting path of the modem, filters modem signals to be transmitted from the modem. The ADC, which is located in a receiving path of the modem, converts any incoming analog signal to corresponding digital signals to be used by the modem. The echo canceler, which is coupled to the SAS and CAS tone detectors, cancels any echoes in modem signals before sending said modem signals to the SAS and CAS tone detectors.

Abstract: An echo processing technique for attenuating echo components of a direct signal X1n in a return signal Y2n. A receive gain Grn and a send gain Gen are calculated. The receive gain Grn is applied to the direct signal and an input signal X2n is produced and emitted into an echo generator system. The send gain Gen is applied to an output signal Y1n from the echo generator system and the return signal Y2n is produced. A coupling variable COR is calculated which is characteristic of the acoustic coupling between the direct signal X1n or the input signal X2n and the output signal Y1n. The receive gain Grn and the send gain Gen are calculated on the basis of the coupling variable.

Abstract: An echo removing apparatus for reducing the echo caused by sound returning from a speaker to a microphone of a small-sized communication terminal, such as a portable telephone. The echo removing apparatus includes a filter unit for outputting a pseudo echo signal estimating an echo component returning to the microphone based upon a generated sound signal supplied to the speaker, a subtractor for subtracting the pseudo echo signal supplied from the filter unit from the sound generated collection signal supplied from the microphone and a first characteristics conversion unit for converting frequency characteristics of sound generated collection signals from the microphone on the frequency axis. The characteristics of the filter unit are controlled for minimizing an error component between an output signal of the first characteristics conversion unit and an output signal of the filter unit.

Abstract: The present invention provides a solution to the needs described above through a method and apparatus for reducing echo and noise. The apparatus includes a microphone array for receiving and audio signal, the audio signal including a voice signal component and a noise signal component. The apparatus further includes a voice processing path having an input coupled to the microphone array and a noise processing path having an input coupled to the microphone array. The voice processing path is adapted to detect voice signals and the noise processing path is adapted to detect noise signals. A first echo controller is coupled to the voice processing path and a second echo controller is coupled to the noise processing path. A noise reducer is coupled to the output of the first echo controller and second echo controller.

Abstract: Bridge circuit for echo suppression for a reception signal of a communication device connected to a transmission line, to which can be supplied a reception signal received via the transmission line and a transmission signal to be transmitted by the communication device via the transmission line. The bridge circuit is designed such that on balancing the bridge circuit, the reception signal there can be tapped echo-compensated with a transmission signal part generated by the transmission signal being suppressed. To balance the bridge circuit a variable simulation device is provided to simulate at least one circuit section of at least one bridge branch and connect with the at least one bridge branch. By such an arrangement, the signal level in the simulation device may be reduced so far that this can be designed as an integrated circuit and to be programmable.

Abstract: A system and method for signal analysis in a network. The method includes attempting, by a first processor, to compute optimal coefficients for filtering a signal, determining that computing the optimal coefficients exceeds the computational capabilities of the first processor, notifying a second processor that computing the optimal coefficients exceeds the computational capabilities of the first processor, and computing, by the second processor, the optimal coefficients. The system and method account for limited computational resources allocated to certain processors in a telecommunications system.

Abstract: A combined sidetone and hybrid balance apparatus and method of operating same are disclosed. An embodiment of the present invention may provide both a hybrid balance mode of operation and a sidetone generation mode of operation within a single integrated circuit device. The functionality provided by an embodiment of the present invention may be used in both Internet protocol (IP)-based telephones and residential gateways, and may be incorporated within the IP telephone chip used in such devices. An embodiment of the present invention may be used to reduce processor demand and the cost of materials, permitting greater IP telephone or residential gateway functionality at lower cost.

Abstract: A noise level calculator for detecting noise in a telephone line echo canceller that utilizes adaptive filters enables silencing of noise switching so that it is not heard on the far end side. The calculator promotes determining whether the reference signal applied to the adaptive filter is a noise or non-noise segment. The calculator operates by calculating the difference in energy of two sample windows, calculating the difference in the energy of the signal within each of the sample windows, updating a variance parameter based on the difference, and performing further alternative operations based on the value of the variance parameter.

Abstract: A switching center for use in a communication network includes a pool of echo cancellation units for use in providing echo cancellation services to users associated with the switching center on an “as needed” basis. A communication connection being supported by the switching center is analyzed to determine whether intolerable reflections are being received from an associated trunk. If such reflections are detected, one of the echo cancellation units in the pool is assigned to the communication connection for use in reducing or eliminating the reflections. When the communication connection terminates, the echo cancellation unit is returned to the pool for subsequent use with another communication connection.

Abstract: The invention is directed to techniques for suppressing the voice of a user of an audio electronic device, such as a mobile phone, from being heard by an unintended listener. In one arrangement, the invention includes an input microphone, an electronics module, and a suppression speaker. The user speaks into the input microphone, and the electronics module generates an antivoice signal from a voice signal received from the input microphone. The suppression speaker outputs an antivoice output that combines with the voice of the user to form a voice suppression zone next to the speaker. The user thus can carry on his or her conversation in private as long as the unintended listener is within the voice suppression zone. Alternately, the user can avoid distracting other users of similar devices nearby, such as in a crowded office environment with many individuals using telephones at the same time.

Abstract: A distributed echo cancelling architecture is provided where echo-cancelling functions are performed at locations remote from devices receiving signals with echoes. The echo cancelling functions use a reference signal, which has been corrupted with the echoes at the devices, for echo cancellation. As echo canceller resources are located at a central system and not at each individual device, the echo canceller resources can therefore be shared between the devices.

Abstract: The invention relates to a communications network, including switching centers having no echo canceling equipment and switching centers having echo canceling equipment. The switching centers are capable of changing the call party or the call during the call. The switching center which controls the change of call party or call type is arranged to command the nearest switching center having the echo canceling capability to connect/disconnect an echo canceling equipment to/from the connection. In other words, in these special situations the echo cancellation is controlled by a new signaling feature within the communications network.

Abstract: A non-linear processor for managing a speech signal is disclosed. The non-linear processor includes an adaptive lattice filter that generates a prediction error from a residual echo of the speech signal, a signum non-linearity unit that generates an excitation component from the prediction error, an excitation signal mixer that generates an excitation signal from the excitation component and a noise component, an inverse lattice filter that generates a modified residual echo from the excitation signal, and a gain adjuster that adjusts a power of the modified residual echo.

Abstract: Methods and apparatus compensating for background noise associated with a transmitted signal. In a first embodiment, an adder combines an echo estimate with the the transmitted signal to form a processed signal, a noise reduction circuit uses a background noise estimate to subtract the background noise from the processed signal, and a non-linear processor uses the background noise estimate to combine a compensating background noise signal with the proccssed signal. In another embodiment, the noise reduction circuit divides the processed signal into sub-bands. With variations of an embodiment, the nonlinear processor is a sub-band non-linear processor, the processed signal is divided into sub-bands, and the background estimate includes sub-band noise estimates.

Abstract: A wraparound delay amount detecting part calculates a cross-correlation r(k) from an output speech signal “ai” supplied to a loudspeaker and an input speech sigal “bi” inputted through a microphone array to obtain a delay amount “d” of a wraparound speech signal. The delay processing part generates a speech signal “ai-d” obtained by delaying the output speech signal “ai” by the delay amount “d”. Even if there is a change in delay amount due to the variation in environment, appropriate delay processing can be conducted by the delay processing part. In an adaptive filter, an estimated wraparound speech signal ai-d? is generate from the speech signal “ai-d” subject to delay processing. A subtracter subtracts the estimated wraparound speech signal ai-d? from the input speech signal “bi” to generate an echo cancellation signal “ei”. A coefficient updating part updates the coefficient of the adaptive filter.

Abstract: A system for updating filter coefficients for use with an echo canceller, a related method for updating filter coefficients and an echo canceller including the system or the method. In one embodiment, the echo canceller has a nonadaptive filter and an adaptive filter, the nonadaptive filter having nonadaptive filter coefficients and configured to develop a nonadaptive error signal as a function of the nonadaptive filter coefficients, and the adaptive filter having adaptive filter coefficients and configured to develop an adaptive error signal as a function of the adaptive filter coefficients. The system includes a monitoring subsystem configured to monitor a quality of the nonadaptive and adaptive error signals and a selection subsystem configured to select one of the nonadaptive and adaptive filter coefficients for use by the nonadaptive filter based on the quality of the nonadaptive and adaptive error signals.

Abstract: A method of controlling an echo canceller in a communications channel, is disclosed wherein input signals from the communications channel are first subbanded into a subband. Echo locations are then identified within the subband and are used to control the echo canceller. Typically, the echo canceller will be a fullband echo canceller with an adaptive filter, in which case the echo locations are used to control the filter coefficients.

Abstract: A method and system for measuring the signal transmission time through a network link bounded by at least one echo canceller. The method generally includes the steps of determining a signal transmission time (tA) along a network path including the network link bounded by the echo canceller between a first endpoint and a second endpoint, transmitting a test signal from the first endpoint to the second endpoint through the network path, transmitting an echo signal which simulates the test signal from the second endpoint to the first endpoint through the network path, measuring a minimum time delay between transmission of the test signal and transmission of the echo signal which causes the echo canceller to cancel the echo signal and calculating the signal transmission time through the network link bounded by the echo canceller based on the measured minimum time delay and the determined network path signal transmission time (tA).

Abstract: The present invention provides an acoustic echo canceler for use in a telephone set having a handsfree conversation function. This acoustic echo canceler simultaneously achieves both the stabilization and speedup of an estimation operation and also attains the more improvement of speech quality. Moreover, the present invention provides a handsfree telephone set employing this acoustic echo canceler. Furthermore, this acoustic echo canceler is operative to cancel an echo generated by inputting an output of an acoustic device to itself substantially simultaneously with the outputting the output thereof. Further, this acoustic echo canceler comprises an adaptive filter for performing an operation of estimating the frequency characteristic and the phase characteristic of a part, whose frequency characteristic and phase characteristic vary, on an acoustic path and a fixed coefficient filter for simulating a part, whose frequency characteristic and phase characteristic are fixed, on the acoustic path.

Abstract: Methods and apparatus for processing a received voice signal from a variable-delay network by a communications system that has at least one echo canceller. An echo canceller determines delay characteristics that are associated with the received voice signal and correspondingly modifies echo cancellation processing. In a variation of the embodiment of the invention, a first echo canceller sends silence descriptor information to a second echo canceller. The second echo canceller reconstructs a voice signal based upon the silence descriptor information and excitation vector information.

Abstract: A method for suppressing echo signals generated in a communication path such as acoustic coupling between a speaker and a microphone in a telephone device handset includes the steps of monitoring signals supplied to the communication path to determine an attribute thereof and masking signals received from the communication path as a function of the determined attribute of the monitored signals thereby to suppress echo.

Abstract: A method of converging a step size control for an adaptive filter of a communication channel including: (1) initializing a nominal step size value and a penalty point value; (2) combining the nominal step size value and the penalty point value to generate a step size value; and (3) dynamically changing the step size value in response to a characteristic measure of a quality of the communication channel. The step size value is changed by adjusting the nominal step size value, the penalty point value, or both. In a preferred embodiment the penalty point value is adjusted dependant on: (1) a tone originating from the far end (2) full convergence (3) the power level of a residual error signal (4) the channel's near-end background noise and/or (5) weak double-talk in the communication channel. The nominal step size value is adjusted when an achieved initial combined loss is about 15 dB or greater and is reset by divergence.

Abstract: An echo canceling system, method of attenuating echo, and a bit pump and transceiver employing the system and method. The echo canceling system is couplable between a transmit and receive path of the bit pump and receives and attenuates the echo in a receive signal propagating along the receive path. In one embodiment, the echo canceling system includes a slave echo canceling stage that employs a filter coefficient to attenuate the echo. The echo canceling system also includes a separation circuit, coupled to the slave echo canceling stage, that generates data representing a residual echo substantially exclusive of the receive signal. The echo canceling system still further includes a master echo canceling stage, coupled to the separation circuit, that receives the data and modifies the filter coefficient based thereon.

Abstract: An echo canceller, which includes, receives and sends paths connected to standard telecommunication interfaces, a non adaptive filter with filter reflection coefficients which generate an estimated echo signal, which when subtracted from the send path input produces a nearly echo free send path output, an adaptive filter generating a second estimated echo signal, which when subtracted from the send signal, provides a possible alternative nearly echo free send path signal, a fast non iterative least squares method of estimating a reflection, a controller means which, in response to an observed non echo free send path output, causes the fast non iterative least squares method to search for possible new reflections, and a controller means for expurgating unnecessary reflection coefficients in the non adaptive filter.

Abstract: A method is provided for detecting echo cancellation in a communication network. The method includes the steps of transmitting from an originating unit a pre-defined echo cancellation detection signal to a receiving unit. The resulting signal is detected by the receiving unit and analyzed to determine whether the differences between the resulting signal and a stored pre-defined signal indicate the detection of echo cancellation on the communication network.

Abstract: A communication system having an echo canceller is disclosed. One embodiment of the echo canceller includes an adaptive filter used to provide an estimate of reflected echo which is removed from the send signal. The echo canceller may also include a near-end talker signal detector which may be used to prevent the adaptive filter from adapting when a near-end talker signal is present. The echo canceller may also include a nonlinear processor used to further reduce any residual echo and to preserve background noise. The echo canceller may also include a monitor and control unit which may be used to monitor the filter coefficients and gain of the adaptive filter to maintain stability of the echo canceller, estimate pure delay, detect a tone, and inject a training signal. The echo canceller may also include a nonadaptive filter used to reduce the length of the adaptive filter.

Abstract: An echo canceler includes an recursive least squares lattice to whiten a far-end signal s1(t) and provide whitened time delays. The echo canceler further decorrelates a microphone signal based on the whitened time delays to reduce echoes of the far-end signal s1(t) that are contained in the microphone signal x2(t). The echo canceler does not use a double-talk detector and avoids all problems inherent with their use. Thus, speaker phones, and other communication devices, can continuously operate in full-duplex mode of operation thereby providing natural conversational hands-free communication.

Abstract: A method and apparatus for transmitting a clear voice signal while effectuating speech privacy and unobtrusiveness through adaptive signal processing; includes a voice input microphone, an electrical line for transmitting representations of the received voice signal from the microphone and having a modulator in it, actuators or speakers spherically disposed about the microphone for creating sound canceling the ambient spatial transmission of the voice inputted into the microphone, an adaptive signal processor for receiving from the transmission line before the modulator the representations of the received voice signal from the microphone and for providing appropriate output to the actuators or speakers for them to create sound canceling the spatial transmission of the microphone inputted voice and to the modulator to remove from the transmission line downstream of the modulator the speaker sounds signals picked up by the voice input microphone.

Abstract: A method of estimating an echo return loss of a communication link measures the peak power value of a signal received from a far end of a communication link and the corresponding peak power value of a signal received from the near end of the communication link. When the near end signal is free from near end voice and excessive noise, the near end corresponding peak will be the echo of the far end power. The far end power is monitored and when a peak is detected, a period, which can be equal to a filter length period, is initiated. When the period has run, the delay line attached to the near end is polled to determine the peak power in the delay line. This peak power will correspond to the far end peak. If a peak, exceeding the first peak is detected before the period has run, the period is reinitiated. The echo return loss estimate is calculated as a ratio of the far-end peak power value to the near-end peak power value.

Abstract: A method includes receiving a plurality of packets from at least two voice packet streams. The method also includes generating at least two voice signals using the plurality of packets. Each voice signal is associated with one of the voice packet streams. In addition, the method includes identifying an echo of one of the voice signals in at least one other of the voice signals.

Abstract: A method and apparatus for reducing echo feedback in a wireless communication system (10) is accomplished when a receiving communication unit (24) senses a feedback signal, or echo, via an ancillary communication path. The receiving communication unit is a targeted recipient of an original audio signal generated by a transmitting communication unit (22), where the original audio signal (42) is conveyed to the receiving communication unit. Upon detecting the feedback signal and determining that it exceeds a feedback threshold, the receiving communication unit attenuates an audible output of the original signal to reduce echo to the transmitting communication unit. In addition, the receiving communication unit, and/or the transmitting communication unit include echo canceller to further minimize the echo within the digital communication system.

Abstract: A communication system being made up of a two-wire/four-wire hybrid circuit, an echo canceller, and a control device and having functions of forming a plurality of communication paths and changing communication paths is provided which is capable of ensuring high speech quality by suppressing and canceling an echo occurring in telephone speech after establishment of path connection. The communication system also includes a training signal source to feed a training signal to the echo canceller, a switching circuit to do switching of a signal to be fed to the echo canceller between an ordinary signal and the training signal, and a control device to exert control on path connection and path changing and to feed the training signal to the switching circuit to make a training signal be fed from the training signal source to the echo canceller and to have the echo canceller converge its training operation.

Abstract: An echo canceller includes two parallel filters and a controller. The controller chooses the best of the two filters for the final echo cancellation. The filter coefficients are exchanged between the two filters constantly so that both filters retain performance all the time even if double-talk and echo path variations occur very closely in time. One filter is strongly robust and will not diverge during double-talk, and another filter is weakly robust and will converge rapidly during echo path variation.

Abstract: A process is described which generates matrix coefficients using zero-lag auto and cross-correlations from signals commonly found in echo cancellers. Double-talk and path changes are then detected using matrix operations such as determinants, eigendecompositions, or singular value decompositions (SVDs). In a preferred embodiment, the determinant of the correlation-based matrix is compared against predetermined threshold values.

Abstract: Controlling echo cancellation includes receiving signals associated with a call. A signal of the signals is detected. Whether the detected signal is a high speed signal or a low speed signal is determined. Echo cancellation is disabled if the detected signal is a high speed signal. The echo cancellation is enabled if the detected signal is a low speed signal.

Abstract: A method for allocating echo canceling devices in a telecommunications network having at least two networks connected to one another by network switching nodes. The network switching nodes have trunk groups interconnecting the networks so that connected terminal devices can be connected to one another. Devices for canceling echo are provided in the networks and can be requested and, if certain criteria are fulfilled, inserted into existing connections to cancel echo signals. The method includes marking selected trunk groups originating from or leading to another network with an echo cancellation mark characteristic, and providing available echo canceling devices based upon the echo cancellation mark characteristic when echo canceling is requested for a connection being set up through one of the selected trunk groups. A system for allocating echo canceling devices in a telecommunications network is also provided.

Abstract: An echo canceler for generating an echo replica and subtracting the echo replica from a local input signal to create a residual signal for outgoing transmission. An echo canceler has adaptive filters that have different computational accuracy generating the echo replica. An evaluator coupled to the adaptive filters groups coefficients into each of segments, and evaluating a computational accuracy information according to the coefficients for the segments. A computational accuracy controller in the evaluator assigns the local input signal to the adaptive filters, and adjusts the coefficients according to the computational accuracy information.

Abstract: An apparatus of a digital echo canceller comprises a first-set delay circuits, a selector, a second-set delay circuits, a plurality of multipliers and an adder. The first-set delay circuits are arranged into groups, and each group has N delay circuits. An exhaustive search function is carried out to produce a plurality of energy sums. The selector will select the biggest energy sum to serve as a significant part and then transmit to the outputs of the second-set delay circuits, the multipliers and the adder. An estimated echo signal is produced to cancel the echo signal.

Abstract: A communication transmitting and receiving system in which the effects of near-end echo and near-end crosstalk signal from the communication medium are mitigated by adaptively reproducing the near-end echo and near-end crosstalk signal, which is then subtracted from the received signal. Filter coefficients for a Finite Impulse Response filter are adaptively generated to reproduce the near-end echo and near-end crosstalk. The filter coefficients are regenerated for the Finite Impulse Response filter in an adaptive correlator at the arrival of each received signal and whereby each new filter coefficient is a weighted sum of a previous coefficient and one received signal multiplied by a time delayed version of one transmitted signal.

Abstract: Provided is a method and apparatus for inband testing of an echo canceller. The apparatus includes a signal generator for generating an excitation signal including a preamble portion and a test portion. The echo canceller receives the excitation signal at a decoder. The decoder differentiates the preamble from the test portion and obtains control information by decoding the preamble portion. A controller configures the echo canceller during testing according to the control information obtained from the preamble portion. A strength of the present invention is that the preamble portion allows precise control of the echo canceller during testing by synchronizing the test control to the location of the preamble. This allows exacting control of the echo canceller during testing to within a single sample time of the excitation signal, e.g., 125 microseconds.

Abstract: System and method for processing communication signals in a communication system having a detector for detecting a parameter of a communication signal. A communication signal is provided to a non-linear processor (NLP) adapted to examine the signal and to decide whether or not to enter an active state based upon a parameter of the signal. If the NLP enters an active state, the NLP performs non-linear processing on the signal. The NLP communicates to the detector whether the NLP is active or inactive. If the NLP is active, a processing step of the detector is disabled.