Abstract: An apparatus and method for cross clock domain interference cancellation is provided to a communication system which includes a transmitter operated in a first clock domain and a receiver operated in a second clock domain. The apparatus comprises a First-In-First-Out (FIFO) circuit and a cancellation signal generator. The FIFO circuit receives a digital transmission signal of the transmitter in the first clock domain, and outputs the digital transmission signal in the second clock domain according to an accumulated timing difference between the first and second clock domains. The cancellation signal generator generates a cancellation signal for canceling an interference signal received by the receiver according to the digital transmission signal outputted by the FIFO circuit. The interference signal is generated in response to the digital transmission signal.

Abstract: A satellite communication system comprised of a hub and plurality of remote terminals, wherein the system is configured for frequency reuse, a method and apparatus for signal cancellation are disclosed. The disclosed method and apparatus enable the hub to extract return link signals overlaying a transmitted forward link signal, wherein the forward link signal is transmitted at a power level higher than that of the overlaying return link signals.

Abstract: Alien noise is removed from one or more receptor DSL lines after self-FEXT has been eliminated or reduced. Information about the alien noise in the form of slicer errors can be obtained from one or more donor DSL lines that may or may not be in the same domain (e.g., a vectored DSL system).

Abstract: An inband signaling modem receives digital user data for transmission to a remote location, via wireless and land line telecommunication networks. The modem converts the user data into audio tones for transmission, and encodes the audio tones into digital form suitable for transmission through a voice channel call session of a digital wireless network. After establishing a voice channel call session on a digital wireless network, the modem disables any echo cancellation or echo suppression means that may be encountered in the voice channel call session; and then transmits the user data audio tones. Preferably, disabling the echo cancellation or echo suppression means comprises transmitting a predetermined tone in the voice channel call session. Further, the modem preferably repeats the tone, to again disable echo cancellation or echo suppression means, at the beginning of each data burst during the call session.

Abstract: Disclosed herein are systems, methods, and computer-readable storage media for enabling improved cancellation of self-interference in full-duplex communications, or the transmitting and receiving of communications in a single frequency band without requiring time, frequency, or code divisions. The system estimates the signal strength and phase of a self-interference signal, generates a cancellation signal based on this estimate, then uses the cancellation signal to suppress the self-interference before sampling received analog signal. After applying the cancellation signal, the system samples and digitizes the remaining analog signal. The digitized signal is then subjected to additional digital cancellation, allowing for extraction of the desired signal.

Abstract: A method for full duplex communication that includes creating a canceling self interference signal using a passive noise cancellation, and attaining full-duplex simultaneous in time and overlapping in space wireless transmission and reception on same frequency band responsive to the step of creating a canceling self interference signal.

Abstract: Techniques are disclosed for compensating for crosstalk using adaptation of data signals transmitted over respective channels of a communication network. In one example, a method comprises the following steps. Data is transmitted to a communication network device via a communication line during a sequence of periods. For each period of the sequence of periods, a separate value of a measure of crosstalk that was measured at the communication network device is received, each value being an average of measurements at the device of measures of crosstalk for a plurality of communication network signal subcarriers. For each individual signal subcarrier of the plurality, a matrix is updated based on the received values, the matrix being configured to precode data transmissions to the communication network device over the individual signal subcarrier. The communication network may be a DSL system, the signal subcarriers may be DSL tones, and the measure of crosstalk may be a SINR value.

Abstract: In order to reduce interference in an audio signal during a call on a mobile communication device, a plurality of transforms of the audio signal is performed, each transform containing phase information and amplitude information of corresponding samples of the audio signal. The results of the transforms are then averaged in order to generating a compensation signal that can be subtracted from the audio signal.

Abstract: A communication device includes multiple paths that are provided in the device and transmit signals; an adjuster that adjusts transmission characteristics to be a favorable state by adjustment of the waveform of the signals on the paths; and a controller that controls the adjustment of the transmission characteristics of the paths by the adjuster, identifies other path(s) that affects a path to be adjusted, and controls suppression of crosstalk due to the other path(s).

Abstract: 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.

Abstract: Disclosed herein are systems, methods, and non-transitory computer-readable storage media for a modified MAC protocol which can facilitate communications with both full-duplex and half-duplex devices. A system configured according to the disclosed method can enable communications between an Access Point (AP) and a client in either full duplex or half duplex. The system can similarly enable peer-to-peer communications in both full duplex and half duplex communication modes.

Abstract: In some implementations, an apparatus includes an echo canceller that generates an echo interference compensation signal that compensates for an echo interference signal in a communication signal, a crosstalk canceller that generates a crosstalk interference compensation signal that compensates for a crosstalk interference signal in the communication signal, and a combiner that generates a combined interference compensation signal based on the echo interference compensation signal and the crosstalk interference compensation signal.

Abstract: Techniques for performing analysis of a cellular telephone signaling environment in the presence of interferers. The techniques do the analysis by employing a receiver to listen to the cellular environment during holes in the interference. The holes have a timing which differs from that used by the cellular telephone signaling environment and will thus over time overlap with structures of interest in the cellular telephone environment. The holes may be smaller than the structure of interest. The signals which the receiver hears in the holes are analyzed and combined to reproduce the structure. The combination may involve statistical methods and weighted decoding. The analysis obtains information which permits surgical attacks on individual wireless devices which are in the traffic state. Example applications of the techniques are given for the GSM and CDMA cellular telephone standards.

Abstract: A single channel full duplex wireless communication system includes a processor, a transmitter, a receiver, a secondary transmission path, a combining element, a primary transmission feedback path and a secondary transmission feedback path. The transmitter transmits a transmission signal via a transmission path. The receiver receives a received signal via a reception path. The transmitter and the receiver utilize one channel to transmit and receive signals. The transmission signal causes self-interference. The processor estimates a first transfer function and feeds the secondary transmission path with the transmission signal adjusted by the first transfer function to reduce the transmission signal leaked to the reception path. The combining element combines the transmission signal with the adjusted secondary transmission path signal to remove the self-interference. The primary transmission feedback path output is modified by a second transfer function.

Abstract: A full-duplex wire-line transceiver is provided with echo cancellation line driver. The transceiver has an impedance matching network with a network interface, and a transmit interface to accept a differential transmit signal for transmission via the network. The impedance matching network has a receive interface to supply a differential receive signal accepted at the network interface, where the transmit interface is coupled to the receive interface. A hybrid circuit has an input to accept the differential receive signal combined with a coupled differential transmit signal, and input to accept a differential echo cancellation (EC) signal. The hybrid circuit has an output to supply the differential receive signal with the coupled differential transmit signal attenuated in response to the differential EC signal. A line driver uses an active current mirror to generate matched transmit and EC signals.

Abstract: Embodiments are directed to eliminating false audio using an egress gateway in a communications network. At least one false audio packet is received by an egress gateway. The false audio packet includes false audio. A DTMF packet is received by the egress gateway. The DTMF packet is received subsequent to the at least one false audio packet. The false audio in the false audio packet is replaced with a substitute signal by the egress gateway.

Abstract: An echo signal processing apparatus is disclosed. The echo signal processing apparatus is utilized for generating a cancellation signal by using group phenomenon of a frequency response of an echo signal to remove the echo signal. The echo signal processing apparatus has lower cost and is able to remove the echo efficiently.

Abstract: Networked modems configurable to establish a communication system on a wired communication medium. Each modem includes: a network module, transmit and receive path modules and a frequency domain echo canceller. The network module is configured to communicate with network modules of remaining ones of the at least three modems to allocate bandwidth of the shared communications medium for at least two discrete point-to-point communication links between corresponding pairs of the at least three modems. The transmit and receive path modules are configured for multi-tone modulation and demodulation of communications on the wired communication medium and are responsive to the bandwidth allocation of the network module to concurrently process at least a first discrete point-to-point communication link with a first modem among remaining ones of the at least three modems and at least a second discrete point-to-point communication link with a second among remaining ones of the at least three modems.

Abstract: An audio processing device for reducing the effect on a first signal of echo from a second signal, the device comprising: an echo reduction processor for processing the first signal to reduce echo in it, the echo reduction unit having: a first mode of operation for reducing echo of a first function from the first signal; and a second mode of operation for reducing echo of a second function from the first signal, the second function being more complex than the first function and the echo reduction processor being such as to consume more power in the second mode of operation than in the first mode of operation; and an echo reduction controller for controlling the echo reduction processor to operate in a selected one of the first mode of operation and the second mode of operation.

Abstract: A coded multidimensional modulation system called generalized OFDM (GOFDM) uses orthogonal subcarriers as bases functions, and the signal constellation points of corresponding multidimensional constellation diagram are obtained as N-dimensional Cartesian product of one-dimensional PAM/two-dimensional QAM. In GOFDM, the N-dimensional/2N-dimensional signal constellation point is transmitted over all N subcarriers/2N-subcarriers, which serve as individual bases functions. Even if some of the subcarriers are severely affected by channel distortion, the overall signal constellation point will face only small distortion, when strong channel capacity achieving channel codes are used. In addition, because the channel capacity is a linear function of number of dimensions, the spectral efficiency of optical transmission systems is significantly improved.

Abstract: Techniques to reduce distortion in acoustic signals in mobile computing devices are described. For example, a mobile computing device may comprise a speaker operative to receive a first signal and output a second signal. The mobile computing device may further comprise a first microphone operative to receive the second signal and a second microphone operative to receive a third signal. An echo canceller may be coupled to the first microphone and the second microphone and may be operative to compare the second signal and the third signal and reduce distortion in the third signal based on the comparison. Other embodiments are described and claimed.

Abstract: 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.

Abstract: Various embodiments of a wireless multimode receiver having an off-chip duplex filter associated with a multimode band, and a blocker cancellation circuit disposed on a semiconductor chip are described in the present disclosure.

Abstract: A detection system includes a receiver configured to generate a receiver signal representative of detected electromagnetic energy, and an analog-to-digital converter (ADC) configured to generate a plurality of signal samples based on the receiver signal. The detection system also includes a detection module configured to identify a plurality of sample offsets for the signal samples, and execute a plurality of autocorrelation functions on the signal samples to provide an output of each of the autocorrelation functions, wherein each autocorrelation function is executed on at least a portion of the signal samples identified by a sample offset of the plurality of sample offsets. The detection module is also configured to compute a sum of the autocorrelation function outputs, normalize the sum of the autocorrelation function outputs, and determine whether a signal of interest is present within the electromagnetic energy based on the normalized sum.

Abstract: A method for reducing a disturbance in an input signal caused by an output signal in a multi-port connector, a multi-port connector circuit for reducing a disturbance in an input signal caused by an output signal, and a mobile device are described.

Abstract: A transceiver system is disclosed. The transceiver system comprises a first transceiver physical layer circuit (PHY) having a first plurality of channels and a second transceiver PHY disposed adjacent the first transceiver PHY and having a second plurality of channels. Filter circuitry is coupled between at least one of the plurality of first channels and at least one of the plurality of second channels.

Abstract: An interference canceller comprises a composite interference vector (CIV) generator configured to produce a CIV by combining soft and/or hard estimates of interference, an interference-cancelling operator configured for generating a soft projection operator, and a soft-projection canceller configured for performing a soft projection of the received baseband signal to output an interference-cancelled signal. Weights used in the soft-projection operator are selected to maximize a post-processing SINR.

Abstract: A system and method for identifying minor echoes present in an input signal in the situation where a set of major echoes has already been identified from the input signal. The method includes: computing a spectrum F corresponding to a sum of the major echoes; computing a weighted power spectrum SM of the spectrum F; subtracting the weighted power spectrum SM from a weighted power spectrum PIN of the input signal to obtain a difference spectrum; performing a stabilized division of the difference spectrum by a conjugate of the spectrum F to obtain an intermediate spectrum; computing an inverse transform of the intermediate spectrum to obtain a time-domain signal; and estimating parameters one or more of the minor echoes from the time-domain signal. The echo parameters are usable to remove at least a portion of the one or more estimated minor echoes from the input signal.

Abstract: A signal generator produces a victim signal having crosstalk emulation by filtering and combining a victim signal waveform record file and an aggressor signal waveform record file generated using parameters selected by a user. A signal channel or a cascaded signal channel is characterized using one or more S-parameter arrays. The S-parameter array or arrays represent a mixed-mode multiple-port device under test. Coefficients of a NEXT filter, a FEXT filter and a forward transmission filter are derived from selected S-parameters of the S-parameter array. The aggressor signal is filtered individually by the NEXT and FEXT filters. The victim signal is summed with the filtered aggressor signal from the NEXT filter with the resulting summed signal being filtered by the forward transmission filter. The filtered signal from the forward transmission filter is summed with the filtered aggressor signal from the FEXT filter to generate a victim signal having crosstalk emulation.

Abstract: 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.

Abstract: An apparatus is provided for suppressing an echo signal included in a measured signal corresponding to a measured sound. In the apparatus, the measured signal and a reference signal in a time domain are transformed into a frequency domain, and calculated for obtaining each value of a ratio and a correlation between the measured signal and the reference signal in the frequency domain. With executing a comparison of the values of the ratio and the correlation, a coefficient is derived, where a product of the coefficient and the measured sound in the frequency domain gives an estimated value of the echo signal. The echo in the measured signal is suppressed with subtracting the estimation of the echo signal from the measured signal, respectively in the frequency domain.

Abstract: A transceiver mitigates signal leakage into a receive path from a transmit path. A subtraction circuit determines a difference between a receive signal and a compensation signal to produce a compensated receive signal prior to demodulation by a demodulator. An equalizer both amplitude adjusts and phase adjusts orthogonal baseband transmit signals based on the difference from the subtraction circuit to produce the compensation signal. A digital tuning circuit determines at least one amplitude adjust coefficient to be used by the equalizer. The equalizer can have a polarity switch or a variable attenuator or a variable delay.

Abstract: In one embodiment, a signal processing method is disclosed. The method can perform filter processing of convoluting a tap coefficient in a first signal sequence to generate a second signal sequence. The method can subtract the second signal sequence from a third signal sequence to generate a fourth signal sequence. The third signal sequence includes an echo signal of the first signal sequence. The method can correct the tap coefficient in accordance with an amount of correction determined using a function. The function includes at least one of a first region and a second region, and has values limited. The first region is included in a negative value region of the fourth signal sequence. The second region is included in a positive value region of the fourth signal sequence.

Abstract: A wireless repeater includes a receiver circuit implemented as an intermediate frequency (IF) subsampling receiver and a transmitter circuit implemented as a direct conversion (zero-IF) transmitter. The repeater further includes a reference receiver implemented as an IF subsampling receiver to sample a portion of the transmit signal prior to over-the-air transmission for use as the reference signal for channel estimation. Highly accurate channel estimation is obtained by using the reference signal from the reference receiver as the reference signal accounts for distortions in the transmitter circuit of the repeater. The repeater may include an echo canceller to cancel an estimated feedback amount from an input signal based on the channel estimation.

Abstract: An adaptive hybrid system is coupled to a loop for adjusting trans-hybrid loss. The system comprises a fixed portion comprising a first receiver transfer function block and a first hybrid transfer function block. The fixed portion is configured to receive a far-end signal and mitigate frequency dependent attenuation experienced by the far-end signal. The system also comprises a variable portion comprising a second receiver transfer function block and a second hybrid transfer function block configured to subtract a transmit echo from the received far-end signal.

Abstract: A system and method for provide a stable gain from an adaptive gain control device in a signal path. An echo canceller is also located in the signal path, and is used to provide performance information regarding losses in the signal. This performance information is fed to the automatic gain control device via a connection. The automatic gain control device thereafter uses the performance information to determine a maximum gain that might be provided based upon losses cause by echo conditions. The gain however is limited in order to provide for a stable system. The performance information includes a loss rate that includes a combination of the echo return loss and the echo return loss enhancement.

Abstract: VoIP phones according to the present invention include a microphone, which may be internal or external, and allow the user to communicate unobtrusively, check voice mail and conduct other activities in an environment which can be noisy in general and extremely noisy sometimes. Speech recognition functionally may also be used to generate and send touch tone or DTMF tones such as in response to call trees or voice recognition functionality used by airlines, credit card companies, voice mail systems, and other applications. A system and method of audio processing which provides enhanced speech recognition is provided. Audio input is received at the microphone which is processed by adaptive noise cancellation to generate an enhanced audio signal. The operation of the speech recognition engine and the adaptive noise canceller may be advantageously controlled based on Voice Activity Detection (VAD).

Abstract: Methods and systems for echo modulation are described. In one embodiment, intensities of a plurality of values in multiple windows of an audio signal may be obtained. The windows may be subject to a periodic boundary condition. A plurality of echo values may be calculated for each of the respective windows. The audio signal may be altered in one or more of the windows using a windowing function and echo values. Additional methods and systems are disclosed.

Abstract: Systems, methods, and other embodiments associated with echo cancellation are described. According to one embodiment, an apparatus includes a cable tester that determines whether a fault in a cable exists by using echo cancellation values.

Abstract: Methods and apparatus of managing a communication system, wherein a decision regarding a level of activity at a first end is made based at least in part on the level of activity at the second end. In one embodiment, the energy level of a first-end audio signal is measured. The first end is declared voice-active if the first-end energy level is greater than or equal to a first threshold value. The first end is declared voice-inactive if the first-end energy level is less than the first threshold value. To determine the value of the first threshold value, the energy level of a second-end audio signal is measured. If the second-end energy level is greater than or equal to a second threshold value, the second end is declared voice-active, in which case the first threshold is maintained at a relatively high level. If the second-end energy level is less than the second threshold value, the second end is declared voice-inactive, in which case the first threshold is maintained at a relatively lower level.

Abstract: A system and methods for pre-configuring echo cancellers are shown and described. The system includes a storage device for storing one or more settings of the echo cancellation parameters developed during one or more previously established data connections, and an echo canceller for cancelling echo associated with one or more data connections according to echo cancellation parameters, the echo canceller initially configuring the echo cancellation parameters according to settings developed during previous data connections.

Abstract: To assist with the detection of unfiltered device(s), a system observes how the received noise changes between two links as the transmit signal is changed. Harmful unfiltered nonlinear devices will generate significant noise that depends on the transmitted signals; therefore, this additional noise can be quantified to some extent by comparing the observed noise for two different transmit signals. The total noise can be determined from the SNR if the received signal is known. The received signal may be read directly in some non-standard systems, or it may be determined from the known transmit signal and channel attenuation, which is sometimes the case in standard-compliant links, but often with a relatively large error. To circumvent this problem, certain embodiments of this invention only consider the change in noise between two links with the same channel attenuation. This differential comparison makes it unnecessary to accurately know the channel attenuation.

Abstract: A wireless repeater employing echo cancellation uses a non-linear element in digital baseband to compress the digital transmit signal waveform, thereby allowing distortions in the transmitter circuit as well as interference to be cancelled. In one embodiment, the repeater applies non-linear baseband compression to the digital transmit signal in the digital domain to reduce the peak-to-average amplitude of the digital transmit signal prior to digital-to-analog conversion and prior to over-the-air transmission and prior to sampling of the digital transmit signal for use as the reference signal for echo cancellation. The intentionally introduced non-linear distortion in the transmit signal improves echo cancellation and stability of the repeater. In one embodiment, the non-linear compression is applied only when the digital transmit signal is at or exceed a given power level or a given gain level.

Abstract: A system and method for packet communication is disclosed. Echo in a received symbol stream may be reduced to produce an echo-reduced symbol stream. The echo-reduced symbol stream may be buffered and aligned according to a deskew signal to produce a deskewed symbol stream. The deskewed symbol stream may be decoded to produce a decoded packet.

Abstract: A communication apparatus with echo cancellation includes a transmitter, a receiver, a digital echo cancellation circuit, a parameter control circuit, and an analog echo cancellation circuit. The digital echo cancellation circuit determines an echo estimation component according to a digital output signal, and performs a digital echo cancellation on a digital input signal according to the echo estimation component. The parameter control circuit generates a control signal according to the echo estimation component. The analog echo cancellation circuit includes a first echo cancellation resistor and a second echo cancellation resistor, wherein the resistances of the first echo cancellation resistor and the second echo cancellation resistor are adjusted according to the control signal.

Abstract: A method and arrangement for cancelling echoes in a communication terminal (400) during a voice call with an opposite party. The communication terminal (400) comprises an echo cancelling unit (416,600) adapted to produce an estimate of echo information in received speech signals coming from a microphone in the communication terminal (400), and subtract the estimate from the received microphone signals, before being transmitted to the opposite party. The estimate is produced based on down-sampled received microphone signals and down-sampled received speech signals from the opposite party. The down-sampled speech signals from the opposite party are filtered in a digital filter (606), and the output signals from the filter (606) are up-sampled to form the estimate.

Abstract: An echo cancellation circuit in a full duplex two-way communication system comprising: an input/output terminal; a subtractor having a positive and a negative input terminals, in which a first transmission signal is inputted to the negative input terminal as a pseudo echo signal, the first transmission signal is inputted through an output buffer to the positive input terminal as an echo signal, the pseudo echo signal inputted to the negative input terminal is subtracted from the echo signal inputted to the positive input terminal; and a result of the subtraction is outputted; and an echo cancellation error reducing unit having a D/A converter at an input side or an output side of the subtractor.

Abstract: Systems, methods, and other embodiments associated with echo cancellation are described. According to one embodiment, a method uses two signals from a transmitter as input to a look-up table to generate a non-linear echo cancellation signal. The non-linear echo cancellation signal is applied to a receiving path to reduce non-linear echo distortion on the receiving path based at least in part on the current signal and the previous signal.

Abstract: The present invention relates to a method and a system of implementing a signal processing facility in a digital transmission system environment. In the invention, the signal between the switching field (GSW) and the interface unit ETS1 is divided into a first (DEOS, DSOE) and second signal (DGO, DSO). The first signal is directed through the signal processing unit and the second signal past it. Either one of the signals is selected and activated depending on the need of the signal processing and the operational status of the signal processing unit; this information the interface unit gets from the control unit.

Abstract: A system for wireless communication comprises an architecture of routers connected to a network and having connected transceivers for wireless transmission and reception of data, and a plurality of hand-held commuoicators adapted for users to communicate with the network through the routers. The system is adapted to provide wireless Data Network Telephony (DNT), and the hand-held communicators execute Quality of Service (QoS) code adapted to prioritize DNT packet code over all non-DNT traffic, thereby preserving the real-time nature of the DNT code.