Abstract: A multi-microphone hands-free device distinguishes between non-steady noise and speech and adapts the de-noising to the presence and characteristics of the detected non-steady noise without spoiling any speech that is present. In the frequency domain, the method comprises calculating a first noise reference by analyzing spatial coherence of signals picked up, calculating a second noise reference by analyzing directions of incidence of signals picked up, estimating a main direction of incidence of signals picked up, selecting as a referent noise signal noise references as a function of estimated main direction, combining signals picked up into a noisy combined signal, calculating probability that speech is absent in the noisy combined signal on basis of respective spectral energy levels of the noisy combined signal and of the referent noise signal, and selectively reducing noise by applying variable gain that is specific to each frequency band and to each time frame.

Abstract: A system and method for providing call privacy for a wireless communication device. A voice communication is received from a user. The voice communication is processed to determine a response signal in response to receiving the voice signal. The response signal is broadcast about the periphery of the user as the voice input is received. The response signal is operative to cause the voice communication to be less discernible by one or more bystanders.

Abstract: A method to discriminate a real echo peak from an aliased echo peak comprises: computing ‘a correlation between N samples of a digital data and a copy of the same N samples delayed by a time delay ?1,0 to obtain a first correlation result, time delay ?1,0 being equal to a time interval T between a first and a second distinct power peaks of an estimated channel impulse response, the first peak being the highest power peak within the temporal window, and/or computing—a correlation between the N samples and a copy of the same N samples delayed by a time delay TIFFT-?1,0 to obtain a second correlation result, and deciding whether the second peak is a real echo peak or an aliased echo peak based on the first and/or second correlation results.

Abstract: In a signal processing system, a set of channel signals from an array of sensors of different operating characteristics are processed in calibration circuitry that calculates individual average values of the channel signals and calculates an average of the individual average values of channel signals as a reference value. Reciprocal calculators calculate reciprocal values of the individual average values of the channel signals. Scaling circuitry scales the reciprocal values by the reference value to produce a set of amplitude calibration signals and scales the channel signals by the calibration signals respectively. As a result, the channel signals are normalized by their own average values and scaled by the reference value to produce a set of calibrated channel signals.

Abstract: A system includes an antenna to receive a communications signal, an amplifier coupled to the antenna to amplify the communications signal, and a processor coupled to the amplifier to process the communications signal using high-order statistics to suppress noise in the communications signal. The processor may use a bispectrum function to remove at least a portion of the noise, and at least one of the phase of the bispectrum and the amplitude of the bispectrum to reconstruct the communications signal.

Abstract: In a speech communication device capable of bidirectional communication, a clock deviation between the speaker side (the receiving side) and the microphone side (the transmitting side) is detected, and based on the above deviation, either a first frequency signal (speaker signal (reference signal)) or a second frequency signal (microphone signal) is frequency-shifted in the frequency domain, and therefore, an influence caused by the clock deviation can simply be corrected without an increased processing amount, and thus, an echo can be suppressed effectively.

Abstract: A wireless headset includes a first earpiece and a second earpiece, where the first and second earpieces communicate with each other over a wireless link. In some configurations, the first earpiece includes both a primary wireless interface for receiving audio from an audio source and a secondary wireless interface transmitting a portion of the audio to the second earpiece. The earpieces can incorporate Near Field Communication (NFC) technology to provide the wireless link between each other. The wireless headset can be configured to synchronize audio output at the earpieces, and can also include a second-earpiece detection mechanism that permits the first earpiece to be used in either a stand-alone mode, with audio output at only the first earpiece, or full-headset mode, with audio output at both earpieces when the second earpiece is detected within wireless range of the first earpiece.

Abstract: A mobile radio apparatus wherein the degradation of communication performance caused by electromagnetic noise can be precluded with enhanced reliability. This mobile telephone unit (100) comprises a camera body (107); a circuit board (106) that includes partial board parts (104, 105) located on the two respective sides of the camera body (107); a camera shield (108) that is located close to and opposed to the back surface of the camera body (107) (which is opposite to the image pickup plane); a camera connection connector (110) that is connected to the camera body (107) and grounded in the partial board part (104); a frequency limiting part (111) that is connected to the camera shield (108) and grounded in the partial board part (105); a feeding part (117) that is located in the partial board part (105); and a matching circuit part (113) that is located and grounded in the partial board part (105).

Abstract: Techniques for explicit feedback delay measurement are described. An apparatus may comprise a processor to generate a steering matrix for transmit spatial processing over a channel, determine a delay time associated with explicit feedback information for the channel, and determine whether to modify the steering matrix with the explicit feedback information based on the delay time. Other embodiments are described and claimed.

Abstract: Duplex audio is provided for a mobile communication device and an accessory. In some embodiments, the accessory can selectably operate in a duplex audio mode, concurrently sending audio to and receiving audio from the mobile communication device, or in another audio mode. In duplex audio mode, the accessory can enable its internal audio processing operations (e.g., echo cancellation) while the mobile communication device disables its corresponding internal operations or vice versa. The mobile communication device can control when the accessory transitions into and/or out of duplex audio mode.

Abstract: An apparatus is disclosed comprising a transducer, which transducer comprises at least one electrical connection point configured to enable an external electrical connection of the transducer. The transducer further comprises at least one decoupling coil configured to electrically decouple the transducer from the at least one electrical connection point at a frequency above an operating frequency of the transducer. Moreover, a method for assembling the described apparatus is disclosed.

Abstract: A system for suppressing interference imposed on a victim communication signal by an aggressor communication signal including a circuit that comprises an input port, an output port, and a signal processing circuit connected between the input port and the output port, the signal processing circuit being operative to produce an interference compensation signal at the output port, for application to the victim communication signal, via processing a sample of the aggressor communication signal transmitted through the input port, and the input port being configured to connect to a sampling system that includes a first circuit trace running along a surface of a flex circuit of a portable wireless device that is dedicated to sensing the aggressor communication signal flowing on a second circuit trace running along the surface of the flex circuit.

Abstract: A method in a communications device includes the following operations. During a call, a process automatically detects that the device has moved from an at-the-ear position to an away-from-the-ear position. Based on the detection, a noise suppressor that operates upon an uplink signal for the call is signaled to change its noise suppression performance. Other embodiments are also described and claimed.

Abstract: An apparatus and method for interference cancellation is provided to cancel the interference such as echo and cross-talk received by a receiver of a communication system. The apparatus includes a digital cancellation signal generator, a first canceller, and a second canceller. The digital cancellation signal generator can generate a digital cancellation signal, which includes a first and a second portion and represents an interference signal within a received signal. The first canceller can perform an analog cancellation on the received signal to output a partially-interference-canceled received signal according to the first portion of the digital cancellation signal. The second canceller can perform a digital cancellation on the partially-interference-canceled received signal according to the second portion of the digital cancellation signal.

Abstract: A mobile communication apparatus usable for voice communication exchanging a received sound and a spoken sound is provided. The mobile communication apparatus includes a first section, a second section movably connected to the first section in an ordinary mechanical mode or an extra mechanical mode, a detector configured to detect the mechanical mode, a speaker included in the first section and configured to produce the received sound, and a microphone included in the second section and configured to pick up the spoken sound. The mobile communication apparatus includes an echo canceller configured to cancel an echo caused by leakage of the received sound, an AGC circuit configured to produce a gain-controlled signal, and a controller configured to provide the AGC circuit with a first input/output characteristic and a second input/output characteristic in the ordinary mechanical mode and in the extra mechanical mode, respectively.

Abstract: A method and apparatus for removing an echo signal in a signal transmission/reception apparatus of a communication system is provided. A signal transmission/reception apparatus estimates an input channel response using a training sequence, generates a first signal by removing the input channel response from a first reception signal, detects an echo channel impulse response using the first signal, detects an echo signal removing coefficient using the echo channel impulse response, generates a second signal in which an echo signal is removed by applying the echo signal removing coefficient to a second reception signal, and removes the second signal from a third signal, wherein the first signal is received prior to receiving the second signal and the second signal is received prior to receiving the third signal.

Abstract: A household appliance, such as a microwave oven or cordless phone, reduces interference with a wireless network by requesting control of the network's channel during a period of time when the appliance will be emitting signals that may interfere with network communications on that channel. Some embodiments contend for the channel before transmitting the request by using standard protocols, while other embodiments simply transmit the request during a detected idle period. Some embodiments don't bother sending a request if no activity is detected on the channel.

Abstract: An active-noise-reduction (ANR) headset includes at least one auxiliary connection to an output of at least one device, such as a personal communications, computing, and/or entertainment device. An exemplary headset also includes a primary connection to an aircraft two-way radio or public-address system and circuitry for automatically suppressing or muting the volume of an auxiliary input signal relative to that of a primary input signal. Other exemplary features include a headset power supply, a microphone, a microphone preamplifier, and a device-detection circuit. The device-detection circuit selectively couples the power supply to the microphone preamplifier, enabling it to provide audio signals to the microphone input of the auxiliary device.

Abstract: The present invention is a system and method that improves upon voice activity detection by packetizing actual noise signals, typically background noise. In accordance with the present invention an access network receives an input voice signal (including noise) and converts the input voice signal into a packetized voice signal. The packetized voice signal is transmitted via a network to an egress network. The egress network receives the packetized voice signal, converts the packetized voice signal into an output voice signal, and outputs the output voice signal. The egress network also extracts and stores noise packets from the received packetized voice signal and converts the packetized noise signal into an output noise signal. When the access network ceases to receive the input voice signal while the call is still ongoing, the access network instructs the egress network to continually output the output noise signal.

Abstract: A signal correction device including: an orthogonal transform section configured to perform an orthogonal transform for an input signal that includes a speech as a target signal and an unnecessary non-target signal; an interval determining section configured to determine whether each frame of the input signal is an interval in which the non-target signal is dominantly included; a suppressing gain calculating section configured to calculate suppressing gain for suppressing the non-target signal for each first frequency band width for a frame determined to be the interval, and to calculate suppressing gain for suppressing the non-target signal for each second frequency bandwidth for a frame determined not to be the interval; and a signal correcting section configured to perform a signal correcting process for suppressing the non-target signal for a transform coefficient acquired by the orthogonal transform section by using the suppressing gain.

Abstract: Signal detectors are described herein. By way of example, a system for detecting signals can include a microphone signal detector, a loudspeaker signal detector, a signal discriminator and a decision component. When the microphone signal detector detects the presence of a microphone signal, the loudspeaker signal detector detects the presence of a loudspeaker signal and the signal discriminator determines that near-end speech dominates loudspeaker echo, the decision component can confirm the presence of doubletalk. When the microphone signal detector detects the presence of a microphone signal and the signal discriminator determines that near-end speech dominates loudspeaker echo, the decision component confirms the presence of near-end signal.

Abstract: An integrated transceiver for wireless applications has both a frequency determining means and a power amplifier. A transmission filter suppresses unwanted spurious outputs in an integrated circuit before a power amplifier stage amplifies and transmits the desired signal. A differential to single ended converter is able to be implemented to further enhance efficiency.

Abstract: An echo canceller which can respond to a sudden change in echo characteristics in real time and does not require an alteration outside the echo canceller, includes a smoothed sending-speech signal calculation means for calculating a smoothed sending-speech signal from the sending-speech signal, the smoothed sending-speech signal being obtained by smoothing the sending-speech signal; a smoothed receiving-speech signal calculation means for calculating a smoothed receiving-speech signal from the receiving-speech signal, the smoothed receiving-speech signal being obtained by smoothing the receiving-speech signal; a delay time information generation means for obtaining delay time information reflecting delay characteristics of an echo path in accordance with a correlation between the smoothed sending-speech signal and the smoothed receiving-speech signal; and an update information generation means for obtaining update information indicating execution or suspension of updating of the tap coefficients of the adapti

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: One feature provides for establishing an ad hoc peer-to-peer network over an existing channel allocation for another network. To mitigate interference between multiple peer-to-peer devices, a plurality of receiver chains in a receiver device may be configured with beamforming coefficients so as to focus reception in the direction of an intended signal from a transmitter device while minimizing reception from other directions. Similarly, the receiver device may also use a plurality of antennas and a transmitter chain to beamform in the direction of the transmitter device, thereby focusing its transmission toward the transmitter device. The receiver device may also notify nearby devices that it is employing a plurality of receive antennas. This information can be used by the nearby devices to more intelligently perform transmitter yielding. By utilizing beamforming information to make the transmitter and/or receiver yielding decision, better interference mitigation may be achieved.

Abstract: 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.

Abstract: A method includes transmitting a first signal over a network from a first communication link to a second communication link. The method further includes receiving a second signal with the first communication link from the second communication link. The method further includes canceling signal echo from the first signal present in the second signal with a digital echo canceller. The method further includes providing correction data from a memory array to the digital echo canceller during the cancellation of the signal echo. An associated apparatus is also disclosed.

Abstract: Duplex audio communications over a network use compressed audio data, with linear prediction coefficients (LPCs) and variances by which sample values differ from predictions. A adaptive echo canceller for a transceiver develops finite impulse response filter (FIR) coefficients characterizing an echo path between its local audio output and audio input. The received/decompressed audio data is applied to the FIR coefficients, and the predicted echo is subtracted from the uplink signal. Echo is detected as cross-correlation of the receive signal versus the uplink/send signal over time. In one embodiment, the cross-correlation is determined using a pre-whitened receive signal, obtained by adopting the variance values received over the network by the downlink Codec. Apart from the uplink Codec, no speech analysis filter or process is needed. The technique is apt for GSM, AMR and similar compressed audio communications.

Abstract: An echo canceller uses an adaptive filter to remove an echo of an incoming far-end signal from an outgoing near-end signal. Filter coefficients are calculated and updated while the far-end signal is active so as to minimize the residual echo. In addition, the far-end signal and near-end signal are sampled to generate simulated far-end and near-end signals, from which substitute filter coefficients are similarly calculated while the far-end signal is silent. When the far-end signal changes from silent to active, the substitute filter coefficients are swapped in as initial values for the filter coefficients, thereby speeding up subsequent convergence of the filter coefficients without significant added computational cost.

Abstract: A device comprising a circuit for picking up acoustic signals with the microphone; a circuit for playing back audio signals with an amplifier and a loudspeaker; an interface circuit for interfacing with a telephone network or a cell phone; and a circuit for digitally processing audio signals and reducing the acoustic echo that results from interaction of the loudspeaker with the microphone. The circuit for digitally processing audio signals comprises: an echo cancellation stage with an adaptive linear filter suitable for subtracting from the signal picked up by the microphone a reference signal that is derived from the signal received at the output from the interface; a gain control stage for suppressing the residual echo, and a stage for selectively reducing the background noise present in the signal received at the output from the echo suppression stage.

Abstract: A passive processing device (D) is adapted to be interfaced in a full integrated way on at least a first audio signal path defined between a first audio signal source and an audio signal processing means of an electronic device, such as a mobile communication device. This device (D) comprises a first protection means (DE11; DE12) for rejecting electrostatic discharges on the first path, a first rejection means (CR11, R11; CR12) for rejecting radio signals at least in a chosen frequency band on the first path, and a first AC-coupling means (CC1) for interfacing voltage levels between the first audio signal source and the audio signal processing means.

Abstract: The device comprises a microphone for detecting a speech signal from a near speaker, and a loudspeaker for reproducing a speech signal from a remote speaker. The processing for canceling the interfering acoustic echo implements an adaptive linear filtering algorithm. Double talk situations are detected by: evaluating an index representative of the convergence or divergence of the algorithm; assessing a predetermined condition for detecting a double talk situation; and if the condition is satisfied, modifying at least one parameter of the algorithm in response to the detection. The representative index may be the norm of the gradient vector describing the adaptation of the filter from one iteration of the algorithm to the next, the conditions being a comparison between the gradient and a threshold. The parameter that is modified double talk situation may be the adaptation stepsize of the algorithm, and also the gain control of an echo suppression stage.

Abstract: The present invention is a desktop speakerphone having a base-station and a detachable microphone pod. The base-station includes standard telephone components, as well as a wireless receiver and a housing for a detachable microphone pod. The detachable pod contains at least one microphone and a wireless transmitter. When the pod is attached to the base-station, and the conference mode of operation is activated, the pod microphone's audio signal goes directly to base-station audio circuitry via a wired connection. When the pod is detached and the conference mode activated, the pod microphone's audio signal now goes via the pod's wireless transmitter to the base-station's wireless receiver. This detached, wireless mode allows the microphone to be positioned anywhere in the room, thereby improving the quality of transmitted speech by increasing the speech-signal-to-room-noise ratio, and lessening the potential for room echo by reducing the acoustic coupling between base-station loudspeaker and pod microphone.

Abstract: A computing system for managing site security through a communication device includes a mobile communication device, a notification, and the communication device. Using BLUETOOTH technology, the mobile communication device communicates with and activates the communication device and the notification. The communication device detects any noteworthy event and captures visual data accordingly, and transmits the visual data to the mobile communication device. The notification generates visual and audio alerts. A related method and storage medium with instructions for performance of the method also provided.

Abstract: An apparatus for position-dependent control has a control unit, where the control unit takes the position of the apparatus as a basis for: a) controlling damping and/or echo cancellation for the apparatus, and/or b) switching a summit of the apparatus on or off or to a power saving mode, and/or c) prompting call acceptance.

Abstract: A wireless headset has improved immunity to RF electromagnetic interference produced from wireless communications devices. A headset body is adapted to be worn by a user and includes a microphone and earpiece. An antenna receives wireless communication signals and passes them to RF and audio circuitry mounted within the headset body. The RF and audio circuitry include a Bluetooth module operatively connected to the antenna for transmitting and receiving wireless communication signals, an audio CODEC connected to the Bluetooth module, and audio connection lines connected between the CODEC and the earpiece and between the CODEC and the microphone. A filter is connected into each of the audio connection lines at the earpiece and microphone and operative for reducing the RF coupling from a mobile wireless communications device.

Abstract: The invention provides a method and system for responding to digital vehicle requests. After a telematics unit receives a voice query and converts the voice query to a compressed digital signal, the signal is transmitted to a call center node. The signal is then parsed at the call center node to determine an inquiry. The call center node may then formulate at least one response to the inquiry and transmit the at least one formulated response in a digital format over the wireless network to the telematics unit. The at least one formulated response is then translated to an analog format at the telematics unit.

Abstract: In a signal processing system, a set of channel signals from an array of sensors of different operating characteristics are processed in calibration circuitry that calculates individual average values of the channel signals and calculates an average of the individual average values of channel signals as a reference value. Reciprocal calculators calculate reciprocal values of the individual average values of the channel signals. Scaling circuitry scales the reciprocal values by the reference value to produce a set of amplitude calibration signals and scales the channel signals by the calibration signals respectively. As a result, the channel signals are normalized by their own average values and scaled by the reference value to produce a set of calibrated channel signals.

Abstract: To provide a noise suppressing device which accurately suppresses weak electric field strength pulse noise. A band-limiting unit (5) band-limits a composite signal obtained by demodulating an FM baseband signal, to a frequency band equal to or lower than a predetermined frequency so as to output a monaural audio signal. A pulse detecting unit (62) which detects pulse noise in the audio signal outputted by the band-limiting unit (5). A pulse judging unit (63) judges that a detection result of the pulse detecting unit (62) is valid in the case where pulse noise is detected in the composite signal, at a position corresponding to the detected pulse noise. A pulse suppressing unit (64) suppresses the pulse noise detected in the audio signal, in the case where the pulse judging unit (63) judges that the detection result is valid.

Abstract: A method (300) and apparatus (200) for signaling uplink scheduling information is disclosed. The method may include determining (320) whether an enhanced general packet radio service 2-B mobile device and an enhanced general packet radio service non-2-B mobile device are assigned to a same uplink time slot. The method may also include limiting (330) downlink communications to Ap and B radio link control block families when sending packet data to the enhanced general packet radio service 2-B mobile device, if the enhanced general packet radio service 2-B mobile device and the enhanced general packet radio service non-2-B mobile device are assigned to the same uplink time slot.

Abstract: A vehicle communication system detects the presence of a passenger wearable communication device. The system receives audio signals from multiple sources inside or outside of a vehicle. The system processes the signals before routing the signals to multiple destinations. The destinations may include wearable personal communication devices, front and/or rear speakers, and/or a remote mobile device.

Abstract: A communication device contains multiple microphones that receive acoustic signals from a user and from the background. The acoustic signals from the user are enhanced using the background acoustic signals to reduce background noise. The enhanced signal are transmitted to an emergency network when an emergency call is made from the communication device. The raw signals are stored in the communication device for later retrieval or are transmitted simultaneously with the enhanced signals. The enhanced signals are transmitted using a circuit-switched voice mode while the raw signals are transmitted using a packet-switched voice mode.

Abstract: Embodiments related to echo compensation have been described and depicted.

Abstract: Among other features, a boom microphone has a microphone connector; an earcup module includes an earcup connector jack to connect to a headphone and a boom lead-in to receive the microphone connector; and a control module communicates voice signals wirelessly between (a) the boom microphone and headphone and (b) a telephone.

Abstract: Disclosed herein are portable teleconferencing products that implement a doubletalk detector in a low frequency range or in a frequency range commensurate with the frequencies through which sound may be efficiently transferred between a speaker and a microphone through an enclosure. Also disclosed herein are teleconferencing systems that implement a secondary doubletalk detector, a non-presumptive doubletalk detector, a confirmatory doubletalk detector, and/or a false doubletalk detector, whereby echo cancellation coefficients may be better adapted after echo path changing events through the use of accelerated coefficient adaptation or half-duplex operation until adaptation is restored.

Abstract: Embodiments of the invention relate to a feedback mechanism that informs a user of a communication device to adjust the volume, pitch, tone or other characteristic of his voice so as to compensate for noise in the surrounding environment. The feedback mechanism includes feedback circuitry that analyzes audio signals from the microphone and preferably from one or more additional environmental noise sensors. From the analysis, the feedback circuitry determines characteristics of the user's voice and characteristics of the environmental noise, and provides an analysis of how the user might modify his voice to best compensate for environmental noise. This analysis results in an indication to the user, such as through a vibration, a sound, or graphical indication on the device, which tells the user whether and to what extent the user should adjust a characteristic of his voice to best overcome such environmental noise.

Abstract: A mobile communication device is provided. The mobile communication device includes a terminal body, and a speaker module located in the terminal body. The speaker module includes an enclosure located in the terminal body, the enclosure defining a chamber therein, and a speaker having a front surface and a rear surface, the speaker being located in the enclosure such that the front surface of the speaker is exposed from the enclosure and the rear surface thereof is positioned within the chamber, to allow a sound generated from the rear surface to resonate within the chamber. A mutual interference between the sound generated from the front side of the sound emission part and the sound emitted from the rear side thereof can be reduced to thereby improve the performance of the middle and low sound.

Abstract: An audio interface adapted to reduce a subscriber voice may receive a subscriber voice and a background noise. The subscriber voice may then be compared to the to the background noise. If the received subscriber voice is louder than the received background noise, the audio interface may output a message to the cellular telephone subscriber indicating the subscriber may reduce his speaking volume. Additionally, an audio interface may process a voice waveform that corresponds to the subscriber voice and a background waveform that corresponds to the background noise to generate a substantially opposite voice waveform and a substantially opposite background waveform respectively. The substantially opposite voice waveform and background waveform may be substantially out of phase from the voice waveform and background waveform respectively and output via one or more output ports of the audio interface.

Abstract: A wireless headset has improved immunity to RF electromagnetic interference produced from wireless communications devices. A headset body is adapted to be worn by a user and includes a microphone and earpiece. An antenna receives wireless communication signals and passes them to RF and audio circuitry mounted within the headset body. The RF and audio circuitry include a Bluetooth module operatively connected to the antenna for transmitting and receiving wireless communication signals, an audio CODEC connected to the Bluetooth module, and audio connection lines connected between the CODEC and the earpiece and between the CODEC and the microphone. A filter is connected into each of the audio connection lines at the earpiece and microphone and operative for reducing the RF coupling from a mobile wireless communications device.

Abstract: An echo cancellation circuit for an RFID reader and the method thereof are provided. The echo cancellation circuit includes a gain calculator, a gain adjustment circuit, and a subtraction circuit. The gain calculator provides a complex gain value according to a carrier signal and a received signal through an adaptive algorithm. The gain adjustment circuit is coupled to the gain calculator. The gain adjustment circuit multiplies the carrier signal by the complex gain value, and outputs the result of the multiplication. The subtraction circuit is coupled to the gain adjustment circuit. The subtraction circuit subtracts the output of the gain adjustment circuit from the received signal, and then provides the result of the subtraction as the output signal of the echo cancellation circuit.