Abstract: An echo canceling circuit comprising a double talk detector, an upper band signal filter configured to pass only near-end upper band signals to the double talk detector and remove lower band signals, an adaptive filter circuit, a control circuit operatively coupled to the double talk detector and to the adaptive filter circuit, and a threshold estimator configured to iteratively calculate an upper adaptive decision threshold value and a lower adaptive decision threshold value. The double talk detector declares near-end speech to be present if an estimated power level of the upper band signals exceeds the upper adaptive decision threshold value, and declares the near-end speech to be absent if the estimated power level of the upper band signals falls below the lower adaptive decision threshold value for a predetermined number of iterative cycles.

Abstract: An apparatus and method for enhancing a handheld communication device via a telematics system in a vehicle is disclosed. Audio received at the handheld device is transferred to the telematics system in the vehicle. The received audio is then analyzed to determine whether it contains speech, and if so, an audio present signal is generated and the received audio is recorded into a memory coupled to the telematics system. The user can then engage the user interface of the telematics system to replay the recorded audio. Bluetooth protocol is preferably used to establish a channel between the handheld device and the telematics system, which can occur automatically when the two are in proximity. Analysis of the received audio preferably comprises use of a voice detector as part of a speech recognition system otherwise used by the telematics system to assess spoken commands.

Abstract: A method for reducing a computational complexity of an m-stage adaptive filter is provided by expanding a weighted sum of forward prediction error squares into a corresponding binomial expansion series, expanding a weighted sum of backward prediction error squares into a corresponding binomial expansion series, and determining coefficient updates of the adaptive filter with the weighted sums of forward and backward prediction error squares approximated by a select number of terms of their corresponding binomial expansion series.

Abstract: A method for reducing a computational complexity of an m-stage adaptive filter is provided by updating recursively forward and backward error prediction square terms for a first portion of a length of the adaptive filter, and keeping the updated forward and backward error prediction square terms constant for a second portion of the length of the adaptive filter.

Abstract: A method for reducing a computational complexity of an m-stage adaptive filter is provided by determining a weighted sum of backward prediction error squares for stage m at time n, determining a conversion factor for stage m at time n, inverting the weighted sum of backward prediction error squares, and approximating a weighted sum of forward prediction error squares by combining the inverted weighted sum of backward prediction error squares with the conversion factor.

Abstract: A downlink activity and double talk probability detector and method for an echo canceler circuit (10) improves the stability of an echo canceler adaptive filter (300) and improves the attenuation of post-echo canceler uplink data (388). The echo canceler circuit (10) includes a downlink activity and double talk probability data generator (30) and an echo canceler stage (20). The downlink activity and double talk probability data generator (30) receives pre-echo canceler uplink data (40) and downlink data (50) and in response produces double talk probability data (60) and downlink activity data (70). The echo canceler stage (20) receives the downlink data (50), the pre-echo canceler uplink data (40), the double talk probability data (60) and the downlink activity data (70), and in response produces uplink data (80).

Abstract: An echo canceler circuit (200) and method performs cascaded echo cancellation and noise suppression in a non-interfering manner. The echo canceler circuit (200) includes pre-noise suppression logic (210), echo canceler coefficient logic (218), noise suppression logic (212) and an echo canceler filter (216). The pre-noise suppression logic (210) receives pre-echo canceler uplink data (64) and downlink data (52), and in response produces pre-noise suppression uplink data (224). The echo canceler coefficient logic(218) receives the pre-noise suppression uplink data (224) and the pre-echo canceler uplink data (64), and in response produces filter coefficient data (226). The noise suppression logic (212) receives the pre-noise suppression uplink data (224), and in response produces noise suppressed uplink data (228). The echo canceler filter (216) receives the noise suppressed uplink data (228) and the filter coefficient data (226) and in response produces final uplink data (230).

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 double talk activity detector (30) and method for an echo canceler circuit (10) improves the probability of detecting a double talk condition based on at least pre-echo canceler uplink data (40). The echo canceler circuit (10) includes a double talk activity probability data generator (30) and an echo canceler stage (20). The double talk activity probability data generator (30) receives pre-echo canceler uplink data (40) and in response produces double talk activity probability data (50). The echo canceler stage (20) is coupled to the double talk activity probability data generator (30) and receives downlink data (60), pre-echo canceler uplink data (40) and the double talk activity probability data (50) and in response produces attenuated uplink data (70).