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| Number | Title | Issue Date |
| 7970124 | Adaptive gain control based on echo canceller performance information 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 ... | 06/28/2011 |
| 7230460 | Digital visual interface Techniques or designs of circuits to correct distortions in signals transported over a high-speed digital connection between a video source (e.g., a PC or a DVD player) and a digital monitors (such as LCDs) are disclosed. According to one aspect of the present inven... | 06/12/2007 |
| 7151828 | Circuit arrangement for the analogue suppression of echoes A circuit arrangement for the analogue suppression of echoes, as in particular can be used in a hybrid-circuit for DSL-transmission systems, comprises a replica (8) for emulating the behaviour of the transmission line (17). In addition, a circuit (3... | 12/19/2006 |
| 7039181 | Consolidated voice activity detection and noise estimation 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 esti... | 05/02/2006 |
| 7027604 | Circuit to prevent acoustic feedback for a cellular speakerphone This invention includes a circuit for the prevention of acoustic feedback between an electronic device and an audio accessory. In a preferred embodiment, the circuit prevents audio feedback between a cellular telephone and a speakerphone accessory. The circuit inclu... | 04/11/2006 |
| 6944290 | Echo cancellation through auxiliary-vector filtering A digit signal processing system may include a near end and a far end connected by a pair of signal transmission paths. A signal processing may be located at the near end through which signal commands are transmitted to the far end. A signal transducing device may b... | 09/13/2005 |
| 6904146 | Full duplex echo cancelling circuit Sub-band filtering, adaptive echo cancellation, and residual echo suppression are selectively and separately applied in hierarchical order under the control of a circuit that monitors four separate signals to determine n machine states. The number of machine states ... | 06/07/2005 |
| 6901141 | Echo canceller An adaptive digital filter (10) is adapted to generate a pseudo echo Se which is produced by imitating a noise, using part of receiving signals Si and to output it. An echo produced through an echo path (15) is mixed, as an echo noise, with a sending s... | 05/31/2005 |
| 6816591 | Voice switching system and voice switching method There are provided a voice switching system and a voice switching method which are capable of carrying out highly accurate voice detection and performing a switching action properly even in the presence of an unstationary noise or under circumstances where the S/N r... | 11/09/2004 |
| 6799062 | Full-duplex hands-free transparency circuit and method therefor A bi-directional hands-free communication device includes a microphone for transmitting a signal along a transmit path and a speaker receiving a signal transmitted along a receive path and outputting a corresponding output signal. An echo canceller, positioned in th... | 09/28/2004 |
| 6757384 | Robust double-talk detection and recovery in a system for echo cancelation Echoes caused by discontinuities in a telecommunications transmission lines cause double talk which cause divergence problems with echo cancellers. Divergence problems in echo cancellers cause considerable problems in interactive caller response systems, they cause ... | 06/29/2004 |
| 6744884 | Speaker-phone system change and double-talk detection A speaker-phone that is operable to perform system change detection, double-talk detection and if desired, optimal step-size control. The invention differentiates between system change and double-talk and is operable to these two situations differently. The inventio... | 06/01/2004 |
| 6618479 | Echo canceler An echo canceler for suppressing an echo of a receive signal contained in a transmit signal directed to a telephone circuit and transferring the transmit signal subjected to echo suppression to the telephone circuit. The echo canceler includes a pseudo ec... | 09/09/2003 |
| 6594360 | Circuit configuration for two-wire/four-wire conversion The invention relates to a circuit configuration for two-wire/four-wire conversion. The circuit configuration has a receiver which is coupled on an input side to a digital two-wire reception path via which its receives a digital signal. A signal-processor... | 07/15/2003 |
| 6580794 | Acoustic echo canceler with a peak impulse response detector In an acoustic echo canceler of a loudspeaking telephone apparatus, a sequence of successively delayed tap signals of a remote speech signal from a transmission line are respectively weighted by filter coefficients and summed together to produce an acoust... | 06/17/2003 |
| 6522746 | Synchronization of voice boundaries and their use by echo cancellers in a voice processing system Methods and apparatus for processing a transmitted voice signal include a centralized frame controller providing at least one boundary control signal to voice processing blocks and controlling the operation of the voice processing blocks on the transmitte... | 02/18/2003 |
| 6496581 | Coupled acoustic echo cancellation system Full acoustic coupling and echo cancellation is provided in implementations where there is acoustic coupling between acoustic zones. In acoustic echo cancellation systems, including active acoustic attenuation systems and communications systems, having a ... | 12/17/2002 |
| 6487178 | Methods and apparatus for providing volume control in communicating systems including a linear echo canceler In handsfree communications devices including a linear echo or noise canceler, both analog and digital gain factors are adjusted in response to user volume control inputs, the analog gain factor being frozen during active communications (e.g., during tele... | 11/26/2002 |
| 6483914 | Telephone filter arrangement A subscriber's telephone installation comprises a plurality of telephone sets coupled in parallel to a subscriber loop so as to provide a voice facility, and a data modern coupled to the subscriber loop so as to provide data facilities at a frequency abov... | 11/19/2002 |
| 6473507 | Apparatus and method for isolating transients associated with a digital subscriber line A communication apparatus includes circuitry operable to facilitate communication over a digital subscriber line. The apparatus also includes a filter operable to be coupled between the circuitry and the digital subscriber line. The filter has a corner fr... | 10/29/2002 |
| 6459790 | System and method for selective filter isolation In a system including a plurality of telephones coupled to an asymmetric digital subscriber line, a circuit operable to facilitate communication using the asymmetric digital subscriber line includes a filter having a corner frequency and being operable to... | 10/01/2002 |
| 6249581 | Spectrum-based adaptive canceller of acoustic echoes arising in hands-free audio The present echo canceller utilizes the principle that the spectrum pattern of human speech does not change much in the short run. The inputs to the present echo canceller are x(t) and y(t), y(t) representing the incoming speech signal from a far-end spea... | 06/19/2001 |
| 6236726 | Transmit power scaling for far-end crosstalk reduction The invention provides a system and a method for decreasing the amount of crosstalk occurring within a data transmission system in which digital data is transmitted at high speeds over a telephone network. The invention makes use of intelligence at a plur... | 05/22/2001 |
| 6002776 | Directional acoustic signal processor and method therefor Two or more microphones are mounted in an environment that contains an equal or lesser number of distinct sound sources. Acoustic energy from each source, with its attendant echoes and reverberation, impinges on each microphone. Using direction-of-arrival... | 12/14/1999 |
| 5943392 | Device for measuring echo return loss in a two-two wire line system The present invention is directed to an adaptor for measuring an echo return loss in a communication system. The adaptor includes two transformers, each having a primary winding and two secondary windings. The secondary windings are cross-connected to for... | 08/24/1999 |
| 5548636 | Method and apparatus for providing user controlled call management services A method of providing call screening to a subscriber of personal communication services facilitates the screening of incoming calls by associating the number dialed by a calling party with a function or role of the dialed number. This function or role is ... | 08/20/1996 |
| 5548638 | Audio teleconferencing apparatus An audio teleconferencing apparatus which permits two-way communications between more than two parties without the necessity of complete switching and does not allow a loss to increase in a communication channel of a particular speaker. The audio teleconf... | 08/20/1996 |
| 5544242 | Speakerphone with event driven control circuit A control circuit for a speakerphone circuit which utilizes an event driven circuit to determine the appropriate gain for the receive and transmit channels is provided. Detectors monitor the relative magnitudes of the signal in the transmit and receive ch... | 08/06/1996 |
| 5414763 | Apparatus and method for providing echo suppression to a plurality of telephones A telephone switching apparatus includes a line network to which first and second telephones are connected and a hands-free trunk whose input and output terminals are connected to the line network. The line network is controlled such that voices from the ... | 05/09/1995 |
| 5212722 | Hands-free telephone having a handset volume attenuator for controlling speaker volume in a hands-free adaptor A hands-free telephone for use on a vehicle includes a handset incorporating a radio section therein and a hands-free adapter incorporating a hands-free telephone unit therein. To prevent howling, the telephone includes two variable attenuators, or variol... | 05/18/1993 |
| 5016271 | Echo canceler-suppressor speakerphone An echo canceler-suppressor speakerphone arrangement effectively addresses the limitations of regeneration and reverberant return echo inherent in the design of speakerphones. The tendency for regeneration is eliminated by employing adaptive echo cancella... | 05/14/1991 |
| 4700382 | Voice-switched telephone circuit with center idle state A voice-switched telephone circuit with center idle state improves bi-dirional gain control in loudspeaking telephones and thereby enhances the natural quality of interactive conversation. The voice-switched telephone includes: a transmit channel having ... | 10/13/1987 |
| 4292473 | Loop supervision circuit An impedance network used for ring trip or loopsupervision purposes in a telecommunications system. The network employs a multi-port impedance bridge with one set of opposed terminals (first port) coupled to the line loop being supervised and the opposed ... | 09/29/1981 |
| 4165449 | Echo suppressor circuit Disclosed is an echo suppressor circuit which provides a variable loss in a speaker's transmit path, which loss is a function of the relative speaker volumes. The loss provided in the path of a particular speaker is relative to the volume of the speech em... | 08/21/1979 |
| 4053870 | Digital signal level comparison device A digital level comparison device having a digitally controlled switching network for adding or removing attenuation from a signal channel is described. The device includes a binary counter having an input for pulses corresponding to the received signal l... | 10/11/1977 |
