France Telecom

France Telecom Sa

French State Represented by the Minister of the Post, Telecommunications

Gregoire Le Tourneur

Yannick Mahieux

Alain Saliou

Wolfgang Tager

Freddy Balestro

Wolfgang Taeger

Delphine Feurte

Jean-Pascal Jullien

A method for adaptive control of a multi-channel echo cancellation system including N loudspeakers, where N is an integer greater than or equal to 2, and M microphones, where M is an integer greater than or equal to 1. The system includes N&#xd7;M identification filters with variable coefficients, the identification filters being used to estimate acoustic coupling between the loudspeakers and the microphones as a function of a variable coefficients adaptive step. The variable coefficients adaptive step depends on whether or not there is a signal present on the loudspeakers. The method is applicable to hands-off operation of communication tools.

Method for adaptive control of multichannel acoustic echo cancellation system and device therefor

A sound pick-up and reproduction system includes at least two sound sensors, such as microphones, situated at different distances from a sound reproduction device, such as a loudspeaker. A processor responds to amplitudes and phases of signals outputted by the at least two sound sensors to control a signal outputted to an amplifier and adapted to drive the sound reproduction device, thereby reducing echoes in the sound reproduction device output caused by acoustic coupling between the at least two sound sensors and the sound reproduction device.

Sound pick-up and reproduction system for reducing an echo resulting from acoustic coupling between a sound pick-up and a sound reproduction device

The output signals of the acoustic sensors of the antenna are subjected to a processing of the superdirective kind, with a constraint as regards the modulus and a non-linear constraint which fixes the incoherent noise reduction. The theoretical formulation of these constraints being as follows ##EQU1## the first constraint signifying that the total transfer function is a pure delay .tau., and the second constraint signifying that a limit is fixed for the incoherent noise reduction. The antenna is provided to improve the near-field reception.

Antenna formed of a plurality of acoustic pick-ups

A device for programmable delay of an analog signal in an acoustic antenna that comprises at least one analog/digital converter circuit delivering, from the analog signal, a digital signal at a first sampling frequency, followed by a delay memory receiving the digital signal in write mode, making it possible to store M consecutive samples in memory. A circuit for write and read access to the delay memory is provided to address the delay memory in write and read mode, which, under read access control, delivers a series of samples delayed by a defined value, a function of the number of samples M stored therein. A sub-sampling circuit receives the delayed digital signal and delivers a sub-sampled delayed digital signal at a second sampling frequency less than the first sampling frequency.

Device for programmable delay of an analog signal and corresponding

An acoustic antenna for computer workstation, used for video conferencing that comprises a plurality of microphones connected to a summator circuit. The microphones are distributed in a layout so as to form a substantially straight line and are each spaced with respect to a reference microphone placed in the vicinity of the vertical axis of symmetry of the screen of the workstation according to a specified law. The layout exhibits a substantially cylindrical directivity pattern whose axis of revolution is formed by the straight line.

Acoustic antenna for computer workstation

A system for selective sound capture for hands-free telephony and multimedia workstations of the acoustic antenna type with an aerial formed by a member with a concave cylindrical surface. The system includes a plurality of electro-acoustic transducers which are distributed over and in the vicinity of the cylindrical surface. Circuits for partial summation of a plurality of analog sound signals make it possible to form elementary acoustic antennas and a summation circuit produces a resultant analog signal representative of the sound signal arising from a useful speaking area.

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St-Quay-Perros, France

Gregoire Le Tourneur