Imagination Technologies Limited

Srinivas Akella

Senthil Kumar Mani

Sai Ravi Teja Pulugurtha

Gandhi Namani

Anupama Ghantasala

Ghandhi Namani

An echo cancellation detector for controlling an acoustic echo canceller that is configured to cancel an echo of a far-end signal in a near-end signal in a telephony system, the echo cancellation detector comprising a comparison generator configured to compare the far-end signal with the near-end signal, a decision unit configured to make a determination about a first acoustic echo canceller based on that comparison and a controller configured to control an operation of a second acoustic echo canceller in dependence on the determination.

Detection of acoustic echo cancellation

A gain control system for dynamically tuning an echo canceller, the echo canceller being configured to estimate an echo of a far-end signal and subtract that echo estimate from a microphone signal to output an echo cancelled signal, the gain control system comprising a monitoring unit configured to estimate an energy associated with an impulse response of an adaptive filter configured to generate the echo estimate from the far-end signal and a gain tuner configured to adjust an attenuation of at least one of the microphone signal and the far-end signal in dependence on the estimated energy.

Auto-tuning of acoustic echo canceller

A gain control system for dynamically tuning an echo canceller, the echo canceller being configured to estimate an echo of a far-end signal and subtract that estimate from a microphone signal to output an echo cancelled signal, the system comprising an echo measurement unit configured to calculate a ratio of the microphone signal to the far-end signal, an attenuation unit configured to attenuate at least one of the microphone signal and the far-end signal to output a second microphone signal and a second far-end signal to the echo canceller, the ratio of the second microphone signal to the second far-end signal being different from the calculated ratio, and an attenuation controller configured to control the attenuation unit, in dependence on the calculated ratio, so as to alter the ratio of the second microphone signal to the second far-end signal and control the echo-cancelled signal.

Auto-tuning of an acoustic echo cancellar

A system for generating comfort noise for a stream of frames carrying an audio signal includes frame characterizing logic configured to generate a set of filter parameters characterising the frequency content of a frame; an analysis filter adapted using the filter parameters and configured to filter the frame so as to generate residual samples; an analysis controller configured to cause the residual samples to be stored in a store responsive to receiving an indication that the frame does not comprise speech; and a synthesis controller operable to select stored residual samples from the store and cause a synthesis filter, inverse to the analysis filter and adapted using filter parameters generated by the frame characterizing logic for one or more frames not comprising speech, to filter the selected residual samples so as to generate a frame of comfort noise.

Comfort noise generation

A threshold control system for controlling a non-linear processor in an echo canceller, the non-linear processor being configured to remove any signal energy below a threshold that remains in a microphone signal after the echo canceller has subtracted an echo estimate from it, the threshold control system comprising a convergence unit configured to determine an indication of the stability of an adaptive filter, the adaptive filter being configured to continuously model an echo path so as to generate the echo estimate, and a threshold tuner configured to adjust the threshold of the non-linear processor in dependence on the indication.

Auto-tuning of non-linear processor threshold

Auto-tuning of an acoustic echo canceller

A method and system for acoustic echo cancellation stores received far-end data in a first buffer. When the far-end data in the first buffer exceeds a predefined length, the stored far-end data is used to calculate echo estimate data. The echo estimate data is stored in a second buffer. Whenever microphone data is received the error data is calculated independent of echo estimate data availability. In particular, subsequent to sufficient echo estimate data being stored in the second buffer and responsive to the reception of the microphone data, the error data is calculated by subtracting, from the microphone data, corresponding echo estimate data stored in the second buffer.

Acoustic echo cancellation

A method and system for acoustic echo cancellation varies a step size of an adaptive filter in an acoustic echo canceller. Far-end data is received and echo estimate data is calculated using the received far-end data. Microphone data is received and error data is calculated using the received microphone data and the echo estimate data. A first average of the microphone data and a second average of the error data are computed over a predefined number of samples. An echo leakage is estimated using the first average and the second average wherein the echo leakage indicates an extent to which the far-end data is present in the error data, and the step size of the adaptive filter is varied based on the echo leakage and a maximum allowed step size.

Growing community of inventors

Hyderabad Telangana, India

Srinivas Akella