Methods and apparatus for providing volume control in communicating systems including a linear echo canceler
AssigneeEricsson Inc.
InventorsEric Douglas Romesburg, Thomas John Makovicka
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Abstract
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 telephone calls). By providing dual user controls, one of which is disabled when a call is in progress, embodiments of the invention provide the wide dynamic range required in most handsfree applications without degrading performance of the linear echo canceler.
Claims18
A bi-directional communications device, comprising:
- a digital multiplier receiving a far-end digital input signal and scaling the far-end digital input signal by a digital gain factor to provide a far-end digital reference signal;
- a digital-to-analog converter receiving the far-end digital reference signal and processing the far-end digital reference signal to provide a far-end analog reference signal;
- an analog multiplier receiving the far-end analog reference signal and scaling the far-end analog reference signal by an analog gain factor to provide a far-end analog output signal for presentation to a near-end user;
- an analog-to-digital converter receiving a near-end analog input signal and digitizing the near-end analog input signal to provide a near-end digital input signal, the near-end digital input signal including an echo component resulting from coupling of the far-end analog output signal through an echo path to the analog-to-digital converter;
- and
- a linear echo canceler receiving the far-end digital reference signal, processing the far-end digital reference signal to provide an estimate of the echo component of the near-end digital input signal, and subtracting the estimate from the near-end digital input signal to thereby provide an echo-canceled near-end digital output signal for presentation to a far-end user,
- wherein both the analog gain factor and the digital gain factor are variable in dependence upon near-end user input when the near-end and far-end users are not communicating with one another via the device, and wherein the analog gain factor is fixed and the digital gain factor is variable in dependence upon near-end user input when the near-end and far-end users are communicating with one another via the device.
A bi-directional communications device, comprising:
- a near-end signal processing path and a far-end signal processing path, the far-end signal processing path including a digital-domain multiplier and an analog-domain multiplier;
- and
- an echo canceler receiving a far-end digital reference signal from the far-end signal processing path and providing an echo estimate to the near-end signal processing path,
- wherein both an analog gain factor of said analog-domain multiplier and a digital gain factor of said digital-domain multiplier are adjustable in dependence upon user input when users of said device are not communicating with one another via the device, and
- wherein the analog gain factor of said analog-domain multiplier is fixed and the digital gain factor of said digital-domain multiplier is adjustable in dependence upon user input when users of said device are communicating with one another via the device.
A method of processing bidirectional communication signals, comprising the steps of:
- fixing a value of an adjustable analog gain factor;
- receiving a far-end digital input signal;
- multiplying the far-end digital input signal by an adjustable digital gain factor to provide a far-end digital reference signal;
- translating the far-end digital reference signal to the analog domain to thereby provide a far-end analog reference signal;
- multiplying the far-end analog reference signal by the fixed-value analog gain factor to provide a far-end analog output signal;
- receiving a near-end analog input signal, the near-end analog input signal including an analog echo component resulting from coupling of the far-end analog output signal through a near-end echo path;
- digitizing the near-end analog input signal to provide a near-end digital input signal, the near-end digital input signal including a digital echo component corresponding to the analog echo component of the near-end analog input signal;
- processing the far-end digital reference signal to provide an estimate of the digital echo component of the near-end digital input signal;
- and
- subtracting the estimate of the digital echo component from the near-end digital input signal to provide a near-end digital output signal.
A method of processing signals in a telephone, the telephone including near-end and far-end signal processing paths and an echo canceler, the far-end signal processing path including a digital domain multiplier and an analog domain multiplier, the method comprising the steps of:
- determining whether a telephone call is in progress;
- permitting adjustments of a digital gain of the digital domain multiplier and permitting adjustments of an analog gain of the analog domain multiplier when said determination is negative;
- and
- permitting adjustments of the digital gain of the digital domain multiplier and blocking adjustments of the analog gain of the analog domain multiplier when said determination is affirmative.
Dependencies are inferred from the claim text.