Echo canceler gain tracker for cellular modems
First Claim
1. Data communications equipment apparatus comprising:
- a filter for echo canceling that provides an echo estimate signal;
an amplifier comprising an infinite impulse response filter, said amplifier configured to adjust the magnitude of the echo estimate signal as a function of an amount of correlation between the echo estimate signal and an echo-canceled signal to provide an adjusted echo estimate signal, said amplifier including first multiplication means for multiplying said echo estimate signal with said echo-canceled signal; and
a means for combining a received signal with the adjusted echo estimate signal to provide said echo-canceled signal, while the data communications apparatus is operating in a data transfer mode.
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Accused Products
Abstract
A fast response gain tracker operates to adjust the magnitude of an echo cancellation signal. The latter signal is developed from an echo canceler. The fast response gain tracker provides an adjusted echo cancellation signal that is subtracted from an echo-corrupted received signal to provide an echo-canceled signal. In particular, the fast response gain tracker correlates the echo-canceled signal with the echo cancellation signal from the echo canceler. If the gain of the gain tracker is correct the echo is canceled and there is zero correlation between the echo-canceled signal and the echo cancellation signal. However, if the echo level changes then a residual echo component appears in the echo-canceled signal, which now becomes correlated with the echo cancellation signal. In response, the magnitude of the gain tracker automatically adjusts the gain of the echo cancellation signal to match the change in echo level and thereby subsequently eliminates the residual echo.
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Citations
13 Claims
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1. Data communications equipment apparatus comprising:
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a filter for echo canceling that provides an echo estimate signal; an amplifier comprising an infinite impulse response filter, said amplifier configured to adjust the magnitude of the echo estimate signal as a function of an amount of correlation between the echo estimate signal and an echo-canceled signal to provide an adjusted echo estimate signal, said amplifier including first multiplication means for multiplying said echo estimate signal with said echo-canceled signal; and a means for combining a received signal with the adjusted echo estimate signal to provide said echo-canceled signal, while the data communications apparatus is operating in a data transfer mode. - View Dependent Claims (2, 3)
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4. Data communications equipment apparatus comprising:
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a filter for echo canceling that provides an echo estimate signal; an infinite impulse response filter that adjusts the magnitude of the echo estimate signal to provide an adjusted echo estimate signal during a period in which data transfer is occurring, said infinite impulse response filter including first multiplication means for multiplying said echo estimate signal with an echo-canceled signal; and a means for combining a received signal with the echo adjusted estimate signal as a function of an amount of correlation between the echo estimate signal and the echo-canceled signal to provide an echo-canceled signal. - View Dependent Claims (5, 6, 7, 8)
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9. A method for use in data communications equipment apparatus to quickly reduce a residual echo signal, the method comprising the steps of:
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training an echo canceler during a training sequence; receiving an echo-corrupted data signal from a communications channel during a data phase of a data connection with a far-end data communications equipment; generating an echo estimate signal; adjusting, using an infinite impulse response filter, a magnitude of the echo estimate signal by an adjustment factor; and subtracting the adjusted echo estimate signal from the received echo-corrupted signal to provide an echo-canceled signal; wherein said infinite impulse response filter includes a first multiplier for multiplying said echo estimate signal with said echo-canceled signal. - View Dependent Claims (10, 11, 12, 13)
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Specification