Telephone network apparatus and method using echo delay and attenuation
First Claim
1. A method for providing speech recognition in a telephone system, comprising:
- receiving a telephone signal from a first of a plurality of user communication devices;
sending a chirp signal to said first user communication device;
receiving an echo signal based on said chirp signal, obtaining attenuation data using at least one of said chirp signal and said echo signal;
determining whether echo cancellation should be performed, using said attenuation data;
obtaining a time delay using said chirp signal and said echo signal;
determining a value for a bulk delay filter element using said time delay;
using an adaptive filter to determine one or more filter coefficient values for performing echo cancellation;
configuring echo cancellation means using at least said value for said bulk delay filter element and said one or more filter coefficient values;
receiving a speech signal from said first user communication device after said configuring step; and
recognizing said speech signal;
wherein said steps of obtaining attenuation data and determining whether echo cancellation should be performed are performed after said step of receiving said echo signal.
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Abstract
The present invention provides a telephone network apparatus for performing speech recognition services in a telephone system in substantially real time. The apparatus uses a telephone channel signal to determine the echo delay of a telephone channel and then uses this delay to configure an echo cancellation filter for use in performing speech recognition. Use of echo delay in configuring the filter allows the echo cancellation function to be done using much less computational time than would be needed without its use, thereby granting a speech recognition unit greater access to a resident microprocessor to perform its function in substantially real time.
59 Citations
9 Claims
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1. A method for providing speech recognition in a telephone system, comprising:
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receiving a telephone signal from a first of a plurality of user communication devices; sending a chirp signal to said first user communication device; receiving an echo signal based on said chirp signal, obtaining attenuation data using at least one of said chirp signal and said echo signal;
determining whether echo cancellation should be performed, using said attenuation data;obtaining a time delay using said chirp signal and said echo signal; determining a value for a bulk delay filter element using said time delay; using an adaptive filter to determine one or more filter coefficient values for performing echo cancellation; configuring echo cancellation means using at least said value for said bulk delay filter element and said one or more filter coefficient values; receiving a speech signal from said first user communication device after said configuring step; and recognizing said speech signal; wherein said steps of obtaining attenuation data and determining whether echo cancellation should be performed are performed after said step of receiving said echo signal. - View Dependent Claims (2, 3, 4)
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5. An apparatus for providing speech recognition in a telephone system comprising:
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a plurality of user communication devices including a first user communication device; a central unit responsive to said plurality of user communication devices through which speech and non-speech signals are communicated; a telephone network apparatus communicating with said central unit said telephone network apparatus including; first means for sending a telephone channel signal for evaluating a telephone channel communicating with said first user communication device; second means for obtaining a magnitude related to a time delay based on said telephone channel signal and an echo signal related to said telephone channel signal; an adaptive filter, responsive to said second means for determining values for a bulk delay parameter and one or more variable tap coefficients; an echo cancellation unit electrically connected to said adaptive filter for canceling an echo signal received from said central unit; means for obtaining attenuation data using at least one of said telephone channel signal and said echo signal; means for determining whether echo cancellation should be performed based on said attenuation data; speech recognition means for recognizing a speech signal from said first user communication device; and control means for controlling sending and receiving of signals relative to said central unit and said user devices. - View Dependent Claims (6, 7, 8, 9)
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Specification