Echo-canceling system and method using echo estimate to modify error signal
First Claim
1. An echo-canceling system comprising:
- first means for converting a first acoustic signal into a first electrical signal;
second means for converting a second electrical signal into a second acoustic signal;
means, responsive to said second electrical signal, for adaptively estimating an echo in said second electrical signal to produce an echo estimate electrical signal;
means for obtaining a difference between said echo estimate electrical signal and said first electrical signal to produce an electrical error signal;
means, responsive to said electrical error signal and to said echo estimate electrical signal, for modifying said electrical error signal based upon said echo estimate electrical signal to produce a modified electrical error signal; and
means for transmitting said modified electrical error signal to a remote receiving system.
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Accused Products
Abstract
An echo-canceling system and method uses an echo estimate to modify the error signal which is obtained by the difference between an echo signal and the echo estimate. The modified error signal, rather than the error signal itself, is transmitted. By using the echo estimate as a parameter for modifying the error signal, improved hands-free performance may be obtained in a vehicular radiotelephone, such as a cellular telephone. Preferably, modification of the electrical error signal is performed by a center clipper which removes a portion of the electrical error signal which is below a variable threshold, wherein the variable threshold is determined by the echo estimate electrical signal. The variable threshold may be produced from the echo estimate electrical signal using an envelope detector.
87 Citations
28 Claims
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1. An echo-canceling system comprising:
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first means for converting a first acoustic signal into a first electrical signal; second means for converting a second electrical signal into a second acoustic signal; means, responsive to said second electrical signal, for adaptively estimating an echo in said second electrical signal to produce an echo estimate electrical signal; means for obtaining a difference between said echo estimate electrical signal and said first electrical signal to produce an electrical error signal; means, responsive to said electrical error signal and to said echo estimate electrical signal, for modifying said electrical error signal based upon said echo estimate electrical signal to produce a modified electrical error signal; and means for transmitting said modified electrical error signal to a remote receiving system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A hands-free vehicular radiotelephone comprising:
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a microphone, adapted for mounting in a vehicle for hands-free operation by a vehicle occupant, to convert a first acoustic signal into a first electrical signal; a loudspeaker, adapted for mounting in a vehicle for hands-free operation by a vehicle occupant, to convert a second electrical signal into a second acoustic signal; means, responsive to said second electrical signal, for adaptively estimating an echo in said second electrical signal to produce an echo estimate electrical signal; means for obtaining a difference between said echo estimate electrical signal and said first electrical signal to produce an electrical error signal; means responsive to said electrical error signal and to said echo estimate electrical signal, for modifying said electrical error signal based upon said echo estimate electrical signal to produce a modified electrical error signal; and radiotelephone transmitting means, for transmitting said modified electrical signal to a radiotelephone network. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An echo-canceling method comprising the steps of:
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converting a first acoustic signal into a first electrical signal; converting a second electrical signal into a second acoustic signal; adaptively estimating an echo in said second electrical signal to produce an echo estimate electrical signal; obtaining a difference between said echo estimate electrical signal and said first electrical signal to produce an electrical error signal; modifying said electrical error signal based upon said echo estimate electrical signal to produce a modified electrical error signal; and transmitting said modified electrical error signal to a remote receiving system. - View Dependent Claims (21, 22, 23, 24)
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25. An echo-canceling method for a hands-free vehicular radiotelephone, said hands-free vehicular radiotelephone including a microphone, adapted for mounting in a vehicle for hands-free operation by a vehicle occupant to convert a first acoustic signal into a first electrical signal, and a loudspeaker, adapted for mounting in a vehicle for hands-free operation by a vehicle occupant to convert a second electrical signal into a second acoustic signal, said echo-canceling method comprising the steps of:
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adaptively estimating an echo in said second electrical signal to produce an echo estimate electrical signal; obtaining a difference between said echo estimate electrical signal and said first electrical signal to produce an electrical error signal; modifying said electrical error signal based upon said echo estimate electrical signal to produce a modified electrical error signal; and transmitting said modified electrical signal to a radiotelephone network. - View Dependent Claims (26, 27, 28)
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Specification