US 4,649,505 AGranted

Two-input crosstalk-resistant adaptive noise canceller

AssigneeGeneral Electric Company

InventorsRichard L. Zinser, Jr., Seth D. Silverstein, Steven R. Koch

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Abstract

A two-input crosstalk-resistant adaptive noise canceller receives a primary input signal including a desired speech signal portion and an undesired noise signal portion and also receives a reference input signal having a reference noise input portion and a crosstalk speech portion. The canceller has first and second summer means and first and second adaptive filter means. The first summer means provides a canceller output signal which is the difference between the primary input signal and the first adaptive filter output signal. The canceller output signal is applied to the reference input of the second adaptive filter and to one of a pair of error-control inputs of the first adaptive filter. The second error-control input of the first adaptive filter is provided by the signal at the output of the second adaptive filter, which receives a single error-control input signal from the output of the second summer means. The second summer provides an output signal which is the difference between the reference input signal and the second adapter filter output signal. With the correlation bias between the desired primary input (speech) signal and the crosstalk (speech) signal in the reference input substantially reduced, the canceller output signal is then related substantially only to the primary input desired signal.

Claims25

Dependent claims

An adaptive noise canceller, comprising:

first means for receiving a primary signal having a first desired portion and a second undesired noise portion;
second means for receiving, during each of a successive sequence of time intervals (n);
a reference signal (r(n)) having a first crosstalk portion with a time-amplitude characteristic similar to that of said primary signal first portion and a second noise portion with a time-amplitude characteristic similar to that of said primary signal second portion;
first summer means for subtracting from said primary signal, received from said first means, a noise reference signal (w(n)) to provide an output signal (S(n)) having said primary signal first portion and a second undesirable noise portion which is of reduced amplitude with respect to the amplitude of the primary signal second portion;
first adaptive filter means having a reference input receiving said reference signal (r(n)) from said second means, a first error-control input receiving said output signal (S(n)), and a second error-control input receiving an estimation signal (S.sub.1 (n)), for providing said noise reference signal (w(n)) responsive to a predetermined response pattern dependent upon the conditions of all of said signals then present at said reference input, said first error-control input and said second error-control input;
second adaptive filter means having a reference input receiving said output signal (S(n)) and a single error-control input receiving an auxiliary signal (w.sub.1 (n)) for providing said estimation signal (S.sub.1 (n)) to said first adaptive filter means second error-control input;
and
second summer means for subtracting said estimation signal (S.sub.1 (n)) from said reference signal (r(n)) to provide said auxiliary signal (W.sub.1 (n)) to said second adapter filter means signal error-control input.

5 more elements

An adaptive noise canceller, comprising:

microcontroller means for processing digital signals, said microcontroller means comprising at least a central processing unit and a plurality of register sets each containing at least one storage register of at least one storage location and at least two storage register sets for storing first and second adaptive filter coefficient sets b.sub.k and c.sub.k each having at least one coefficient term therein;
first means, receiving from a first transducer a primary input analog signal, containing a first desired signal portion and a second undesired random noise signal portion and having a first ratio of the amplitudes of the desired signal to the noise signal, for converting said primary analog signal to a digitally-encoded primary signal at a rate responsive to at least one clock signal;
second means, receiving from a second transducer, different from said first transducer, a reference input analog signal, having a first crosstalk signal portion with a time-amplitude characteristic similar to that of said first portion of said primary signal and having a second random noise portion with a time-amplitude characteristic similar to that of the second portion of said primary signal and having a crosstalk signal to noise signal amplitude ratio independent of the first ratio of the primary input analog signal, for converting said reference analog signal to a digitally-encoded reference signal at a rate responsive to said at least one clock signal;
clock means for providing said first and second converting means with said at least one clock signal;
memory means for storing a sequence of digital control signals to be sequentially provided to said microcontroller means responsive to requests therefrom, and for causing:
(a) said microcontroller means to alternately obtain for storage in first and second register sets, respectively, the digitally-encoded primary and reference signals, respectively, from the respective first and second converting means;
(b) to cause said microcontroller means to obtain, for storage in a third register set, at least one digital signal estimating the crosstalk speech portion in said reference signal;
(c) for causing said microcontroller means to obtain, for storage in a fourth register set, at least one other signal estimating the noise portion of said reference signal;
and (d) for causing said microcontroller means to then obtain, from the data in at least said first through fourth register sets and said first and second coefficient register sets, an output signal, for storage in a fifth register set, having the desired signal portion of said primary input and said second undesired portion of said primary input reduced in amplitude responsive to the reference signal noise portion estimation signal;
and
means receiving the reduced-noise-portion output signal from said fifth register set for providing a canceller output signal.

8 more elements

Dependencies are inferred from the claim text.