ECHO AND NOISE CANCELLATION
First Claim
1. A method for echo cancellation in a system having a speaker and a microphone, the speaker receiving a speaker signal x(t), the microphone receiving a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t), wherein the echo signal x1(t) is dependent on the speaker signal x(t), the method comprising:
- filtering the microphone signal d(t) in parallel with a first adaptive filter and a second adaptive filter, wherein the first adaptive filter has complementary echo cancellation properties relative to the second adaptive filter;
determining a minimum echo output e3(t) from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter, wherein the minimum echo output has a smaller energy and less correlation to the speaker signal x(t); and
generating a microphone output using the minimum echo output e3(t).
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Abstract
Methods and apparatus for echo cancellation in a system having a speaker and a microphone are disclosed. The speaker receives a speaker signal x(t). The microphone receives a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t) that is dependent on the speaker signal x(t). The microphone signal d(t) is filtered in parallel with first and second adaptive filters having complementary echo cancellation properties relative to each other. A minimum echo output e3(t) is determined from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter. The minimum echo output has a smaller energy and less correlation to the speaker signal x(t). A microphone output is then generated using the minimum echo output e3(t).
63 Citations
32 Claims
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1. A method for echo cancellation in a system having a speaker and a microphone, the speaker receiving a speaker signal x(t), the microphone receiving a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t), wherein the echo signal x1(t) is dependent on the speaker signal x(t), the method comprising:
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filtering the microphone signal d(t) in parallel with a first adaptive filter and a second adaptive filter, wherein the first adaptive filter has complementary echo cancellation properties relative to the second adaptive filter;
determining a minimum echo output e3(t) from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter, wherein the minimum echo output has a smaller energy and less correlation to the speaker signal x(t); and
generating a microphone output using the minimum echo output e3(t). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An echo cancellation apparatus for use in a system having a speaker and a microphone, the speaker being adapted to receive a speaker signal x(t), the microphone being adapted to generate a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t), wherein the echo signal x1(t) is dependent on the speaker signal x(t), the apparatus comprising:
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a first adaptive filter coupled to the speaker and the microphone; and
a second adaptive filter coupled to the speaker and the microphone in parallel with the first adaptive filter, wherein the second adaptive filter has complementary echo cancellation properties relative to the first adaptive filter;
an integrator coupled to the first adaptive filter and the second adaptive filter, wherein the integrator is configured to determine a minimum echo output e3(t) from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter, wherein the minimum echo output has a smaller energy and less correlation to the speaker signal x(t). - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An audio signal processing system, comprising:
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a microphone;
a speaker;
a processor coupled to the microphone and the speaker;
a memory coupled to the processor, the memory having embodied therein a set of processor readable instructions for implementing a method for method for echo cancellation in a system having a speaker and a microphone, the speaker receiving a speaker signal x(t), the microphone receiving a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t), wherein the echo signal x1(t) is dependent on the speaker signal x(t), the processor readable instructions including;
instructions for filtering the microphone signal d(t) in parallel with a adaptive filter and a second adaptive filter, wherein the first adaptive filter has complementary echo cancellation properties relative to the second adaptive filter;
instructions for determining a minimum echo output e3(t) from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter, wherein the minimum echo output has a smaller energy and less correlation to the speaker signal x(t); and
instructions for generating a microphone output using the minimum echo output e3(t).
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32. A processor readable medium having embodied therein a memory coupled to the processor, the memory having embodied therein a set of processor readable instructions for implementing a method for method for echo cancellation in a system having a speaker and a microphone, the speaker receiving a speaker signal x(t), the microphone receiving a microphone signal d(t) containing a local signal s(t) and an echo signal x1(t), wherein the echo signal x1(t) is dependent on the speaker signal x(t), the processor readable instructions including:
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instructions for filtering the microphone signal d(t) in parallel with a adaptive filter and a second adaptive filter, wherein the first adaptive filter has complementary echo cancellation properties relative to the second adaptive filter;
instructions for determining a minimum echo output e3(t) from an output e1(t) of the first adaptive filter and an output e2(t) of the second adaptive filter, wherein the minimum echo output has a smaller energy and less correlation to the speaker signal x(t); and
instructions for generating a microphone output using the minimum echo output e3(t).
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Specification