Active noise control apparatus
First Claim
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1. An active noise control apparatus comprising:
- a controller for generating a first control signal for canceling out a noise in a passenger compartment of a vehicle;
a sound output unit for outputting a canceling sound for canceling out said noise based on said first control signal into said passenger compartment; and
a canceling error signal detecting unit for outputting a canceling error signal representing a canceling error sound between said noise and said canceling sound to said controller;
wherein said controller comprises;
an A/D converter for converting said canceling error signal from an analog signal into a digital signal;
an echo canceler for correcting said first control signal into a digital echo canceling signal based on a corrective value corresponding to transfer characteristics between said sound output unit and said canceling error signal detecting unit;
a subtractor for generating a first basic signal by subtracting said digital echo canceling signal from the digital canceling error signal;
a delay filter for generating a second basic signal by delaying said first basic signal by a time corresponding to a ¼
period of a resonant frequency determined by resonant characteristics of said passenger compartment;
a first adder for combining said first basic signal and said second basic signal into said first control signal;
a basic signal generating unit for generating a third basic signal having a predetermined control frequency based on the frequency of a vibratory noise generated by a vibratory noise source mounted on said vehicle;
a reference signal generating unit for generating a reference signal by correcting said third basic signal based on said corrective value;
an adaptive filter for generating a second control signal for canceling out said noise based on said third basic signal;
a filter coefficient updating unit for successively updating a filter coefficient of said adaptive filter in order to minimize said first basic signal based on said first basic signal and said reference signal;
a second adder for adding said first control signal and said second control signal into a third control signal; and
a D/A converter for converting said third control signal from a digital signal into an analog signal and outputting the analog third control signal to said sound output unit;
wherein said sound output unit outputs said canceling sound based on said third control signal into said passenger compartment.
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Abstract
A subtractor subtracts an echo canceling signal Ĉ·y1(n−1) from a canceling error signal e(n) to estimate a residual noise to be silenced at the position of a microphone, and outputs a first basic signal x1(n) representing the residual noise. A first control circuit section generates a first control signal y1(n) based on the first basic signal x1(n) and a second basic signal x2(n) that is generated by delaying the first basic signal x1(n) by a time Z−n. A second circuit section generates a second control signal y2(n) based on the first basic signal x1(n) and an engine rotation signal.
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Citations
9 Claims
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1. An active noise control apparatus comprising:
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a controller for generating a first control signal for canceling out a noise in a passenger compartment of a vehicle; a sound output unit for outputting a canceling sound for canceling out said noise based on said first control signal into said passenger compartment; and a canceling error signal detecting unit for outputting a canceling error signal representing a canceling error sound between said noise and said canceling sound to said controller; wherein said controller comprises; an A/D converter for converting said canceling error signal from an analog signal into a digital signal; an echo canceler for correcting said first control signal into a digital echo canceling signal based on a corrective value corresponding to transfer characteristics between said sound output unit and said canceling error signal detecting unit; a subtractor for generating a first basic signal by subtracting said digital echo canceling signal from the digital canceling error signal; a delay filter for generating a second basic signal by delaying said first basic signal by a time corresponding to a ¼
period of a resonant frequency determined by resonant characteristics of said passenger compartment;a first adder for combining said first basic signal and said second basic signal into said first control signal; a basic signal generating unit for generating a third basic signal having a predetermined control frequency based on the frequency of a vibratory noise generated by a vibratory noise source mounted on said vehicle; a reference signal generating unit for generating a reference signal by correcting said third basic signal based on said corrective value; an adaptive filter for generating a second control signal for canceling out said noise based on said third basic signal; a filter coefficient updating unit for successively updating a filter coefficient of said adaptive filter in order to minimize said first basic signal based on said first basic signal and said reference signal; a second adder for adding said first control signal and said second control signal into a third control signal; and a D/A converter for converting said third control signal from a digital signal into an analog signal and outputting the analog third control signal to said sound output unit; wherein said sound output unit outputs said canceling sound based on said third control signal into said passenger compartment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification