Digital automatic gain control
First Claim
Patent Images
1. A system, comprising:
- a delay element configured to delay an input signal to produce a delayed signal;
a first filter configured to filter the delayed signal to produce a first filtered signal;
a second filter configured to filter the input signal to produce a second filtered signal;
an adder configured to combine the first and second filtered signals to produce a smooth envelope;
a comparator configured to calculate a difference between the smooth envelope and a threshold; and
an adjuster configured to adjust a gain based on whether the difference is greater than or less than zero.
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Abstract
Systems, devices, and methods are provided to inhibit apparent amplitude modulation in non-linear processing that causes distortion in a processed signal. One aspect of the invention includes a hearing aid. The hearing aid includes a microphone to receive an input signal, a speaker to reproduce the input signal, and a processor. The processor processes the input signal using a gain. The processor includes an inhibitor, which inhibits distortions, and an adjuster, which adjusts the gain. The inhibitor acts to smooth an envelope of the input signal to inhibit undesired modulation. The adjuster adjusts the gain if the envelope is either above or below a threshold.
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Citations
18 Claims
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1. A system, comprising:
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a delay element configured to delay an input signal to produce a delayed signal; a first filter configured to filter the delayed signal to produce a first filtered signal; a second filter configured to filter the input signal to produce a second filtered signal; an adder configured to combine the first and second filtered signals to produce a smooth envelope; a comparator configured to calculate a difference between the smooth envelope and a threshold; and an adjuster configured to adjust a gain based on whether the difference is greater than or less than zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A digital analog gain control, comprising:
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a delay element configured to delay an input signal to produce a delayed signal; a first infinite-impulse-response (IIR) filter configured to produce a first filtered signal from the delayed signal; a second IIR filter configured to produce a second filtered signal from the input signal; an adder configured to combine the first and second filtered signals to produce a smooth envelope; a comparator configured to calculate a difference between the smooth envelope and a threshold; and an adjuster configured to; receive the difference, a release time constant, and an attack time constant; adjust a gain based at least in part on the difference being one of two conditions, wherein the two conditions include being a negative number and being a positive number, increase the gain if the difference is negative; and decrease the gain if the difference is positive. - View Dependent Claims (11, 12)
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13. A method for controlling a gain of an amplifier, comprising:
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delaying an input signal to produce a delayed signal, filtering the delayed signal to produce a first filtered signal; filtering the input signal to produce a second filtered signal; combining the first and second filtered signals to produce a smooth envelope; and subtracting the smooth envelope from a threshold to form a difference, wherein the difference is used to control the gain. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification