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US 8,036,402 B2Granted
Distortion compensation
AssigneeHarman International Industries, Incorporated
InventorKenneth Carl Furge
Life of this patent
Estimating the term…
Abstract
A distortion compensation system minimizes distortion in an audio system by monitoring a supply voltage and adjusting a clipping threshold and/or compression knee. An adjustable gain circuit controls the gain of the audio signal according whether the audio signal exceeds a variable threshold. The variable threshold is adjusted within a threshold range based on the supply voltage. Distortion due to clipping of the audio signal is minimized while available power at any given time is maximized.
Claims22
An automotive audio amplifier comprising:
- an acoustic signal processor configured to control gain for at least one channel of a multi-channel audio signal, the gain being controlled according to a gain adjust signal;
- a voltage sensor configured to generate a voltage sense signal associated with a battery supply voltage for the amplifier;
- and
- a threshold detector configured to generate the gain adjust signal according to detecting whether an output of the gain circuit exceeds a clipping threshold, the clipping threshold being adjustable according to the voltage sense signal;
- where the clipping threshold is adjusted to clip channels of the multi-channel audio signal in accordance with a threshold corresponding to the battery supply voltage at a time of tuning the automotive audio amplifier.
2 more elements
An automotive audio system comprising:
- a controller configured to control gain adjustment for each channel of a multi-channel audio signal according to whether the multi-channel audio signal exceeds a clipping threshold;
- the controller further configured to adjust the clipping threshold according to a supply voltage for the audio system relative to a tuning voltage, the clipping threshold being adjusted to clip channels of the multi-channel audio signal in accordance with a threshold corresponding to the tuning voltage at a time of tuning the automotive audio system;
- and
- an amplifier configured to process a gain-adjusted multi-channel audio signal, where the controller lowers the clipping threshold when the supply voltage is less than the tuning voltage.
1 more element
An automotive audio system comprising:
- a controller configured to control gain adjustment for each channel of a multi-channel audio signal according to whether the multi-channel audio signal exceeds a clipping threshold;
- the controller further configured to adjust the clipping threshold according to a supply voltage for the audio system relative to a tuning voltage, the clipping threshold being adjusted to clip channels of the multi-channel audio signal in accordance with a threshold corresponding to the tuning voltage at a time of tuning the automotive audio system;
- and
- an amplifier configured to process a gain-adjusted multi-channel audio signal, where the controller increases the clipping threshold when the supply voltage is above the tuning voltage.
1 more element
A method for compensating for acoustic distortion in an automotive audio system comprising:
- controlling a gain of at least one channel of a multi-channel audio signal with a controller according to whether the audio signal exceeds a clipping threshold;
- sensing a rail voltage with the controller;
- comparing the sensed rail voltage to a predetermined tuning voltage with the controller, the predetermined tuning voltage being the rail voltage at a time of tuning the automotive audio system;
- and
- adjusting the clipping threshold with the controller according to the comparison of the sensed rail voltage to the predetermined tuning voltage to maintain a substantially fixed level of distortion by clipping channels of the multi-channel audio signal at the adjusted clipping threshold corresponding to the predetermined tuning voltage.
2 more elements
An automotive audio amplifier comprising:
- an acoustic signal processor configured to control gain for at least one channel of a multi-channel audio signal, the gain being controlled according to a gain adjust signal;
- a voltage sensor configured to generate a voltage sense signal associated with a battery supply voltage for the amplifier;
- and
- a threshold detector configured to generate the gain adjust signal according to detection that an output of a gain circuit for the at least one channel exceeds a clipping threshold,
- the clipping threshold being adjustable according to the voltage sense signal so that the clipping threshold maintains a substantially fixed level of distortion by clipping channels of the multi-channel audio signal at a threshold relative to the battery supply voltage, where the clipping threshold is reduced when the threshold detector detects that a voltage sensed by the voltage sense signal is less than a reference voltage corresponding to a tuning voltage at a time of tuning the automotive audio amplifier, and the gain is reduced when the threshold detector detects that the at least one channel of the multi-channel audio signal exceeds the reduced clipping threshold.
2 more elements
Dependencies are inferred from the claim text.