System and method for distortion limiting

Patent metadata

Field	Value
Publication number	US-10742187-B2
Application number	US-201815879989-A
Country	US
Kind code	B2
Filing date	Jan 25, 2018
Priority date	Oct 20, 2015
Publication date	Aug 11, 2020
Grant date	Aug 11, 2020

Abstract

A system is provided for limiting distortion of an audio speaker. The system includes a first lowpass filter circuitry that is configured to receive a system input signal and generate a first lowpass filtered output signal. The system also includes a first limiter circuitry that is configured to limit the first lowpass filtered output signal. Limiting the first low pass filtered output signal includes reducing an amplitude of the first lowpass filtered output signal below a first predetermined threshold value, thereby to generate a first limited output signal. A second lowpass filter circuitry is configured to receive the first limited output signal and to generate a second lowpass filtered output signal.

First claim

What is claimed is:

1. A system for limiting distortion of an audio speaker, the system comprising:
a first lowpass filter circuitry configured to receive a system input signal and generate a first lowpass filtered output signal;
a first limiter circuitry configured to limit the first lowpass filtered output signal, wherein limiting the first low pass filtered output signal comprises reducing an amplitude of the first lowpass filtered output signal below a first predetermined threshold value, thereby to generate a first limited output signal;
a highpass filter circuitry configured to receive the system input signal, the highpass filter circuitry configured to generate a highpass filtered output signal;
a second limiter circuitry configured to limit the highpass filtered output signal, wherein limiting the highpass filtered output signal comprises reducing an amplitude of the highpass filtered output signal below a second predetermined threshold value, thereby to generate a second limited output signal;
a first combiner circuitry configured to receive and combine respective signals from the first limiter circuitry and the second limiter circuitry to provide a first combined output signal; and
a second lowpass filter circuitry configured to receive the first combined output signal and to generate a second lowpass filtered output signal.

2. The system of claim 1 , further comprising:
a third limiter circuitry configured to limit the second lowpass filtered output signal, wherein limiting the second lowpass filtered output signal comprises reducing an amplitude of the second lowpass filtered output signal below a third predetermined threshold value, thereby to provide a distortion limiting output signal.

3. The system of claim 2 , further comprising:
an allpass filter circuitry configured to receive a signal from the second limiter circuitry and to generate an allpass filtered output signal;
a second combiner circuitry configured to combine the second lowpass filtered output signal and the allpass filtered output signal to provide a second combined output signal,
wherein limiting the second lowpass filtered signal comprises limiting the second combined output signal.

4. The system of claim 3 , further comprising polarity circuitry arranged between the allpass filter circuitry and the second combiner circuitry, and configured to adjust a polarity of the allpass filtered output signal before transmission to the second combiner circuitry.

5. The system of claim 2 , further comprising
a first equalization circuitry configured to boost an amplitude of a first set of frequency components in the system input signal; and
a second equalization circuitry configured to reduce the amplitude of the first set of frequency components in the distortion limiting output signal.

6. The system of claim 1 , further comprising
a first equalization circuitry configured to boost an amplitude of a first set of frequency components in the system input signal; and
a second equalization circuitry configured to reduce the amplitude of the first set of frequency components in the second filtered output signal.

7. A system for limiting distortion of an audio speaker, the system comprising:
a first lowpass filter circuitry configured to receive a system input signal and generate a first lowpass filtered output signal;
a first limiter circuitry configured to limit the first lowpass filtered output signal, wherein limiting the first low pass filtered output signal comprises reducing an amplitude of the first lowpass filtered output signal below a first predetermined threshold value, thereby to generate a first limited output signal;
a highpass filter circuitry configured to receive the system input signal, the highpass filter circuitry configured to generate a highpass filtered output signal;
a first combiner circuitry configured to receive and combine respective signals from the first limiter circuitry and the highpass filter circuitry to provide a first combined output signal;
a second lowpass filter circuitry configured to receive the first combined output signal and to generate a second lowpass filtered output signal; and
a master limiter circuitry configured to limit the second lowpass filtered output signal, wherein limiting the second lowpass filtered output signal comprises reducing an amplitude of the second lowpass filtered output signal below a master threshold value, thereby to provide a distortion limiting output signal.

8. The system of claim 7 , further comprising
a first equalization circuitry configured to boost an amplitude of a first set of frequency components in the system input signal; and
a second equalization circuitry configured to reduce the amplitude of the first set of frequency components in the distortion limiting output signal.

9. A method for limiting distortion of an audio speaker, the method comprising:
lowpass filtering a system input signal to provide a first lowpass filtered output signal;
limiting the first lowpass filtered output signal to provide a first limited output signal, wherein limiting the first lowpass filtered output signal comprises reducing an amplitude of the first lowpass filtered output signal below a first predetermined threshold value;
highpass filtering the system input signal to provide a highpass filtered output signal;
combining the first limited output signal and the highpass filtered output signal to provide a first combined output signal
lowpass filtering the first combined output signal to provide a second lowpass filtered output signal; and
limiting the second lowpass filtered output signal to provide a distortion limiting output signal, wherein limiting the second lowpass filtered output signal comprises reducing an amplitude of the second lowpass filtered output signal below a third predetermined threshold value.

10. The method of claim 9 , further comprising: transducing the distortion limiting output signal to acoustic energy via an electro-acoustic transducer.

11. The method of claim 9 , further comprising: transducing the distortion limiting output signal to acoustic energy via an electro-acoustic transducer.

12. The method of claim 9 , further comprising:
allpass filtering the second limited output signal to provide an allpass filtered output signal; and
combining the second lowpass filtered output signal and the allpass filtered output signal to provide a second combined output signal,
wherein limiting the second lowpass filtered output signal comprises limiting the second combined output signal.

13. The method of claim 12 , further comprising reversing a polarity of the allpass filtered output signal to provide a polarity adjusted output signal, wherein combining the second lowpass filtered output signal and the allpass filtered output signal comprises combining the second lowpass filtered output signal and the polarity adjusted output signal to provide the second combined output signal.

14. The method of claim 12 , further comprising:
equalizing the system input signal to boost an amplitude of a first set of frequency components in the system input signal; and
equalizing the distortion limiting output signal to reduce the amplitude of the first set of frequency components in the distortion limiting output signal.

15. The method of claim 9 , further comprising:
limiting the highpass filtered output signal to provide a second limited output signal, wherein limiting the highpass filtered output signal comprises reducing an amplitude of the highpass filtered output signal below a second predetermined threshold value;
wherein combining th

Assignees

• Bose Corp

Inventors

• Song Zukui
• Dublin Michael S
• Cheng Christopher J
• Vautin Jeffery R

Classifications

• H04R3/007 Primary

  Protection circuits for transducers · CPC title

• H04R2430/01

  Aspects of volume control, not necessarily automatic, in sound systems · CPC title

• H03G11/00 Primary

  Limiting amplitude; Limiting rate of change of amplitude · CPC title

• H04R3/04

  for correcting frequency response · CPC title

• H04R3/002

  Damping circuit arrangements for transducers, e.g. motional feedback circuits · CPC title