System output control method and apparatus

• US 7,027,981 B2
• Filed: 11/29/2000
• Issued: 04/11/2006
• Est. Priority Date: 11/29/1999
• Status: Active Grant

• Current Assignee: Karl M. Bizjak
• Original Assignee: Karl M. Bizjak
• Inventors: Bizjak, Karl M.
• Primary Examiner(s): Abebe, Daniel
• Application Number:
  US09/728,526
• Publication Number:
  US 20020085725A1
• Time in Patent Office: 1,959 Days
• Field of Search: 704/225, 381/106
• US Class Current: 704/225
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain
• CPC Class Codes: H03G 3/3089 Control of digital or coded signals
• CPC Class Codes: H03G 3/32 the control being dependent upon ambient noise level or sound level
• CPC Class Codes: H03G 7/002 in untuned or low-frequency amplifiers, e.g. audio amplifiers H03G7/007, H03G7/001, H03G7/008, H03G7/02, H03G7/06 take precedence
• CPC Class Codes: H03G 7/007 of digital or coded signals
• CPC Class Codes: H03G 7/06 having semiconductor devices
• CPC Class Codes: H03G 9/005 of digital or coded signals
• CPC Class Codes: H03G 9/025 frequency-dependent volume compression or expansion, e.g. multiple-band systems H03G9/10, H03G9/18 take precedence
• CPC Class Codes: H04R 2227/005 Audio distribution systems for home, i.e. multi-room use
• CPC Class Codes: H04R 25/356 Amplitude, e.g. amplitude shift or compression
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 3/002 Damping circuit arrangements for transducers, e.g. motional feedback circuits

Abstract

Output control system and method includes calculating gain for an input signal, detecting a predetermined condition, and modifying the gain calculation in accordance with one or more kneepoints to provide a varying output signal. A companding ratio is then established in accordance with the kneepoints. System gain is then adjusted, and the companding ratio may be further adjusted by adjusting one of the kneepoints relative to another.

Claims

1. A method for controlling system output comprising the steps of

providing an input signal,

providing an adjustable system gain for varying the amplitude of the input signal,

establishing a first kneepoint wherein the first kneepoint represents a first output value corresponding to a first value of the input signal,

establishing a second kneepoint, wherein the second kneepoint represents a second output value corresponding to a second value of the input signal,

establishing a companding ratio as a ratio of the absolute value of the difference of second input signal value less the first input signal value, divided by the absolute value of the difference of the second output signal value less the first input signal value,

adjusting the system gain,

adjusting the companding ratio in response to the adjusting of the system gain by adjusting one of the kneepoints relative to the other.

2. The method of claim 1 wherein the adjusting of the system gain corresponds to adjusting of a volume control.

3. The method of claim 1 wherein the adjusting of the system gain corresponds to variation of an environmental input.

4. The method of claim 1 wherein at least one of the kneepoints is adjusted in response to variation of an environmental input.

5. The method of claim 3 wherein the environmental input is selected from a group including noise, speed, acceleration, and tachometer.

6. The method of claim 4 wherein the environment input is selected from a group including noise, speed, acceleration, and tachometer.

7. The method of claim 1 wherein one kneepoint remains fixed.

8. The method of claim 7 wherein the first kneepoint remains fixed.

9. The method of claim 7 wherein the second kneepoint remains fixed.

10. The method of claim 1 further comprising the steps of

establishing an adjustment threshold,

adjusting the companding ratio by adjusting the system gain and at least one of the kneepoints when the input signal exceeds the adjustment threshold, and

adjusting the companding ratio by adjusting at least one of the kneepoints when the input signal is less than the adjustment threshold.

11. The method of claim 10 further comprising the step of modifying the adjustment threshold based on historical performance characteristics.

12. The method of claim 10 wherein the adjustment threshold includes a system gain change indicator and a threshold indicator.

13. The method of claim 12 wherein the system gain change indicator is a volume control.

14. The method of claim 12 wherein the threshold indicator includes historical performance characteristics.

15. The method of claim 1 further including the steps of

establishing a third kneepoint wherein the third kneepoint represents a third output value corresponding to a third value of the input signal,

establishing a fourth kneepoint, wherein the fourth kneepoint represents a fourth output value corresponding to a fourth value of the input signal,

establishing a second companding ratio as a ratio of the absolute value of the difference of fourth input signal value less the third input signal value, divided by the absolute value of the difference of the fourth output signal value less the third input signal value,

adjusting each of the companding ratios in response to the adjusting of the system gain by adjusting one of the kneepoints relative to the other.

16. The method of claim 1 wherein the step of adjusting system gain comprises at least one of a group comprising use of a digital multiplier, use of an analog amplifier, and varying the kneepoints by a negative offset.

17. The method of claim 1 wherein the output value for the first kneepoint is the same as the input value.

18. The method of claim 1 wherein the output value for the second kneepoint is the same as the input value.

19. The method of claim 1 wherein the output value for the first kneepoint is determined by adjusting the input signal to a predetermined value.

20. The method of claim 1 wherein the output value for the second kneepoint is determined by adjusting the input signal to a predetermined value.

21. The method of claim 19 wherein the predetermined value is a maximum value.

22. The method of claim 20 wherein the predetermined value is a minimum value.

23. The method of claim 19 wherein the predetermined value is set by setting the input signal to a corresponding predetermined value and adjusting system gain.

24. A method for controlling system output wherein a plurality of companders operate in parallel comprising the steps of

providing to each of a plurality of companders an associated input signal,

providing to a plurality of companders an adjustable system gain for varying the amplitude of the associated input signal,

establishing for each of a plurality of companders a first kneepoint wherein the first kneepoint represents a first output value corresponding to a first value of the input signal,

establishing for each of a plurality of companders a second kneepoint, wherein the second kneepoint represents a second output value corresponding to a second value of the input signal,

establishing for each of a plurality of companders a companding ratio as a ratio of the absolute value of the difference of second input signal value less the first input signal value, divided by the absolute value of the difference of the second output signal value less the first input signal value,

adjusting for the plurality of companders the system gain,

adjusting for the plurality of companders the companding ratio in response to the adjusting of the system gain by adjusting one of the kneepoints relative to the other.