Input level adjust system and method

• US 7,190,292 B2
• Filed: 11/29/2000
• Issued: 03/13/2007
• Est. Priority Date: 11/29/1999
• Status: Expired due to Term

• Current Assignee: Karl M. Bizjak
• Original Assignee: Karl M. Bizjak
• Inventors: Bizjak, Karl M.
• Primary Examiner(s): Williams; Howard L.
• Application Number:
  US09/726,982
• Publication Number:
  US 20030098805A1
• Time in Patent Office: 2,295 Days
• Field of Search: 341/139, 341/141, 341/110, 381 56- 58, 381104-109
• US Class Current: 341/139
• 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: 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

Abstract

A method of matching input amplitudes in a system wherein one or more of a plurality of inputs may be selected, with each input capable of having different characteristics, involving selecting an input signal and mapping the input signal to a predetermined signal amplitude through the use of level matching logic. The level matching logic may include a gain cell for increasing or decreasing the amplitude of the input signal.

Claims

1. An input level matching system comprising

an input for providing at least one signal associated with a selected input device,

level matching logic for mapping the at least one signal to a desired signal amplitude to generate a modified signal, wherein the level matching logic includes a gain cell and the level matching logic maps the at least one signal based on one or more gain values associated with the selected input device,

an output for providing the modified signal,

a clip signal,

clip detection logic responsive to the clip signal for comparing the clip signal to a threshold signal for detecting signal clipping at the output of the gain cell, and

direct calculation logic for detecting when the clip detection logic detects a clipping condition and directly calculating a maximum permissible gain value.

2. The input level matching system of claim 1 wherein the clip signal is a function of the input to the gain cell.

3. The input level matching system of claim 2 wherein the output of the gain cell is a 0 dB signal, and the gain of the gain cell may be adjusted to provide a current gain value.

4. The input level matching system of claim 3 wherein the threshold signal is a function of a maximum 0 dB signal divided by the current gain of the gain cell.

5. The input level matching system of claim 1 wherein the clip signal is a function of the output of the gain cell.

6. The input level matching system of claim 5 wherein the output of the gain cell is a 0 dB signal, and the gain of the gain cell may be adjusted to provide a current gain value.

7. The input level matching system of claim 6 wherein the clip signal is compared to a maximum 0 dB signal.

8. An input level matching system comprising

an input for providing at least one signal associated with a selected input device,

level matching logic for mapping the at least one signal to a desired signal amplitude to generate a modified signal, wherein the level matching logic includes a gain cell and the level matching logic maps the at least one signal based on one or more gain values associated with the selected input device,

an output for providing the modified signal,

a clip signal,

clip detection logic responsive to the clip signal for comparing the clip signal to a threshold signal for detecting signal clipping at the output of the gain cell, and

gain reducing logic for reducing the current gain of the gain cell when the clip detection logic detects a clipping condition.

9. The input level matching system of claim 8 wherein the gain reducing logic is adjusted iteratively to reduce the gain to an acceptable level.

10. The input level matching system of claim 8 wherein the gain reducing logic is adjusted iteratively to reduce the gain to an acceptable level.

11. An input level matching system comprising

an input for providing at least one signal associated with a selected input device,

level matching logic for mapping the at least one signal to a desired signal amplitude to generate a modified signal, wherein the level matching logic includes a gain cell and the level matching logic maps the at least one signal based on one or more gain values associated with the selected input device,

an output for providing the modified signal,

a clip signal,

clip detection logic responsive to the clip signal for comparing the clip signal to a threshold signal for detection signal clipping at the output of the gain cell, and

a clip detection logic counter.

12. The input level matching system of claim 11 further including signaling logic for indicating the occurrence of a clip condition.

13. The input level matching system of claim 12 further including

signal processing logic for performing at least one of signal selection, filtering, or analog-to-digital conversion of the at least one signal.

14. An input level matching system comprising

an input for providing at least one signal associated with a selected input device,

level matching logic for mapping the at least one signal to a desired signal amplitude to generate a modified signal, wherein the level matching logic includes a gain cell and the level matching logic maps the at least one signal based on one or more gain values associated with the selected input device,

an output for providing the modified signal, and

a gain cell gain storage wherein the gain cell provides a gain value such that at least one gain value can be stored in and retrieved from the gain storage,

wherein the at least one input signal comprises multiple input signals arranged in groups.

15. The input level matching system of claim 14 wherein the input receives a selected one of the at least one signal and wherein the modified signal is subsequently processed by a processor without regard to source of the input.

16. The input level matching system of claim 14 wherein the output of a gain cell is a 0 dB signal.

17. The input level matching system of claim 14 wherein the gain cell operates to provide digital amplification.

18. The input level matching system of claim 14 wherein the gain cell operates to provide analog amplification.

19. The input level matching system of claim 14 wherein a gain value can be stored for each of the multiple input signals.

20. The input level matching system of claim 19 wherein a plurality of gain values can be stored and retrieved for each of the multiple input signals.

21. The input level matching system of claim 14 further including bandsplit and equalization logic.

22. The input level matching system of claim 21 wherein equalization comprises scaling.

23. An input level matching system comprising

an input for providing at least one signal associated with a selected input device,

level matching logic for mapping the at least one signal to a desired signal amplitude to generate a modified signal, wherein the level matching logic includes a gain cell and the level matching logic maps the at least one signal based on one or more gain values associated with the selected input device,

an output for providing the modified signal,

a gain cell gain storage wherein the gain cell provides a gain value such that at least one gain value can be stored in and retrieved from the gain storage,

wherein the at least one input signal comprises multiple input signals, and wherein the gain value for all input signals within a group is the same.

24. The input level matching system of claim 23 wherein the gain value for a group is determined by the maximum input signal within that group.

25. A method for adjusting input level comprising

receiving an input signal from a selected input device,

matching amplitude of the input signal to a desired amplitude to generate an adjusted signal, and

providing the adjusted signal at an output,

wherein the step of matching amplitude includes

providing the input signal to a gain cell having a gain controlled by a gain value associated with the selected input device

setting the gain value to a stored minimum gain value associated with the selected input device, and

optionally decreasing the gain value to obtain the desired amplitude.

26. A method for adjusting input level comprising

receiving an input signal from a selected input device,

matching amplitude of the input signal to a desired amplitude to generate an adjusted signal, and

providing the adjusted signal at an output,

wherein the step of matching amplitude includes

providing the input signal to a gain cell having a gain controlled by a gain value associated with the selected input device

wherein the step of matching amplitude includes

responsive to a reset signal, setting the gain value to a maximum gain value, and

optionally decreasing the gain value to obtain the desired amplitude.