Voice enhancement system and method

• US 5,592,545 A
• Filed: 06/07/1995
• Issued: 01/07/1997
• Est. Priority Date: 12/02/1993
• Status: Expired due to Fees

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: DSC Communications Corp. (Nokia Corporation)
• Inventors: Lim, Pong C., Ho, Helena S., Pratt, Michael K., Oshidari, Thomas T.
• Primary Examiner(s): Zele, Krista M.
• Assistant Examiner(s): Hunter, Daniel S.
• Application Number:
  US08/484,677
• Time in Patent Office: 580 Days
• Field of Search: 379/343, 379/346, 379/394, 379/398, 379/404, 379/400, 379/401, 379/406, 379/409, 379/410, 379/347
• US Class Current: 379/347
• CPC Class Codes: H03G 5/22 having semiconductor devices
• CPC Class Codes: H04M 3/002 Applications of echo suppressors or cancellers in telephonic connections in two-way loud-speaking telephone systems H04M9/08, echo suppressors or cancellers per se H04B3/20
• CPC Class Codes: H04M 3/40 Applications of speech amplifiers

Abstract

A telecommunications network (120) is provided with adaptive gain control (AGC) of the voice signals in network (120). Network (120)includes an input (12) for receiving a voice signal, an output (14) for receiving the voice signal, and a coupling between input (12) and output (14) including at least one switch (124) or (126). Network (120) also includes voice enhancer (10) including power averager (18) for measuring and determining the average power of an input signal. Voice enhancer (10) also includes bass band equalizer (16) to attenuate a predetermined portion of the input signal to provide an equalized input signal. From the average power of the input signal is determined a scaling factor from a gain/attenuation look-up table (28). Voice enhancer (10) also includes output scaler (30) coupled to output (14), output scaler (30) scales the equalized input signal with the scaling factor and provides the scaled signal to output (14). Voice enhancer (10) also includes bass to treble power comparator (20) for detecting tandem enhancement and voice-band data detector (22) which cause enhancer (10) to be disabled appropriately.

Claims

1. A method for providing voice enhancement in a telecommunications network, comprising the steps of:

determining the average power of an input voice-band signal;

determining a scaling factor in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice signal;

scaling the equalized input voice-band signal with the scaling factor;

coupling the scaled voice-band signal to an output; and

wherein said determining a scaling factor step further comprises the step of limiting the amount of change between consecutive scaling factors.

2. The method of claim 1 further comprising the steps of:

detecting voice-band data in the input signal; and

decoupling the scaled voice-band signal from the output.

3. The method of claim 1 further comprising the steps of:

detecting tandem enhancement in the network; and

decoupling the scaled voice-band signal from the output.

5. The method of claim 1 wherein said determining the average power, determining a scaling factor, equalizing, scaling, and coupling steps are performed in an echo canceller of a telecommunications network.

6. The method of claim 1 wherein the predetermined portion of the input voice-band signal is above substantially 300 Hz.

7. The method of claim 1 wherein the predetermined portion of the input voice-band signal is above substantially 400 Hz.

8. The method of claim 1 wherein said scaling the input signal step further comprises using the scaling factor for scaling the equalized input signal for a predetermined period of time.

9. The method of claim 1 further comprising the steps of:

dividing the input voice-band signal into a plurality of frames, each frame representative of a period of time; and

scaling the equalized input signal with the scaling factor for a predetermined number of frames.

10. The method of claim 1 wherein said equalizing step further comprises filtering the input signal such that the power of the input signal above a predetermined frequency is attenuated.

11. The method of claim 1 wherein said determining the average power step further comprises low pass filtering a rectified input voice-band signal.

13. The method of claim 1 further comprising the steps of:

dividing the input voice-band signal into a plurality of frames, each frame representative of a period of time;

continuously performing said determining the average power, determining a scaling factor, equalizing, scaling, and coupling steps upon the expiration of a predetermined number of frames.

4. A method for providing voice enhancement in a telecommunications network, comprising the steps of:

determining the average power of an input voice-band signal;

determining a scaling factor in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice signal;

scaling the equalized input voice-band signal with the scaling factor;

coupling the scaled voice-band signal to an output;

detecting at least one of voice-band data in the input signal and tandem enhancement in the network; and

decoupling the scaled voice-band signal from the output.

12. A method for providing voice enhancement in a telecommunications network, comprising the steps of:

determining the average power of an input voice-band signal;

determining a scaling factor in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice signal;

scaling the equalized input voice-band signal with the scaling factor;

coupling the scaled voice-band signal to an output;

comparing the determined average power of the input voice-band signal to power measurements expected for a previously scaled signal; and

decoupling the scaled voice-band signal from the output in response to said comparing step.

14. A method for providing voice enhancement in a telecommunications network, comprising the steps of:

determining the average power of an input voice-band signal;

determining a scaling factor in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice signal;

scaling the equalized input voice-band signal with the scaling factor

coupling the scaled voice-band signal to an output;

detecting periods of silence in the input voice-band signal at the input; and

decoupling the scaled voice-band signal from the output.

15. The method of claim 14 further comprising the step of attenuating the input voice-band signal so that the noise level of the detected periods of silence is minimized.

16. A method for providing voice enhancement in a telecommunications network, comprising the steps of:

determining the average power of an input voice-band signal;

determining a scaling factor in response to the average power of the input voice-band signal;

equalizing the input voice-band signal by attenuating a predetermined portion of the input voice-band signal;

scaling the equalized input voice-band signal with the scaling factor;

coupling the scaled voice-band signal to an output; and

detecting at least one of voice-band data in the input signal and tandem enhancement in the network and decoupling the scaled voice-band signal from the output.

17. The method of claim 16 wherein said determining the average power, determining a scaling factor, equalizing, scaling, and coupling steps are performed in an echo canceller of a telecommunications network.

18. The method of claim 16 wherein the predetermined portion of the input voice-band signal is above substantially 300 Hz.

19. (Amended) The method of claim 16 further comprising the steps of:

dividing the input voice-band signal into a plurality of frames, each frame representative of a period of time; and

scaling the equalized input signal with the scaling factor for a predetermined number of frames.

20. The method of claim 16 further comprising the steps of:

dividing the input voice-band signal into a plurality of frames, each frame representative of a period of time;

continuously performing said determining the average power, determining a scaling factor, equalizing scaling and coupling steps upon the expiration of a predetermined number of frames.

21. The method of claim 16 further comprising the steps of:

detecting periods of silence in the input voice-band signal at the input; and

decoupling the scaled voice-band signal from the output.

22. The method of claim 21 further comprising the step of attenuating the input voice-band signal so that the level of the detected periods of silence is minimized.

23. A system for providing enhancement to a voice-band signal in a telecommunications network, comprising:

a power averager for determining the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal; and

an output scaler for scaling the equalized voice-band signal with a scaling factor in response to the determined average power, and wherein said output scaler is further operable to limit the amount of change between consecutive scaling factors.

24. The system of claim 23 further comprising a voice-band data detector for detecting voice-band data in the voice-band signal and preventing said output scaler from scaling the voice-band signal.

25. The system of claim 23 further comprising a tandem voice enhancement detector for detecting when the voice-band signal has been previously scaled and preventing said output scaler from scaling the voice-band signal.

26. The system of claim 23 further comprising:

a voice-band data detector for detecting voice-band data in the voice-band signal;

a tandem voice enhancement detector for detecting when the voice-band signal has been previously scaled; and

wherein at least one of said voice-band data detector and said tandem voice enhancement detector is operable to prevent said output scaler from scaling the voice-band signal.

27. The system of claim 23 wherein said power averager, equalizer, and output scaler are located in an echo canceller of a telecommunications network.

28. The system of claim 23 wherein the predetermined portion of the voice-band signal attenuated by said equalizer is above substantially 300 Hz.

29. The system of claim 23 wherein the predetermined portion of the voice-band signal attenuated by said equalizer is above substantially 400 Hz.

30. The system of claim 23 wherein said output scaler is operable to scale equalized voice-band signals with a previously determined scaling factor for a predetermined period of time.

31. The system of claim 23 wherein said output scaler is further operable to divide the voice-band signal into a plurality of frames, each frame representative of a period of time, and to scale the voice-band signal for a predetermined number of frames.

32. The system of claim 23 wherein said equalizer comprises a digital filter operable to filter the voice-band signal above a predetermined frequency.

33. The system of claim 23 wherein said power averager comprises a low pass filter.

34. A system for providing enhancement to a voice-band signal in a telecommunications network, comprising:

a power averager for determining the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal;

an output scaler for scaling the equalized voice-band signal with a scaling factor in response to the determined average power; and

a gain/attenuation look-up table for providing the scaling factor to be used by said output scaler in scaling the voice-band signal.

35. A system for providing enhancement to a voice-band signal in a telecommunications network, comprising:

a power averager for determining the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal;

an output scaler for scaling the equalized voice-band signal with a scaling factor in response to the determined average power; and

a gain/attenuation look-up table for providing the scaling factor to be used by said output scaler in scaling the voice-band signal, and wherein said gain/attenuation look-up table is organized such that low power voice-band signals are assigned large scaling factors relative to high power voice-band signals, the high power voice-band signals being assigned low or negative scaling factors.

36. A system for providing enhancement to a voice-band signal in a telecommunications network, comprising:

a power averager for determining the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal;

an output scaler for scaling the equalized voice-band signal with a scaling factor in response to the determined average power;

a transparent path for providing the input voice-band signal directly to an output so that the input voice-band signal avoids scaling; and

an attenuator coupled in said transparent path for variably attenuating the input voice-band signal during periods of silence in the input voice-band signal.

37. A system for providing enhancement to a voice-band signal in a telecommunications network, comprising:

an input for accepting the voice-band signal;

an output for receiving the voice-band signal; and

a coupling between said input and output including a voice enhancer, said voice enhancer comprising;

a power averager for determining the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal; and

an output scaler coupled to said output for scaling the equalized voice-band signal with a scaling factor in response to the determined average power and providing the scaled signal to said output, and wherein said output scaler is further operable to limit the amount of change between consecutive sealing factors.

38. The system of claim 37 further comprising a voice-band data detector for detecting voice-band data in the voice-band signal and for decoupling said output scaler from said output.

39. The system of claim 37 further comprising a tandem voice enhancement detector for detecting when the voice-band signal has been previously scaled and for decoupling said output scaling circuitry from said output.

40. A system for providing enhancement to a voice-band signal in a telecommunications network, comprising:

an input for accepting the voice-band signal;

an output for receiving the voice-band signal; and

a coupling between said input and output including a voice enhancer, said voice enhancer comprising;

a power averager for determining the average power of the voice-band signal;

an equalizer for attenuating a predetermined portion of the voice-band signal;

an output scaler coupled to said output for scaling the equalized voice-band signal with a scaling factor in response to the determined average power and providing the scaled signal to said output;

a voice-band data detector for detecting voice-band data in the voice-band signal;

a tandem voice enhancement detector for detecting when the voice-band signal has been previously scaled; and

wherein at least one of said voice-band data detector and said tandem voice enhancement detector being operable to decouple said output scaler from said output.