Synchronization of voice boundaries and their use by echo cancellers in a voice processing system

• US 6,522,746 B1
• Filed: 11/03/2000
• Issued: 02/18/2003
• Est. Priority Date: 11/03/1999
• Status: Expired due to Term

• Current Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Original Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Inventors: Marchok, Daniel J., Younce, Richard C., Gritton, Charles W. K., Chandran, Ravi
• Primary Examiner(s): Isen, Forester W.
• Assistant Examiner(s): SINGH, RAMNANDAN P
• Application Number:
  US09/706,120
• Time in Patent Office: 837 Days
• Field of Search: 379/88-1-, 379/88.13, 379/406-1-4, 704/201, 704/220, 704/221, 704/229, 704/249, 704/278
• US Class Current: 379/406.03
• CPC Class Codes: G10L 15/30 Distributed recognition, e.g. in client-server systems, for mobile phones or network applications
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 2021/02082 the noise being echo, reverberation of the speech
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23

Abstract

Methods and apparatus for processing a transmitted voice signal include a centralized frame controller providing at least one boundary control signal to voice processing blocks and controlling the operation of the voice processing blocks on the transmitted voice signal based upon the boundary control signal.

Claims

1. In a communication system comprising a centralized frame controller and a plurality of voice processing blocks, coupled thereto, used to process a transmitted voice signal, a method for controlling operation of the plurality of voice processing blocks, the method comprising steps of:

providing at least one boundary control signal to the plurality of voice processing blocks by the centralized frame controller; and

controlling operation of each of the plurality of voice processing blocks on the transmitted voice signal based upon the at least one boundary control signal.

2. The method of claim 1, wherein the at least one boundary control signal is determined based on at least one of a frame boundary and a plurality of sub-frame boundaries corresponding to operation of a speech codec.

3. The method of claim 2, wherein the frame boundary and sub-frame boundaries correspond to the codec frame and sub-frame boundaries.

4. The method of claim 3, wherein the at least one boundary control signal delineates periods of time, and wherein the at least one automatic level control circuit, in response to the at least one boundary control signal, maintains a gain factor at constant levels during each period of time.

5. The method of claim 2, wherein the plurality of voice processing blocks comprises at least one automatic level control circuit.

6. The method of claim 5, wherein the at least one automatic level control circuit, for each period of time, determines the gain factor by analyzing the transmitted voice signal delimited by the period of time.

7. The method of claim 6, wherein the at least one boundary control signal delineates periods of time, and wherein the at least one noise reduction circuit, in response to the at least one boundary control signal and for each period of time, performs noise reduction processing on the transmitted voice signal delineated by the period of time.

8. The method of claim 7, wherein the at least one boundary control signal delineates periods of time, and wherein the at least one echo canceller, in response to the at least one boundary control signal and for each period of time, performs echo cancellation processing on the transmitted voice signal delineated by the period of time.

9. The method of claim 1, wherein the plurality of voice processing blocks comprises at least one noise reduction circuit.

10. The method of claim 1, wherein the plurality of voice processing blocks comprises at least one echo canceller.

11. The method of claim 1, wherein the plurality of voice processing blocks comprises at least one echo canceller coupled to a variable-delay network, the method further comprising the steps of:

determining, by a first echo canceller of the at least one echo canceller, delay characteristics related to at least one voice signal received via the variable delay network;

determining by the first echo canceller, that delay characteristics corresponding to the at least one voice signal have changed; and

modifying, by the first echo canceller, echo cancellation processing on the at least one voice signal in response to the changed delay characteristics.

12. The method of claim 11, further comprising the step of:

prior to the step of determining that the delay characteristics have changed, determining that echo cancellation performance has degraded, wherein the performance is indicative of a magnitude of echo.

13. The method of claim 11, wherein the step of determining that the delay characteristics have changed further comprises the step of inspecting a jitter buffer used to store the at least one voice signal.

14. The method of claim 11, wherein the at least one voice signal comprises a plurality of packets, wherein the step of modifying comprises the step of discontinuing echo cancellation processing for a portion of the plurality of packets, the method further comprising the steps of:

correlating the delay characteristics with the portion of the plurality of packets.

15. The method of claim 14, wherein the step of modifying further comprises the step of substituting previously echo cancelled packets for missing packets of the plurality of packets.

16. The method of claim 11, wherein the step of modifying comprises the step of adjusting a time domain function used to perform the echo cancellation processing.

17. The method of claim 11, wherein the step of determining that the delay characteristics have changed comprises the step of receiving information regarding changes to delay characteristics corresponding to a second echo canceller of the at least one echo canceller.

18. The method of claim 1, wherein the plurality of voice processing blocks comprises at least two echo cancellers, the method further comprising the steps of:

determining, by a first echo canceller of the at least two echo cancellers, silence descriptor information related to a portion of a transmitted voice signal sent from the first echo canceller to a second echo canceller of the at least two echo cancellers;

transmitting by the first echo canceller to the second echo canceller, the silence descriptor information and excitation vector information; and

reconstructing, by the second echo canceller, the portion of the transmitted voice signal based upon the silence descriptor information and the excitation vector information.

19. The method of claim 18, wherein the silence descriptor information comprises spectral information regarding the portion of the transmitted signal.

20. The method of claim 19, wherein the excitation vector information identifies a particular excitation vector that, when filtered according to the spectral information, provides an estimate of the portion of the transmitted signal.

21. The method of claim 18, further comprising the steps of:

receiving, by the first echo canceller from the second echo canceller, a received voice signal based upon the silence descriptor information and the excitation vector information; and

modifying, by the first echo canceller, echo cancellation processing on the transmitted voice signal based upon the received voice signal.

22. An apparatus for processing a transmitted voice signal, comprising:

a plurality of voice processing blocks that each operate upon the transmitted voice signal; and

a centralized frame controller, coupled to each of the plurality of voice processing blocks, that provides at least one boundary control signal to the plurality of voice processing blocks,

wherein operation of each of the plurality of voice processing blocks on the transmitted voice signal is dependent upon the at least one boundary control signal.

23. The apparatus of claim 22, further comprising a programmable processor coupled to a storage device, wherein the centralized frame controller is implemented via instructions executed by the programmable processor and stored in the storage device.

24. The apparatus of claim 22, wherein the centralized frame controller determines the at least one boundary control signal based on at least one of a frame boundary and a plurality of sub-frame boundaries corresponding to operation of a speech codec.

25. The apparatus of claim 22, wherein the plurality of voice processing blocks comprises at least one automatic level control circuit.

26. The apparatus of claim 25, wherein the at least one boundary control signal delineates periods of time, and wherein the at least one automatic level control circuit, in response to the at least one boundary control signal, maintains a gain factor at constant levels during each period of time.

27. The apparatus of claim 25, wherein the at least one automatic level control circuit, for each period of time, determines the gain factor by analyzing the transmitted voice signal delimited by the period of time.

28. The apparatus of claim 22, wherein the plurality of voice processing blocks comprises at least one noise reduction circuit.

29. The apparatus of claim 28, wherein the at least one boundary control signal delineates periods of time, and wherein the at least one noise reduction circuit, in response to the at least one boundary control signal and for each period of time, performs noise reduction processing on the transmitted voice signal delineated by the period of time.

30. The apparatus of claim 22, wherein the plurality of voice processing blocks comprises at least one echo canceller.

31. The apparatus of claim 30, wherein the at least one boundary control signal delineates periods of time, and wherein the at least one echo canceller, in response to the at least one boundary control signal and for each period of time, performs echo cancellation processing on the transmitted voice signal delineated by the period of time.