Circuit method and system for transmitting information

Abstract

Disclosed is an echo suppresser or cancellation circuit including a speech signal extrapolation unit. The speech extrapolation unit may provide extrapolated signal segment approximations to an echo segment replacement unit. The echo segment replacement unit may replace a segment of a first speech signal suspected of being corrupted with an echo component of a second signal using the extrapolated signal segment approximated to represent the corrupted signal segment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

FIG. 1 shows a diagram of an exemplary voice communication link across an exemplary voice communication network, including echo suppressers on both ends of the link;

FIG. 2 shows a simplified circuit diagram of an echo suppresser connected to one end of a voice communication link established over a communication network such as the one exemplified in FIG. 1;

FIG. 3 shows a block diagram of an echo suppresser according to some embodiments of the present invention;

FIG. 4 shows a simplified circuit diagram of an echo suppresser according some embodiments of the present invention in which a non-linear processor may be utilized;

FIG. 5 is a flowchart including the steps of a method of echo suppression according to some embodiments of the present invention;

FIGS. 6A and 6B shows a set of signal graphs illustrating signal processing according to some aspects of the present invention.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as “processing”, “computing”, “calculating”, “determining”, or the like, refer to the action and/or processes of a computer or computing system, or similar electronic computing device, that manipulate and/or transform data represented as physical, such as electronic, quantities within the computing system's registers and/or memories into other data similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices.

Embodiments of the present invention may include apparatuses for performing the operations herein. This apparatus may be specially constructed for the desired purposes, or it may comprise a general purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs) electrically programmable read-only memories (EPROMs), electrically erasable and programmable read only memories (EEPROMs), magnetic or optical cards, or any other type of media suitable for storing electronic instructions, and capable of being coupled to a computer system bus.

The processes and displays presented herein are not inherently related to any particular computer or other apparatus. Various general purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform the desired method. The desired structure for a variety of these systems will appear from the description below. In addition, embodiments of the present invention are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the inventions as described herein. One of ordinary skill in the art should understand that the described invention may be used for all kinds of wireless or wire-line system

According to some embodiments of the present invention, there is provided an echo suppresser or cancellation circuit including a speech signal extrapolation unit. The speech extrapolation unit may provide extrapolated signal segment approximations to an echo segment replacement unit. The echo segment replacement unit may replace a segment of a first speech signal suspected of being corrupted with an echo component of a second signal using the extrapolated signal segment approximated to represent the corrupted signal segment.

According to some embodiments of the present invention, the extrapolated signal segment may be produced using speech prediction of conventional packet loss concealment methods. Either the residual signal and/or the output clean signal can be used as an input for the extrapolation process. Any methods known today or to be devised in the future for speech signal extrapolation may be applicable to the present invention.

According to some embodiments of the present invention, the segment replacement unit may be functionally associated with a non-linear processor. A non-linear processor according to the present invention may replace signal segment suspected of being corrupted with an echo with a signal segment extrapolated using speech prediction of conventional packet loss concealment methods. Either the residual signal and/or the output clean signal can be used as an input for the extrapolation process. Any methods known today or to be devised in the future for speech signal extrapolation may be applicable to the present invention.

Turning now to FIG. 3, there is shown a block diagram of an echo suppresser according to some embodiments of the present invention. The echo suppresser 40 may include an echo detection unit 42, a speech signal extrapolation unit 44 and an echo component replacement unit 46 which may replace segments of an uplink speech signal suspected of being corrupted with a downlink speech signal echo component using an approximate uplink speech signal component. The operation of the echo suppresser of FIG. 3 may be described in conjunction with the steps of the flow chart shown in FIG. 5, which flowchart includes the steps of a method of echo suppression according to some embodiments of the present invention.

In the event that the echo detection unit 42 determines that there is an echo component from a downlink echo signal within an uplink speech signal (FIG. 5, step 1000), the echo detection unit may produce a signal indicating one or more parameters of the echo component. The parameters provided may include location within the uplink speech signal, energy level of the echo component, etc. Any circuits or methodology for echo detection, known today or to be devised in the future, may be applicable to the present invention.

The speech signal extrapolation unit 44 may approximate one or more speech signal components (FIG. 5, step 2000) associated with the uplink signal, either continually or only upon receiving an indication that an echo component may exist within an uplink speech signal. Any circuits or methodology for speech signal extrapolation, known today or to be devised in the future, may be applicable to the present invention.

The echo component replacement unit 46 may replace a segment of an uplink speech signal suspected of being corrupted with an echo component of a downlink speech signal (FIG. 5, step 3000). The location of the component suspected of being corrupted may be provided by the echo detection unit 42, and the approximated speech signal segment with which the segment suspected of being corrupted is replaced may be provided by the speech signal extrapolation unit 44. FIG. 6 shows a set of signal graphs illustrating signal processing according to some aspects of the present invention. The signal segment replacement described above is illustrated within FIG. 6. Any circuits or methods of signal segment replacement, known today or to be devised in the future, may be applicable to the present invention.

FIG. 4 shows a simplified circuit diagram of an echo suppresser according some embodiments of the present invention in which a non-linear processor may be utilized. The embodiment shown in FIG. 4 is substantially analogous to the echo suppressers shown and described as part of FIGS. 1 and 2, with the addition of a speech signal extrapolation unit 12. Instead of using comfort noise to replace speech signal segments suspected of being corrupted, the suppresser of FIG. 4 uses an approximated speech signal segment generated by the speech signal extrapolation unit 12.

Turning now to FIGS. 6A and 6B, there is shown a set of signal graphs illustrating signal processing according to some aspects of the present invention. According to further embodiments of the present invention, FIG. 6A shows a voice signal after NLP (non-linear processor) clipping, while FIG. 6B shows the same voice signal after a concealment process.

According to yet further embodiments of the present invention, the concealment process may also be referred to as “speech prediction method”, or as “packet loss concealment method”. Any methods of speech prediction and/or packet loss concealment, known today or to be devised in the future, may be applicable to the present invention. Some known methods in the art are taught by the below listed publications, and are hereby incorporated by reference:

• • Altman, E., Avrachenkov, K., Barakat, C., TCP in the Presence of Bursty Losses, Performance Evaluation 42 (2000) 129-147
  • Berger J. M., Mandelbrot B. A New Model for Error Clustering in Telephone Circuits. IBM J R&D July 1963
  • Blank H. A, Trafton P. J., A Markov Error Channel Model, Proc Nat Telecomm Conference 1973
  • Bolot J. C., Vega Garcia A. The case for FEC based error control for packet audio in the Internet, ACM Multimedia Systems 1997
  • Boutremans C., Iannaccone G., Diot C., Impact of Link Failures on VoIP Performance, Sprint Labs technical report IC/2002/015
  • Cain J. B., Simpson R. S., The Distribution of Burst Lengths on a Gilbert Channel, IEEE Trans IT-15 September 1969
  • Clark A., Modeling the Effects of Burst Packet Loss and Recency on Subjective Voice Quality, IPtel 2001 Workshop
  • Drajic D., Vucetic B., Evaluation of Hybrid Error Control Systems, IEE Proc F. Vol 131, 2 Apr. 1984
  • Ebert J-P., Willig A., A Gilbert-Elliott Model and the Efficient Use in Packet Level Simulation. TKN Technical Report 99-002 [10] Elliott E. O., Estimates of Error Rates for Codes on Burst Noise Channels. BSTJ 42, September 1963
  • Elliott E. 0. A Model of the Switched Telephone Network for Data Communications, BSTJ 44, January 1965
  • ETSI TIPHON TS 101 329-5 Annex E, QoS Measurements for Voice over IP
  • Gilbert E. N. Capacity of a Burst Noise Channel, BSTJ September 1960
  • ITU-T SG12 D.139: “Study of the relationship between instantaneous and overall subjective speech quality for time-varying quality speech sequences”, France Telecom
  • Jiang W., Schulzrinne H., Modeling of Packet Loss and Delay and their effect on Real Time Multimedia Service Quality, NOSSDAV 2000
  • Lewis P, Cox D., A Statistical Analysis of Telephone Circuit Error Data. IEEE Trans COM-14 1966
  • Mertz P., Statistics of Hyperbolic Error Distributions in Data Transmission, IRE Trans CS-9, December 1961
  • Sanneck H., Carle G., A Framework Model for Packet Loss Metrics Based on Loss Runlengths. Proc ACM MMCN January 2000
  • Yajnik M., Moon S., Kurose J., Towsley D., Measuring and Modelling of the Temporal Dependence in Packet Loss, UMASS CMPSCI Tech Report #98-78
  • ITU SG12 D.22 A framework for setting packet loss objectives for VoIP, AT&T October 2001
  • T1.521-1999—Packet Loss Concealment for Use with ITU-T Recommendation G.711 (American National standard)
  • T1.521a-2000—Supplement to T1.521-1999

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

1. An echo suppresser apparatus comprising: a. a speech signal extrapolation unit.

2. The apparatus according to claim 1, wherein the speech signal extrapolation unit provides extrapolated signal segment approximation to an echo segment replacement unit.

3. The apparatus according to claim 2, wherein the echo segment replacement unit replaces a segment of a first speech signal suspected of being corrupted with an echo component of a second signal using the extrapolated signal segment approximated to represent the corrupted signal segment.

4. The apparatus according to claim 2, wherein the echo segment replacement unit is functionally associated with a non-linear processor.

5. The apparatus according to claim 2, wherein the extrapolated signal segment is produced using speech prediction and/or conventional packet loss concealment methods.

6. The apparatus according to claim 1, wherein the extrapolation unit input is either the residual signal or the output clean signal.

7. An echo suppression system comprising: a. a speech extrapolation unit; andb. communication device adapted to produce the speech signal.

8. The system according to claim 7, wherein the speech extrapolation unit provides extrapolated signal segment approximation to an echo segment replacement unit.

9. The system according to claim 8, wherein the echo segment replacement unit replaces a segment of a first speech signal suspected of being corrupted with an echo component of a second signal using the extrapolated signal segment approximated to represent the corrupted signal segment.

10. The system according to claim 8, wherein the echo segment replacement unit is functionally associated with a non-linear processor.

11. The system according to claim 8, wherein the extrapolated signal segment is produced using speech prediction and/or conventional packet loss concealment methods.

12. The system according to claim 7, wherein the extrapolation unit input is either the residual signal or the output clean signal.

13. A method of echo suppression comprising: a. replacing a segment of a first speech signal suspected of being corrupted with an echo component from a second speech signal using a signal segment extrapolated from the first speech signal.

14. The method according to claim 13, wherein the extrapolated signal segment was provided using a speech extrapolation unit.

15. The method according to claim 14, wherein said replacing takes place using a replacement unit.

16. The method according to claim 15, wherein the replacement unit is functionally associated with a non-linear processor.

17. The method according to claim 13, wherein the extrapolated signal segment is produced using speech prediction and/or conventional packet loss concealment methods.

18. The method according to claim 14, wherein the extrapolation unit input is either the residual signal or the output clean signal.