Method and arrangement for changing source signal bandwidth in a telecommunication connection with multiple bandwidth capability

• US 6,782,367 B2
• Filed: 05/08/2001
• Issued: 08/24/2004
• Est. Priority Date: 05/08/2000
• Status: Expired due to Term

• Current Assignee: Crystal Mountain Communications, LLC (Ascend Innovation Management, LLC)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Vainio, Janne, Mikkola, Hannu, Rotola-Pukkila, Jani
• Primary Examiner(s): To, Doris H.
• Assistant Examiner(s): Vo, Huyen X
• Application Number:
  US09/850,889
• Publication Number:
  US 20010044712A1
• Time in Patent Office: 1,204 Days
• Field of Search: 704/223, 704/258, 704/264, 704/217, 704/206, 704/278, 704/500, 704/501, 704/503, 704/504
• US Class Current: 704/500
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes

Abstract

A speech encoding or decoding arrangement (711, 721, 811, 821) comprises a speech signal input and a multiple mode speech encoder (402) or decoder (411) for encoding or decoding speech signals coupled to the speech signal input selectabily with a first encoding or decoding mode associated with a first bandwidth or a second encoding or decoding mode associated with a second bandwidth. It comprises a soft bandwidth switching block (401, 412, 500) with an input (IN) and an output (OUT). In an encoding arrangement the input (IN) is coupled to the speech signal input and the output (OUT) is coupled to the multiple mode speech encoder (402). In a decoding arrangement the input (IN) is coupled to the multiple mode speech decoder (411) and the output (OUT) is the output of the decoding arrangement. The soft bandwidth switching block (401, 412, 500) is arranged to gradually change the bandwidth of a speech signal coupled to the multiple mode speech encoder or decoder as a response to an instruction for changing speech signal bandwidth (421).

Claims

1. A speech encoding arrangement, comprising:

a speech signal input,

a multiple mode speech encoder for encoding speech signals coupled to the speech signal input selectabily with a first encoding mode associated with a first bandwidth or a second encoding mode associated with a second bandwidth, and

a soft bandwidth switching block with an input coupled to the speech signal input and an output coupled to the multiple mode speech encoder, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal coupled to the multiple mode speech encoder as a response to an instruction for changing speech signal bandwidth.

2. A speech encoding arrangement according to claim 1, wherein said soft bandwidth switching block comprises:

a first processing branch and a second processing branch,

band combining means for combining the outputs of said first processing branch and said second processing branch into the output of said soft bandwidth switching block and

at least within said second processing branch adjustable means for controllably changing the relative properties of signals which are processed in said first and second processing branches.

3. A speech encoding arrangement according to claim 2, wherein said adjustable means comprise an adjustable gain block.

4. A speech encoding arrangement according to claim 2, wherein said adjustable means comprise an adjustable filter.

5. A speech encoding arrangement according to claim 2, comprising band splitting means for directing a first frequency band of a speech signal coupled to the speech signal input into said first processing branch and a second frequency band of a speech signal coupled to the speech signal input into said second processing branch.

6. A speech encoding arrangement according to claim 2, comprising a noise generator coupled to said second processing branch through an adjustable filter for controllably producing an artificial signal into said second processing branch.

7. A speech encoding arrangement according to claim 6, comprising:

band splitting means for directing a first frequency band of a speech signal coupled to the speech signal input into said first processing branch and a second frequency band of a speech signal coupled to the speech signal input into said second processing branch,

within said second processing branch adjustable means for changing the relative properties of said second frequency band of a speech signal and said artificial signal, and

within said second processing branch combining means for combining said second frequency band of a speech signal and said artificial signal into the output of said second processing branch.

8. A speech encoding arrangement according to claim 2, comprising a bandwidth switching control unit which is coupled to said adjustable means for controlling the changes in the relative properties of signals which are processed in said first and second processing branches.

9. A digital radio telephone, comprising:

a speech encoding arrangement,

a speech signal input to the speech encoding arrangement,

within the speech encoding arrangement a multiple mode speech encoder for encoding speech signals coupled to the speech signal input selectabily with a first encoding mode associated with a first bandwidth or a second encoding mode associated with a second bandwidth, and

a soft bandwidth switching block with an input coupled to the speech signal input and an output coupled to the multiple mode speech encoder, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal coupled to the multiple mode speech encoder as a response to an instruction for changing speech signal bandwidth.

10. A transcoder and rate adaptor unit of a cellular radio system, comprising:

a speech encoding arrangement,

a speech signal input to the speech encoding arrangement,

within the speech encoding arrangement a multiple mode speech encoder for encoding speech signals coupled to the speech signal input selectabily with a first encoding mode associated with a first bandwidth or a second encoding mode associated with a second bandwidth, and

a soft bandwidth switching block with an input coupled to the speech signal input and an output coupled to the multiple mode speech encoder, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal coupled to the multiple mode speech encoder as a response to an instruction for changing speech signal bandwidth.

11. A speech decoding arrangement, comprising:

a speech signal input,

a multiple mode speech decoder for decoding speech signals coupled to the speech signal input selectabily with a first decoding rate associated with a first bandwidth or a second decoding rate associated with a second bandwidth, and

a soft bandwidth switching block with an input coupled to the multiple mode speech decoder and an output, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal received from the multiple mode speech decoder as a response to an instruction for changing speech signal bandwidth.

12. A speech decoding arrangement according to claim 11, wherein said soft bandwidth switching block comprises:

a first processing branch and a second processing branch,

band combining means for combining the outputs of said first processing branch and said second processing branch into the output of said soft bandwidth switching block and

at least within said second processing branch adjustable means for controllably changing the relative properties of signals which are processed in said first and second processing branches.

13. A speech decoding arrangement according to claim 12, wherein said adjustable means comprise an adjustable gain block.

14. A speech decoding arrangement according to claim 12, wherein said adjustable means comprise an adjustable filter.

15. A speech decoding arrangement according to claim 12, comprising band splitting means for directing a first frequency band of a speech signal received from the multiple mode speech decoder into said first processing branch and a second frequency band of a speech signal received from the multiple mode speech decoder into said second processing branch.

16. A speech decoding arrangement according to claim 12, comprising a noise generator coupled to said second processing branch through an adjustable filter for controllably producing an artificial signal into said second processing branch.

17. A speech decoding arrangement according to claim 16, comprising:

band splitting means for directing a first frequency band of a speech signal received from the multiple mode speech decoder into said first processing branch and a second frequency band of a speech signal received from the multiple mode speech decoder into said second processing branch,

within said second processing branch adjustable means for changing the relative properties of said second frequency band of a speech signal and said artificial signal, and

within said second processing branch combining means for combining said second frequency band of a speech signal and said artificial signal into the output of said second processing branch.

18. A speech decoding arrangement according to claim 12, comprising a bandwidth switching control unit which is coupled to said adjustable means for controlling the changes in the relative properties of signals which are processed in said first and second processing branches.

19. A digital radio telephone, comprising:

a speech decoding arrangement,

a speech signal input to the speech decoding arrangement,

within the speech decoding arrangement a multiple mode speech decoder for decoding speech signals coupled to the speech signal input selectabily with a first decoding rate associated with a first bandwidth or a second decoding rate associated with a second bandwidth, and

a soft bandwidth switching block with an input coupled to the multiple mode speech decoder and an output, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal received from the multiple mode speech decoder as a response to an instruction for changing speech signal bandwidth.

20. A transcoder and rate adaptor unit of a cellular radio system, comprising:

a speech decoding arrangement,

a speech signal input to the speech decoding arrangement,

within the speech decoding arrangement a multiple mode speech decoder for decoding speech signals coupled to the speech signal input selectabily with a first decoding rate associated with a first bandwidth or a second decoding rate associated with a second bandwidth, and

a soft bandwidth switching block with an input coupled to the multiple mode speech decoder and an output, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal received from the multiple mode speech decoder as a response to an instruction for changing speech signal bandwidth.

21. A method for changing the bandwidth of a speech signal in association with multiple mode encoding or decoding, comprising the steps of:

receiving an indication of a change in speech signal bandwidth and

gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement as a response to said instruction for changing speech signal bandwidth.

22. A method according to claim 21, comprising the steps of:

receiving an early warning about an oncoming command for changing speech signal bandwidth,

initiating a process of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement as a response to said early warning and

completing the process of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement essentially just before executing a received command for changing speech signal bandwidth.

23. A method according to claim 21, comprising the steps of:

receiving a command for changing speech signal bandwidth,

delaying the execution of said received command for changing speech signal bandwidth,

conducting a process of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement after receiving but before executing said command for changing speech signal bandwidth and

executing said command for changing speech signal bandwidth by changing from one mode of said multiple mode speech encoding or decoding arrangement to another mode of said multiple mode speech encoding or decoding arrangement.

24. A method according to claim 21, comprising the steps of:

receiving a command for changing speech signal bandwidth and executing said command for changing speech signal bandwidth by changing from one mode of said multiple mode speech encoding or decoding arrangement to another mode of said multiple mode speech encoding or decoding arrangement, and

conducting a process of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement after executing said command for changing speech signal bandwidth.

25. A method according to claim 21, comprising the steps of:

receiving an early warning about an oncoming command for changing speech signal bandwidth,

initiating a process of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement as a response to said early warning,

receiving a command for changing speech signal bandwidth and executing said command for changing speech signal bandwidth by changing from one mode of said multiple mode speech encoding or decoding arrangement to another mode of said multiple mode speech encoding or decoding arrangement, the execution of said command causing an interruption in the process of gradually changing the bandwidth of a speech signal, and

completing the process of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement after executing said command for changing speech signal bandwidth.

26. A method according to claim 21, wherein the step of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement comprises the substeps of:

processing a first frequency band of a speech signal in a first processing branch and a second frequency band of a speech signal in a second processing branch and

changing a gain factor in said second processing branch.

27. A method according to claim 26, wherein:

the substep of processing a first frequency band of a speech signal in a first processing branch and a second frequency band of a speech signal in a second processing branch comprises the substep of directing a frequency band extracted from an actual speech signal present at an speech signal input of the multiple mode speech encoding or decoding arrangement through a first adjustable gain unit and

the substep of changing a gain factor in said second processing branch comprises the substep of adjusting the gain in said first adjustable gain unit.

28. A method according to claim 26, wherein:

the substep of processing a first frequency band of a speech signal in a first processing branch and a second frequency band of a speech signal in a second processing branch comprises the substeps of generating, within the multiple mode speech encoding or decoding arrangement, an artificial input signal and directing said artificial input signal through a second adjustable gain unit and

the substep of changing a gain factor in said second processing branch comprises the substep of adjusting the gain in said second adjustable gain unit.

29. A method according to claim 26, wherein:

the substep of processing a first frequency band of a speech signal in a first processing branch and a second frequency band of a speech signal in a second processing branch comprises the substeps of;

directing a frequency band extracted from an actual speech signal present at an speech signal input of the multiple mode speech encoding or decoding arrangement through a first adjustable gain unit,

generating, within the multiple mode speech encoding or decoding arrangement, an artificial input signal and directing said artificial input signal through a second adjustable gain unit, and

combining the outputs of said first and second adjustable gain units; and

the substep of changing a gain factor in said second processing branch comprises the substep of adjusting the gain in said first and second adjustable gain units.

30. A method according to claim 21, wherein the step of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement comprises the substeps of:

processing a first frequency band of a speech signal in a first processing branch and a second frequency band of a speech signal in a second processing branch and

changing the frequency response of an adjustable filter in said second processing branch.

31. A method according to claim 21, wherein the step of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement comprises the substep of determining the rate of said gradual changing on the basis of the momentary contents of said speech signal.

32. A method according to claim 21, wherein the step of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement comprises the substep of determining the rate of said gradual changing on the basis of the number of recently occurred changes in speech signal bandwidth.

33. A method according to claim 21, wherein the step of gradually changing the bandwidth of a speech signal processed in a multiple mode speech encoding or decoding arrangement comprises the substep of determining the rate of said gradual changing on the basis of the frequency of recently occurred changes in speech signal bandwidth.