Clipping detection device and method

• US 8,392,199 B2
• Filed: 05/21/2009
• Issued: 03/05/2013
• Est. Priority Date: 07/30/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Otani, Takeshi, Tanaka, Masakiyo, Ota, Yasuji, Ito, Shusaku
• Primary Examiner(s): COLUCCI, MICHAEL C
• Application Number:
  US12/470,233
• Publication Number:
  US 20100030555A1
• Time in Patent Office: 1,384 Days
• Field of Search: 455/136, 455/127.1, 381/71.14, 381/94.1, 381/62, 381/56, 379/406.13, 715/201, 704/276, 704/270, 704/226, 704/225, 704/207, 370/210, 361/88, 359/279, 359/237, 359/207.8, 359/199.1, 348/223.1, 347/74, 330/109, 324/458, 250/201.4, 153/19
• US Class Current: 704/500
• CPC Class Codes: G10L 21/02 Speech enhancement, e.g. noise reduction or echo cancellation reducing echo effects in line transmission systems H04B3/20; echo suppression in hands-free telephones H04M9/08
• CPC Class Codes: H03G 3/002 Control of digital or coded signals H03G3/3089 take precedence
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A clipping detection device calculates an amplitude distribution of an input signal for each predetermined period, calculates a deflection degree of the distribution on the basis of the calculated amplitude distribution, and then detects clipping of a communication signal on the basis of the calculated deflection degree of the distribution.

Claims

1. A clipping detection device which detects clipping of a communication signal, the clipping detection device comprising:

an amplitude distribution calculation device to calculate amplitude distribution of an input signal for each predetermined period;

a deflection degree of the distribution calculation device to calculate a deflection degree of the distribution on a basis of the amplitude distribution; and

a clipping detection device to detect clipping on a basis of the deflection degree of the distribution,

wherein the deflection degree of the distribution calculation device estimates normal amplitude distribution in a high amplitude area in the case when no clipping occurs from a low amplitude area of the amplitude distribution calculated by the amplitude distribution calculation device, and calculates a difference between a value on a basis of the amplitude distribution calculated by the amplitude distribution calculation device in the high amplitude area and a value of the normal amplitude distribution as the deflection degree of the distribution.

2. The device according to claim 1,

further comprising an amplitude distribution normalization device to normalize the amplitude distribution,

wherein the deflection degree of the distribution calculation device calculates the deflection degree of the distribution on a basis of the normalized amplitude distribution.

3. The device according to claim 1, wherein the deflection degree of the distribution calculation device calculates a difference between a value on a basis of the amplitude distribution calculated by the amplitude distribution calculation device and a value of a predetermined amplitude distribution as the deflection degree of the distribution.

4. The device according to claim 1, wherein the deflection degree of the distribution calculation device detects a peak in the amplitude distribution calculated by the amplitude distribution calculation device, and calculates the deflection degree of the distribution on a basis of a number of the peaks.

5. The device according to claim 1,

further comprising a voice activity detection device detecting a voice period in which audio data is include for each of the predetermined periods in the input signal,

wherein a clipping detecting operation is performed only when the voice activity detection device detects the voice period.

6. The device according to claim 1, wherein the deflection degree of the distribution calculation device calculates the deflection degree of the distribution on a basis of the amplitude distribution having an amplitude absolute value equal to or exceeding a predetermined value.

7. A method for detecting clipping of a communication signal, the method comprising:

calculating amplitude distribution of an input signal for each predetermined period;

calculating a deflection degree of the distribution on a basis of the amplitude distribution; and

detecting clipping on a basis of the deflection degree of the distribution,

wherein the calculating the deflection degree of the distribution estimates normal amplitude distribution in a high amplitude area in the case when no clipping occurs from a low amplitude area of the amplitude distribution, and calculates a difference between a value on a basis of the amplitude distribution in the high amplitude area and a value of the normal amplitude distribution as the deflection degree of the distribution.

8. The method according to claim 7, further comprising normalizing the amplitude distribution, wherein the calculating the deflection degree of the distribution calculates a deflection degree of the distribution on a basis of the normalized amplitude distribution.

9. The method according to claim 7, wherein the calculating the deflection degree of the distribution calculates a difference between a value on a basis of the amplitude distribution and a predetermined value of amplitude distribution as the deflection degree of the distribution.

10. The method according to claim 7, wherein the calculating the deflection degree of the distribution detects a peak in the amplitude distribution and calculates the deflection degree of the distribution on a basis of the number of peaks.

11. The method according to claim 7,

further comprising detecting a voice period where the input signal includes audio data for each of the predetermined periods,

wherein a clipping detecting operation is performed only when the voice period is detected.

12. The method according to claim 7, wherein the calculating the deflection degree of the distribution calculates the deflection degree of the distribution on a basis of the amplitude distribution having an amplitude absolute value equal to or exceeding a predetermined value.