System and method of smart audio logging for mobile devices

• US 9,112,989 B2
• Filed: 03/30/2011
• Issued: 08/18/2015
• Est. Priority Date: 04/08/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lee, Te-Won, El-Maleh, Khaled Helmi, Yoo, Heejong, Shin, Jongwon
• Primary Examiner(s): MCCORD, PAUL C
• Application Number:
  US13/076,242
• Publication Number:
  US 20120078397A1
• Time in Patent Office: 1,602 Days
• Field of Search: 700/94
• US Class Current: 1/1
• CPC Class Codes: G10L 17/00 Speaker identification or verification techniques
• CPC Class Codes: G10L 2015/088 Word spotting
• 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: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/10546 specifically adapted for audio data
• CPC Class Codes: H04M 1/6008 in the transmitter circuit
• CPC Class Codes: H04M 1/656 for recording conversations
• CPC Class Codes: H04M 1/72433 for voice messaging, e.g. dictaphones for answering incoming calls H04M1/64

Abstract

A mobile device that is capable of automatically starting and ending the recording of an audio signal captured by at least one microphone is presented. The mobile device is capable of adjusting a number of parameters related with audio logging based on the context information of the audio input signal.

Claims

1. A method of processing a digital audio signal for a mobile device, the method comprising:

receiving an acoustic signal by at least one microphone;

converting the received acoustic signal into the digital audio signal;

extracting auditory context information from the digital audio signal;

in response to automatically detecting a start event indicator, performing an audio logging for the digital audio signal; and

in response to automatically detecting an end event indicator, ending the audio logging,

wherein the detecting the start event indicator comprises;

selecting at least one context information from the auditory context information; and

in response to comparing the selected context information with a threshold, determining if the start event indicator has been detected, and

wherein the auditory context information relates to at least one of followings—

audio classification, keyword identification, or speaker identification, and

wherein the auditory context information is based at least in part on non-auditory information.

2. The method of processing a digital audio signal according to claim 1, wherein the converting comprises:

transforming the received acoustic signal into an electrical signal;

sampling the electrical signal to obtain the digital audio signal; and

storing the digital audio signal into a buffer,

wherein the sampling is based on a sampling frequency and a data width.

3. The method of processing a digital audio signal according to claim 1, wherein the auditory context information is based at least in part on one of followings—

signal-to-noise ratio, spectral tilt, or zero-crossing rate.

4. The method of processing a digital audio signal according to claim 1, wherein the non-auditory information comprises scheduling or calendaring information.

5. The method of processing a digital audio signal according to claim 1, wherein the detecting the start event indicator is based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

6. The method of processing a digital audio signal according to claim 1, wherein the performing the audio logging comprises:

updating at least one parameter related with the converting based at least in part on the auditory context information;

in response to determining if an additional processing is required based at least in part on the auditory context information, applying the additional processing to the digital audio signal to obtain a processed audio signal; and

storing the processed audio signal into a memory storage.

7. The method of processing a digital audio signal according to claim 6, wherein the additional processing includes signal enhancement processing.

8. The method of processing a digital audio signal according to claim 7, wherein the signal enhancement processing includes at least one of followings—

acoustic echo cancellation (AEC), receiving voice enhancement (RVE), active noise cancellation (ANC), noise suppression (NS), acoustic gain control (AGC), acoustic volume control (AVC), or acoustic dynamic range control (ADRC).

9. The method of processing a digital audio signal according to claim 8, wherein the noise suppression is based on a plurality of microphones.

10. The method of processing a digital audio signal according to claim 6, wherein the additional processing includes signal compression processing.

11. The method of processing a digital audio signal according to claim 10, wherein the signal compression processing includes speech compression or audio compression.

12. The method of processing a digital audio signal according to claim 10, wherein at least one compression parameter is determined based on the auditory context information.

13. The method of processing a digital audio signal according to claim 12, wherein said at least one compression parameter includes compression mode, bitrate, or channel number.

14. The method of processing a digital audio signal according to claim 6, wherein the memory storage comprises a local memory inside the mobile device or a remote memory connected to the mobile device through a wireless channel.

15. The method of processing a digital audio signal according to claim 14, wherein the memory storage is selected based at least in part on the auditory context information.

16. The method of processing a digital audio signal according to claim 1, wherein the detecting the end event indicator comprises:

selecting at least one context information from the auditory context information; and

in response to comparing the selected context information with a threshold, determining if the end event indicator has been detected.

17. The method of processing a digital audio signal according to claim 1, wherein the detecting the end event indicator is based at least in part on non-occurrence of auditory event during pre-determined period of time.

18. The method of processing a digital audio signal according to claim 1, wherein the detecting the end event indicator is based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

73. The method of processing a digital audio signal according to claim 3, wherein said performing an audio logging for the digital audio signal comprises initiating an audio logging of the digital audio signal.

74. The method of processing a digital audio signal according to claim 73, wherein said ending the audio logging comprises terminating said initiated audio logging of the digital audio signal.

75. The method of processing a digital audio signal according to claim 3, wherein said method comprises, based on said auditory context information, selecting at least one among a compression mode, a bitrate, and a number of channels of the digital audio signal.

76. The method of processing a digital audio signal according to claim 3, wherein said method comprises, during said audio logging and based on said auditory context information, adjusting at least one among (A) a number of active microphones among said at least one microphone, (B) a sampling frequency of the digital audio signal, and (C) a data width of the digital audio signal.

77. The method of processing a digital audio signal according to claim 76, wherein said adjusting is performed during an inactive portion of the received acoustic signal.

78. The method of processing a digital audio signal according to claim 3, wherein said method is performed by said mobile device, and

wherein during said receiving the acoustic signal, the mobile device is in an idle mode.

79. The method of processing a digital audio signal according to claim 3, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said receiving the acoustic signal, the mobile device is not engaged in any voice call.

80. The method of processing a digital audio signal according to claim 79, wherein said mobile phone is capable of performing video recording, and

wherein during said receiving the acoustic signal, the mobile device is not performing video recording.

81. The method of processing a digital audio signal according to claim 79, wherein said method comprises periodically sending a signal to at least one base station during said receiving the acoustic signal.

82. The method of processing a digital audio signal according to claim 79, wherein said method comprises periodically receiving a signal from at least one base station during said receiving the acoustic signal.

83. The method of processing a digital audio signal according to claim 3, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said converting the received acoustic signal, the mobile device is not engaged in any voice call.

84. The method of processing a digital audio signal according to claim 3, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said extracting auditory context information, the mobile device is not engaged in any voice call.

85. The method of processing a digital audio signal according to claim 1, wherein said performing an audio logging for the digital audio signal comprises initiating an audio logging of the digital audio signal.

86. The method of processing a digital audio signal according to claim 85, wherein said ending the audio logging comprises terminating said initiated audio logging of the digital audio signal.

87. The method of processing a digital audio signal according to claim 1, wherein said method comprises, based on said auditory context information, selecting at least one among a compression mode, a bitrate, and a number of channels of the digital audio signal.

88. The method of processing a digital audio signal according to claim 1, wherein said method comprises, during said audio logging and based on said auditory context information, adjusting at least one among (A) a number of active microphones among said at least one microphone, (B) a sampling frequency of the digital audio signal, and (C) a data width of the digital audio signal.

89. The method of processing a digital audio signal according to claim 88, wherein said adjusting is performed during an inactive portion of the received acoustic signal.

90. The method of processing a digital audio signal according to claim 1, wherein said method is performed by said mobile device, and

wherein during said receiving the acoustic signal, the mobile device is in an idle mode.

91. The method of processing a digital audio signal according to claim 1, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said receiving the acoustic signal, the mobile device is not engaged in any voice call.

92. The method of processing a digital audio signal according to claim 91, wherein said mobile phone is capable of performing video recording, and

wherein during said receiving the acoustic signal, the mobile device is not performing video recording.

93. The method of processing a digital audio signal according to claim 91, wherein said method comprises periodically sending a signal to at least one base station during said receiving the acoustic signal.

94. The method of processing a digital audio signal according to claim 91, wherein said method comprises periodically receiving a signal from at least one base station during said receiving the acoustic signal.

95. The method of processing a digital audio signal according to claim 1, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said converting the received acoustic signal, the mobile device is not engaged in any voice call.

96. The method of processing a digital audio signal according to claim 1, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said extracting auditory context information, the mobile device is not engaged in any voice call.

97. The method of processing a digital audio signal according to claim 16, wherein said performing an audio logging for the digital audio signal comprises initiating an audio logging of the digital audio signal.

98. The method of processing a digital audio signal according to claim 97, wherein said ending the audio logging comprises terminating said initiated audio logging of the digital audio signal.

99. The method of processing a digital audio signal according to claim 16, wherein said method comprises, based on said auditory context information, selecting at least one among a compression mode, a bitrate, and a number of channels of the digital audio signal.

100. The method of processing a digital audio signal according to claim 16, wherein said method comprises, during said audio logging and based on said auditory context information, adjusting at least one among (A) a number of active microphones among said at least one microphone, (B) a sampling frequency of the digital audio signal, and (C) a data width of the digital audio signal.

101. The method of processing a digital audio signal according to claim 100, wherein said adjusting is performed during an inactive portion of the received acoustic signal.

102. The method of processing a digital audio signal according to claim 16, wherein said method is performed by said mobile device, and

wherein during said receiving the acoustic signal, the mobile device is in an idle mode.

103. The method of processing a digital audio signal according to claim 16, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said receiving the acoustic signal, the mobile device is not engaged in any voice call.

104. The method of processing a digital audio signal according to claim 103, wherein said mobile phone is capable of performing video recording, and

wherein during said receiving the acoustic signal, the mobile device is not performing video recording.

105. The method of processing a digital audio signal according to claim 103, wherein said method comprises periodically sending a signal to at least one base station during said receiving the acoustic signal.

106. The method of processing a digital audio signal according to claim 103, wherein said method comprises periodically receiving a signal from at least one base station during said receiving the acoustic signal.

107. The method of processing a digital audio signal according to claim 16, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said converting the received acoustic signal, the mobile device is not engaged in any voice call.

108. The method of processing a digital audio signal according to claim 16, wherein said method is performed by said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls, and

wherein during said extracting auditory context information, the mobile device is not engaged in any voice call.

19. An apparatus for processing a digital audio signal for a mobile device, the apparatus comprising:

at least one microphone configured to receive an acoustic signal;

a converter configured to convert the received acoustic signal into the digital audio signal;

a context identifier configured to extract auditory context information from the digital audio signal;

a start event manager configured to automatically detect a start event indicator;

an end event manager configured to automatically detect an end event indicator; and

an audio logging processor configured to;

perform an audio logging for the digital audio signal in response to the detecting of the start event indicator; and

end the audio logging in response to the detecting of the end event indicator,

wherein the start event manager is configured to;

select at least one context information from the auditory context information;

compare the selected context information with a threshold; and

determine if the start event indicator has been detected in response to the comparing, and

wherein the auditory context information relates to at least one of followings—

audio classification, keyword identification, or speaker identification, and

wherein the auditory context information is based at least in part on non-auditory information.

20. The apparatus for processing a digital audio signal according to claim 19, wherein the converter configured to:

transform the received acoustic signal into an electrical signal;

sample the electrical signal to obtain the digital audio signal; and

store the digital audio signal into a buffer,

wherein the sampling is based on a sampling frequency and a data width.

21. The apparatus for processing a digital audio signal according to claim 19, wherein the auditory context information is based at least in part on one of followings—

signal-to-noise ratio, spectral tilt, or zero-crossing rate.

22. The apparatus for processing a digital audio signal according to claim 19, wherein the non-auditory information comprises scheduling or calendaring information.

23. The apparatus for processing a digital audio signal according to claim 19, wherein the detecting the start event indicator is based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

24. The apparatus for processing a digital audio signal according to claim 19, wherein the audio logging processor is configured to:

update at least one parameter related with the converter based at least in part on the auditory context information;

determine if an additional processing is required based at least in part on the auditory context information;

apply the additional processing to the digital audio signal to obtain a processed audio signal, in response to the determining; and

store the processed audio signal into a memory storage.

25. The apparatus for processing a digital audio signal according to claim 24, wherein the additional processing includes signal enhancement processing.

26. The apparatus for processing a digital audio signal according to claim 25, wherein the signal enhancement processing includes at least one of followings—

acoustic echo cancellation (AEC), receiving voice enhancement (RVE), active noise cancellation (ANC), noise suppression (NS), acoustic gain control (AGC), acoustic volume control (AVC), or acoustic dynamic range control (ADRC).

27. The apparatus for processing a digital audio signal according to claim 26, wherein the noise suppression is based on a plurality of microphones.

28. The apparatus for processing a digital audio signal according to claim 24, wherein the additional processing includes signal compression processing.

29. The apparatus for processing a digital audio signal according to claim 28, wherein the signal compression processing includes speech compression or audio compression.

30. The apparatus for processing a digital audio signal according to claim 28, wherein at least one compression parameter is determined based on the auditory context information.

31. The apparatus for processing a digital audio signal according to claim 30, wherein said at least one compression parameter includes compression mode, bitrate, or channel number.

32. The apparatus for processing a digital audio signal according to claim 24, wherein the memory storage comprises a local memory inside the mobile device or a remote memory connected to the mobile device through a wireless channel.

33. The apparatus for processing a digital audio signal according to claim 32, wherein the memory storage is selected based at least in part on the auditory context information.

34. The apparatus for processing a digital audio signal according to claim 19, wherein the end event manager is configured to:

select at least one context information from the auditory context information;

compare the selected context information with a threshold; and

determine if the end event indicator has been detected in response to the comparing.

35. The apparatus for processing a digital audio signal according to claim 19, wherein the detecting the end event indicator is based at least in part on non-occurrence of auditory event during pre-determined period of time.

36. The apparatus for processing a digital audio signal according to claim 19, wherein the detecting the end event indicator is based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

109. The apparatus according to claim 19, wherein said audio logging processor is configured to perform said audio logging by initiating an audio logging of the digital audio signal, and

wherein said apparatus is within said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls and capable of performing video recording, and

wherein said converter is configured to convert said received acoustic signal while the mobile device is neither engaged in any voice call nor performing video recording, and

wherein said mobile device is configured to periodically send a signal to at least one base station and to periodically receive a signal from at least one base station while said converter is converting said received acoustic signal.

37. An apparatus for processing a digital audio signal for a mobile device, the apparatus comprising:

means for receiving an acoustic signal by at least one microphone;

means for converting the received acoustic signal into the digital audio signal;

means for extracting auditory context information from the digital audio signal;

means for automatically detecting a start event indicator;

means for performing an audio logging for the digital audio signal in response to the detecting the start event indicator;

means for automatically detecting an end event indicator; and

means for ending an audio logging for the digital audio signal in response to the detecting the end event indicator,

wherein the means for automatically detecting the start event indicator comprises;

means for selecting at least one context information from the auditory context information;

means for comparing the selected context information with a threshold; and

means for determining if the start event indicator has been detected in response to the comparing, and

wherein the auditory context information relates to at least one of followings—

audio classification, keyword identification, or speaker identification, and

wherein the auditory context information is based at least in part on non-auditory information.

38. The apparatus for processing a digital audio signal according to claim 37, wherein the means for converting comprises:

means for transforming the received acoustic signal into an electrical signal;

means for sampling the electrical signal to obtain the digital audio signal; and

means for storing the digital audio signal into a buffer,

wherein the sampling is based on a sampling frequency and a data width.

39. The apparatus for processing a digital audio signal according to claim 37, wherein the auditory context information is based at least in part on one of followings—

signal-to-noise ratio, spectral tilt, or zero-crossing rate.

40. The apparatus for processing a digital audio signal according to claim 37, wherein the non-auditory information comprises scheduling or calendaring information.

41. The apparatus for processing a digital audio signal according to claim 37, wherein the detecting the start event indicator is based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

42. The apparatus for processing a digital audio signal according to claim 37, wherein the means for performing the audio logging comprises:

means for updating at least one parameter related with the means for converting based at least in part on the auditory context information;

means for determining if an additional processing is required based at least in part on the auditory context information;

means for applying the additional processing to the digital audio signal to obtain a processed audio signal, in response to the determining; and

means for storing the processed audio signal into a memory storage.

43. The apparatus for processing a digital audio signal according to claim 42, wherein the additional processing includes signal enhancement processing.

44. The apparatus for processing a digital audio signal according to claim 43, wherein the signal enhancement processing includes at least one of followings—

acoustic echo cancellation (AEC), receiving voice enhancement (RVE), active noise cancellation (ANC), noise suppression (NS), acoustic gain control (AGC), acoustic volume control (AVC), or acoustic dynamic range control (ADRC).

45. The apparatus for processing a digital audio signal according to claim 44, wherein the noise suppression is based on a plurality of microphones.

46. The apparatus for processing a digital audio signal according to claim 42, wherein the additional processing includes signal compression processing.

47. The apparatus for processing a digital audio signal according to claim 46, wherein the signal compression processing includes speech compression or audio compression.

48. The apparatus for processing a digital audio signal according to claim 46, wherein at least one compression parameter is determined based on the auditory context information.

49. The apparatus for processing a digital audio signal according to claim 48, wherein said at least one compression parameter includes compression mode, bitrate, or channel number.

50. The apparatus for processing a digital audio signal according to claim 42, wherein the memory storage comprises a local memory inside the mobile device or a remote memory connected to the mobile device through a wireless channel.

51. The apparatus for processing a digital audio signal according to claim 50, wherein the memory storage is selected based at least in part on the auditory context information.

52. The apparatus for processing a digital audio signal according to claim 37, wherein the means for detecting the end event indicator comprises:

means for selecting at least one context information from the auditory context information;

means for comparing the selected context information with a threshold; and

means for determining if the end event indicator has been detected in response to the comparing.

53. The apparatus for processing a digital audio signal according to claim 37, wherein the means for detecting the end event indicator is based at least in part on non-occurrence of auditory event during pre-determined period of time.

54. The apparatus for processing a digital audio signal according to claim 37, wherein the means for detecting the end event indicator is based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

110. The apparatus according to claim 37, wherein said means for performing the audio logging is configured to perform said audio logging by initiating an audio logging of the digital audio signal, and

wherein said apparatus is within said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls and capable of performing video recording, and

wherein said means for converting is configured to convert said received acoustic signal while the mobile device is neither engaged in any voice call nor performing video recording, and

wherein said mobile device is configured to periodically send a signal to at least one base station and to periodically receive a signal from at least one base station while said means for converting is converting said received acoustic signal.

55. A non-transitory computer-readable medium comprising instructions for processing a digital audio signal for a mobile device, which when executed by a processor cause the processor to:

receive an acoustic signal by at least one microphone;

convert the received acoustic signal into the digital audio signal;

extract auditory context information from the digital audio signal;

automatically detect a start event indicator;

perform an audio logging for the digital audio signal in response to the detecting the start event indicator;

automatically detect an end event indicator; and

end the audio logging in response to the detecting the end event indicator,

wherein the instructions which when executed by a processor cause the processor to detect the start event indicator are configured to cause the processor to;

select at least one context information from the auditory context information;

compare the selected context information with a threshold; and

determine if the start event indicator has been detected in response to the comparing, and

wherein the auditory context information relates to at least one of followings—

audio classification, keyword identification, or speaker identification, and

wherein the auditory context information is based at least in part on non-auditory information.

56. The computer-readable medium according to claim 55, wherein the instructions which when executed by a processor cause the processor to convert the received acoustic signal are configured to cause the processor to:

transform the received acoustic signal into an electrical signal;

sample the electrical signal to obtain the digital audio signal; and

store the digital audio signal into a buffer, wherein the sampling is based on a sampling frequency and a data width.

57. The computer-readable medium according to claim 55, wherein the auditory context information is based at least in part on one of followings—

signal-to-noise ratio, spectral tilt, or zero-crossing rate.

58. The computer-readable medium according to claim 55, wherein the non-auditory information comprises scheduling or calendaring information.

59. The computer-readable medium according to claim 55, wherein the instructions which when executed by a processor cause the processor to detect the start event indicator are configured to detect the start event indicator based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

60. The computer-readable medium according to claim 55, wherein the instructions which when executed by a processor cause the processor to perform the audio logging are configured to cause the processor to:

update at least one parameter related with the converting based at least in part on the auditory context information;

determine if an additional processing is required based at least in part on the auditory context information;

apply the additional processing to the digital audio signal to obtain a processed audio signal, in response to the determining; and

store the processed audio signal into a memory storage.

61. The computer-readable medium according to claim 60, wherein the additional processing includes signal enhancement processing.

62. The computer-readable medium according to claim 61, wherein the signal enhancement processing includes at least one of followings—

acoustic echo cancellation (AEC), receiving voice enhancement (RVE), active noise cancellation (ANC), noise suppression (NS), acoustic gain control (AGC), acoustic volume control (AVC), or acoustic dynamic range control (ADRC).

63. The computer-readable medium according to claim 62, wherein the noise suppression is based on a plurality of microphones.

64. The computer-readable medium according to claim 60, wherein the additional processing includes signal compression processing.

65. The computer-readable medium according to claim 64, wherein the signal compression processing includes speech compression or audio compression.

66. The computer-readable medium according to claim 64, wherein at least one compression parameter is determined based on the auditory context information.

67. The computer-readable medium according to claim 66, wherein said at least one compression parameter includes compression mode, bitrate, or channel number.

68. The computer-readable medium according to claim 60, wherein the memory storage comprises a local memory inside the mobile device or a remote memory connected to the mobile device through a wireless channel.

69. The computer-readable medium according to claim 68, wherein the memory storage is selected based at least in part on the auditory context information.

70. The computer-readable medium according to claim 55, wherein the instructions which when executed by a processor cause the processor to detect the end event indicator are configured to cause the processor to:

select at least one context information from the auditory context information;

compare the selected context information with a threshold; and

determine if the end event indicator has been detected in response to the comparing.

71. The computer-readable medium according to claim 55, wherein the instructions which when executed by a processor cause the processor to detect the end event indicator are configured to detect the end event indicator based at least in part on non-occurrence of auditory event during pre-determined period of time.

72. The computer-readable medium according to claim 55, wherein the instructions which when executed by a processor cause the processor to detect the end event indicator are configured to detect the end event indicator based at least in part on non-auditory information, and wherein the non-auditory information comprises scheduling or calendaring information.

111. The medium according to claim 55, wherein said instructions that cause the processor to perform the audio logging cause the processor to perform said audio logging by initiating an audio logging of the digital audio signal, and

wherein said processor is within said mobile device, and

wherein said mobile device is a mobile phone capable of engaging in voice calls and capable of performing video recording, and

wherein said instructions that cause the processor to convert cause the processor to convert said received acoustic signal while the mobile device is neither engaged in any voice call nor performing video recording, and

wherein said medium includes instructions that cause the processor to cause the mobile device to periodically send a signal to at least one base station and to periodically receive a signal from at least one base station while said instructions that cause the processor to convert are executing.