Decimation synchronization in a microphone
First Claim
1. A method in a microphone, the method comprising:
- decimating data obtained from an electrical signal representative of acoustic energy using a decimator;
determining whether voice activity is present in the electrical signal while buffering the decimated data and while clocking the microphone with an internal clock signal;
receiving an external clock signal after determining the likely presence of voice activity;
applying a decimation factor to the decimator after receiving the external clock signal,the decimation factor based on a specified sampling frequency and a signal having a frequency that is the same as, or substantially the same as, a frequency of the external clock signal.
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Accused Products
Abstract
An external clock signal having a first frequency is received. A division ratio is automatically determined based at least in part upon a second frequency of an internal clock. The second frequency is greater than the first frequency. A decimation factor is automatically determined based at least in part upon the first frequency of the external clock signal, the second frequency of the internal clock signal, and a predetermined desired sampling frequency. The division ratio is applied to the internal clock signal to reduce the first frequency to a reduced third frequency. The decimation factor is applied to the reduced third frequency to provide the predetermined desired sampling frequency. Data is clocked to a buffer using the predetermined desired sampling frequency.
175 Citations
23 Claims
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1. A method in a microphone, the method comprising:
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decimating data obtained from an electrical signal representative of acoustic energy using a decimator; determining whether voice activity is present in the electrical signal while buffering the decimated data and while clocking the microphone with an internal clock signal; receiving an external clock signal after determining the likely presence of voice activity; applying a decimation factor to the decimator after receiving the external clock signal, the decimation factor based on a specified sampling frequency and a signal having a frequency that is the same as, or substantially the same as, a frequency of the external clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A microphone having an internal clock signal, the microphone comprising:
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an analog-to-digital (A/D) converter having an input and an output, the A/D converter configured to convert an electrical signal representative of acoustic energy to digital data; a decimator interconnecting an output of the A/D converter and a buffer, wherein the buffer is configured to buffer decimated data representative of the electrical signal; a voice activity detector (VAD) coupled to the output of the A/D converter, wherein the VAD is configured to determine whether voice activity is likely present in the electrical signal while decimated data is buffered in the buffer, the decimator has a decimation factor based on a specified sampling frequency and a signal having a frequency that is the same as, or substantially the same as, a frequency of an external clock signal present at an external-device interface of the microphone. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A microphone comprising:
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an analog-to-digital (A/D) converter having an input and an output, the A/D converter configured to convert an electrical signal representative of acoustic energy to digital data; a decimator interconnecting an output of the A/D converter and a buffer, wherein the buffer is configured to buffer decimated data representative of the electrical signal; a voice activity detector (VAD) coupled to the output of the A/D converter, wherein the VAD is configured to determine whether voice activity is likely present in the electrical signal while decimated data is buffered in the buffer, the microphone clocked by an internal clock signal during a first time period and the microphone clocked by an external clock signal during a second time period that occurs after the VAD determines that voice activity is likely present, the decimator having a first decimation rate based on a first decimation factor during the first time period, and the decimator having a second decimation rate based on a second decimation factor during the second time period, the second decimation factor based on a specified sampling frequency and a signal having a frequency that is the same as, or substantially the same as, a frequency of an external clock signal present at an external-device interface of the microphone. - View Dependent Claims (21, 22, 23)
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Specification