Microphone noise rejection system
First Claim
1. A method of rejecting repetitive noise introduced into an information signal, comprising the steps of:
- receiving from a first source a repetitive noise signal;
identifying a characteristic frequency of the repetitive noise signal received from the first source;
receiving from a second source that is distinct from the first source an information signal having an information component and a repetitive noise component originating from the first source;
delaying the information signal for a period of time based on the identified characteristic frequency of the repetitive noise signal to form a phase-shifted or delayed information signal; and
processing the delayed information signal with a non-delayed information signal received from the second source to form a processed information signal in which the information component is substantial and the noise component is negligible.
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Accused Products
Abstract
An apparatus and method removes repetitive background noise from an information signal originating from a first source, such as a microphone. The noise originates from a second source, such as a siren, and is picked up by the first source along with the information. The noise signal has a characteristic frequency and associated period. The information signal is delayed for a selected period of time based on the characteristic frequency of the repetitive noise signal and forms a phase-shifted or delayed information signal. The delayed information signal is processed with a substantially non-delayed information signal and forms a processed information signal in which the information component is substantial and the noise component is negligible.
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Citations
26 Claims
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1. A method of rejecting repetitive noise introduced into an information signal, comprising the steps of:
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receiving from a first source a repetitive noise signal; identifying a characteristic frequency of the repetitive noise signal received from the first source; receiving from a second source that is distinct from the first source an information signal having an information component and a repetitive noise component originating from the first source; delaying the information signal for a period of time based on the identified characteristic frequency of the repetitive noise signal to form a phase-shifted or delayed information signal; and processing the delayed information signal with a non-delayed information signal received from the second source to form a processed information signal in which the information component is substantial and the noise component is negligible. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for removing repetitive background noise from an information signal comprising:
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a first input interface for receiving a repetitive noise signal and identifying a characteristic frequency of a repetitive noise signal from a repetitive noise generator; a second input interface distinct from the first input interface for receiving an information signal having an information component and a repetitive noise component originating from the repetitive noise generator; means for delaying the information signal for a period of time based on the characteristic frequency of the repetitive noise signal to form a phase-shifted or delayed information signal; and means for processing the delayed information signal with a non-delayed information signal received from the second input interface to form a processed information signal in which the information component is substantial and the noise component is negligible. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method of rejecting repetitive noise from an information signal comprising the steps of:
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receiving from a source an information signal containing a repetitive noise component; identifying the period of the repetitive noise component; delaying the information signal a length of time in accordance with the identified period of the repetitive noise component to produce a delayed information signal containing the repetitive noise component; and processing (1) a non-delayed information signal received from said source and containing the repetitive noise component and (2) the delayed information signal containing the repetitive noise component to produce a processed information signal from which the repetitive noise component is substantially eliminated. - View Dependent Claims (19, 20)
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21. An apparatus for removing repetitive background noise from an information signal comprising:
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means for receiving from a source an information signal containing a repetitive noise component; means for identifying the period of the repetitive noise component; means for delaying the information signal a length of time in accordance with the identified period of the repetitive noise component to produce a delayed information signal containing the repetitive noise component; and means for processing (1) a non-delayed information signal received from said source and containing the repetitive noise component and (2) the delayed information signal containing the repetitive noise component to produce a processed information signal from which the repetitive noise component is substantially eliminated. - View Dependent Claims (22, 23)
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24. A method of rejecting repetitive noise introduced into an information signal, comprising the steps of:
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identifying a characteristic frequency of a repetitive noise signal from a first source; receiving from a second source that is distinct from the first source an information signal having an information component and a repetitive noise component originating from the first source; delaying the information signal for a selected period of time based on the identified characteristic frequency of the repetitive noise signal to form a phase-shifted or delayed information signal; processing the delayed information signal with the information signal which has not been delayed to form a processed information signal in which the information component is substantial and the noise component is negligible, and wherein the steps of identifying and delaying include; generating a clock signal having a frequency that is a predetermined multiple of the characteristic frequency of the repetitive noise signal; supplying the information signal to an input of a bucket brigade device having a predetermined number of stages between an input and output; and advancing portions of the information signal stage-by-stage through the bucket brigade device, the frequency of the clock signal determining the length of time each portion of the information signal remains in a stage, and the total time interval for a portion of the information signal to pass through the bucket brigade device corresponding to the desired delay for generating the delayed information signal. - View Dependent Claims (25)
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26. An apparatus for removing repetitive background noise from an information signal comprising:
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a first input interface for identifying a characteristic frequency of a repetitive noise signal from a repetitive noise generator; a second input interface distinct from the first input interface for receiving an information signal having an information component and a repetitive noise component originating from the generator; means for delaying the information signal for a selected period of time based on the characteristic frequency of the repetitive noise signal to form a phase-shifted or delayed information signal, the delaying means including; a phase-locked loop having first and second channel inputs and an output, the first input being connected with the first input interface for receiving the repetitive noise signal; a counter/divide circuit having an input coupled to the output of the phase-locked loop and an output coupled to the second channel input of the phase-locked loop such that the phase-locked loop generates a clock signal at its output having a frequency that is a predetermined multiple of the characteristic frequency of the repetitive noise signal; a clock driver having an input coupled to the output of the phase-locked loop for generating a control signal; and a bucket brigade device having a predetermined number of stages each storing portions of the information signal, the bucket brigade device including an input terminal for receiving the information signal, an output terminal for supplying a delayed information signal, and a control terminal for receiving the control signal from the phase-locked loop which instructs the bucket brigade device to advance a portion of the information signal by at least one stage, a total time interval for a portion of the information signal to pass through the bucket brigade device being equal to the desired delay to the information signal; and means for processing the delayed information signal with a non-delayed information signal to form a processed information signal in which the information component is substantial and the noise component is negligible.
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Specification