Vehicle accessory microphone having mechanism for reducing line-induced noise
First Claim
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1. A vehicle accessory comprising:
- a housing for attaching to a vehicle;
a microphone assembly carried by said housing and comprising at least one transducer, the microphone assembly generating an audio signal;
a microphone interface circuit electrically coupled between said transducer and a remote processing circuit located remote from said vehicle accessory, said microphone interface circuit comprising;
a first electrical signal path extending between said transducer and the remote processing circuit, an impedance matching circuit for providing an electrical connection to ground having an impedance matching that of said transducer, and a second electrical signal path extending between said impedance matching circuit and the remote processing circuit adjacent said first electrical signal path, the second electrical signal path providing the remote processing circuit with a reference of the line-induced noise present on said first signal path such that the remote processing circuit may cancel the line-induced noise from the first electrical signal path by subtracting the noise signal received from the second electrical signal path from the signal received from the first electrical signal path.
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Abstract
A microphone assembly includes one or more transducers positioned in one or more housings. A processing circuit is coupled to the transducer for outputting an electrical signal such that the microphone in combination with the processing circuit very effectively cancels noise. The microphone assembly can be employed in a vehicle accessory.
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Citations
11 Claims
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1. A vehicle accessory comprising:
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a housing for attaching to a vehicle;
a microphone assembly carried by said housing and comprising at least one transducer, the microphone assembly generating an audio signal;
a microphone interface circuit electrically coupled between said transducer and a remote processing circuit located remote from said vehicle accessory, said microphone interface circuit comprising;
a first electrical signal path extending between said transducer and the remote processing circuit, an impedance matching circuit for providing an electrical connection to ground having an impedance matching that of said transducer, and a second electrical signal path extending between said impedance matching circuit and the remote processing circuit adjacent said first electrical signal path, the second electrical signal path providing the remote processing circuit with a reference of the line-induced noise present on said first signal path such that the remote processing circuit may cancel the line-induced noise from the first electrical signal path by subtracting the noise signal received from the second electrical signal path from the signal received from the first electrical signal path. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A rearview assembly for a vehicle, comprising:
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a housing for attaching to the vehicle;
a rearview element disposed in said housing for providing a view to the rear of the vehicle;
a microphone assembly carried by said housing and comprising at least one transducer, the microphone assembly generating an audio signal; and
a microphone interface circuit electrically coupled between said transducer and a remote processing circuit located remote from said vehicle accessory, said microphone interface circuit comprising;
a first electrical signal path extending between said transducer and the remote processing circuit, an impedance matching circuit for providing an electrical connection to ground having an impedance matching that of said transducer, and a second electrical signal path extending between said impedance matching circuit and the remote processing circuit adjacent said first electrical signal path, the second electrical signal path providing the remote processing circuit with a reference of the line-induced noise present on said first signal path such that the remote processing circuit may cancel the line-induced noise from the first electrical signal path by subtracting the noise signal received from the second electrical signal path from the signal received from the first electrical signal path. - View Dependent Claims (9, 10)
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11. A method for reducing line-induced noise in a first electrical signal path extending between a microphone transducer and a remote processing circuit, which is located remote from the microphone transducer, the method comprising:
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providing an impedance matching circuit proximate the microphone transducer for providing an electrical connection to ground having an impedance matching that of said transducer;
providing a second electrical signal path extending between the impedance matching circuit and the remote processing circuit adjacent the first electrical signal path, the second electrical signal path providing the remote processing circuit with a reference of the line-induced noise present on the first signal path; and
subtracting a signal received at the remove processing circuit from the second electrical signal path, from a signal received from the first electrical signal path to cancel the line-induced noise from the first electrical signal path.
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Specification