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US 5,398,281 AGranted
Telephone with hands-free operation
AssigneeKabushiki Kaisha Toshiba
InventorsOsamu Kurokawa, Buntaro Sawa, Takuya Kanazumi
Life of this patent
Estimating the term…
Abstract
A hands-free circuit includes a transmit noise level detector which detects a transmit noise level and a first comparator which compares the transmit noise level with a reference level. If the transmit noise level is higher than the reference level, the first comparator provides a control signal indicating a noisy state has been detected. In response to the control signal, a transmit audio level is attenuated. Further the attenuated transmit audio level is compared with a receive audio level by a second comparator which provides an output signal indicating either a transmit-mode or a receive-mode. In response to the output of the second comparator, one audio signal is attenuated.
Claims18
A hands-free circuit for controlling the application of a receive audio signal from a communication path to a signal reproducing means and the application of a transmit audio signal from an audio signal source to the communication path, comprising:
- receive audio level detecting means for detecting a receive audio level of the receive audio signal;
- transmit noise level detecting means for extracting a transmit noise signal out of the transmit audio signal and for detecting a transmit noise level of the transmit noise signal;
- transmit voice level detecting means for extracting a transmit voice signal out of the transmit audio signal and for detecting a transmit voice level of the transmit voice signal;
- first comparing means for comparing the transmit noise level with the transmit voice level and for generating an output signal having a first predetermined state when the transmit noise level is higher than the transmit voice level and having a second predetermined state when the transmit voice level is higher than the transmit noise level;
- first attenuating means for attenuating the transmit voice level and for generating an attenuated transmit voice level as an output level in response to the first predetermined state of the first comparing means output signal and for generating the transmit voice level as an output level in response to the second predetermined state of the first comparing means output signal;
- second comparing means for comparing the output level of the first attenuating means with the receive audio level and for generating an output signal having a first predetermined state when the output level of the first attenuating means is higher than the receive audio level and having a second predetermined state when the receive audio level is higher than the output level of the first attenuating means;
- second attenuating means for attenuating the receive audio signal applied to the signal reproducing means in response to the first predetermined state of the second comparing means output signal;
- and
- third attenuating means for attenuating the transmit audio signal applied to the communication path in response to the second predetermined state of the second comparing means output signal.
6 more elements
A hands-free circuit for controlling the application of a receive audio signal from a communication path to a signal reproducing means and the application of a transmit audio signal from an audio signal source to the communication path, comprising:
- receive audio level detecting means for detecting a receive audio level of the receive audio signal;
- transmit noise level detecting means for extracting a transmit noise signal out of the transmit audio signal and for detecting a transmit noise level of the transmit noise signal;
- transmit voice level detecting means for extracting a transmit voice signal out of the transmit audio signal and for detecting a transmit voice level of the transmit voice signal;
- first comparing means for comparing the transmit noise level with the transmit voice level and for generating an output signal having a first predetermined state when the transmit noise level is higher than the transmit voice level and having a second predetermined state when the transmit voice level is higher than the transmit noise level;
- amplifying means for amplifying the receive audio level and for generating an amplified receive audio level as an output level in response to the first predetermined state of the first comparing means output signal and for generating the receive audio level as an output level in response to the second predetermined state of the first comparing means output signal;
- second comparing means for comparing the transmit voice level with the output level of the amplifying means and for generating an output signal having a first predetermined state when the transmit voice level is higher than the output level of the amplifying means and having a second predetermined state when the output level of the amplifying means is higher than the transmit voice level;
- first attenuating means for attenuating the receive audio signal to the signal reproducing means in response to the first predetermined state of the second comparing means output signal;
- and
- second attenuating means for attenuating the transmit audio signal to the communication path in response to the second predetermined state of the second comparing means output signal.
6 more elements
A hands-free circuit for controlling the application of a receive audio signal from a communication path to a signal reproducing means and the application of a transmit audio signal from an audio signal source to the communication path, comprising:
- transmit noise level detecting means for extracting a transmit noise signal out of the transmit audio signal and for detecting a transmit noise level of the transmit noise signal;
- transmit voice level detecting means for extracting a transmit voice signal out of the transmit audio signal and for detecting a transmit voice level of the transmit voice signal;
- first comparing means for comparing the transmit noise level with the transmit voice level and for generating an output signal having a first predetermined state when the transmit noise level is higher than the transmit voice level and having a second predetermined state when the transmit voice level is higher than the transmit noise level;
- receive audio level detecting means for amplifying the receive audio signal by a first amplification factor in response to the first predetermined state of the first comparing means output signal and by a second amplification factor less than the first amplification factor in response to the second predetermined state of the first comparing means output signal and means for detecting a receive audio level of an amplified receive audio signal;
- second comparing means for comparing the transmit voice level with the receive audio level output by the receive audio level detecting means and for generating an output signal having a first predetermined state when the transmit voice level is higher than the receive audio level output by the receive audio level detecting means and having a second predetermined state when the receive audio level output by the receive audio level detecting means is higher than the transmit voice level;
- first attenuating means for attenuating the receive audio signal to the signal reproducing means in response to the first predetermined state of the second comparing means output signal;
- and
- second attenuating means for attenuating the transmit audio signal to the communication path in response to the second predetermined state of the second comparing means output signal.
5 more elements
A hands-free circuit for controlling the application of a receive audio signal from a communication path to a signal reproducing means and the application of a transmit audio signal from an audio signal source to the communication path, comprising:
- receive audio level detecting means for detecting a receive audio level of the receive audio signal;
- transmit noise level detecting means for extracting a transmit noise signal out of the transmit audio signal and for detecting a transmit noise level of the transmit noise signal;
- transmit voice level detecting means for extracting a transmit voice signal out of the transmit audio signal and for detecting a transmit voice level of the transmit voice signal;
- first comparing means for comparing the transmit noise level with the transmit voice level and for generating an output signal having a predetermined state when the transmit noise level is higher than the transmit voice level;
- second comparing means for comparing the transmit voice level with the receive audio level and for generating an output signal in response to the predetermined state of the first comparing means output signal;
- and
- controlling means, responsive to the output signal of the second comparing means, for controlling the receive audio signal and the transmit audio signal.
4 more elements
A hands-free circuit for controlling the application of a receive audio signal from a communication path to a signal reproducing means and the application of a transmit audio signal from an audio signal source to the communication path, comprising:
- receive audio level detecting means for detecting a receive audio level of the receive audio signal;
- transmit noise level detecting means for extracting a transmit noise signal out of the transmit audio signal and for detecting a transmit noise level of the transmit noise signal;
- transmit audio level detecting means for detecting a transmit audio level of the transmit audio signal;
- first comparing means for comparing the transmit noise level with a reference signal and for generating an output signal having a first predetermined state when the transmit noise level is higher than the reference signal and having a second predetermined state when the reference signal is higher than the transmit noise level;
- first attenuating means for attenuating the transmit audio level and for generating the attenuated transmit audio level as an output level in response to the first predetermined state of the first comparing means output signal and for generating the transmit audio level as an output level in response to the second predetermined state of the first comparing means output signal;
- second comparing means for comparing the output level of the first attenuating means with the receive audio level and for generating an output signal having a first predetermined state when the output level of the first attenuating means is higher than the receive audio level and having a second predetermined state when the receive audio level is higher than the output level of the first attenuating means;
- second attenuating means for attenuating the receive audio signal to the signal reproducing means in response to the first predetermined state of the second comparing means output signal;
- and
- third attenuating means for attenuating the transmit audio signal to the communication path in response to the second predetermined state of the second comparing means output signal.
6 more elements
A hands-free circuit for controlling the application of a receive audio signal from a communication path to a signal reproducing means and the application of a transmit audio signal from an audio signal source to the communication path, comprising:
- receive audio level detecting means for detecting a receive audio level of the receive audio signal;
- transmit noise level detecting means for extracting a transmit noise signal out of the transmit audio signal, for detecting a transmit noise level of the transmit noise signal, and for detecting a noisy state when the transmit noise level is higher than a reference level;
- adjusting means for adjusting the bias voltage of the receive audio level detecting means, thereby altering the receive audio level when the noisy state is detected by the transmit noise detecting means;
- and
- controlling means, responsive to the adjusting means, for controlling the receive audio signal and the transmit audio signal.
2 more elements
A hands-free circuit for controlling the application of received audio signals from a communication path to a signal reproducing apparatus and the application of transmit audio signals from an audio signal source to the communication path, comprising:
- receive audio level detecting means for detecting a receive audio level of the received audio signals;
- transmit noise level detecting means for extracting transmit noise signals out of the transmit audio signals and for detecting a transmit noise level of the transmit noise signals;
- transmit voice level detecting means for extracting transmit voice signals out of the transmit audio signals and for detecting a transmit voice level of the transmit voice signals;
- comparing means for comparing the receive audio level, the transmit noise level, and the transmit voice level, and for outputting a signal when the receive audio level is more than a first predetermined level, the transmit noise level is more than a second predetermined level, and the transmit voice level is less than a third predetermined level;
- and
- attenuating means for attenuating the transmit audio signals to the communication path in response to the signal outputted from the comparing means.
3 more elements
Dependencies are inferred from the claim text.