Loudspeaking communication terminal apparatus and method of operation

Claim 2

In a loudspeaking communication terminal apparatus for connection to a transmission facility and having a transmit channel including a microphone, a receive channel including a loudspeaker, and a control means for activating the transmit channel to provide a transmit mode of operation and for activating the receive channel to provide a receive mode of operation, an improvement in the control means comprising: means, responsive to signals from the microphone, having substantially monotonous amplitude envelope characteristics and substantially non-responsive to other signals, for generating a noise reference signal, representative of sounds of a substantially steady nature in the operating environment; means, responsive to the activating of the transmit channel, for regulating the amplification thereof in inverse relation to the amplitude of the noise reference signal, whereby the natural tendency of a user to speak more loudly in a noisy environment, characterized by substantially monotonous noise, than in a quieter environment, is compensated to present a more constant signal level to the transmission facility.

Claim 3

In a voice controlled loudspeaking communication terminal apparatus for connection to a transmission facility and having a transmit channel including a microphone, a receive channel including a loudspeaker, and a control means for activating the transmit channel to provide a transmit mode of operation and for activating the receive channel to provide a receive mode of operation, an improvement in the control means comprising: means, responsive to signals from the microphone, having a substantially monotonous amplitude envelope characteristic and substantially non-responsive to other signals, for generating a noise reference signal, representative of sounds of a substantially steady nature in the operating environment; means, responsive to the activating of the transmit channel for regulating the amplification thereof in inverse relation to the amplitude of the noise reference signal, whereby the natural tendency of a user to speak more loudly in a noisy environment, characterized by substantially monotonous noise, than in a quieter environment, is compensated to present a more constant signal level to the transmission facility; means for comparing signals received by the transmit channel with a threshold level as determined by the noise reference signal, whereby the presence of voice speech-like envelope signals received by the transmit channel and in excess of the threshold level is indicated, said indication functioning to urge the apparatus into the transmit mode of operation in the absence of significant signals from the transmission facility; means for augmenting the threshold level during operation in the receive mode and for a time thereafter whereby the comparing means is substantially prevented from providing said indication in response to the ends of syllables and words from the receive channel which have been acoustically delayed by the operating environmenT.

Claim 4

In a voice controlled loudspeaking communication terminal apparatus for connection to a transmission facility and having a transmit channel including a microphone, a receive channel including a loudspeaker, and a control means for activating the transmit channel to provide a transmit mode of operation and for activating the receive channel to provide a receive mode of operation, an improvement in the control means comprising: means, responsive to signals from the microphone, having a substantially monotonous amplitude envelope characteristic and substantially non-responsive to other signals, for generating a noise reference signal, representative of sounds of a substantially steady nature in the operating environment; means, responsive to the activating of the transmit channel for regulating the amplification thereof in inverse relation to the amplitude of the noise reference signal, whereby the natural tendency of a user to speak more loudly in a noisy environment, characterized by substantially monotonous noise, than in a quieter environment, is compensated to present a more constant signal level to the transmission facility; means for comparing signals received by the transmit channel with a threshold level as determined by the noise reference signal, whereby the presence of voice speech-like envelope signals received by the transmit channel and in excess of the threshold level is indicated, said indication functioning to urge the apparatus into the transmit mode of operation in the absence of significant signals from the transmission facility; means for augmenting the threshold level during operation in the receive mode and for a time thereafter whereby the comparing means is substantially prevented from providing said indication in response to the ends of syllables and words from the receive channel which have been acoustically delayed by the operating environmenT.

Claim 5

In a voice switched loudspeaking communications terminal apparatus capable of being operated in transmit, idle and receive modes and having: a terminal channel and a microphone connected to the input thereof, a receive channel, the channels including a variable transmit attenuator and a variable receive attenuator respectively, said attenuators controllable so that the product of their respective insertion losses is substantially constant; and a coupling means, for coupling signals from the output of the tranmit channel to a transmission facility and for coupling signals from the transmission facility to the receive channel; a control circuit comprising; means responsive to signals at the input of the receive channel, having substantially monotonous amplitude envelope characteristics, as distinguished in comparison with the impulse amplitude envelope characteristics of voice speech-like signals, for generating a noise signal corresponding only to substantially monotonous amplitude sounds received by the transmit channel; means for generating a reference signal having a first predetermined potential corresponding to operation in the receive mode, when the signal from the coupling means is effectively greater than the signal from the transmit attenuator; the reference signal having a second predetermined potential corresponding to operation in the transmit mode, when the signal from the transmit attenuator is effectively greater than the signal from the coupling means; the reference voltage having a third predetermined potential intermediate the first and second potentials corresponding to operation in the idle mode, when the signal from the transmit attenuator is effectively about the same magnitude as the signal from the coupling means and substantially corresponds to the noise signal; means for generating a control signal to control the insertion losses of the attenuators, the control signal generating means responsive to the reference signal and to the noise signal, the control signal being proportional to the reference signal in one case where the potential of the reference signal is said first potential, the control signal otherwise being restrained from being proportional to the reference signal by an amount derived as a function of said noise signal, so that when the terminal apparatus is operating in the transmit or idle modes, the overall gain in the transmit channel is inversely tempered by the noise signal.

Claim 6

In a voice switched loudspeaking communications terminal apparatus capable of being operated in transmit, idle and receive modes and having: a terminal channel and a microphone connected to the input thereof, a receive channel, the channels including a variable transmit attenuator and a variable receive attenuator respectively, said attenuators controllable so that the product of their respective insertion losses is substantially constant; and a coupling means, for coupling signals from the output of the tranmit channel to a transmission facility and for coupling signals from the transmission facility to the receive channel; a control circuit comprising; means responsive to signals at the input of the receive channel, having substantially monotonous amplitude envelope characteristics, as distinguished in comparison with the impulse amplitude envelope characteristics of voice speech-like signals, for generating a noise signal corresponding only to substantially monotonous amplitude sounds received by the transmit channel; means for generating a reference signal having a first predetermined potential corresponding to operation in the receive mode, when the signal from the coupling means is effectively greater than the signal from the transmit attenuator; the reference signal having a second predetermined potential corresponding to operation in the transmit mode, when the signal from the transmit attenuator is effectively greater than the signal from the coupling means; the reference voltage having a third predetermined potential intermediate the first and second potentials corresponding to operation in the idle mode, when the signal from the transmit attenuator is effectively about the same magnitude as the signal from the coupling means and substantially corresponds to the noise signal; means for generating a control signal to control the insertion losses of the attenuators, the control signal generating means responsive to the reference signal and to the noise signal, the control signal being proportional to the reference signal in one case where the potential of the reference signal is said first potential, the control signal otherwise being restrained from being proportional to the reference signal by an amount derived as a function of said noise signal, so that when the terminal apparatus is operating in the transmit or idle modes, the overall gain in the transmit channel is inversely tempered by the noise signal.

Claim 7

An apparatus as defined in claim 3 in which the means for generating the control signal comprises: means for amplifying the reference signal; means for generating a direct current substantially proportional to the noise signal; feedback means for regulating the gain of the amplifying means, the feedback means responsive to the direct current whereby in the absence of the direct current the amplifying means has a predetermined amount of gain and in the presence of the direct current the amplifying means has a gain effectively reduced in inverse relation to the direct current; direct current switching means for connecting the direct current from the direct current generating means to the feedback means when the reference voltage is at said second or third potentials.

Claim 8

An apparatus as defined in claim 3 in which the first and second potentials are determined by an upper reference voltage and a lower reference voltage, respectively, supplied to the reference signal generating means via upper and lower reference voltage terminals respectively, the reference signal generating means further comprising: first, second and third resistance means, the third resistance means connected between the lower reference voltage terminal and the first and second resistance means, the reference signal being obtained from the first resistance means, first control means for permitting current to flow from the upper reference voltage terminal via the first and third resistance means, to the lower reference voltage terminal when tHe signal from the coupling means is effectively greater than the signal from the transmit attenuator, second control means for permitting current to flow from the upper reference voltage terminal via the second and third resistance means, to the lower reference voltage terminal essentially when there are substantially only monotonous amplitude signals at the input of the transmit attenuator and also essentially when the signal from the coupling means is effectively greater than the signal from the transmit attenuator.

Claim 9

An apparatus as defined in claim 3 in which the control circuit further comprises: comparing means for generating a noise/speech signal, as an indication of whether or not the signal from the output of the transmit attenuator substantially corresponds to the noise signal, the comparing means responsive to the noise signal and to acoustic signals in total received by the transmit channel, whereby when the acoustic signals are less than a level as determined by the noise signal, said correspondence with the signals at the output of the transmit attenuator is indicated; means for augmenting the level determined by the noise signal during operation in the receive mode, and for a time thereafter so that the comparing means is substantially prevented from being responsive to acoustic voice speech-like signals from the receive channel somewhat delayed by room reverberation and therefore tending to appear as similar to speech from the user.

Claim 10

In a method of operating a loudspeaking communication terminal apparatus including the steps of; activating a transmit channel to pass signals from a microphone to a transmission facility, to provide a transmit mode of operation and, activating a receive channel to pass signals from the transmission facility to a loudspeaker, to provide a receive mode of operation, an improvement in the method of operating, comprising the steps of: a. generating a noise reference signal representing sounds received by the microphone which are of a substantially monotonous nature; and when the transmit channel is activated, b. regulating the amplification of the transmit channel, in inverse relation to the noise reference signal, whereby the natural tendency of a user to speak more loudly in an environment characterized by the presence of substantially steady noise is compensated for, to present a more constant signal level to the transmission facility.

Claim 11

In a method of operating a loudspeaking communication terminal apparatus including the steps of; activating a transmit channel to pass signals from a microphone to a transmission facility, to provide a transmit mode of operation and, activating a receive channel to pass signals from the transmission facility to a loudspeaker, to provide a receive mode of operation, an improvement in the method of operating, comprising the steps of: a. generating a noise reference signal representing sounds received by the microphone which are of a substantially monotonous nature; and when the transmit channel is activated, b. regulating the amplification of the transmit channel, in inverse relation to the noise reference signal, whereby the natural tendency of a user to speak more loudly in an environment characterized by the presence of substantially steady noise is compensated for, to present a more constant signal level to the transmission facility.

Claim 12

In a method of operating a voice controlled loudspeaking communication terminal apparatus including a receive channel connected to a loudspeaker, a microphone connected to a transmit channel, the product of the amplifications of the receive and transmit channels being substantially constant, and a control means for operating the terminal apparatus in transmit, receive, and idle modes of operation, an improvement in the method of operation comprising the steps of: a. generating a noise reference signal representing sounds received by the microphone which are of a substantially monotonous nature; b. regulating the amplification of the transmit channel when in the transmit and idle modes of operation, in inverse relation to the noise reference signal; c. comparing signals received by the transmit channel with a threshold level as determined by the noise reference signal, whereby the presence of voice speech-like envelope signals received by the transmit channel and in excess of the threshold level is indicated, said indication functioning to urge the apparatus into the transmit mode of operation in the absence of significant signals from the transmission facility; d. augmenting the threshold level during operation in the receive mode and for a time thereafter whereby said indication is substantially prevented in response to the ends of syllables and words from the loudspeaker, which have been acoustically delayed by the operating environment.

Claim 13

In a method of operating a voice controlled loudspeaking communication terminal apparatus including a receive channel connected to a loudspeaker, a microphone connected to a transmit channel, the product of the amplifications of the receive and transmit channels being substantially constant, and a control means for operating the terminal apparatus in transmit, receive, and idle modes of operation, an improvement in the method of operation comprising the steps of: a. generating a noise reference signal representing sounds received by the microphone which are of a substantially monotonous nature; b. regulating the amplification of the transmit channel when in the transmit and idle modes of operation, in inverse relation to the noise reference signal; c. comparing signals received by the transmit channel with a threshold level as determined by the noise reference signal, whereby the presence of voice speech-like envelope signals received by the transmit channel and in excess of the threshold level is indicated, said indication functioning to urge the apparatus into the transmit mode of operation in the absence of significant signals from the transmission facility; d. augmenting the threshold level during operation in the receive mode and for a time thereafter whereby said indication is substantially prevented in response to the ends of syllables and words from the loudspeaker, which have been acoustically delayed by the operating environment.

Claim 14

An apparatus as defined in claim 3 in which the reference signal generating means includes meaNs for momentarily augmenting the signal received by the reference signal generating means from the coupling means, at the moment the signal from the coupling means becomes effectively greater than the signal from the transmit attenuator, to prevent a rapid return from said first predetermined potential to said second predetermined potential, in the case where the first speech syllable from a party at the remote end of the transmission facility is of an abnormally low level.