JPH0480580B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a loudspeaker telephone device, and more particularly to a loudspeaker telephone device that appropriately interrupts the receiving state.

[Technical Background of the Invention] FIG. 1 is a block diagram showing an example of a conventional loudspeaker telephone device. The audio signal captured by the microphone 1 is amplified by a transmitting amplifier AMP2, attenuated by a transmitting loss circuit TVL3, and then sent to a line 5 through a hybrid circuit HYB4. On the other hand, the voice signal transmitted through the line 5 passes through the hybrid circuit 4 to the reception loss circuit.
The signal reaches RVL6, is attenuated there, is amplified by receiver amplifier AMP7, and is sent out from speaker 8.

A transmission signal on the output side of the transmission amplifier 2 is input to a transmission detection circuit TT9. Further, the transmission signal on the output side of the reception loss circuit 6 is input to the reception detection circuit RT10. The output signals of the transmitting call detection circuit 9 and the receiving call detecting circuit 10 are transmitted to the audio switch control circuit, respectively.
Input to VS11. Further, the voice switch control circuit 11 is inputted with the voice threshold level output from the voice threshold level generator 12, and furthermore, the control signal outputted by the voice switch control circuit 11 is transmitted to the voice loss circuit 3 and the voice loss loss circuit 3. It is input to circuit 6. The audio switch control circuit 11 compares the transmission level from the transmission detection circuit 9 and the reception level from the reception detection circuit 10, and adjusts the respective losses of the transmission loss circuit 3 and the reception loss circuit 6 according to the comparison result. The amount is controlled to increase or decrease reciprocally.

Note that the microphone 1, the transmitting amplifier 2, the transmitting loss circuit 3, the hybrid circuit 4, and the line 5 form a transmitting path, and the line 5, the hybrid circuit 4,
Receiving loss circuit 6, receiving amplifier 7 and speaker 8
forms the receiving channel. The transmitting threshold level generated by the transmitting threshold level generator 12 refers to the transmitting threshold level generated by the microphone 1 when the circuit interrupts from the receiving state to the transmitting state when there is no receiving signal from the line 5.
This indicates the input level.

Next, the operation of the above conventional example will be explained. First, when no transmission is being performed, the input level of the microphone 1 is lower than the transmission threshold level, so the transmission detection level output by the transmission detection circuit 9 is equal to the reception detection level output by the reception detection circuit 10. , the audio switch control circuit 11 controls the transmission loss circuit 3 to increase the loss amount and the reception loss circuit 6 to decrease the loss amount, and the circuit enters the reception state. In this state, when voice is input from the microphone 1 and the sending detection level of the sending detection circuit 9 increases and becomes higher than the receiving detection level of the receiving detection circuit 10, the audio switch control circuit 11 activates the sending speech loss circuit 3. Control is performed to reduce the amount of loss in the receiving loss circuit 6 and increase the amount of loss in the receiving loss circuit 6, and the circuit is brought into a transmitting state.

FIG. 2 is a diagram showing the interrupt characteristics in the conventional example shown in FIG. 1, in which the vertical axis shows the sending level input from the microphone 1, and the horizontal axis shows the receiving level input from the line 5. Further, symbol A indicates a transmitting interrupt curve, symbol B indicates a receiving interrupt curve, and N
indicates the noise level, and T indicates the transmission threshold level. The above operation will be explained with reference to FIG. 2. In the conventional device shown in FIG. 1, when there is a transmitting level equal to or higher than the transmitting interrupt curve A, the transmitting state is entered, and when there is a receiving level equal to or higher than the receiving interrupt curve B, the receiving state is entered. to move to. In this example, the interrupt level is set according to the audio level of each of the transmitting and receiving calls, and if there is no noise, a natural loudspeaker call can be carried out.

Next, the operation when there is noise will be explained.
When the noise level N is lower than the transmission threshold level T,
When no voice is input from the microphone 1, the device is always in a receiving state, as in the case where there is no noise as described above. In such a state, when an audio signal higher than the level shown by the transmitting interrupt curve A in FIG. 2 is input, the audio switch control circuit 11 reduces the amount of loss in the transmitting loss circuit 3, and 6 becomes large and the circuit enters a transmitting state. Next, when a reception signal of a level equal to or higher than the reception interrupt curve B is input from the line 5, the device enters the reception state. In this way, for the noise level N below the transmitting threshold level T,
Good call operation can be ensured even with the conventional circuit configuration.

[Problems with background technology]

By the way, when the noise level N is higher than the transmitting threshold level T as shown in FIG. The volume becomes large enough that the device is always in a transmitting state. In order to enter the receiving state from such a transmitting state, the receiving level input from the line 5 must be equal to or higher than the level indicated by point P in the figure, and if there is no input receiving level higher than this level, It becomes impossible to interrupt the receiving state. Such a situation occurs when the reception level input from the line 5 is low, such as during a long-distance call, resulting in the inconvenience of deteriorating call performance. Therefore, in order to avoid this inconvenience, in the conventional circuit shown in FIG. 1, by raising the transmitting threshold level T, the interrupt characteristics are adjusted so that the transition to the receiving state can be easily made even when the noise level N is large. It's improving. However, if this is done, in the case of a call in a quiet place where the noise is lower than the transmitting threshold level T, the transmitting threshold level T is high, so it is difficult to enter the transmitting state.

[Purpose of the invention]

In view of the above drawbacks, an object of the present invention is to easily transition from a transmitting state to a receiving state even under high noise conditions;
Another object of the present invention is to provide a loudspeaker telephone device that does not make it difficult to shift from a receiving state to a transmitting state even under low noise conditions.

[Summary of the invention]

In the present invention, there is provided a transmitting path for transmitting an inputted transmitting signal to a line via a transmitting loss circuit, a receiving path for outputting a receiving signal coming from the line from a speaker via a receiving loss circuit, A first step that compares the level of the transmitting signal and the level of the receiving signal, and controls the transmitting loss circuit and the receiving loss circuit to place the device in either the transmitting state or the receiving state based on the comparison result. a noise detection circuit that detects a noise level from the inputted transmission signal; and when the noise level detected by the noise detection circuit is higher than a preset noise level; A second control unit controls the transmission loss circuit to increase the loss amount and the reception loss circuit to decrease the loss amount.
The above object is achieved by providing the following control circuit.

[Embodiments of the invention]

Hereinafter, an embodiment of the loudspeaker telephone device of the present invention will be described with reference to the drawings, with the same parts as those of the conventional example being given the same reference numerals. FIG. 3 is a block diagram showing one embodiment of the loudspeaker telephone device of the present invention. The audio signal captured by the microphone 1 is amplified by the transmitting amplifier AMP2, and then sent to the second transmitting loss circuit TVL2,1.
3 and the first transmission loss circuit TVL1, 14, and is further sent to the line 5 through the hybrid circuit HYB4. On the other hand, the audio signal transmitted through the line 5 passes through the hybrid circuit 4 to the first reception loss circuit RVL1, 15 and the second reception loss circuit RVL2, 16, where it is attenuated and then sent to the reception amplifier. 7 and sent out from the speaker 8.

A transmission signal on the output side of the transmission amplifier 2 is input to a transmission detection circuit TT9. Further, the reception signal on the output side of the second reception loss circuit 16 is output from the reception detection circuit RT.
10 is entered. These call detection circuits 9
The detection level of the receiving detection circuit 10 is input to the audio switch control circuit 11, respectively. This audio switch control circuit 11 is inputted with the transmission threshold level generated by the transmission threshold level generator TL12, and the control signal outputted from this audio switch control circuit 11 is transmitted to the first and second transmission loss circuits. 1
4, 13, first and second reception loss circuits 5, 16,
Loss amount control circuit CMP17 and reception detection circuit 10
has been entered. The transmission level detected by the transmission detection circuit 9 is determined by the loss amount control circuit 17 and the noise detection circuit.
The noise level input to the NT 18 and detected by the noise detection circuit 18 is input to another input of the loss amount control circuit 17. This loss amount control circuit 17 includes:
Further, the set noise level from the noise level setter NL19 is input. The control signal output by the loss amount control circuit 17 is transmitted to the second transmission loss circuit 13 and the second transmission loss circuit 13.
The signal is input to the reception detection circuit 16 of the receiver. In addition, the loss amount control circuit 17 compares the above-mentioned transmission level and the noise level, and based on the result, the second transmission loss amount control circuit 1
The noise detection circuit
When the noise level output by the NT 18 is equal to or higher than the set noise level, control is performed such that the loss amount of the second transmission loss circuit 13 is always large and the loss amount of the second reception loss circuit 16 is small. It is.

Next, the operation of this embodiment will be explained. When there is no noise or voice, the voice input level of the microphone 1 is below the transmitting threshold level, so the voice receiving detection circuit 10 is input to the voice switch control circuit 11.
is controlled so that the output level of is greater than the output level of the transmitting speech detection circuit 9, the loss amount of the first transmitting speech loss circuit 14 is large, and the loss amount of the first receiving speech loss circuit 15 is small, The circuit goes into a listening state. In such a receiving state, the voice switch control circuit 11 causes the loss amount of the second transmission loss circuit 13 to be large;
The loss amount of the reception loss circuit 16 is controlled to be small.

Here, the sum of the loss amount of the first transmission loss circuit 14 and the loss amount of the second transmission loss circuit 13 is equal to the loss amount of the transmission loss circuit 3 of the conventional circuit, and the sum of the loss amount of the first reception loss circuit 14 is equal to the loss amount of the transmission loss circuit 3 of the conventional circuit. The sum of the loss amount of 15 and the loss amount of the second reception loss circuit 16 is set equal to the loss amount of the reception loss circuit 6 in the conventional example. With this setting, the input from the microphone 1 is transmitted to the transmitting amplifier 2 and the second transmitting loss circuit 1.
3. Passes through the first transmitting loss circuit 14, the hybrid circuit 4, and the second receiving loss circuit 15.
the transmitting level output to the receiving loss circuit 16;
In the conventional example, the transmitting level that goes around in the same way and is output to the receiving loss circuit is the same level,
Since the transmitting signal passes through the hybrid circuit 4 and goes around the receiving channel, it is possible to prevent a malfunction in which the transmitting signal is regarded as a receiving signal.

When sound is input to the microphone 1 in FIG. 3 in the absence of noise, the sound switch control circuit 11
Since the transmission detection level of the transmission detection circuit 9 that is input to the transmission transmission detection circuit 9 becomes larger than the reception detection level of the reception detection circuit 10, each loss amount of the first transmission loss circuit 14 and the second transmission loss circuit 13 is reduced. is small, and the losses of the first reception loss circuit 15 and the second reception loss circuit 16 are controlled to be large, and the circuits enter the transmission state. In this manner, the operation of this embodiment in the absence of noise is the same as that of the conventional example shown in FIG.

Next, there is only noise and its level exceeds the transmitting threshold level, the loss amount of the first transmitting loss circuit 14 is small and the loss amount of the first receiving loss circuit 15 is large, and the device transmits. When in the talking state, the noise level detected by the noise detection circuit 18 becomes higher than the voice level detected by the transmission detection circuit 9, so the loss amount control circuit 17
The loss amount of the second receiving loss circuit 16 is controlled to be large, and the loss amount of the second reception loss circuit 16 is small. At this time, the detection gain of the reception detection circuit 10 is controlled to be increased by the control signal of the audio switch control circuit 11. Note that in a state where the detection gain of the receiving voice detection circuit 10 increases, the second transmitting voice loss circuit 13 and the second voice receiving loss circuit 16 are preferentially controlled by the loss amount control circuit 17 and the voice switch control circuit 11 is controlled. become uncontrolled. Therefore, the loss amount of the first reception loss circuit 15 is large, but the loss amount of the second reception loss circuit 16 is small, and the detection gain of the reception detection circuit 10 is increased. , line 5, hybrid circuit 4, first reception loss circuit 1
The output level of the received voice detection circuit 10 for the received voice signal input through 5 and the second received voice loss circuit 16 is equal to the increase in the detection gain and the decrease in the loss amount of the second received voice loss circuit 16. growing. In other words, the present device is more likely to enter the receiving state by the increase in the detection gain of the receiving signal detecting circuit 10 and the decrease in the loss amount of the second receiving loss circuit 16.

FIG. 4 is an interrupt characteristic diagram of the loudspeaker telephone device of this embodiment shown in FIG. Symbol A indicates a transmission interruption curve, symbol B indicates a reception interruption curve when the noise level N is below the transmission threshold level T, and symbol C indicates a reception interruption curve when the noise level is above the transmission threshold level T. It shows. Noise level N as shown
When is below the transmitting threshold level T, the receiving interrupt curve B is the same as the receiving interrupt curve in the conventional device shown in FIG. However, as described above, when the noise level N is equal to or higher than the transmitting threshold level T, the receiving interrupt curve changes as shown in the figure by the increase in the detection gain of the receiving detecting circuit 10 and the decrease in the loss amount of the second receiving loss circuit 16. It is shifted to the center left, and comes to the position shown by symbol C. Therefore, when the noise level N is the magnitude shown in FIG. It becomes possible to interrupt the device into the listening state even if the receiving signal is lower by the shift.

By the way, when voice is input from the microphone 1 under noise exceeding the transmission threshold level T and the voice level is below the noise level N, the apparatus operates in the same way as when there is only noise as described above. However, when the voice level becomes equal to or higher than the noise level N, the loss amount control circuit 17 decreases the loss amount of the second transmission loss circuit 13 and increases the loss amount of the second reception loss circuit 16. Control. Therefore, the audio signal input from the microphone 1 is sent to the line 5 through the hybrid circuit 4 without being attenuated much because the loss amount of the second transmission loss circuit 13 is small. In this way, in the apparatus of this embodiment, when voice is input from the microphone 1, the loss amount of the second transmission loss circuit 13 is reduced, so that the transmission quality does not deteriorate. In this situation,
When the voice transmission ends, the transmission signal becomes only a noise signal, and the loss amount control circuit 17 increases the loss amount of the second transmission loss circuit 13 and increases the loss amount of the second reception loss circuit 1.
6 is controlled to be small, and the reception interruption curve is again shifted to position C in the figure, making it easier to shift to the reception state compared to the conventional device.

However, when the noise is intense and its level becomes equal to the audio signal level, the control signal of the loss amount control circuit 17 fluctuates due to the fluctuation of the audio signal, and the loss amount of the second speech transmission loss circuit 13 fluctuates. This results in
There is a risk that the level of the transmitting signal sent to the line 5 will fluctuate, which will deteriorate the quality of the call. In order to prevent this and to prevent the other party's telephone device from feeling uncomfortable when receiving a call when the noise is intensified, if the noise detection level output by the noise detection circuit 18 exceeds the level set by the noise level setting device 19, The loss amount control circuit 17 always makes the loss amount of the second transmission loss circuit 13 large and the loss amount of the second reception loss circuit 16 always small. For this reason, by using this device even under any noise, the quality of the outgoing call will not deteriorate, and the interruption characteristics to the receiving state can be improved to ensure a good call.

According to this embodiment, when the noise level N becomes larger than the transmission threshold level T, the loss amount control circuit 17
In order to increase the detection level of the reception detection circuit 10 and reduce the loss amount of the second reception loss circuit 16, the reception interruption curve is shifted to the position indicated by C in the figure, as shown in FIG. , it is possible to easily shift to the receiving state even under high noise conditions by the amount of this shift. Furthermore, since the transmitting threshold level T is at the same level as the conventional example, it is possible to avoid the inconvenience that it becomes difficult to shift to the transmitting state under low noise conditions. Furthermore, when the noise level exceeds the level set by the noise level setting device, the loss amount control circuit 17 always increases the loss amount of the second transmission loss circuit 13, thereby reducing the noise level and reducing the noise level under high noise conditions. However, it is possible to perform good transmission.

In order to shift the reception interruption curve as shown in FIG. A configuration in which the circuit 13 is omitted, or the detection gain of the reception detection circuit 10 is left unchanged, and the loss amount of the second reception loss circuit 16 is reduced more than that of the above embodiment, and the loss of the second transmission loss circuit 13 is reduced. Although it is possible to consider a configuration in which the amount of shift is larger than that of the above embodiment, the configuration of the above embodiment is the most practical one when considering the stability of the device and ensuring an appropriate shift amount.

〔Effect of the invention〕

As described above, according to the loudspeaker telephone device of the present invention, when the noise level is higher than a preset noise level, the loss amount of the transmitting loss circuit is controlled to increase, and the loss amount of the receiving loss circuit is controlled to increase. Since the level of the reception signal is controlled so as to be reduced, the amount of reception loss is reduced at times of high noise, and the level of the reception signal is subjected to comparison by the first control circuit without being lowered. Even if there is a problem, the transition from the transmitting state to the receiving state becomes easier.

Further, when the noise level is lower than a preset noise level, the loss amount of the transmitting loss circuit and the loss amount of the receiving loss circuit are controlled by comparing the level of the transmitting signal and the level of the receiving signal, Based on this comparison result, the device is placed in either the transmitting state or the receiving state, and it does not make it difficult to transition from the receiving state to the transmitting state under low noise conditions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional loudspeaker telephone device, FIG. 2 is a diagram showing the transmitting and receiving interrupt characteristics of the conventional example shown in FIG. 1, and FIG. 3 is a loudspeaker telephone according to the present invention. FIG. 4 is a block diagram showing one embodiment of the apparatus, and is a diagram showing the transmitting and receiving interrupt characteristics in this embodiment shown in FIG. 3. DESCRIPTION OF SYMBOLS 1...Microphone, 4...Hybrid circuit, 5...Line, 8...Speaker, 9...Talking detection circuit, 10...Receiving call detection circuit, 11...Audio switch control circuit, 12...Talking Threshold level generator, 13...second transmission loss circuit, 14...first
transmitting loss circuit, 15...first receiving loss circuit,
16...Second reception loss circuit, 17...Loss amount control circuit, 18...Noise detection circuit, 19...Noise level setter.

Claims (1)

[Scope of Claims] 1. A transmitting path for transmitting an inputted transmitting signal to a line via a transmitting loss circuit, and a receiving path for outputting a receiving signal coming from the line from a speaker via a receiving loss circuit. and comparing the level of the transmitting signal and the level of the receiving signal, and controlling the transmitting loss circuit and the receiving loss circuit to place the device in either a transmitting state or a receiving state based on the comparison result. A loudspeaker telephone device comprising: a noise detection circuit that detects a noise level from the input transmission signal; and a noise level at which the noise level detected by the noise detection circuit is set in advance. If greater than
A loudspeaker telephone device comprising: a second control circuit that controls the transmitting loss circuit to increase a loss amount and also controls the receiving loss circuit to decrease a loss amount. 2. If the noise level detected by the noise detection circuit is higher than the preset noise level,
The loudspeaker telephone device according to claim 1, characterized in that the control of the second control circuit is given priority to the control of the first control circuit on the transmission loss circuit and the reception loss circuit. . 3. The transmitting loss circuit includes first and second transmitting loss circuits, the receiving loss circuit includes first and second receiving loss circuits, and the first control circuit includes first and second receiving loss circuits. While controlling the transmitting loss circuit and the first and second receiving loss circuits, the second control circuit controls the second transmitting loss circuit and the first and second receiving loss circuits.
The loudspeaker telephone device according to claim 1 or 2, characterized in that the second reception loss circuit is controlled.