JPS60126950A - Public-address telephone set - Google Patents

Abstract

PURPOSE:To easily enter a reception state in a high-noise atmosphere and to easily enter a transmission state in a low-noise atmosphere by dividing a reception loss circuit and a transmission loss circuit respectively, and combining those loss circuits properly when a noise level exceeds a preset transmission threshold level. CONSTITUTION:When a voice is inputted to a microphone 1 in a no-noise state, the 1st and the 2nd transmission loss circuits 14 and 15 are controlled to the large amounts of loss and the 1st and the 2nd reception loss circuits 15 and 16 are controlled to the large amounts of loss, so that the circuit enters a transmission state. Then, if there is a noise exceeding the transmission threshold level and the device is in the transmission state while the amount of loss of the 1st transmission loss circuit 14 is large and the amount of loss of the 1st reception loss circuit is large, a loss amount control circuit 17 increases the amount of loss of the 2nd transmission loss circuit 13 and decreases the amount of loss of the 2nd reception loss circuit 16. At this time, the gain of areception detecting circuit 10 is increased with the control signal of a speech switch control circuit 11.

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 the transmitting amplifier (AMP) 2, attenuated by the transmitting loss circuit (TVL) a, and then passed through the entire hybrid circuit (HYB) 4 to the line 5. Sent out. On the other hand, the voice signal transmitted through the line 5 passes through the hybrid circuit 4 and reaches the reception loss circuit (IjVL) 6, where it is attenuated and then amplified by the reception amplifier (AMP) 7 and sent out from the speaker power 8. Ru.

The transmission signal on the output side of the transmission amplifier 2 is transmitted to the transmission detection circuit (T
T) is input to 9. Further, the received signal on the output side of the received received loss circuit 6 is inputted to a received received signal detection circuit (RT) 10. The output signals of the sending detection circuit 9 and the receiving detection circuit 10 are respectively input to a voice switch control circuit (VS) 11. Further, the voice switch control circuit 11 is input with the voice threshold level output from the voice threshold level generator 12, p1, and the control signal output from the sound angle switch control circuit 11 is transmitted to the voice loss circuit 3 and the voice receiving loss circuit 3. It is input to the loss circuit 6. Voice switch control circuit 111'i, voice transmission detection circuit 9
The transmitting speech level from the receiving speech detecting circuit 10 is compared with the receiving speech level from the receiving speech detecting circuit 10, and the respective losses of the transmitting speech loss circuit 3 and the receiving speech loss circuit 6 are controlled to increase or decrease in a reciprocal manner according to the comparison result.

In addition, a microphone 1, a transmitting amplifier 2, a transmitting loss circuit 3, a hybrid circuit 4 and a transmitting path of 5 lines are formed, and a transmitting path of 5 lines, a line 5, a hybrid circuit 4, a receiving loss circuit 6, a receiving amplifier 7, and a speaker 8 are provided. forms the receiving channel. Also, when the transmitting threshold level generated by the transmitting threshold level generator 12 is exceeded, the microphone 1 when the circuit interrupts from the receiving state to the transmitting state in a state where there is no receiving signal from the line 5.
This indicates a 0 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 lower than the reception detection level output by the reception detection circuit 10. Low, voice switch control circuit 11V
i The loss amount of the transmission loss circuit 3 is controlled to be large and the loss amount of the reception loss circuit 6 is controlled to be small, and the circuit enters the reception state. In this state, when a voice is input from the microphone 1 and the transmission detection level of the transmission detection circuit 9 increases and becomes higher than the reception detection level of the reception detection circuit 10, the voice switch control circuit 11 controls the transmission loss circuit 3. Control is performed to reduce the amount of loss and increase the amount of loss in the receiving loss circuit 6, and the circuit is placed in 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. In addition, symbol A indicates a transmitting interrupt curve, symbol B indicates a receiving interrupt curve, N indicates a noise level, and T indicates a transmitting 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 the receiving interrupt curve 8 or higher, 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 sending and receiving calls, and when there is no noise, a natural loudspeaker call can be made.

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 sound is input from the microphone 1, the device is always in the receiving state as in the case where there is no noise as described above. In such a state, when a voice signal higher than the level shown by the transmitting interrupt curve A in FIG. The amount of loss in the loss circuit 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, even with the conventional circuit configuration, good call operation can be ensured for the noise level N below the transmitting threshold level T.

[Problems with background technology]

By the way, as shown in FIG. 2, when the noise level N is higher than the transmission threshold level T, the voice switch control circuit 11
As a result, the amount of loss in the transmission loss circuit 3 becomes small, whereas the amount of loss in the reception loss circuit 6 becomes large, so that the device is always in the transmission 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. This happens when the reception level input from the line 5 is low, such as during long-distance calls, 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, with K like this, the transmitting threshold level T
In the case of a call in a quiet place where the noise is lower than that of the user, the problem arises in that it is difficult to enter the transmitting state because the transmitting threshold level T is high.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above drawbacks, an object of the present invention is to provide a loudspeaker telephone device that can easily shift to a receiving state under high noise conditions and easily shift to a transmitting state under low noise conditions.

[Summary of the invention]

The present invention provides a transmission path for transmitting an input transmission signal to a line through a transmission loss circuit, a reception path for transmitting a reception signal input from a 0 line from a speaker through a reception loss circuit, and a transmission signal level. In the loudspeaker telephone device comprising a control circuit that compares received signal levels and sets the device to a transmitting state or a receiving state, the receiving loss circuit and the transmitting loss circuit are divided into first and second circuits, respectively. No. 20 reception loss circuit and first and second transmission loss circuits are provided, and when the noise level exceeds a preset transmission threshold level, the amount of loss in the first transmission loss circuit is small, and During the transmitting state in which the loss amount of the receiving loss circuit is large, the control circuit performs all the controls to increase the detection gain of the receiving detecting circuit that detects the receiving signal level, and when the receiving receiving loss circuit is in the transmitting state, The above object is achieved by providing a loss amount control circuit that reduces the amount of loss in the loss circuit and minimizes the amount of loss in the second transmission loss circuit.

[Embodiments of the invention]

An embodiment of the loudspeaker telephone system of the present invention will be described below 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 an embodiment of the loudspeaker telephone device of the present invention. The audio signal captured by the microphone 1 is amplified by a transmitting amplifier (AMP) 2 and then passed through a second transmitting loss circuit (TVL 2 ) 13 and a first transmitting loss circuit (T
VLI) 14 and is further attenuated by the hybrid circuit (
HYB) 4 to line 5. On the other hand, line 5
The transmitted audio signal passes through the hybrid circuit 4 to the first reception loss circuit (RVLI) 15 and the second reception loss circuit (R, VL2) 16, where it is attenuated and then sent to the reception amplifier. 7 and sent out from the speaker 8.

The transmission signal on the output side of the transmission amplifier 2 is transmitted to the transmission detection circuit (T
T) is input to 9. Further, the received signal on the output side of the 20th received reception loss circuit 16 is input to the received reception detection circuit (RT) 10. These, the sending detection circuit 9 and the receiving detection circuit 1
Each detection level of 0 is input to the audio switch control circuit 11. The voice switch control circuit 11 is inputted with the voice threshold level generated by the voice threshold level generator (TL) 12, and the control signal outputted from the voice switch control circuit 11 is the first and second one. Transmission loss circuit 1
4.13, first and second reception loss circuits 15 and 16, loss amount control circuit (CMP) 17, and reception detection circuit 10. The transmission level detected by the transmission detection circuit 9 is input to the loss amount control circuit 17 and the noise detection circuit (NT) 18, and the noise level detected by this noise detection circuit 18 is input to another input of the loss amount control circuit 17. is input.

A set noise level from a noise level generalizer (NL) 19 is also input to this loss amount control circuit 17 . The control signal output by the loss amount control circuit 17 is input to the second transmission loss circuit 13 and the twentieth reception detection circuit 16. The loss amount control circuit 17 compares the transmitting speech level and the noise level, and controls to reciprocally increase or decrease the loss amount of the second transmitting loss circuit 13 and the twentieth receiving loss circuit 16 based on the result. The noise detection circuit (N T ) 1
When the noise level output by 8 is equal to or higher than the set noise level, control is performed to always reduce the loss amount of the second transmission loss circuit 13 and the loss amount of the second reception loss circuit 16. 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 output level of the receiving detecting circuit 10 that is input to the audio switch control circuit 11 is lower than the output level of the transmitting detecting circuit 9. Large, first transmit loss circuit 1
The loss amount of the 10th receiving loss circuit 15 is controlled so as to be large, and the loss amount of the 10th receiving loss circuit 15 is small, and the circuit enters the receiving state. In such a reception state, the voice switch control circuit 11 performs pressure control such that the loss amount of the second transmission loss circuit 13 is large and the loss amount of the second reception loss circuit 16 is 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 the sum of the loss amount of the transmission loss circuit 3 of the conventional circuit.
In addition, the sum of the loss amount of the tenth reception loss circuit 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. By setting in this way, the input from the microphone 1 is transmitted to the transmitting amplifier 2 and the second transmitting loss circuit 13.
, the transmission level that passes through the first transmission loss circuit 14, the hybrid circuit 4, the first acupuncture loss circuit 15, and is output to the 20th reception loss circuit 16. The transmitting signal level outputted to the receiving loss circuit becomes the same level, and the transmitting signal passes through the cut circuit 4 and goes around to the receiving channel, thereby preventing a malfunction in which the signal is considered to be a receiving signal. .

When a voice is input to the microphone 1 shown in FIG. 3 in the absence of noise, the voice detection level of the voice detection circuit 9 input to the voice switch control circuit 11 is higher than the voice reception detection level of the voice reception detection circuit 10. Therefore, each loss amount of the first transmission loss circuit 14 and the second transmission loss circuit 13 is small;
The losses of the first receiving loss circuit 15 and the twentieth receiving loss circuit 16 are controlled to be large, and the circuits enter the transmitting 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, and the loss amount of the first transmitting loss circuit 14 is small.
The amount of loss in the reception loss circuit 15 becomes large, and when the device is in the transmitting state, the noise level detected by the noise detection circuit 18 becomes higher than the voice level detected by the transmission detection circuit 9. The loss amount control circuit 17 controls the loss amount of the second transmission loss circuit 13 to be large and the loss amount of the second reception loss circuit 16 to be 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 110. In addition, when the detection gain of the reception detection circuit 10 increases, the second transmission loss circuit 13 and the 20th reception loss circuit 16Jli loss amount control circuit 17 are preferentially controlled and the voice switch control circuit 11 is controlled. I will not accept it. Therefore, the loss amount of the tenth reception loss circuit 15 is large, but the loss amount of the second reception loss circuit 16 is small, and the loss amount of the reception loss circuit 15 is small.
Since the detection gain of 0 is increasing, the output level of the reception detection circuit 10 with respect to the reception signal inputted through the line 5, the high-solit circuit 4, the first reception loss circuit 15, and the 20th reception loss circuit 16t- is as follows. It increases by the increase in the detection gain and the decrease in the loss amount of the second receiving loss circuit 16. That is, the present device is more likely to enter the receiving state by the amount of increase in the detection gain of the receiving signal detecting circuit 10 and the decrease in the amount of loss of the 20th receiving loss circuit 16.

FIG. 4 is an interrupt characteristic diagram of the loudspeaker telephone device of the present embodiment shown in FIG. 3; The symbol Ait indicates the outgoing interrupt curve,
Symbol BFi indicates a receiving interrupt curve when the noise level N is below the transmitting threshold level T, and symbol C indicates a receiving interrupt curve when the noise level is equal to or higher than the transmitting darkness value level 1. As shown in the figure, when the noise level N is below the transmission threshold level T, the reception interruption curve B is the same as the reception interruption curve in the conventional device shown in FIG. However, as mentioned above, when the noise level N is equal to or higher than the transmitting threshold level 1, the receiving detecting circuit 1
The reception interrupt curve is shifted to the left in the figure by the increase in the detection gain of 0 and the decrease in the loss amount of the 20th reception loss circuit 16, and comes to a position as shown by C. Therefore, when the noise level N is as large as shown in Figure 4, the conventional reception interrupt level at point P will be shifted to the left to the level at point Q, and the interruption level from line 5 will be shifted to the left to the level at point Q. Even if the reception signal is low by the shift, it is possible to interrupt the device into the reception state.

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, the audio level is the noise level N
If this occurs, the loss amount control circuit 17 controls the loss amount of the second transmitting loss circuit 13 to be small and the loss amount of the second receiving loss circuit 16 to be large. 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 amount of loss in the second transmission loss circuit 13 is small. In this way, in the device of this embodiment, when a voice is input from the microphone 1, the loss amount of the second speech transmission loss circuit 13 is reduced, so that the transmission quality does not deteriorate. When voice transmission ends in this state, the transmission signal becomes only a noise signal, and the loss amount control circuit 17 returns to the second transmission loss circuit 13.
The loss amount of the 20th reception loss circuit 16 is controlled to be large, and the loss amount of the 20th reception loss circuit 16 is controlled to be small, and the reception interrupt curve is shifted again to the position C in the figure, and the transition to the reception state is made easier than in the conventional device. Make it easy.

However, when the noise is intense and its level is equal to the audio signal level, the loss amount control circuit 17 due to fluctuations in the audio signal.
The control signal changes, and the loss amount of the second transmission loss circuit 13 changes. This may cause the level of the transmission signal sent to the line 5 to fluctuate, resulting in deterioration of speech quality. 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, Loss amount control circuit 17
As a result, the loss amount of the second transmitting loss circuit 13 is always kept large, and the loss amount of the second receiving loss circuit 16 is always kept small. Therefore, by using this device even under any noise environment, 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 transmitting threshold level T, the loss amount control circuit 17 operates to increase the detection level of the receiving voice detection circuit 10 and reduce the loss of the second receiving loss circuit 16. In order to reduce the amount of noise, the reception interrupt curve is shifted to the position shown by C in the figure as shown in FIG. 4, and it is possible to easily shift to the reception state by the shifted amount even under high noise conditions. 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 1o is left as is, the loss amount of the 20th reception loss circuit 16 is greatly reduced compared to 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, the transmitting and receiving loss circuits are divided into two, and the first and second loss circuits are divided into two.
A transmitting loss circuit and first and second receiving loss circuits are provided, and when the noise level exceeds the transmitting threshold level and the device is in the transmitting state, the amount of loss in the first receiving loss circuit is large. However, by controlling the loss amount of the second reception loss circuit to be small, the loss amount of the second transmission loss circuit to be large, and increase the detection gain of the reception detection circuit, it is possible to reduce the loss under high noise conditions. This has the effect of making it easier to shift to the receiving state, and also making it easier to shift to the transmitting state under low noise conditions.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional loudspeaker telephone device, FIG. 2 is a diagram showing transmission and reception interrupt characteristics in 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 transmission and reception interrupt characteristics in the embodiment shown in FIG. 3. 1...Microphone 4...Hybrid circuit 5
...Line 8...Speaker 9...Sending detection circuit 10...Receiving detection circuit 11...Audio switch control circuit 12...Sending threshold level generator 13゛°°second
Transmission loss circuit 14...First transmission loss circuit 15
...-10th receiving loss circuit 16...20th receiving loss circuit 17...Loss amount control circuit 18...Noise detection circuit 19...Noise level setting device agent Patent attorney Hon 1) Takashi

Claims (2)

[Claims] (1) A sending path that sends the inputted sending signal to the line through the sending loss circuit, and a receiving path that sends the receiving signal input from the line from the speaker through the receiving loss circuit;
In a loudspeaker telephone device comprising a control circuit that compares a transmitting signal level and a receiving signal level and sets the device to a transmitting state or a receiving state, the receiving loss circuit is divided into first and second receiving loss circuits. and when the noise level exceeds a preset transmitting threshold level and the loss amount in the transmitting loss circuit is small and the loss amount in the first receiving loss circuit is large, the control is performed. A loss amount control circuit is provided which controls the circuit to increase the detection gain of the reception detection circuit that detects the reception signal level, and reduces the loss amount of the second reception loss circuit during the transmission state. A public address telephone device characterized by: (2) The transmission loss circuit is divided into first and second transmission loss circuits, and when the noise level exceeds the set level, the amount of loss in the first transmission loss circuit becomes small and the device is activated. 2. The loudspeaker telephone device according to claim 1, wherein the loss amount of the second transmission loss circuit is increased when the telephone is in the transmission state.