JPS60236557A - Telephone device - Google Patents

Abstract

PURPOSE:To improve the speech quality in a simultaneous call mode, etc. by using an arithmetic means which calculates the difference between the levels of transmission and reception signals and controlling the amount of loss of a variable loss circuit in response to the level of the output signal of the arithmetic means. CONSTITUTION:The outputs of rectifying/charging circuits 9 and 10 are converted into digital signals by A/D converters 12 and 13 and supplied to an arithmetic circuit 14. The circuit 14 calculates the difference between both inputs. Based on this difference value, the amount of loss is set for variable loss circuits 5 and 6 respectively. The digital signal outputted from the circuit 14 and corresponding to the amount of loss of a speech transmission system is supplied to a D/A converter 15 and converted into the analog value. This analog value is applied to the control terminal of the circuit 5. In the same way, the digital signal corresponding to a speech reception system is supplied to a D/A converter 16 to be converted into the analog value and applied to the control terminal of the circuit 6. Both circuits 5 and 6 work so that the amounts of their losses are varied by the voltage levels of their terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a telephone device, and particularly to a control mechanism for controlling a variable loss circuit of a telephone device.

[Prior art]

FIG. 1 shows the configuration of a conventional telephone device disclosed in Japanese Patent Publication No. 56-117463.

This is a diagram. In the figure, 1 is a microphone.

2 is an amplifier circuit, 3 is a speaker, and 4 is a power amplifier circuit.

5 and 6 are variable loss circuits, and 7 is a hybrid circuit.

8 is a telephone line, 9 and 10 are rectifier charging circuits, and 11 is a voice switch circuit. This device enables hands-free calls without using a handset using a microphone 1 for transmitting and a speaker 3 for receiving. The receiving system is configured by: Further, the transmitting system, the receiving system, and the telephone line 8 are connected via a hybrid circuit 7. In order to prevent howling caused by the closed loop A of the audio signal from the speaker 3 to the microphone 1, and the closed loop B formed via the hybrid circuit 7, variable loss circuits 5 and 6 are installed in the transmitting system and the receiving system, respectively.
has been inserted. The variable loss circuits 5 and 6 are rectifier charging circuits 9. It is controlled by the IO and audio switch circuitry 1. In such a configuration, a transmission signal from the microphone 1 escapes to the amplifier circuit 2, is amplified, and is input to the variable loss circuit 5 and the rectifier charging circuit 9. On the other hand, telephone line 8
The reception signal from the variable loss circuit 6 and the rectifier charging circuit 10
is input. The rectifying and charging circuits 9 and 10 convert each of the above signals into DC voltages corresponding to the signal levels and output the DC voltages to the audio switch circuit 11.

The audio switch circuit 11 determines the magnitude relationship between the two input terminals and controls the variable loss circuits 5 and 6. For example, the transmitting signal level from microphone 1 is telephone port lv! 8, the loss amount of the variable loss circuit 6 inserted in the receiving system is increased, and in the opposite case, the loss amount of the variable loss circuit 5 inserted in the transmitting system is increased. It works to increase.

In this way, in the conventional device, the total gain of the transmitting system and the receiving system is increased by increasing the loss amount of the variable loss circuit 6 of the receiving system, and increasing the loss amount of the variable loss circuit 5 of the transmitting system when receiving a call. is always suppressed to a gain value that does not cause howling.

However, in conventional devices, a variable loss circuit is used that determines when a call is being sent or when a call is being received based on the signal levels of the send signal and the receive signal, and increases the amount of loss by a certain value based on this determination. There is a drawback that the amount of loss in the transmitting system and the receiving system during switching is always fixed at a constant value, and it is difficult to expect improvement in call quality during simultaneous calls.

[Summary of the invention]

The present invention provides a calculating means for calculating the difference between the signal level of a transmitting signal and a signal level of a receiving signal, and controls each variable loss circuit in accordance with the magnitude of the output signal of this calculating means. This eliminates the above drawbacks. The present invention will be explained in detail below using examples.

[Embodiments of the invention]

FIG. 2 is a block diagram showing the configuration of an embodiment of the telephone device according to the present invention. The same reference numerals are used for the same or corresponding parts as in FIG. 1. As shown in the figure, the rectifier charging circuit 9
．． An analog/digital circuit 12.13, an arithmetic circuit 14 as an arithmetic means, and a digital/analog circuit 15.16 are inserted between the variable loss circuit 10 and the variable loss circuit 5.6.

Next, the operation of this apparatus configured as above will be explained. A transmission signal from the microphone 1 is amplified by the amplifier circuit 2 and then inputted to the variable loss circuit 5 and the rectifier charging circuit 9. The rectifier charging circuit 9 outputs a DC voltage v1 corresponding to the signal level of the transmitting signal. On the other hand, telephone line 8
The reception signal inputted from the receiver is inputted to the variable loss circuit 6 and the rectifier charging circuit 10 via the hybrid circuit 7. Like the rectifier charging circuit 9, the rectifying charging circuit 10 outputs a DC voltage v2 corresponding to the signal level of the reception signal. Each output of the rectifier charging circuit 9.10 is converted into a digital signal by an analog/digital circuit 12.13, and then sent to the arithmetic circuit 1.
4 is input. The arithmetic circuit 14 calculates the difference between the above-mentioned two-person power, and sets each loss amount of the variable loss circuits 5 and 6, ie, each loss amount of the transmitting system and the receiving system, from that value. A digital signal corresponding to the loss amount of the transmission system output from the arithmetic circuit is input to the digital-to-analog conversion circuit 15, converted to an analog value, and applied to the control terminal of the variable loss circuit 5. Similarly, a digital signal corresponding to the amount of loss in the receiving system is inputted to the digital-to-analog conversion circuit 16, converted into an analog value, and applied to the control terminal of the variable loss circuit 6. The variable loss circuits 5 and 6 operate so that the loss amount of the circuit changes depending on the voltage value of the control terminal.

Figure 3 shows the set loss amount L (dB) for the transmitting system and receiving system,
It is a characteristic diagram showing an example of. As shown in the figure, the receiving system setting loss amount Lr takes a value that increases as the difference (Vl - V2) between the transmitting signal level ■1 and the receiving signal level v2 increases, and the transmitting system setting loss amount Lt is the opposite. The difference m-V2
) increases, the value decreases. In this case, the total gain of the transmitting system and the receiving system is always suppressed to a constant value, and this total gain is always set to a value that does not cause howling.

Therefore, in the conventional example, when the transmitting signal level V1 is higher than the receiving signal level ■2 (Vl-V2 > 0), the amount of loss in the receiving system uniformly increases regardless of the magnitude of the difference, and vice versa. Similarly, when (Vl-V2 <O), the amount of loss in the transmitting system uniformly increases, making it difficult to hear the other party's calls during simultaneous calls. In this embodiment, each loss amount is changed in accordance with the magnitude of the difference between (Vl-V2), so that it is possible to hear the call from the other party with good quality even during simultaneous calls.

As explained above, according to this embodiment, the loss amount of each variable loss circuit 5.6 is changed in response to the difference in signal level of the transmitting and receiving signals, so the call quality is improved even during simultaneous calls. In addition, since each signal level is converted into a digital value and the arithmetic processing is performed, the arithmetic processing becomes easy.

In this embodiment, the transmitting signal and the receiving signal are processed by analog-to-digital conversion circuits 12, 13, arithmetic circuit 14, and digital-to-analog conversion circuits 15 and 16, but analog-to-digital conversion or digital-to-analog conversion circuits Even if a one-chip microcomputer with a built-in microcomputer is used, the same effect as described above can be obtained. The one-chip microcomputer described above has recently been used in multi-function telephones that store and display telephone numbers, and can also be used.

〔Effect of the invention〕

As explained above, according to the telephone device according to the present invention,
A calculating means for calculating the difference between the signal level of the transmitting signal and the signal level of the receiving signal is provided, and the loss amount of each variable loss circuit is controlled in accordance with the magnitude of the output signal of this calculating means. This has the effect of improving call quality even during simultaneous calls.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional telephone device;
The figure is a block diagram showing one embodiment of the telephone device according to the present invention, and FIG. 3 is a characteristic diagram showing the set loss amount according to the above embodiment. 5.6... Variable loss circuit, 12.13... Digital-to-analog conversion circuit, 14... Arithmetic circuit, 15.16.
...Analog-digital conversion circuit. Note that the same reference numerals are used for the same or corresponding parts in the figures. Agent Masuo Oiwa (and 2 others) Figure 1 0 (Vl-V2) Procedural amendment (voluntary) 2. Name of the invention Telephone device 3. Relationship to the case of the person making the amendment Patent applicant address Tokyo Chiyoda-ku Marunouchi Sara-chome 2-3 Name
(601) Mitsubishi Electric Co., Ltd. Representative Katayuni 8 Department 4, Agent 5, Claims to be amended, Detailed explanation of the invention column 6, Contents of the amendment (1) The scope of claims is as attached. (2) Lines 14 and 15 of page 4 of the specification, line 8 of page 5, “
Correct "Circuit J" to "1 conversion circuit". What is claimed in the above patents: In a telephone device having a variable loss circuit in the transmitting system and the receiving system, the transmitting and -2 speech levels are converted to digital. A telephone comprising a calculation means for calculating the difference between the level and the signal level of the received signal, and the loss amount of the variable loss circuit is controlled in accordance with the magnitude of the output signal of the calculation means. Device.

Claims (1)

[Claims] A telephone device in which a variable loss circuit is provided in a transmitting system and a receiving system includes a calculation means for calculating the difference between the signal level of the transmission signal and the signal level of the reception signal, and the magnitude of the output signal of the calculation means is A telephone device characterized in that the loss amount of the variable loss circuit is controlled accordingly.