KR920002783B1 - Two way communication method in speakerphone - Google Patents

Abstract

The method eliminates howling for clear two way communication of speaker phone. The method includes: (A) dividing audio signals of receiver and transmitter; (B) synthesizing audio signals of transmitter (B) and receiver (A); and (C) compensating the in phase voltage of audio signal of a receiver (A) according to gain of buffer amplifiers so that the audio signal of the transmitter is transmitted to a speaker.

Description

Signal separator and two-way communication method of speakerphone

1 is an overall block diagram of the present invention.

2 is a voice buffer circuit diagram of the present invention.

3 is an in-phase removal circuit diagram of the present invention.

4 is a detailed circuit diagram according to FIG.

5 is a waveform diagram of a microphone (transmission) input signal of the present invention.

6 is a waveform diagram of a line input signal of the present invention.

7 is a line-side synthesized signal waveform diagram of the present invention.

8 is a waveform diagram of a speaker-side received signal of the present invention.

9 is a circuit diagram showing a conventional speakerphone one-way method.

* Explanation of symbols for main parts of the drawings

A, B: Voice buffer, LA: Buffer amplifier

E: Phase voltage elimination circuit G: Gain adjustment

v _R : Reference voltage OP ₁ -OP ₅ : OP amplifier

R ₁₁ -R ₂₃ : Resistor L: Line

The present invention relates to a signal separator and a two-way communication method of a speakerphone in a telephone, and in particular, an object of the present invention is to allow a two-way method to be used in a one-way method.

In general, a telephone currently used mainly uses a handset to make a call, which is inconvenient to carry a call with a handset.

However, the conventional speakerphone uses a one-way method. As a result, as shown in FIG. 9 (Recently-disclosed patent publication No. 81-2088), the call is most appropriately switched by switching the signal and the sign signal. It's done, but it's also one-way, so it's not perfect.

In other words, the most perfect loudspeaker phone (speaker phone) should be the same as a regular phone that is simultaneously two-way (non-switching), not a switching method, but the same simultaneous call as a regular phone, even during a call (talk).

However, the loudspeaker of such a system is still a long story. For this reason, if a simultaneous call is made, the received signal from the other party is driven and output by the speaker, and a part of the sound enters the microphone as the voice input signal and goes out to the other party. Comes out.

This repeats howling, making it impossible to talk. For this reason, the switching control system, which is a general call one-ware method rather than a two-way communication method, is used in a loudspeaker. The biggest difficulty with this method is that it does not make natural calls compared to the two-way method. Therefore, it is important to design as close to the natural sound as possible. Therefore, the switching control system used in conventional loudspeakers makes it either in a sign language state or in a talk state when there is no signal, i.e., in a normal state (no voice input to a talk system or a talk system). During the conversation, the system is turned on and the system is off to enter the talk mode. Then, when the call is interrupted (when there is no voice input signal), it is put into the talk state.

However, although publication No. 81-2088 solves the above problem and most ideally switches between sending and receiving hydration to remove the housing, this also cannot completely remove the howling. In other words, the one-way method can reduce the howling but not completely remove it. Therefore, there is a problem in that parts of the transmission and reception signals are cut off.

In addition, if one speaks louder from the other side while he is speaking, a big disadvantage occurs that the transmission of voice is blocked while he is speaking. There are many problems in the convenience of pursuing these shortcomings in the call and the function that allows several people to make a conference call. In order to make up for these drawbacks, it is very difficult to compensate unless the two-way route is adopted. Therefore, the present invention is to enable the signal processing operation when the two-way method is adopted in the speakerphone function, the problem that occurs when the two-way method is adopted in the speakerphone function and the circuit of the present invention handles the problem. It will be described in detail as follows.

As shown in FIGS. 1 and 4, the output of the microphone Mic is composed of the voice buffer A consisting of the amplifier OP ₁ and the resistors R ₁₁ , R ₁₃ , and R ₁₄ , and the OP amplifier OP ₂ . Input to the voice buffer B (b) consisting of resistors R ₁₂ , R ₁₅ , and R ₁₆ , so that the output of the voice buffer A (a) is adjusted through the line communication line (L) signal and gain via a resistor (R ₂₅ ). (G) is input to a buffer amplifier B (D) consisting of an OP amplifier (OP ₄ ) and a resistor (R ₁₆ ) to which a signal is applied, and the output of the voice buffer B (I) is transmitted through a resistor (R ₁₉ ). The reference voltage (V _R ) is adjusted and input, and the gain adjustment (G) is input to the buffer amplifier A (C) composed of one OP amplifier (OP ₃ ) and a resistor (R ₁₆ ).

The outputs of the buffer amplifiers A, B (C) and (D) are output to the speaker SP through an in-phase voltage removing circuit (E) consisting of an OP amplifier OP ₅ and resistors R ₂₁ -R ₂₃ . do.

2 is a circuit diagram showing an embodiment of the voice buffers A and B (a), and FIG. 3 is a circuit diagram of an embodiment showing the in-phase voltage removing circuit (e).

5, 6, 7, and 8 show signal waveform diagrams for explaining the present invention.

Referring to the operation and effect of the present invention configured as such a circuit as follows.

First, the characteristics of the OP amplifier OP ₁ and the OP amplifier OP ₂ are the same so that the voice buffer A and voice buffer B are the same, and the resistors R ₁₁ = R ₁₂ and R ₁₃ = R ₁₅ , R ₁₄ = R ₁₆ , R ₂₅ = R ₁₉ , R ₁₇ = R ₁₈ ) should be set equal. Gain control (G) is the impedance takes up the track to the design and can be adjusted using a variable resistor can be adjusted to hydration volume resistance, and the reference voltage (V _R) for adjusting a variable resistor and a resistor (R ₂₀ Adjust to the same value as the combined resistance of).

By designing as described above, the operation of transmitting the signal from the other party and the sound of the caller becomes as follows. The voice signal (waveform in FIG. 5) applied to the microphone MIiC flows to the resistors R ₂₅ and R ₁₉ through the voice buffer A and B. Both signals have the same value. . The signal passing through the resistor R ₂₅ is loaded onto the line L and is combined with the voice signal (waveform of FIG. 6) of the other party applied to the line to form a synthesized sound of the two signals (waveform of FIG. 7). Here, assuming that the audio signal (fifth waveform) applied to the microphone Mic is A and the signal (waveform in FIG. 6) applied toward the line is B, the synthesized signal is A + B.

As for the signal applied to the reference voltage (V _R ), the pure microphone signal A and the synthesized signal A + B are applied to the voice buffer (a), respectively, and these signals have amplification degree determined according to the value of the gain adjustment (G) stage. Then, it is applied to the input of the in-phase voltage removing circuit (e) composed of the resistors R ₂₁ , R ₂₂ , R ₂₃ , and R ₂₄ and the OP amplifier OP ₅ . In the in-phase voltage removing circuit (e), A- (A + B) becomes A-B, which is a pure B signal, i.e., only the waveform signal of FIG. 6, which is the voice signal of the other party, is output like the waveform of FIG. Therefore, only the voice signal B of the other party can be heard.

When the two-way method is adopted in the speakerphone circuit, the signal transmitted by the caller through the microphone is loaded on the track. The signal flows back into the other party's sign language, raising the speaker, and the sound from the speaker goes back into the microphone (Mic) and eventually causes howling.

In order to solve this problem, the present invention uses the common-phase voltage removing characteristic of the OP amplifier. The voice signal input through the microphone (Mic) is loaded on the line (L) and the reference value adjustment (V _R ) resistance through two equal voice buffers. The signal on the track is synthesized with the voice signal of the other party and the voice is transmitted to the track.

This synthesized signal is passed through the buffer amplifier B (ra). The signal on the reference value adjusting stage is passed through the buffer amplifier A (C), and the two signals are applied to the in-phase voltage removing circuit (e) so that the in-phase voltage is canceled and only the voice signal of the other party is obtained at the output. Here, the audio buffer A and audio buffer B should be the same as each other, the reference signal attenuation rate must be the same as the line L, and the buffer amplifier A is equal to the buffer amplifier B. Should have

Eventually, the signal input to the microphone terminal is sent out to the line (L) and at the same time the signal applied to the line (L) appears at the output of the in-phase voltage elimination circuit so that the two-way speakerphone communication path It can be seen that.

As described above, the present invention is a breakthrough that enables the speakerphone to transmit and receive voice signals without any howling by using a two-way method rather than a one-way method using a switching circuit.

Claims (2)

In a speakerphone with a microphone (Mic) and a speaker (SP), the input signal of the microphone (Mic) to be transmitted is passed through the voice buffers A and B (A) and the buffer amplifiers A and B (C) (D). The reference voltage (V _R ) is adjusted to the input of the buffer amplifier A (C), and the input of the buffer amplifier B (B) is applied to the line L signal to which the voice signal of the other party is applied. Adjust the gain of the buffer amplifiers A, B (C) (D) so that only the signal input through the line (L) among the output signals of the amplifier (C) (D) can be output to the speaker SP. (E) the signal separator of the speakerphone characterized in that it has. The voice of the caller is separated, and the voice signal (A) of the separated caller and the voice signal (B) of the other party are synthesized, and the synthesized synthesized sound (A + B) is the voice signal of the caller (A) according to gain adjustment and amplification degree. The two-way communication method of the speakerphone characterized in that to cancel the in-phase voltage for the other party's voice signal (B) to be output preferentially.

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