JPH1022880A - Echo suppression circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an echo suppression circuit in which a transmission audio signal is not interrupted. SOLUTION: An input audio is output as a transmission audio signal,
An echo suppression circuit of a communication terminal device that outputs an input received voice signal as voice, a voice input detection unit that determines whether a voice input signal level exceeds a predetermined level, and an output voice is an input voice. Echo suppressors 3 to 5 for suppressing echoes caused by the above, and a received voice signal detector 4 for removing the suppression in the echo suppressors 3 to 5 when the voice input detector determines that the voice input signal level exceeds a predetermined level. With this configuration, an echo suppression circuit in which the transmitted audio signal is not interrupted can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an echo suppressing circuit for suppressing an echo in a communication terminal device.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional echo suppression circuit. In FIG. 3, reference numeral 1 denotes a microphone that inputs audio and outputs an audio input signal, 2 denotes a speaker that receives an audio signal and outputs audio, and 3 denotes a level that lowers the level of the audio input signal output from the microphone 1. The lowering unit 4 is a received audio signal detecting unit that detects a received audio signal, and the reference numeral 5 is a transmitted audio signal selecting unit that selects either an audio input signal from the microphone 1 or an output signal of the level lowering unit 3.

The operation of the echo suppression circuit configured as described above will be described. The voice input to the microphone 1 is output as a voice input signal, and the voice input signal is directly input to the transmission voice signal selection unit 5 and is also input to the transmission voice signal selection unit 5 through the level reduction unit 3. Further, when a received audio signal is detected, the received audio signal detection unit 4 controls the transmission audio signal selection unit 5 so as to select the audio input signal whose level has been lowered by the level reduction unit 3 as a transmission audio signal. . As a result, the sound circulating from the speaker 2 to the microphone 1 is suppressed.

[0004]

However, a conventional echo suppression circuit in a communication terminal device, for example, has the effect of suppressing not only the sound circulating from the speaker 2 to the microphone 1 but also the sound input to the original microphone 1, so that the transmission is suppressed. There has been a problem that the transmission audio signal output from the audio signal selection unit 5 may be interrupted due to a decrease in level.

[0005] As described above, in the echo suppression circuit in the communication terminal device, it is demanded that the transmission audio signal is not interrupted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an echo suppressing circuit in which a transmitted voice signal is not interrupted.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, an echo suppression circuit according to the present invention is an echo suppression circuit that outputs an input voice as a transmission voice signal and outputs an input reception voice signal as a voice. A voice input detection unit that determines whether the voice input signal level exceeds a predetermined level; an echo suppression unit that suppresses an echo generated when the output voice becomes the input voice; When the signal level is determined to have exceeded a predetermined level, a reception audio signal detection unit for eliminating the suppression in the echo suppression unit is provided.

As a result, an echo suppression circuit can be obtained in which, for example, a transmission audio signal is not interrupted in a communication terminal device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is an echo suppressing circuit for outputting an input voice as a transmission voice signal and outputting an input reception voice signal as a voice, and comprising: An audio input detection unit that determines whether the level exceeds a predetermined level; an echo suppression unit that suppresses an echo generated when the output audio is the input audio; and an audio input detection unit that adjusts the audio input signal level to a predetermined level. When it is determined that the audio input signal level has exceeded the predetermined level, the reception audio signal detection unit that eliminates the suppression in the echo suppression unit is determined. It has the effect of

According to a second aspect of the present invention, in the first aspect of the present invention, the echo suppressing section lowers and outputs the audio input signal level, and outputs the audio input signal and the level lowering section output signal. And a transmission audio signal selection unit for selecting any one of the following and outputting the transmission audio signal as a transmission audio signal. Has the effect of selecting

[0011] The invention described in claim 3 is the invention according to claim 1 or 2.
In the invention described in the above, the audio input detection unit determines whether or not the audio input signal level input to the digital logic IC exceeds a predetermined level which is a threshold value of the digital logic IC, The digital logic has an effect that a predetermined level is arbitrarily set.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) FIG. 1 is a block diagram showing an echo suppression circuit according to Embodiment 1 of the present invention. In FIG.
The microphone 1, the speaker 2, the level lowering unit 3, the received audio signal detecting unit 4, and the transmitted audio signal selecting unit 5 are the same as those in FIG. Reference numeral 6 denotes a digital logic IC as a voice input detection unit.

The operation of the thus configured echo suppression circuit will be described with reference to FIG. FIG. 2 (a)
FIG. 2 is a waveform diagram showing an audio input signal c input to the digital logic IC 6, and FIG. 2B is a waveform diagram showing a reset signal d output from the digital logic IC 6. In FIG. 2A, the horizontal axis indicates time t, and the vertical axis indicates a voltage value. In FIG. 2B, the horizontal axis indicates time t, and the vertical axis indicates a logic level.

In FIG. 1, in the initial state, that is, when the received voice signal detector 4 does not detect a received voice signal, the transmitted voice signal selector 5 selects the voice input signal a, and the received voice signal detector 4 When detecting the signal, the transmission audio signal selection unit 5 switches the transmission audio signal from the audio input signal a to the output signal b of the level reduction unit 3. FIG.
The audio input signal of waveform 7 shown in FIG.
6 is input to the digital logic IC 6 in FIG.
As shown in the waveform 8 of (b), when the audio input signal level does not exceed the threshold value (predetermined level) Vth, the logic level "0" is output, and the audio input signal level becomes the threshold value Vt.
If it exceeds h, a logic level "1" is output. When the received voice signal is detected by the received voice signal detection unit 4 and the transmission voice signal selection unit 5 selects the output signal b of the level reduction unit 3, voice is input to the microphone 1 and the waveform is output from the digital logic IC 6. 8 (logical level "1"), the received audio signal detector 4 is reset, and the reset received audio signal detector 4 forcibly converts the transmitted audio signal into the audio input signal a. Switch. Thereby, the transmission audio signal is transmitted without lowering its level.

As described above, according to the present embodiment, when a sound is input to the microphone 1 and the reset signal d of the logic level “1” is output from the digital logic IC 6, the reset received sound signal detecting unit is reset. 4 forcibly switches the transmission audio signal to the audio input signal a, so that transmission can be performed without lowering the level of the transmission audio signal.
There is no occurrence of such a phenomenon that the transmission audio signal is interrupted.

[0016]

As described above, according to the echo suppression circuit of the present invention in a communication terminal, for example, when it is determined that the audio input signal level has exceeded a predetermined level, the reduction in the level of the audio input signal is forcibly stopped. Therefore, transmission can be performed without lowering the level of the transmission voice signal, and an advantageous effect that a phenomenon in which the transmission voice signal is interrupted does not occur can be obtained.

Further, since either the audio input signal or the output signal of the level reduction section can be selected according to the audio input signal level, the transmission can be performed without lowering the level of the transmission audio signal. An advantageous effect that a phenomenon in which the transmission audio signal is interrupted does not occur is obtained.

Further, since the predetermined level can be arbitrarily set by the digital logic, an advantageous effect that an appropriate predetermined level can be easily set is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an echo suppression circuit according to a first embodiment of the present invention.

FIG. 2A is a waveform diagram showing an audio input signal input to a digital logic IC. FIG. 2B is a waveform diagram showing a reset signal output from the digital logic IC.

FIG. 3 is a block diagram showing a conventional echo suppression circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microphone 2 Speaker 3 Level lowering part 4 Reception audio signal detection part 5 Transmission audio signal selection part 6 Digital logic IC

Claims (3)

[Claims] An echo suppression circuit for outputting an input voice as a transmission voice signal and outputting an input reception voice signal as a voice, wherein the voice input circuit determines whether or not a voice input signal level exceeds a predetermined level. A detection unit, an echo suppression unit that suppresses an echo generated when the output sound becomes the input sound, and suppresses the suppression in the echo suppression unit when the sound input detection unit determines that the sound input signal level exceeds a predetermined level. An echo suppression circuit having a received voice signal detection unit to be eliminated. 2. The apparatus according to claim 1, wherein said echo suppressing section lowers the level of the audio input signal and outputs the same, and selects one of the audio input signal and the output signal of the level lowering section to generate a transmission audio signal. The echo suppression circuit according to claim 1, further comprising: a transmission audio signal selection unit for outputting. 3. The digital logic IC according to claim 2, wherein said voice input detecting unit is a digital logic IC.
The level of the audio input signal input to the digital logic I
3. The echo suppression circuit according to claim 1, wherein it is determined whether or not the predetermined level which is a threshold value of C is exceeded.