JPH0523640U - Echo canceller - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The objective is to obtain an echo canceller that does not transmit the indoor noise of its own station to the partner station as much as possible. [Composition] A level detection circuit 7 and a mute circuit 8 which output a detection signal when a microphone input 5 is below a predetermined level and continues for a predetermined time are provided. A configuration in which the component is not transmitted from the transmission signal 9.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 Echo canceller applied to a system with acoustic coupling between a speaker and a microphone.

[0002]

[Prior Art]

 An example of the conventional example is shown in FIG. In the figure, 1 is a reception signal, a voice signal from the partner station, 2 is an echo canceller, 3 is a D / A converter, 4 is a speaker output, 5 is a microphone input, 6 is an A / D converter, and 9 is a transmission signal. is there. In a voice conference, it is assumed that the above-mentioned systems face each other and have a conversation, and the transmission signal of 9 is input to the reception signal of the partner station and the transmission signal of the partner station is input to the reception signal of 1. It is assumed that the D / A converter 3 has an input digital signal converted into an analog signal and outputs it, and the A / D converter 6 has an input analog signal converted into a digital signal and outputs it.

Next, a reception signal 1 whose operation will be described becomes a speaker output 4 by the echo canceller 2 and the D / A converter 3. When the speaker's voice of the partner station is input as the reception signal 1, the voice component of the speaker output 4 is included in the microphone input 5 by acoustic coupling, and this component is input to the A / D converter 6 and the The output of the echo canceller 2 is subtracted only from the component sneak due to acoustic coupling, and is output as a transmission signal 9 to the partner station. The speaker's voice of the own station is sent to the other station as a transmission signal 9 via the A / D converter 6 and the echo canceller 2 as the microphone input 5.

[0004]

[Problems to be solved by the device]

 Since the conventional device is configured as described above, there is a problem that noise at the device installation location is output as a microphone input by a transmission signal, and the partner station hears the noise, causing discomfort due to the feeling of hearing. .

The present invention has been made in order to solve the above problems, and an object of the present invention is to obtain a device which does not output the noise entering the microphone input of the device as a transmission signal as much as possible.

[0006]

[Means for Solving the Problems]

 The device according to the present invention is provided with a level detection circuit and a mute circuit.

[0007]

[Action]

 The level detection circuit detects that the input to the microphone is noise only when the input at a predetermined level or lower continues for a predetermined time, and the mute circuit mutes the transmission signal (silence).

[0008]

【Example】

 Example 1. One embodiment of the present invention is shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts. Reference numeral 7 denotes a level detection circuit, which detects that the microphone input 5 is only noise and outputs a detection signal when a signal below a predetermined level is continuously input for a predetermined time. A mute circuit 8 mutes the output of the echo canceller 2 by the detection output of the level detection circuit 7 to make it a transmission signal. Here, the predetermined level in the level detection circuit 7 means that the speaker voice component is output from the speaker output 4 when the speaker voice of the partner station described in the conventional example is input as the received signal 1 and the acoustic coupling results. It goes around the microphone input 5 and is set lower than the signal level of this voice component that has passed through the A / D converter 6, and the voice of the local speaker is input as the microphone input 5, and the level after passing through the A / D converter 6 is set. Is also low. In addition, the voice of the speaker of the own station or the partner station is intermittent when considering in a short time unit. It is considered to be an indoor noise component of the place.

The received signal 1 is input to the echo canceller 2 and the D / A converter 3, and becomes a speaker output 4 by the D / A converter 3. The microphone input 5 is digitized by the A / D converter 6, and its output is input to the echo canceller 2 and the level detection circuit 7. The output of the echo canceller 2 is output as a transmission signal 9 via the mute circuit 8. When the speaker's voice of the partner station is input to the received signal 1, the wraparound component from the speaker output 4 to the microphone input 5 by acoustic coupling passes through the A / D converter 6 and its output is input to the level detection circuit 7. However, the level detection circuit 7 does not output a detection signal and the mute circuit 8 does not mute (silence) because it is equal to or higher than a predetermined level and has not continued for a predetermined time. Therefore, in this case, the output of the A / D converter 6 is output as the transmission signal 9 after the wraparound component is subtracted by the echo canceller 2. Similarly, when the speaker's voice of the own station is input as the microphone input 5, that input is also input to the level detection circuit 7 via the A / D converter 6, but the level detection circuit 7 operates under the same conditions as above. The detection signal is not output, and the mute circuit 8 does not mute.

[0010]

[Effect of the device]

 According to the present invention, the level detection circuit detects that the microphone input is only noise when there is no talker voice of the other station and there is no talker voice of the own station, and the mute circuit outputs the transmitted signal by the output. Since it is configured to be muted, it is not necessary to send a noise voice signal to the partner station, and the partner station does not hear the noise as the speaker output, and there is an effect that the user does not feel unpleasant to the touch.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

[Explanation of symbols]

 1 Received Signal 2 Echo Canceller 3 D / A Converter 4 Speaker Output 5 Microphone Input 6 A / D Converter 7 Level Detection Circuit 8 Mute Circuit 9 Transmission Signal

Claims (1)

[Scope of utility model registration request] 1. A mute circuit comprising a level detection circuit for a microphone input and a mute circuit for muting (silent) a transmission signal by the output of the level detection circuit, and the mute circuit when the microphone input is below a predetermined level for a predetermined time. Is an echo canceller characterized by muting the transmission signal by the output of the level detection circuit and not transmitting the indoor noise at the device installation location as the transmission signal.