JPH07254822A - Reception amplifier for telephone set - Google Patents

Abstract

PURPOSE:To allow a user to listen to an excellent speech voice by properly reducing a line noise. CONSTITUTION:A silence desiding device 4 decides a sound or silence based on an output signal Sb of a subscriber circuit 1 and outputs a silence decision signal Sf to a line noise extracting device 5 in the case of silence, and an output signal Sb therefrom is subjected to fast Fourier transform device or the like, in which frequency components are obtained. A line noise component signal Se of the frequency component is inputted to a line noise elimination device 6, and an output signal Sb therefrom is subjected to fast Fourier transform and a voice signal Sb resulting from extracting the line noise component signal Se through inverse fast Fourier transform or the like by the line noise elimination device 6 is amplified by an amplifier 2 and an amplified voice signal Sd is sounded by a speaker 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone receiver amplifying device for use in a key telephone device or the like, for reducing line noise and listening to a conversation voice.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing the structure of a conventional telephone receiver amplification apparatus. In FIG. 6, this example shows a subscriber circuit 1 that performs telephone signal processing when an incoming call and a outgoing call are made through a public line of a public line network, an amplifier 2 that amplifies an output signal from the subscriber circuit 1, and a subscriber circuit 1. The speaker circuit 1 and the speaker 3 for outputting the voice of the communication partner processed through the amplifier 2 are provided.

Next, the operation of this conventional example will be described. The line signal Sa from the station line is converted into the output signal Sb by the subscriber circuit 1. Next, the output signal Sb from the amplifier 2
Is amplified, and the amplified output signal Sc is output as voice from the speaker 3, and the voice of the other party is heard by this voice output.

[0004]

However, since the output signal Sb from the subscriber circuit 1 is amplified as it is in the above-mentioned conventional telephone receiver amplifying device, it is superimposed on the signal from the central office line to the subscriber circuit 1. Line noise is also amplified,
There was a problem of listening to noisy voice.

The present invention solves such a conventional problem, and an object of the present invention is to provide an excellent telephone receiver amplifying device capable of accurately reducing line noise and listening to a good conversation voice.

[0006]

In order to achieve the above object, in the telephone receiver amplification apparatus according to claim 1, the silence determining means for determining whether the line signal is voiced or not, and the silence determining means are silent. In the case where the line noise component is determined to be, the line noise extracting means for extracting the frequency component of the line signal as the line noise component and the line noise removing means for removing the line noise component extracted by the line noise extracting means from the line signal are configured. .

According to a second aspect of the present invention, there is provided a telephone receiver amplifying device,
Silence determination means for determining whether the line signal is voiced or silent, and line noise extraction means for extracting the frequency component of the line signal when the silence determination means determines silence as a line noise component,
A line noise component predicting unit that predicts line noise from the output of the line noise detecting unit and a line noise removing unit that removes the line noise component predicted by the line noise predicting unit from the line signal are configured.

[0008]

In the telephone receiver amplifying device according to the present invention having this structure, the line noise is calculated for each silent section and the frequency component thereof is subtracted from the output signal to adaptively extract and remove the line noise. is doing. Therefore, the line noise is reduced and good call voice can be obtained.

According to a second aspect of the present invention, there is provided a telephone receiver amplifying device,
Line noise is predicted from past line noise, and the predicted frequency component is subtracted. Therefore, it is possible to more accurately reduce the line noise, and it is possible to obtain good call voice with reduced line noise.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a telephone receiver amplifying apparatus of the present invention will be described in detail below with reference to the drawings. In the following sentences and figures, the same constituent elements shown in the previous FIG. 6 are designated by the same reference numerals.

FIG. 1 is a block diagram showing the configuration of the first embodiment of the telephone receiver amplification apparatus of the present invention. In FIG. 1, this example shows a subscriber circuit 1 for processing a telephone signal when receiving and transmitting through a public line of a public network, an amplifier 2 for amplifying an output signal from the subscriber circuit 1, and a subscriber. A speaker 3 that outputs the voice of the other party through the circuit 1 and the amplifier 2 and a silence determiner 4 that determines whether the output voice is voiced or not. Furthermore, a line noise component is extracted from the output signal by using the line noise extractor 5 that extracts the frequency component of the output signal that is determined to be silent by the silence determiner 4, and the line noise component signal obtained by the line noise extractor 5. A line noise eliminator 6 for eliminating is provided.

Next, the operation of the first embodiment will be described. First, the line signal Sa from the station line is sent to the subscriber circuit 1
Is converted into an output signal Sb. This output signal Sb
From this, the silence determiner 4 determines whether there is sound or silence. When the output signal Sb is silent, the silence determination signal Sf is output to the line noise extractor 5. Next, the line noise extractor 5 obtains a frequency component of the output signal Sb from the output signal Sb determined to be silent, for example, by fast Fourier transform, and uses this frequency component as a line noise component signal Se to remove the line noise remover. Output to 6. The line noise extractor 5 is the silence determiner 4
It operates only when the silence determination signal Sf is input from.
The line noise eliminator 6 obtains the frequency component of the output signal Sb by performing, for example, fast Fourier transform on the output signal Sb. The line noise eliminator 6 subtracts the line noise component signal Se from this frequency component, and outputs the result, for example, an inverse fast Fourier transformed voice signal Sc to the amplifier 2. Amplifier 2
The amplified audio signal Sd is output as audio from the speaker 3.

FIG. 2 is a diagram showing processed signals in the operation of the first embodiment. In FIG. 2, the line noise component signal Se shown in FIG. 2B and the frequency component of the output signal Sb are subtracted from the silent section and the voiced section of the output signal Sb of FIG. The audio signal Sc shown in is obtained. If there is no silent section from the beginning of the call and the line noise extractor 5 does not calculate the line noise component signal Se, the line noise remover 6 removes the line noise component by a preset initial value. To do. The audio signal Sc calculated by the line noise eliminator 6 is amplified into an amplified audio signal Sd by the amplifier 2 and input to the speaker 3.

As described above, in the first embodiment, the line noise is calculated and removed for each silent section. That is, since the line noise is adaptively extracted and removed, it is possible to listen to a good call voice without noise.

Next, a second embodiment will be described. FIG. 3 is a block diagram showing the configuration of the second embodiment. Figure 3
In this example, the subscriber circuit 1 is similar to the first embodiment.
An amplifier 2, a speaker 3, a silence determiner 4, a line noise extractor 5, and a line noise remover 6 are provided. In addition to this configuration, a line noise component predictor 7 that predicts line noise from the line noise component signal is provided.

Next, the operation of the second embodiment will be described. First, the output signal Sb from the subscriber circuit 1 is determined by the silence determiner 4 to be sounded or silent. When the output signal Sb is silent, the silence determination signal Sf is output to the line noise extractor 5. Next, the line noise extractor 5 obtains the frequency component of the output signal Sb by, for example, fast Fourier transforming the output signal Sb determined to be silent, and uses this frequency component as the line noise component signal Se. Output to. The line noise extractor 5 operates only when it receives the silence determination signal Sf from the silence determiner 4. The line noise component predictor 7 calculates a predicted line noise signal Sg from the line noise component signal Se. The predicted line noise signal Sg is calculated, for example, when there is a continuous silent section, and when the line noise component signal Se in this silent section is extracted, the power of this line noise component signal Se continuously increases. The predicted line noise signal Sg is amplified with a power higher than that of the actually extracted line noise component signal Se.

FIG. 4 is a diagram showing the line noise component signal Se and the predicted line noise signal Sg. Line noise eliminator 6
Of the output signal Sb shown in FIG.
(Fast Fourier transform is performed for each of frames 1 to 4 as shown in FIG. 4B to obtain the frequency component of the output signal Sb, and the line noise component signal Se shown in FIG.
Then, the predicted line noise signal Sg predicted by the line noise component predictor 7 is subtracted, and the result is subjected to, for example, inverse fast Fourier transform to obtain the speech signal Sc.

FIG. 5 is a diagram showing processed signals in the operation of the second embodiment. In FIG. 5, when the line noise extractor 5 does not calculate the line noise component signal Se from the beginning of the call with the output signal Sb shown in FIG. 5A, the line noise eliminator 6 is preset. The line noise component is removed based on the obtained initial value. The audio signal Sc calculated by the line noise eliminator 6 is amplified by the amplifier 2, and the amplified audio signal Sd is input to the amplifier 2. The amplified voice signal Sd from the amplifier 2 is output as voice through the speaker 3, and the voice of the other party is heard.

As described above, in the second embodiment, the line noise is predicted from the line noise in the past, and the frequency component is subtracted, so that the line noise can be more accurately reduced and a good communication voice can be obtained. .

[0020]

As is apparent from the above description, the telephone receiver amplifying apparatus according to the first aspect calculates the line noise for each silent section and subtracts the frequency component from the output signal. That is, since the line noise is adaptively extracted and removed, there is an effect that the line noise is reduced and good call voice can be obtained.

According to a second aspect of the present invention, there is provided a telephone receiver amplifying device,
Since line noise is predicted from past line noise and the predicted frequency component is subtracted, more accurate line noise can be reduced, and good call voice with reduced line noise can be obtained. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of a telephone receiver amplification apparatus of the present invention.

FIG. 2 is an explanatory diagram showing processed signals in the operation of the first embodiment.

FIG. 3 is a block diagram showing a configuration of a second embodiment.

FIG. 4 is an explanatory diagram showing a line noise component signal and a predicted line noise signal in the operation of the second embodiment.

FIG. 5 is an explanatory diagram showing processed signals in the operation of the second embodiment.

FIG. 6 is a block diagram showing a configuration of a conventional telephone receiver amplification apparatus.

[Explanation of symbols]

 1 subscriber circuit 4 silence determiner 5 line noise extractor 6 line noise remover 7 line noise component predictor Sa line signal Sb output signal Sc voice signal Sf silence determination signal Sd amplified voice signal Se line noise component signal Sg predicted line noise signal

Claims (2)

[Claims] 1. A silence determining means for determining whether a line signal is voiced or silent, and a line noise extracting means for extracting a frequency component of the line signal when the silence determining means determines that there is no sound as a line noise component. A telephone reception amplifier comprising: a line noise removing unit for removing the line noise component extracted by the line noise extracting unit from a line signal. 2. A silence determining means for determining whether the line signal is voiced or silent, and a line noise extracting means for extracting a frequency component of the line signal when the silence determining means determines silence as a line noise component. A telephone receiver amplification apparatus including line noise component predicting means for predicting line noise from the output of the line noise detecting means, and line noise removing means for removing the line noise component predicted by the line noise predicting means from a line signal. .