JP3234044B2 - Voice communication device and reception control circuit thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice communication apparatus used in a mobile communication system such as a portable / mobile telephone system and a cordless radio telephone apparatus, and a reception control circuit therefor.

[0002]

2. Description of the Related Art Generally, a portable voice communication device such as a portable telephone or a cordless radio telephone uses a battery as a power supply, and the miniaturization of the battery is important in reducing the size and weight of the device. It has become a challenge. In order to reduce the size of the battery, it is important not only to improve the battery itself but also to reduce the power consumption of the device.

As a part of the power saving, a transmitting circuit is operated to transmit an audio signal only during a section where a speaker is uttering during a call (a sound section), and a standby section (a silent section) between utterances. Has proposed a method of stopping the operation of the transmission circuit.

However, in a device to which this control method is applied, since a silent section is generated during a call, a disadvantage arises in that the natural life of the call is impaired in the receiving system circuit, making it difficult to hear the voice of the other party. . Therefore, some conventional devices of this type detect a voiced section or a silent section of an input voice signal as a function of a reception system circuit, output an input voice signal in a voiced section, and output a speech section in a voiceless section. Was configured to output pseudo background noise.

FIG. 8 shows a main part of a receiving system circuit of a conventional voice communication apparatus which employs this kind of pseudo background noise insertion method, and includes a decoder 81 and a pseudo noise generation circuit 8.
2. It is composed of a pseudo noise control circuit 83 and a selector 84. This circuit corresponds to a functional circuit portion which demodulates an audio signal (ADPCM data) output from a receiver at a preceding stage into PCM data by a decoder 81 and outputs the demodulated signal to a PCM decoder at a subsequent stage.

In this circuit, first, an audio signal (ADPCM data) from the transmitting side, which is received and demodulated by a receiver, is taken into a pseudo noise control circuit 83, and a sound section or a silent section is extracted. And when the audio signal is sound,
The selector 84 is switched to the decoder 81 by the pseudo noise control circuit 83, and the output of the decoder 81 is set to A
In addition to the output to the DPCM decoder, when the audio signal is silent, the pseudo noise control circuit 83 switches the selector 84 to the pseudo noise generation circuit 82 side and outputs the pseudo background noise generated from the pseudo noise generation circuit 82 to A
Operate to output to DPCM decoder.

In such a conventional apparatus, the pseudo background noise output in the silent section and the ambient noise related to the actual call do not usually have any causal relationship. When there is a remarkable difference between the background noise and the pseudo background noise, the receiver hears the received voice that is quite uncomfortable when demodulating the pseudo background noise.

FIG. 9 shows an example of output characteristics of a received voice in the conventional apparatus. In a silent section (pseudo-background noise transmission section), a certain level of extremely unnatural pseudo-background noise is output. You can see how it looks.

[0009]

As described above, in the above-described conventional voice communication apparatus, pseudo background noise irrelevant to actual background noise is output only in a silent section of the voice signal. However, if there is a difference between the actual background noise and the pseudo background noise included in the received sound, there is a problem that the received voice heard by the receiver gives a remarkable discomfort.

[0010] The present invention eliminates the above-mentioned problems, and even when there is a difference between the actual background noise and the pseudo background noise included in the input audio signal, a voiced section and a silence are not generated when the audio signal is received and reproduced. It is an object of the present invention to provide a voice communication device capable of smoothing switching of sections to reduce discomfort in a received voice and thereby maintaining good communication quality, and a reception control circuit therefor.

[0011]

In order to achieve the above object, a first aspect of the present invention is to transmit only a voiced section of an input voice signal and to receive and reproduce the transmitted voice signal of only the voiced section. In the voice communication device to perform, noise generating means for generating pseudo background noise, noise level adjusting means for adjusting the output level of the pseudo background noise, identification means for identifying a sound section and a silent section of the received voice signal, Based on the identification result of the identification means, a pseudo background noise from the noise level adjusting means is reproduced in a silent section of the received audio signal, and the noise level is added to the received audio signal in a sound section of the received audio signal. While controlling so that the pseudo background noise from the adjusting means is superimposed and reproduced,
Control means for variably controlling the output level of the pseudo background noise to be superimposed on the received audio signal in accordance with the audio level of the audio signal in the audio section, by controlling the noise level adjusting means in the audio section. It is characterized by having. Also, a second invention is a reception control circuit for sending a received audio signal to an audio reproduction means, a noise generation means for generating pseudo background noise, a noise level adjustment means for adjusting an output level of the pseudo background noise, Identification means for identifying a sound section and a silent section of the received audio signal; and, based on the identification result of the identification means, a pseudo background noise from the noise level adjustment means in the audio section of the received audio signal. To the voiced section of the received voice signal, and superimposes the pseudo background noise from the noise level adjusting means on the received voice signal and outputs the resultant to the voice playback means. Controls the noise level adjusting means to change the output level of the pseudo background noise superimposed on the received audio signal to the audio level of the audio signal in the sound section. Characterized by comprising a noise output control means for variably controlled in accordance with Le.

[0012]

According to the present invention, pseudo background noise is reproduced in both a silent section and a sound section of a received voice signal, and the output level of the pseudo background noise superimposed on the received voice signal in the voice section is determined by the reception voice of the voice section. It is provided with a function of variably controlling according to the audio level of the signal. According to this configuration, even if there is a difference in timbre between the actual background noise and the pseudo background noise included in the audio signal at the time of input, the pseudo-background not only in the silence section but also in the sound section is received on the receiving and reproducing side. Since the noise is superimposed and reproduced, an unnatural change in voice at the time of switching between a sound section and a silent section can be reduced. Further, since the output level of the pseudo background noise superimposed on the received voice signal in the voiced section is variably controlled in accordance with the voice level of the received voice signal in the voiced section, the output level of the voice signal in the voiced section is sharp When the level is lowered,
It is possible to reduce a phenomenon that only the pseudo background noise is heard loudly and becomes harsh.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the overall configuration of a voice communication apparatus to which a pseudo background noise insertion method according to the present invention is applied, wherein FIG. 1 (a) shows a transmission system circuit, and FIG. 1 (b) shows a reception system. It corresponds to the circuit.

In FIG. 1A, a transmission system circuit 10 comprises:
It comprises a microphone 11, a PCM encoder 12, a coder 13, a transmitter 14, an antenna 15, a sound / silence detection unit 16, and a frequency characteristic detection circuit 17.

In FIG. 1B, the receiving circuit 3
0 indicates an antenna 31, a receiver 32, a decoder 33, a pseudo noise adjuster 34, an adder 35, a PCM decoder 36,
A speaker 37 is provided.

FIG. 2 shows an embodiment of the pseudo-noise adjusting unit 34 in the receiving circuit shown in FIG. 1B, which comprises a pseudo-noise control circuit 341 and a pseudo-noise generating circuit 342. ing.

Hereinafter, the communication operation of the voice communication device according to this embodiment will be described. In FIG. 1A, a transmission voice from a transmitter is converted into a voice signal by a microphone 11, and further,
After being converted into a PCM code by the CM encoder 12, the coder 13, the sound / silence detecting unit 16, the frequency characteristic detecting unit 1
7 is input.

The coder 13 converts PCM code data input from the PCM encoder 12 into ADPCM (AdPCM) data.
aptive Differential Pulse Code Modulation) and outputs it after compression encoding.

The transmitter 14 modulates a carrier with the ADPCM data, and transmits the obtained radio carrier signal from the antenna 15 to a radio line.

The sound / non-speech detector 16 monitors the signal level of the PCM code data input from the PCM encoder 12 to detect the start and end of the voice signal input from the sender. Then, the power supply to the transmitter 14 is turned off and the transmission operation is stopped during a period (silent section) from the detection of the end to the detection of the start.

When the sound / silence detecting section 16 detects the start end, it generates transmission start information at that time, supplies this information to the transmitter 14 and sends it out to the radio line. Further, when the termination is detected, transmission stop notice information is generated, and this information is supplied to the transmitter 14 and transmitted to the wireless line. According to the above control, the transmission system circuit 10 can realize control of extracting and transmitting only the sound portion of the input audio signal.

On the other hand, in FIG.
0, the radio carrier signal transmitted from the transmission system circuit 10 is received by the antenna 31 as described above,
To demodulate into ADPCM data and output.

The received data is transmitted to the transmission circuit 10 described above.
Includes the audio data and the control data (transmission start information and transmission stop notice information) by the transmission processing in. The audio data among them is input to the decoder 33, while the control data is input to the pseudo noise adjusting unit 34. You. The pseudo noise adjusting unit 34 and the peripheral circuits are configured as shown in FIG. 2 as described above.

In FIG. 2, a decoder 33 expands input audio data (ADPCM data) into PCM data and outputs the PCM data to an adder 35. On the other hand, the pseudo noise adjusting unit 3
In step 4, the control data input from the receiver 32 is captured by the pseudo noise control circuit 341.

The pseudo noise control circuit 341 controls, as its components, a notice information detecting unit for detecting notice information relating to the transmission processing in the transmission system circuit 10 described above, and a pseudo noise generation circuit 342 based on the detection result. And a control unit that performs the control.

The notice information detector detects transmission start information and transmission stop notice information in the control data input from the receiver 32. The control section detects a sound section and a silent section of the received voice signal based on the detection result of the notice information detection section. Then, in the present invention, this control unit controls the pseudo noise generation circuit 342 to generate pseudo background noise in both the sounded section and the silent section.

In the silent section according to this control, no audio data is output from the decoder 33.
The pseudo background noise output from the pseudo noise generation circuit 342 is simply output to the PCM decoder 36 at the subsequent stage through the adder 35.

On the other hand, in the sound section, the decoder 33
At this time, the pseudo background noise output from the pseudo noise generation circuit 342 is added to the audio data by the adder 35 at this time, and the PCM at the subsequent stage is added.
This is output to the decoder 36.

PCM decoder 36 (see FIG. 1B)
Decodes the pseudo background noise input from the adder 35 and the superimposed signal of the pseudo background noise and the audio data, and reproduces and outputs the reproduced signal from the speaker 37.

As described above, the present invention not only outputs pseudo background noise when the audio signal sent from the transmission side is silent, but also superimposes the pseudo background noise on the audio signal when the audio signal is sound. It is intended to be sent.

According to the control of the present invention, a received voice having output characteristics as shown in FIG. 4 can be obtained, and the difference between the actual background noise and the pseudo background noise contained in the input voice signal is obtained. Even if there is, the switching from silence to sound can be performed naturally, and the discomfort of the received voice received by the receiver can be reduced.

The above-described embodiment is an example in which pseudo background noise of a constant level is always output over a sound section and a silent section of a received voice signal. The level of the pseudo background noise may be variable.

FIG. 3 shows a main configuration of a receiving system circuit of a voice communication apparatus according to another embodiment of the present invention. The difference from the previous embodiment is that the pseudo noise adjusting section 34 is a pseudo noise adjusting section. The point is that a level adjusting circuit 343 is further provided in addition to the control circuit 341 and the pseudo noise generating circuit 342.

In the receiving system circuit of this embodiment, audio data in ADPCM data sent from the transmitting system circuit 10 is input to the decoder 33, and control data is input to the pseudo noise control circuit 341.

As described above, the pseudo noise control circuit 341 discriminates a sound section and a silent section of the ADPCM data from the control data, and generates the pseudo noise generation circuit 34 in both sections.
2 to output pseudo background noise.

At the same time, the pseudo noise control circuit 341
Supplies a control signal to the level adjustment circuit 343 to variably control the level of the pseudo background noise output from the pseudo noise generation circuit 342 as appropriate.

As a method of controlling the level of the pseudo background noise, for example, a method of lowering the level of the pseudo background noise in the sound section of the received voice signal than the level of the pseudo background noise in the silent section can be considered. FIG. 5 shows the output characteristics of the received voice obtained based on this method. As can be seen from this figure, according to this method, when the level of the audio signal is low, it is possible to prevent the superimposed pseudo background noise from making the audio itself difficult to hear.

As another method of controlling the level of the pseudo noise, a method of gradually changing the level of the pseudo background noise when shifting from a silent section to a sound section or from a sound section to a silent section can be considered. FIG. 6 shows the output characteristics of the received voice obtained based on this method. As can be seen from the figure, according to this method, since the pseudo background noise shows a gradual change at a sound or silence section change point, even when the level of the pseudo background noise is relatively large, It is possible to further reduce the discomfort of the received voice due to the section switching.

As another method of controlling the level of the pseudo noise, a method of variably controlling the level of the pseudo background noise to be superimposed on the audio data in the sound section in accordance with the audio level of the audio data can be considered. FIG. 7 shows the output characteristics of the received voice obtained based on this method. According to this method, it is possible to prevent only the superimposed pseudo background noise from being noticeable and annoying when the sound level fluctuates during a sound interval, for example, when the level is sharply lowered, and a higher quality call can be performed. realizable.

While the representative embodiment has been described above,
It goes without saying that the present invention can be further modified or applied without departing from the spirit thereof.

[0041]

As described above, according to the present invention,
The pseudo background noise is reproduced in both the silent section and the sound section of the received voice signal, and the output level of the pseudo background noise superimposed on the received voice signal in the voice section is changed according to the voice level of the received voice signal in the voice section. Because of the variable control, even if there is a difference in timbre between the actual background noise and the pseudo background noise included in the audio signal at the time of input,
On the receiving and reproducing side, pseudo background noise is superimposed and reproduced not only during the silence section but also during the speech section, so that unnatural voice change at the time of switching between the speech section and the silence section can be mitigated, and It is possible to reduce the sense of incongruity of the received voice. Further, in the present invention, the output level of the pseudo background noise superimposed on the received voice signal in the voiced section is variably controlled according to the voice level of the received voice signal in the voiced section. When the level of the signal suddenly drops, the phenomenon that only the pseudo background noise is heard loudly and is unpleasant can be reduced, and the received voice with higher quality can be reproduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a voice communication device according to an example of the present invention.

FIG. 2 is a diagram showing an embodiment of a pseudo noise adjusting unit of the voice communication device according to the present invention.

FIG. 3 is a diagram showing another embodiment of the pseudo noise adjusting unit of the voice communication device according to the present invention.

FIG. 4 is a diagram showing an example of output characteristics of a received voice when the pseudo noise adjustment unit shown in FIG. 2 is used.

FIG. 5 is a diagram showing an example of output characteristics of a received voice when the pseudo noise adjustment unit shown in FIG. 3 is used.

FIG. 6 is a diagram showing another example of the output characteristic of the received voice when the pseudo noise adjustment unit shown in FIG. 2 is used.

FIG. 7 is a diagram showing still another example of the output characteristics of the received voice when the pseudo noise adjustment unit shown in FIG. 2 is used.

FIG. 8 is a diagram showing an example of a pseudo noise adjustment unit of a conventional voice communication device.

FIG. 9 is a diagram showing output characteristics of a received voice in a conventional voice communication device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 transmission system circuit 11 microphone 12 PCM encoder 13 coder 14 transmitter 15 antenna 16 sound / silence detection unit 17 frequency characteristic detection circuit 30 reception system circuit 31 antenna 32 receiver 33 decoder 34 pseudo noise adjustment unit 341 pseudo noise control circuit 342 Pseudo noise generation circuit 343 Level adjustment circuit 35 Adder 36 PCM decoder 37 Speaker

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-254539 (JP, A) JP-A-5-83208 (JP, A) JP-A-6-29935 (JP, A) JP-A-5-29935 136746 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 14/04-14/06 H04B 7/26 H04Q 7/38

Claims (3)

(57) [Claims] 1. An audio communication apparatus for transmitting only a sound section of an input audio signal and receiving and reproducing the transmitted sound signal of only the sound section, wherein: a noise generating means for generating pseudo background noise; Noise level adjusting means for adjusting the output level of the pseudo background noise; identifying means for identifying a sound section and a silent section of the received audio signal; based on the identification result of the identifying means, The pseudo-background noise from the noise level adjusting unit is reproduced, and in the sound section of the received audio signal, the pseudo-background noise from the noise level adjusting unit is superimposed on the received audio signal and reproduced. In the sound period, the output level of the pseudo background noise superimposed on the received audio signal is controlled by controlling the noise level adjusting means. Voice communication device characterized by comprising a control means for variably controlled in accordance with the audio level of the audio signal segment. 2. A reception control circuit for sending a received audio signal to an audio reproducing unit, wherein: a noise generating unit for generating pseudo background noise; a noise level adjusting unit for adjusting an output level of the pseudo background noise; Identification means for identifying a voiced section and a silent section of the speech signal, based on the identification result of the identification means, outputs a pseudo background noise from the noise level adjustment means to the audio reproduction means in a silent section of the received audio signal. And performing control to superimpose the pseudo background noise from the noise level adjusting means on the received sound signal in the sound section of the received sound signal and output the superimposed background noise to the sound reproducing means. The output level of the pseudo background noise superimposed on the received audio signal is controlled by controlling the level adjusting means. Reception control circuit, characterized by comprising a noise output control means for variably controlled in accordance. 3. The sound reproducing means includes a decoding means, and the noise output control means includes a pseudo background from the noise level adjusting means in a silent section of the received sound signal based on an identification result of the identification means. Outputting noise to the decoding unit, superimposing pseudo background noise from the noise level adjustment unit on the received audio signal in a sound section of the received audio signal, and outputting the superimposed noise to the decoding unit. The reception control circuit according to claim 2.