JPH08265893A - Microphone sensitivity adjustment device and communication equipment using the same - Google Patents

Abstract

PURPOSE: To provide the microphone sensitivity adjustment device in which excellent talking is always attained independently of a surrounding noise level. CONSTITUTION: A level of an output signal from a microphone 7 is controlled by a variable attenuator 22 of a microphone sensitivity adjustment section 19 and fed to a voice CODEC section 5. A level detector 24 detects an output signal level of a microphone 7 and its detection output SLD is fed to a microcomputer 8. The microphone 8 calculates the surrounding noise level based on a detection output SLD in the case of detection of an incoming call or dialing, and an attenuation (gain) of the variable attenuator 22 is controlled based on the surrounding noise level to adjust the microphone sensitivity. For example, when the surrounding noise level is 80dBm or over, the microphone sensitivity is decreased by 6dB. Thus, the level of the surrounding noise component is reduced and the S/N is improved allowing the user to make utterance in more or less louder voice and it becomes easier for the opposite party to hear the voice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microphone sensitivity adjusting device and a communication device using the same. Specifically, it relates to a microphone sensitivity adjusting device and a communication device using the microphone sensitivity adjusting device, which enables good transmission regardless of the ambient noise level by controlling the microphone sensitivity according to the ambient noise level. is there.

[0002]

2. Description of the Related Art Conventionally, portable telephones, which are capable of talking by being wirelessly connected to a base station, have been widely used.
By using such a mobile phone, the user can make a phone call anytime and anywhere in the service area, which is very convenient.

[0003]

In such a mobile phone, since it is possible to make a call anytime and anywhere, the following inconvenience may occur.

A place with a high ambient noise level (for example,
When making a call on the subway platform, the ambient noise is strongly introduced into the microphone that constitutes the transmitter. Therefore, the level of the ambient noise component of the output signal of the microphone increases, and it becomes difficult for the other party to hear the voice.

When the user makes a call in a place where the ambient noise level is low and the user needs to speak in a low voice (for example, a conference room or a theater), the level of the voice component of the output signal of the microphone is low, and the voice of the other party is low. Becomes difficult to hear.

[0006] Therefore, the present invention provides a microphone sensitivity adjusting device and a communication device using the microphone sensitivity adjusting device which can always perform good transmission regardless of the ambient noise level.

[0007]

A microphone sensitivity adjusting apparatus according to the present invention is a level control means for controlling the level of an output signal of a microphone, a noise level detecting means for detecting an ambient noise level, and this noise level detecting means. Gain control means for controlling the gain of the level control means in accordance with the ambient noise level detected in.

Further, the communication device according to the present invention includes level control means for controlling the level of the output signal of the microphone constituting the transmitter, noise level detection means for detecting the ambient noise level, and this noise level detection means. Gain control means for controlling the gain of the level control means in accordance with the ambient noise level detected in.

[0009]

The level of the output signal of the microphone is controlled by the level control means and becomes a transmission voice signal of the communication device, for example. The noise level detecting means detects the level of ambient noise using, for example, an output signal of a microphone. The gain of the level control means is controlled by the level control means according to the ambient noise level. The microphone sensitivity is adjusted by controlling the level of the microphone output signal by the level control means. For example, when the ambient noise level is equal to or higher than a predetermined value, the microphone sensitivity is lowered from the standard level. Further, for example, when the ambient noise level is below a predetermined value, the microphone sensitivity is raised above the standard level.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This example is a simple mobile phone (PH
S: Personal Handyphone System).

The simplified mobile phone of this embodiment has a radio section 2 for performing radio communication with a base station, a digital modulation / demodulation section 3 for performing modulation and demodulation processing of π / 4 shift QPSK, and a plurality of channels. A Time Division Multiple Access (TDMA) processing unit 4 for handling multiplexed signals in slots, a voice codec unit 5 for performing compression encoding and decoding of voice signals, and a micro as a system controller. It has a computer (hereinafter referred to as “microcomputer”) 8.

The signal from the base station received by the antenna 1 is supplied to the digital modulation / demodulation unit 3 via the radio unit 2 and subjected to π / 4 shift QPSK demodulation processing. The signal demodulated by the digital modulation / demodulation unit 3, that is, the time division multiplexed signal of slots for a plurality of channels is supplied to the TDMA processing unit 4. In the TDMA processing unit 4, under the control of the microcomputer 8, a preset slot is selected from a multiplexed signal of slots for a plurality of channels, and compressed audio data and control data are separated from the selected slot.

The control data output from the TDMA processing unit 4 is supplied to the microcomputer 8. In addition, the TDMA processing unit 4
The compressed audio data output by the above is supplied to the audio codec section 5 and subjected to decoding processing (including error correction processing) and then converted into an analog signal. Then, the received audio signal output from the audio codec unit 5 is supplied to the speaker 6 that constitutes the receiver via the amplifier 18.

Further, the transmission voice signal output from the microphone 7 constituting the transmitter is supplied to the voice codec unit 5 via the microphone sensitivity control unit 19 and subjected to compression coding processing (including error correction coding processing). Is done after TDMA
It is supplied to the processing unit 4. In the TDMA processing unit 4, the compressed audio data supplied from the audio codec unit 5 is time-division multiplexed as a preset slot. In this case, the control data output from the microcomputer 8 is also multiplexed in that slot. The signal multiplexed by the TDMA processing unit 4 is supplied to the digital modulation / demodulation unit 3 to generate π / 4.
Shift QPSK modulation processing is performed. The modulated signal output from the digital modulation / demodulation unit 3 is supplied to the antenna 1 via the wireless unit 2 and transmitted to the base station.

Even if not mentioned above, when entering the area of a predetermined base station in the power-on state, wireless communication is performed with the base station, and the location registration of being in the area of the base station is performed. This position registration is performed using the communication frequency and slot position determined as the control channel. In this case, the transmission / reception frequency of the radio unit 2 and the position of the slot selected by the TDMA processing unit 4 are controlled so as to match the communication frequency and slot position of the control channel, respectively. After the location registration, the control channel is controlled to stand by in the reception state on the control channel. In addition, the transmission and reception of the above-mentioned audio signal is performed using a communication channel as described later.

Further, the simple type portable telephone of this example is a DTM.
F (Dual Tone Multiple Frequency) signal to "*",
The DTMF demodulation unit 9 for converting into key data corresponding to the special input key of "#" and the numeric keypad of "0" to "9", the received voice signal is recorded in the answering machine mode, and the recorded reception voice signal or pre-recorded voice signal is recorded. A voice recording / playback unit 10 for playing back a recorded response message (voice signal) by operating a key input unit, which will be described later, or by controlling the microcomputer 8, and a ringing tone by the control of the microcomputer 8 when an incoming call is detected. And a conversion format storage unit 17 for converting key data corresponding to the DTMF signal into character data. The ringing tone output unit 11 is configured to have a speaker, a buzzer, and the like.

The DTMF demodulation unit 9 includes a voice codec unit 5
The received voice signal obtained by the decoding processing is supplied. When the received voice signal is a DTMF signal, DTMF
The demodulation unit 9 outputs key data (hereinafter referred to as “reception data”) corresponding to the DTMF signal, and this reception data is supplied to the microcomputer 8. Thereby, the microcomputer 8 can recognize that the received voice signal is the DTMF signal.

The voice recording / reproducing unit 10 is constituted by including, for example, a semiconductor memory as a voice signal storage means. The operation of the voice recording / reproducing unit 10 is controlled by the microcomputer 8, and the voice recording / reproducing unit 10 supplies a signal indicating the operation state to the microcomputer 8. The voice recording / reproducing unit 10 records the received voice signal when the voice recording / reproducing mode is set by the operation of the key input unit described later.

At a predetermined address of the semiconductor memory of the voice recording / reproducing unit 10, a response message (voice signal) to be transmitted to the calling side in the voice recording mode is recorded in advance. Microcomputer 8
The response message reproduced by the voice recording / reproducing unit 10 under the control of the
The same processing as that of the voice signal output from the antenna 1 is performed and transmitted from the antenna 1 to the base station.

Further, in the simple type portable telephone of this example, the microcomputer 8 is provided with a cursor movement key, a numeric keypad for inputting a telephone number or the like, a special input key, a mode setting key for setting an answering mode, and a voice recording. A key input unit 12 in which operation keys and the like for operating the reproduction operation and the like of the reproduction unit 10 are arranged,
Call key 13 for switching from the on-hook state to the off-hook state or vice versa, the display unit 14 for displaying the telephone number of the other party at the time of calling, the state of the system, the transmitted text message, etc. A non-volatile memory 16 for storing information, character message data transmitted from the other party, etc. is connected.

In the above configuration, the telephone number of the other party is input by the key operation of the key input unit 12 and then the call key 13
When is pressed, first, the telephone number data or the like is supplied as control data from the microcomputer 8 to the TDMA processing unit 4 and transmitted to the base station through the control channel. As a result, a line connection is established with the other party and a call is possible.

Here, the call is performed using the call channel, but during the line connection processing, the control channel is used to transmit the communication frequency and slot position data of the call channel from the base station as control data to perform the TDMA processing. It is supplied from the unit 4 to the microcomputer 8. The microcomputer 8 controls the radio unit 2 based on the communication frequency data so that the transmission / reception frequency matches the communication frequency of the communication channel, and sets the slot selected by the TDMA processing unit 4 based on the slot position data. To do. Therefore, the call is made using the call channel notified from the base station.

When the base station transmits call data as control data using the control channel, and the call data is supplied from the TDMA processing unit 4 to the microcomputer 8 and an incoming call is detected, the microcomputer 8 issues a ring tone. Output unit 11
Is controlled to output the ringing tone. When a response is made by pressing the call key 13 while the calling operation is being performed, the response data is supplied from the microcomputer 8 to the TDMA processing unit 4 as control data and transmitted to the base station through the control channel. As a result, a line connection is established with the other party and a call is possible. Also in this case, the call is made using the call channel notified from the base station. As described above, the control channel is used when call data is transmitted from the base station as control data. Since the call data has identification data such as telephone number data, the microcomputer 8 You can recognize that this is the call data for yourself.

Further, as described above, the calling data is TDM.
In the case where the incoming call is detected by being supplied to the microcomputer 8 from the A processing unit 4, when the answering machine mode is set, the ringing tone is output for a predetermined time and then the call is automatically answered to enable the call. . Then, after the response message indicating that the received voice signal is recorded is transmitted to the calling side, the voice recording / reproducing unit 1
At 0, the recording of the received voice signal is started.

When the other party sends character message data by a DTMF signal during voice recording or during a call, the received data output from the DTMF demodulation unit 9 is stored in a conversion format under the control of the microcomputer 8. The character data is converted into character data by referring to the section 17, the character data is written in the character message area of the non-volatile memory 16, and the character message based on the character data is displayed on the display section 14.

FIG. 2 shows the configuration of the microphone sensitivity adjusting section 19 described above. In the figure, the output signal of the microphone 7 is supplied to the audio codec unit 5 via a series circuit of a microphone amplifier 21, a variable attenuator 22 and a buffer amplifier 23. The variable attenuator 22 constitutes level control means. Further, the output signal of the microphone amplifier 21 is a level detector 24 which constitutes noise level detecting means.
Is supplied to. The level detector 24 is composed of, for example, a rectifying / smoothing circuit. The detection output SLD of the level detector 24 is A /
The digital signal is converted by the D converter 25 into the microcomputer 8
Is supplied to.

The microcomputer 8 calculates the ambient noise level based on the detected output SLD when an incoming call is detected or a call is made, as will be described later. In this case, for example, a conversion table that stores the relationship between the detected output SLD and the ambient noise level is used. Then, the attenuation amount (gain) of the variable attenuator 22 described above is controlled by the microcomputer 8 based on the ambient noise level, and the microphone sensitivity (sending sensitivity) is adjusted.

FIG. 3 is a flow chart showing the operation of adjusting the microphone sensitivity by the microcomputer 8.

When an incoming call is detected or a calling operation is performed in step ST1, the ambient noise level is calculated based on the detection output SLD of the level detector 24 in step ST2. Then, in step ST3, the ambient noise level is 8
It is determined whether it is 0 dBm or more. Here, the threshold value is set to 80 dBm in consideration of, for example, that the noise level of the subway platform is 80 dBm or more. dBm is a logarithm (l) based on 1 mW (milliwatt)
The dBm value, which is a unit of the power level represented by (og), is calculated by the equation (1).

DBm value = 10 × log (power at that time / 1 mW) (1) When the ambient noise level is 80 dBm or more in step ST3, the attenuation amount (gain) of the variable attenuator 22 is determined in step ST4. It is larger than the standard value, and the microphone sensitivity, that is, SPL (sound pressure level) is lowered by 6 dB from the standard level (60 dB) by 5 dB.
Adjust to 4 dB. Then, the process proceeds to step ST5.

When the ambient noise level is not higher than 80 dBm in step ST3, it is determined in step ST6 whether the ambient noise level is 40 dBm or lower. Here, the threshold is set to 40 dBm in consideration of the noise level of 40 dBm or less in, for example, a conference room or a theater. When the ambient noise level is 40 dBm or less in step ST6, the attenuation amount (gain) of the variable attenuator 22 is made smaller than the reference value in step ST7, and the microphone sensitivity (SPL) is set to the standard level (60d).
Increase by 6 dB from B) and adjust to 66 dB. Then, the process proceeds to step ST5.

In step ST5, it is determined whether or not the call state has ended and the line has been disconnected. When the line is disconnected, the attenuation amount (gain) of the variable attenuator 22 is returned to the reference value in step ST8, and the microphone sensitivity (SP
L) is returned to the standard level (60 dB), and the adjustment operation ends.

When the ambient noise level is not less than 40 dBm in step ST6, 40 dBm <ambient noise level <80 dBm, so the attenuation amount (gain) of the variable attenuator 22 is kept at the reference value and the microphone sensitivity (SPL) is set. The adjustment operation ends without adjusting.

According to this example, the ambient noise level is 80 dB.
When it is m or more, the microphone sensitivity (SPL) is lowered by 6 dB from the standard level. Therefore, when making a call in a place where the ambient noise level is 80 dBm or more, the microphone sensitivity adjustment unit 19 supplies the audio codec unit 5 with the microphone. The level of the ambient noise component of the transmitted voice signal becomes small. Therefore, if the user speaks in a slightly loud voice, S /
N can be increased, and the other party can easily hear the voice.

When the ambient noise level is 40 dBm or less, the microphone sensitivity (SPL) is increased by 6 dB from the standard level, so that the ambient noise level is 40 dB.
When making a call in a place where it is necessary to speak in a small voice at dBm or less, the level of the voice component of the transmission voice signal supplied to the voice codec unit 5 from the microphone sensitivity adjusting unit 19 can be increased, and the other party can hear the voice. It will be easy.

Further, according to this example, the microphone sensitivity is adjusted by calculating the ambient noise level at the time of detecting an incoming call or making a call, so that the ambient noise level can be adjusted without being affected by the user's voice or the like. It can be detected and the microphone sensitivity can be adjusted well. Further, since the microphone sensitivity adjustment by controlling the attenuation amount (gain) of the variable attenuator 22 is performed only at the time of detecting an incoming call or making a call, it is possible to suppress the consumption of the battery as compared with the case of continuously adjusting the microphone sensitivity. You can Further, since the ambient noise level is detected using the output signal of the microphone 7, it can be constructed at a lower cost than that which detects the ambient noise level by other means.

The threshold values (80 dBm, 40 dBm) and the adjustment amount (6 dB) of the ambient noise level at which the microphone sensitivity (SPL) is adjusted in the above embodiment are merely examples, and the present invention is not limited to these. . For example, the adjustment amount may be changed according to the ambient noise level. Further, in the above embodiment, the ambient noise level is 8
The microphone sensitivity is lowered by 6 dB when it is 0 dBm or more, and the microphone sensitivity is raised by 6 dB when the ambient noise level is 40 dBm or less. May be adjusted, or ultimately the microphone sensitivity may be adjusted continuously. Further, in the above embodiment, the variable attenuator 22 is used as the level control means, but a variable gain amplifier or the like can be used instead of this.

In the above embodiment, the ambient noise level is detected by processing the output signal of the microphone 7, but the ambient noise level may be detected by other means. With the configuration in which the ambient noise level is detected without using the output signal of the microphone 7, it becomes possible to detect the ambient noise level without being influenced by the speaking voice even in a call state, and there is a benefit that the microphone sensitivity can be adaptively adjusted. is there.

Further, although the above-described embodiments apply the present invention to a simple type portable telephone (PHS), it goes without saying that the present invention can be similarly applied to other telephones and communication devices such as transceivers.

[0040]

According to the present invention, the microphone sensitivity is adjusted by controlling the level of the output signal of the microphone according to the ambient noise level, and good speech transmission is possible regardless of the ambient noise level. There are benefits. For example, when the ambient noise level is equal to or higher than a predetermined value, the microphone sensitivity is lowered to reduce the level of ambient noise components, and the user can increase the S / N ratio by speaking in a slightly loud voice. Will be easier to hear. Further, for example, by increasing the microphone sensitivity when the ambient noise level is equal to or lower than a predetermined value, the level of the voice component can be increased even if the user speaks in a small voice, and the other party can easily hear the voice.

[Brief description of drawings]

FIG. 1 is a system diagram showing a simplified mobile phone as an embodiment of the present invention.

FIG. 2 is a system diagram showing a configuration of a microphone sensitivity adjusting unit.

FIG. 3 is a flowchart showing a microphone sensitivity adjustment operation.

[Explanation of symbols]

 1 Antenna 2 Radio Section 3 Digital Modulation / Demodulation Section 4 TDMA Processing Section 5 Voice Codec Section 6 Speaker 7 Microphone 8 Microcomputer 19 Microphone Sensitivity Adjustment Section

Claims (8)

[Claims] 1. A level control means for controlling the level of an output signal of a microphone, a noise level detecting means for detecting an ambient noise level, and the level according to the ambient noise level detected by the noise level detecting means. A microphone sensitivity adjusting device, comprising: a gain control means for controlling a gain of the control means. 2. The gain control means lowers the gain of the level control means below a reference value when the ambient noise level detected by the noise level detection means is equal to or higher than a predetermined value. Microphone sensitivity adjustment device described. 3. The gain control means increases the gain of the level control means above a reference value when the ambient noise level detected by the noise level detection means is below a predetermined value. Microphone sensitivity adjustment device described. 4. When the ambient noise level detected by the noise level detecting means is less than or equal to a first value, the gain control means increases the gain of the level control means above a reference value and the first value The microphone sensitivity adjusting device according to claim 1, wherein the gain control means lowers the gain of the level control means below the reference value when the second value is larger than the second value. 5. A level control means for controlling a level of an output signal of a microphone constituting a transmitter, a noise level detecting means for detecting an ambient noise level, and an ambient noise level detected by the noise level detecting means. And a gain control unit that controls the gain of the level control unit according to the above. 6. The gain control means lowers the gain of the level control means below a reference value when the ambient noise level detected by the noise level detection means is equal to or higher than a predetermined value. The listed communication device. 7. The gain control means increases the gain of the level control means above a reference value when the ambient noise level detected by the noise level detection means is below a predetermined value. The listed communication device. 8. When the ambient noise level detected by the noise level detecting means is less than or equal to a first value, the gain control means increases the gain of the level control means above a reference value, and the first value 6. The communication device according to claim 5, wherein the gain control means lowers the gain of the level control means below the reference value when the second control value is larger than the second value.