JP2002051111A - Communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication terminal which can prevent nonconformities in sound, generation of echoes, and howling, even if conversation option equipment is used. SOLUTION: A plurality of voice quality modes are prepared, in response to conversation option equipment. Data stored in a ROM 6 are read, and the data are used by a central processing section 4 for controlling a digital equalizer 8, a noise compressor 9, a volume 10, an echo canceller 11, and a side tone adding circuit 12, to control the voice quality of conversation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal such as a portable telephone, and more particularly to a sound quality adjusting function.

[0002]

2. Description of the Related Art Hitherto, adjustment of sound quality of a communication terminal has been mostly one type. An example of a communication terminal equipped with a function that allows a user to select sound quality is “Japanese Patent Application No. 11-31676” by the present applicant. This is a digital voice when the other party's voice is difficult to hear due to the mutual communication environment (quiet, under noise), the line used, the model used by the other party, the loudness and quality of the other party's voice, or this voice is difficult to transmit accurately. Using a processing technique, the user can arbitrarily select the sound quality and volume of the received voice and the sound quality of the transmission signal by operating a button during a call, and the call can be satisfactorily performed.

[0003]

However, in the communication terminal reported in Japanese Patent Application No. 11-31676, the change in sound quality is based on the premise that the telephone call uses the receiving speaker and the transmitting microphone of the communication terminal itself. When other devices are used (an earphone microphone, a hands-free kit, etc.), it is expected that the sound quality mode cannot be adapted to those sound quality characteristics in many cases. The present invention has been made in view of the above points, and has as its object to provide a communication terminal capable of preventing inconsistency in sound quality, echo, and howling even when a call optional device is used. .

[0004]

A communication terminal according to the present invention is characterized in that the speech quality can be adjusted, and that the communication terminal has a plurality of speech quality modes corresponding to optional speech equipment. Examples of the optional call device include an earphone microphone and a hands-free kit.

[0005] A communication terminal according to the present invention has an earphone detection circuit, a hands-free detection circuit, and a digital signal processing unit.
Digital equalizer inside the digital signal processing unit,
Noise suppression circuit, volume adjustment unit, echo removal circuit,
It is characterized in that it has side tone addition circuits, and controls them by a central processing unit during a call to set a sound quality mode corresponding to a call optional device to be used.

The communication terminal of the present invention is characterized in that when the use of the earphone microphone is detected by the earphone detection circuit, the sound quality mode is set to the earphone sound quality mode. The communication terminal of the present invention is characterized in that when the use of the hands-free kit is detected by the hands-free detection circuit, the sound quality mode is set to the hands-free kit sound quality mode.

[0007] The data for adjusting the speech sound quality includes frequency characteristics,
These are noise suppression, echo removal, and sidetone addition, and the communication terminal of the present invention stores these data in a memory and reads out the data for each call optional device used. Control for shifting to various sound quality modes is performed for transmission and reception.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a communication terminal according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a block diagram showing a mobile phone according to an embodiment of the present invention, and FIG. 2 is a flowchart for explaining the embodiment of the present invention. In the present embodiment, an earphone microphone, which is used in a headphone stereo or the like and is attached to the ear, and which is provided with a microphone, is referred to as an “earphone microphone”. The receiving speaker is larger than the earphone microphone. The one that listens to the sound in the open air is called a "hands-free kit."

An object of the present embodiment is to eliminate sound quality dissatisfaction felt by a user during a call. This dissatisfaction with the sound quality can be caused by the fact that the other party's voice is muffled or that it is difficult to understand the contents of the call due to the other party's telephone line or environment, or vice versa. Occurs when not playing. In the former case, it is only necessary to use a setting in which the voice component is emphasized and other noise components and the like are weakened, and this can be realized by setting the frequency characteristic to a narrow band treble emphasis type and strongly applying noise suppression. The latter can be solved by providing a setting that allows all sounds to be heard naturally, and can be realized by making the frequency characteristics flat in a wide band so that noise suppression is weakened or not suppressed at all. This setting is called “sound quality mode”.

[0010] There is a difference in "call optional equipment" which is one of the causes of dissatisfaction in sound quality. Explaining in a specific case, it is assumed that when it is difficult to reproduce a certain audio band by the receiving speaker of the communication terminal body, a sound quality mode in which the level of the band is forcibly increased by digital audio processing is prepared. Some hands-free kits may have speakers with a very wide playback band depending on the model, and when making a call to such a hands-free kit using this sound quality mode, only a certain band will be extremely extreme. It is considered that the sound emphasized in the above is reproduced, and the sound quality becomes very difficult to hear, which may hinder the call.

Another problem is that when side sounds are added for the purpose of improving the sound quality of a call, a speaker having a large reproduction sound, a microphone having high sensitivity, and a side sound of a communication terminal installed in the hands-free kit are used. With the addition, a closed loop of the signal is easily formed, and excessive echo and howling easily occur. Of course, if the hands-free kit itself is equipped with an advanced echo canceller in anticipation of these situations, this problem is unlikely to occur, but countless types of optional equipment for these communication terminals are on the market from various manufacturers. Can not guarantee it.

In view of the above, it is impossible for the communication terminal designer to grasp all of the sound quality characteristics when a communication terminal such as an earphone microphone or a hands-free kit is used for a telephone call. Because
When the sound quality adjustment adapted to the communication terminal body is used, the communication quality may be deteriorated. Accordingly, the present invention provides a communication terminal in which a sound quality mode is provided for each call optional device in order to avoid the above-described problems.

FIG. 1 is a circuit diagram showing a portable telephone which realizes an embodiment of the present invention. The radio wave received by the antenna 2 is supplied to the RF circuit 3 for frequency selection and the like. This output signal is supplied to a modem and a modem 7 of a DSP (Digital Signal Processor) 100 and is converted into a digital signal and voice code-converted. A digital equalizer 8, a noise suppression circuit (noise suppressor) 9, a volume 10, an echo removal circuit (Echo canceller) 1
1. It sequentially goes through the side tone addition circuit 12. The signal output from the side tone adding circuit 12 is converted into an analog signal by the D / A converter 13 and converted into a sound by the speaker 15. on the other hand,
The sound collected by the microphone 16 is converted into a digital signal by the A / D converter 14 and transmitted as a radio wave by the antenna 2 in a reverse procedure.

All changes in call sound quality are made by the DSP 100, and three blocks of a digital equalizer 8, a noise suppressor 9, and a volume 10 are provided for a transmission voice, and a digital equalizer 8, a noise suppressor 9, a volume 10, and a volume 10 are provided for a reception voice. The adjustment is performed by adjusting five blocks of the echo canceller 11 and the side tone adding circuit 12. The portable telephone according to the present invention combines the adjustments of the three blocks on the transmitting side and the five blocks on the receiving side into one "sound quality mode" to form a ROM.
6 is stored.

Therefore, when two sound quality modes are to be provided as the sound quality mode for the earphone and the sound quality mode for the hands-free kit, the adjustment having the adjustment parameters for all of the above-described 5 blocks on the transmitting side and the receiving side is performed. Two parameter groups are prepared and stored in the ROM unit. Regardless of whether the optional telephone equipment used is an earphone microphone or a hands-free kit, it controls all of the above-mentioned five blocks on the transmitting side 3 and the receiving side to adjust the sound quality for the equipment. Each parameter group was given header information so that it could be used for earphone microphones or hands-free kits, and the central processing unit determined the information and used each device. In such a case, the respective adjustment parameters are called.

Next, how the sound quality mode is activated during a call will be described. In FIG. 1, when an earphone microphone is used, an earphone detection circuit 17 is used.
However, when a hands-free kit is used, the hands-free detection circuit 18 detects each of them, and this signal is sent to the central processing unit 4. In the central processing unit 4, the earphone microphone and the hands-free kit are distinguished from each other by an input terminal to which a signal from the earphone detection circuit 17 is input and an input terminal to which a signal from the hands-free kit detection circuit 18 are input. (For example, the earphone microphone has terminal A,
Hands-free kit is determined by the terminal B). Further, the central processing unit 4 receives these signals and
Further, an adjustment parameter suitable for each communication optional device is called, and further, a voice system block of the DSP 100 is controlled. This series of operations will be described with reference to FIG.

FIG. 2 is a flowchart when the operation of the embodiment is performed by the above-mentioned portable telephone. In the flowchart, when a call (or an incoming call) is made in step 201 (or 203), the use of a call optional device (an earphone microphone and a hands-free kit in the case of FIG. 2) is confirmed (step 205). Step 2
If the use of the optional telephone device is not detected in step 05, the operation shifts to the sound quality mode activation operation for the communication terminal body (step 207).

In step 205, when the use of the optional telephone device is detected, the type of the optional telephone device (in this case, the earphone microphone / hands-free kit) used for the telephone call is confirmed (step 209). Next, it is checked whether or not an earphone microphone (indicated as an earphone in FIG. 2) is used (step 211).
The central processing unit 4 reads from the ROM 6 audio parameters (adjustment parameters) suitable for the earphone microphone,
A voice call is started by controlling each audio system block in SP 100 (step 215). The sound quality mode at this time is referred to as an earphone sound quality mode. On the other hand, if the earphone microphone is not used, the process proceeds to step 213.

In step 213, since the use of the hands-free kit is confirmed, the central processing unit 4 sets the voice parameters (adjustment parameters) suitable for the hands-free kit.
Is read from the ROM 6, and each voice system block in the DSP 100 is controlled to start a telephone conversation (step 217).
The sound quality mode at this time is referred to as a hands-free kit sound quality mode. Then, when a call end operation is performed during a call in the earphone sound quality mode or the handsfree kit sound quality mode (step 219), the end call process of step 221 is performed.

Next, returning to FIG. 1, an outline of the structure and control method of the DSP 100 will be described. The following four adjustments are important for sound quality adjustment for call optional equipment. (1) Processing of the frequency characteristics of the sound by the digital equalizer 8 (2) Adjustment of the amount of noise suppression by the noise suppressor 9 (3) Adjustment of the amount of echo suppression by the echo canceller 11 (4) Adjustment of the side sound volume by the side sound addition circuit 12 Adjustment The volume adjustment by the volume 10 does not need to be specially adjusted for the call optional device. This is because the audio input / output level should be set in accordance with the standardized common specifications, and it is considered that there is almost no deviation from the product.

First, (1) digital equalizer 8
The details of the processing of the frequency characteristics of the sound by the method will be described. The digital equalizer 8 is constituted by an FIR type adaptive digital filter, and the adjustment of the frequency characteristic is substantially realized by adjusting the multiplication coefficient of a multiplication circuit included in the FIR type adaptive digital filter. The number of multiplication factors varies, but is generally expressed in tens of bytes. The multiplication coefficient of several tens of bytes becomes control data of the digital equalizer 8 among the adjustment parameters composed of the eight blocks described above.

With regard to the sound quality mode for optional telephone devices such as an earphone microphone and a hands-free kit, speaking of frequency characteristics, there are many optional telephone devices capable of reproducing low, middle, and high-frequency ranges in a well-balanced manner. Avoid processing and taking risks.
Therefore, the frequency characteristics are made as flat as possible with few features. Therefore, it is preferable that the digital equalizer 8 has flat characteristics for both transmission and reception. This is because the speaker 15 of the communication terminal body often has a low sound level of low and high pitches, and thus often performs frequency characteristic correction to increase the level of low and high pitches. This is because the output sound from the device is likely to be excessively processed in sound quality.

Next, the details of (2) the adjustment of the noise suppression amount by the noise suppressor 9 will be described. The noise suppression processing of the noise suppressor 9 uses an algorithm called “frequency domain subtraction method”, and the noise suppression processing is performed by subtracting the artificially created noise component from the noise component included in the signal. The noise suppression amount is adjusted by adjusting the subtraction value. At this time, the parameter of the subtraction value is several bytes.

The noise suppression amount does not need to be considered so much for reception, and there is no problem if the noise suppression amount is set to a value equivalent to that at the time of talking on the communication terminal body. However, sufficient consideration must be given to the amount of noise suppression on the transmitting side depending on the optional model. In particular, since the hands-free kit is often used in a car, the noise suppression amount is set to be slightly larger than the suppression amount at the time of talking on the communication terminal body so as to sufficiently suppress the noise in the car. Next, (3) the adjustment of the echo suppression amount by the echo canceller 11 will be described. The echo canceller 11 cancels the echo by digitally wrapping the opposite phase signal of the reception signal at a certain level to the transmitting side, and adjusts the wraparound amount by several bytes of data.

The setting of the echo canceller 11 does not need to be considered in the case of the earphone microphone, but needs attention in the case of the hands-free kit. Generally, hands-free kits have their own echo cancellation function, but some hands-free kits do not. When a hands-free kit having no echo canceling function is used, the receiving sound of the other party is generated at a high volume, and thus a larger echo may be generated than during a call on the communication terminal body. In order to avoid this danger, it is necessary to set the echo canceller 11 so that the received voice having the opposite phase goes around as much as possible to avoid the generation of the echo. Next, (4) side tone addition circuit 1
2 will be described. The side tone addition circuit 12 digitally circulates the transmission signal to the reception side, and also controls the amount of wraparound using several bytes of data.

The side tone adding circuit 12 sets the amount of wraparound of the transmitted voice to zero. That is, the sidetone addition is OFF. This is because if a sidetone is added, howling easily occurs when a hands-free kit that does not have an echo cancellation function is used. In addition, there is a high sensitivity type of microphone attached to the earphone microphone. In this case, the transmitted voice transmitted by the user is excessively heard from the earphone, which makes it difficult to hear the voice of the other party. As described above, according to the present invention, it is possible to prevent inconsistency in sound quality, echo, and howling even when a call optional device such as an earphone microphone or a hands-free kit whose characteristics are difficult to grasp is used. .

Also, by having adjustment parameters separately from the sound quality adjustment parameters of the communication terminal body, the sound quality adjustment of the communication terminal body does not need to take into account these optional communication devices, and the sound quality adjustment of the communication terminal body is not required. Are greatly reduced. The detection of these call optional devices and the selection of adjustment parameters prepared for them are completely automatically performed by the central processing unit. Therefore, the user's operation is not required at all and convenience is provided. Although the above embodiment has described the operation when the optional telephone device is an earphone microphone and a hands-free kit, the present invention is not limited to the earphone microphone and the hands-free kit. For example, the same system as that of the present invention can prevent the deterioration of the sound quality of a call in any communication mode (for example, a call using a loudspeaker) that does not use the receiving receiver of the communication terminal body or the transmitting microphone. In the above embodiment, the present invention is applied to a mobile phone or a PHS (Personal Handy Phone System).
Although the present invention is applied to a mobile communication terminal including a wireless communication terminal, the present invention can also be applied to a radio device for business use and a hobby. Further, the present invention can be used for fixed telephones, public telephones, and the like.

[0028]

As described above in detail, according to the communication terminal of the present invention, it is possible to prevent inconsistency in sound quality, echo, and howling even when a call optional device is used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a mobile phone according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an embodiment of the present invention.

[Explanation of symbols]

 4 Central Processing Unit 6 ROM 8 Digital Equalizer 9 Noise Suppressor 10 Volume 11 Echo Canceller 12 Sidetone Addition Circuit 100 DSP (Digital Signal Processor)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K011 DA16 DA18 GA06 JA01 KA04 5K027 AA11 BB03 DD01 DD07 DD10 DD16 HH03 5K067 AA34 BB04 FF00 FF38

Claims (7)

[Claims] 1. A communication terminal capable of adjusting call sound quality, the communication terminal having a plurality of sound quality modes corresponding to call optional devices. 2. The communication terminal according to claim 1, wherein said call optional device is an earphone microphone and a hands-free kit. 3. An earphone detection circuit, a hands-free detection circuit, and a digital signal processing unit. The digital signal processing unit includes a digital equalizer, a noise suppression circuit,
By having a volume adjustment unit, an echo removal circuit, and a sidetone addition circuit, and controlling them by an arithmetic processing unit,
The communication terminal according to claim 1, wherein a sound quality mode corresponding to a call option device in use is set. 4. The communication terminal according to claim 1, wherein when the use of an earphone microphone is detected by the earphone detection circuit, a sound quality mode is set to an earphone sound quality mode. . 5. The sound quality mode is set to a hands-free kit sound quality mode when use of the hands-free kit is detected by the hands-free detection circuit. Communication terminal as described. 6. The data for adjusting the call sound quality includes frequency characteristics, noise suppression, echo removal, and sidetone addition. These data are stored in a memory and read out for each call optional device used. The communication terminal according to any one of claims 1 to 5, wherein: 7. The control for shifting to various sound quality modes is performed for transmission and reception.
The communication terminal according to claim 6.