JP4059618B2 - Communication terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication terminal such as a mobile phone, and more particularly to a sound quality adjustment function.
[0002]
[Prior art]
Conventionally, most of the adjustment of the sound quality of the communication terminal is one type. There is "Japanese Patent Application No. 11-311676" by the present applicant as an example of a communication terminal equipped with a function that allows the user to select a sound quality. This is a digital audio when the other party's voice is difficult to hear due to mutual communication environment (under static or noisy), the line used, the other party's model, the other party's voice volume and quality, etc. Using the processing technology, the user can arbitrarily select the sound quality of the received voice, the sound volume, and the sound quality of the transmitted signal by operating a button during a call, so that the call can be performed satisfactorily.
[0003]
[Problems to be solved by the invention]
However, in the communication terminal reported in “Japanese Patent Application No. 11-311676”, the change in sound quality is based on the premise that the call uses the reception speaker and the transmission microphone of the communication terminal main body. When used (earphone microphone, hands-free kit, etc.), it is expected that the sound quality mode cannot be adapted to the sound quality characteristics in many cases.
The present invention has been made in view of the above points, and an object of the present invention is to provide a communication terminal capable of preventing the occurrence of sound quality mismatch, echo, and howling even when a call option device is used. .
[0004]
[Means for Solving the Problems]
The communication terminal of the present invention is characterized in that the call sound quality can be adjusted and has a plurality of sound quality modes corresponding to the call option device.
As an example of the telephone call option device, there are an earphone microphone and a hands-free kit.
[0005]
The communication terminal of the present invention has an earphone detection circuit, a hands-free detection circuit, and a digital signal processing unit. Inside the digital signal processing unit, a digital equalizer, a noise suppression circuit, a volume adjustment unit, an echo removal circuit, and a side sound addition A sound quality mode corresponding to a call option device to be used is set by having a circuit and controlling them by a central processing unit during a call.
[0006]
The communication terminal of the present invention sets the sound quality mode to the sound quality mode for the hands-free kit when the use of the hands-free kit having the microphone and the speaker is detected by the hands-free detection circuit, controls the digital equalizer, , and sending both flat frequency characteristics, the noise suppression circuit, the noise suppression amount of the transmission side is set larger than the reduction amount at the time of the call at the terminal body, echo cancellation circuit, enables the reception sound voice antiphase The side sound adding circuit is characterized in that the amount of wraparound to the receiving side of the transmitted voice is set to zero.
In the communication terminal of the present invention, when the use of the earphone microphone is detected by the earphone detection circuit, the sound quality mode is set to the sound quality mode for the earphone, the digital equalizer is controlled, and both reception and transmission have flat frequency characteristics. The noise suppression circuit sets the noise suppression amount on the receiver side to be equivalent to that during a call on the terminal body, and the side tone addition circuit sets the wraparound amount of the transmitted voice to the receiver side to zero. Features.
[0007]
The data for adjusting the call sound quality is frequency characteristics, noise suppression, echo removal, and side sound addition, and the communication terminal of the present invention stores these data in a memory and reads them for each call option device to be used. It is characterized by.
Control for shifting to various sound quality modes is performed for transmission and reception.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a communication terminal according to the present invention will be described in detail with reference to FIG. 1 and FIG. 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 this embodiment, an earphone microphone that is used in a headphone stereo or the like that is attached to the ear is referred to as an “earphone microphone”, which is larger than the earphone microphone. The one that listens to incoming calls in open air is called a “hands-free kit”.
[0009]
The purpose of this embodiment is to eliminate sound quality dissatisfaction felt by the user during a call. This sound quality dissatisfaction is caused by the details of the sound when the other party's voice is muffled or the other party's call line or environment is difficult to understand, and conversely when listening to music services or other sounds. Occurs when not being played. The former can be realized by emphasizing the voice component and weakening the other noise components, etc., and can be realized by making the frequency characteristics narrow band high tone emphasis type and applying strong noise suppression. The latter can be solved by preparing a setting that allows all sounds to be heard naturally, and can be realized by making the frequency characteristics wideband flat and weakening noise suppression or not suppressing it at all. This setting is called “sound quality mode”.
[0010]
There is a difference between “call option devices”, which is one of the causes of sound quality dissatisfaction. In a specific example, when it is difficult to reproduce a certain voice band by the receiving speaker of the communication terminal main body, it is assumed that a sound quality mode in which the level of the band part is forcibly increased by digital voice processing is prepared. Hands-free kits may have a speaker with a very wide playback band depending on the model, and when a call is made using this sound quality mode for such a hands-free kit, only a certain band is extreme. Therefore, it is possible that the voice emphasized in the above will be reproduced, resulting in a sound quality that is very difficult to hear and hinders the call.
[0011]
Another problem is that when side sounds are added for the purpose of improving the sound quality of the call, the loudspeaker with high playback sound, a microphone with high sensitivity, and the side sound addition part of the communication terminal are installed in the hands-free kit. A closed loop of the signal is easily formed, and excessive echo and howling easily occur. Of course, this problem is unlikely to occur if the hands-free kit itself is equipped with an advanced echo canceller that assumes these situations, but there are countless types of optional equipment for these communication terminals on the market. We cannot guarantee it.
[0012]
Based on the above, when call option devices for communication terminals such as earphone microphones and hands-free kits are used for communication, it is impossible for the communication terminal design side to grasp all of their sound quality characteristics. When the sound quality adjustment adapted to the communication terminal main body is used, the call quality may be deteriorated. Therefore, the present invention provides a communication terminal provided with a sound quality mode for each call option device in order to avoid the above problems.
[0013]
FIG. 1 is a circuit diagram showing a mobile phone that implements 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 modulation / demodulation circuit and a modem 7 of a DSP (digital signal processor) 100, converted into a digital signal, converted into a voice code, a digital equalizer 8, a noise suppression circuit (noise suppressor) 9, a volume 10, and an echo removal circuit. (Echo canceller) 11 and side sound adding circuit 12 are sequentially passed.
The signal output from the side sound adding circuit 12 is converted into an analog signal by the D / A converter 13 and converted into 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 by the reverse procedure.
[0014]
All the changes in the speech quality are performed by the DSP 100. Three blocks of the digital equalizer 8, noise suppressor 9, and volume 10 are set for the transmitted voice, and the digital equalizer 8, noise suppressor 9, volume 10 and the echo canceller 11 are set for the received voice. This is done by adjusting the five blocks of the sidetone adding circuit 12. In the mobile phone according to the present invention, a combination of the three blocks on the transmitting side and the five blocks on the receiving side is grouped as one “sound quality mode” and stored in the ROM 6.
[0015]
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 parameter group having the adjustment parameters for all the transmission side 3 + reception side 5 blocks shown above is obtained. Prepare two and store them in the ROM. Regardless of whether the telephone call option device used is an earphone microphone or a hands-free kit, all the above-mentioned transmitting side 3 + receiving side 5 blocks are controlled to adjust the sound quality for the device.
Each parameter group is given header information so that it can be seen whether it is for an earphone microphone or a hands-free kit, and the central processing unit discriminates that information and used each device. When calling each adjustment parameter.
[0016]
Next, how the sound quality mode is activated during a call will be described. In FIG. 1, the earphone detection circuit 17 detects when the earphone microphone is used, and the handsfree detection circuit 18 detects when the handsfree kit is used, 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 using 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 is input. (For example, the earphone microphone is terminal A, and the hands-free kit is terminal B). Further, the central processing unit 4 receives these signals, calls adjustment parameters suitable for each call option device from the ROM 6, and further controls the audio system block of the DSP 100. This series of movements will be described with reference to FIG.
[0017]
FIG. 2 is a flowchart when the operation of the embodiment is performed on the mobile phone. Explaining this flowchart, when a call is made (or received) in step 201 (or 203), the use of a call option device (in the case of FIG. 2, an earphone microphone and a hands-free kit) is confirmed (step 205).
If the use of the call option device is not detected in step 205, the operation proceeds to the sound quality mode starting operation for the communication terminal body (step 207).
[0018]
If the use of the call option device is detected in step 205, the type of the call option device used for the call (in this case, the earphone microphone / hands-free kit) is confirmed (step 209). Subsequently, the presence / absence of use of the earphone microphone (indicated as “earphone” in FIG. 2) is confirmed (step 211). If the earphone microphone is used, the central processing unit 4 sends the voice parameter (adjustment parameter) suitable for the earphone microphone from the ROM 6. Read and control each block of the voice system in the DSP 100 to start a call (step 215). The sound quality mode at this time is defined as an earphone sound quality mode. On the other hand, if the earphone microphone is not used, the process proceeds to step 213.
[0019]
In step 213, since the use of the hands-free kit is confirmed, the central processing unit 4 reads out the voice parameters (adjustment parameters) suitable for the hands-free kit from the ROM 6, and controls each voice block in the DSP 100 to make a call. Start (step 217). The sound quality mode at this time is set as a hands-free kit sound quality mode. When a call end operation is performed during a call in the sound quality mode for the earphone or the sound quality mode for the handsfree kit (step 219), the call end processing in step 221 is performed.
[0020]
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 the sound quality adjustment for the telephone option equipment.
(1) Processing of frequency characteristics of sound by digital equalizer 8 (2) Adjustment of noise suppression amount by noise suppressor 9 (3) Adjustment of echo suppression amount by echo canceller 11 (4) Side sound volume by side sound addition circuit 12 It should be noted that the volume adjustment by the volume 10 does not need to be adjusted specifically for the call option device. This is because the audio input / output levels should be set in accordance with standardized common specifications, and it is unlikely that a product deviates.
[0021]
First, the details of (1) processing of the frequency characteristics of sound by the digital equalizer 8 will be described. The digital equalizer 8 is composed of an FIR type adaptive digital filter, and the adjustment of the frequency characteristic is substantially realized by adjusting the multiplication coefficient of the multiplication circuit included in the FIR type adaptive digital filter. The number of multiplication coefficients varies, but is generally represented by several 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 8 blocks described above.
[0022]
To describe the sound quality mode for call option devices such as earphone microphones and hands-free kits, in terms of frequency characteristics, there are many call option devices that play back in a balanced manner in the low, mid, and high frequencies, so extra processing is required. Avoid taking risks. Therefore, the frequency characteristics are as flat as possible and have 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 main body often has a low treble sounding level, and therefore frequency characteristic correction is often performed to increase the low treble level. Therefore, the call option controlled by such sound quality adjustment is used. This is because the output sound from the equipment is likely to be excessively processed in terms of sound quality.
[0023]
Next, details of (2) adjustment of the amount of noise suppression 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 has a mechanism for performing noise suppression 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.
[0024]
The amount of noise suppression need not be so much considered for incoming calls, and can be set to a value equivalent to that during a call on the communication terminal body. However, the amount of noise suppression on the transmitter side needs to be fully examined depending on the option model. In particular, since hands-free kits are often used in automobiles, the noise suppression amount is set slightly larger than the suppression amount during a call in the communication terminal body so as to sufficiently suppress noise in the vehicle.
Next, (3) the adjustment of the echo suppression amount by the echo canceller 11 will be described. The echo canceller 11 digitally circulates the opposite phase signal of the received signal to the transmitting side at a certain level, and adjusts the amount of wraparound with several bytes of data.
[0025]
The setting of the echo canceller 11 hardly needs to be considered in the case of an earphone microphone, but care must be taken in the case of a hands-free kit. In general, hands-free kits have their own echo cancellation function, but there are also hands-free kits that do not. When a hands-free kit that does not have an echo cancellation function is used, the other party's received sound is produced at a high volume, so there is a possibility that 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 to circulate as much as possible the reception voice in the opposite phase to avoid the occurrence of echo.
Subsequently, (4) side sound volume adjustment by the side sound adding circuit 12 will be described. The side-tone adding circuit 12 digitally circulates the transmission signal to the reception side, and this also controls the amount of wrap-around with data of several bytes.
[0026]
The side tone adding circuit 12 sets the amount of wraparound of the transmitted voice to zero. That is, the side sound addition is OFF. This is because when side sounds are added, howling occurs easily when using a hands-free kit that does not have an echo cancellation function. Some microphones attached to the earphone microphones are of high sensitivity type. In this case, it is because the transmitted voice that I uttered can be heard from the earphone excessively, making it difficult to hear the other party's voice.
As described above, according to the present invention, it is possible to prevent occurrence of non-conformity of sound quality, echo, and howling even when a call option device such as an earphone microphone or a hands-free kit whose characteristics are difficult to grasp is used. .
[0027]
In addition, by having an adjustment parameter separately from the sound quality adjustment parameter of the communication terminal main body, the sound quality adjustment of the communication terminal main body does not need to take into account these call option devices, and restrictions on the sound quality adjustment of the communication terminal main body Is greatly reduced.
Further, detection of these call option devices and selection of adjustment parameters prepared for them are made completely automatically by the central processing unit. Therefore, there is no need for any user operation, which is convenient.
The above embodiment describes the operation when the call option device is an earphone microphone and a hands-free kit. However, the call option device is not limited to the earphone microphone or the hands-free kit. Etc.) or any communication mode that does not use the receiver and the microphone of the communication terminal (for example, a call using a loudspeaker), it is possible to prevent the deterioration of the sound quality of the call with the same system as the present invention.
The above embodiment is a case where the present invention is applied to a mobile communication terminal including a mobile phone or a PHS (Personal Handyphone System). However, the present invention is also used for a radio for business use or a hobby. it can. Furthermore, the present invention can be used for fixed telephones, public telephones, and the like.
[0028]
【The invention's effect】
As described above in detail, according to the communication terminal of the present invention, it is possible to prevent the occurrence of sound quality mismatch, echo, and howling even when a call option device is used.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a mobile phone according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining 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 Side Sound Addition Circuit 100 DSP (Digital Signal Processor)

Claims (3)

A communication terminal that has a digital signal processor having a digital equalizer, a noise suppression circuit, a volume adjustment unit, an echo removal circuit, and a side sound addition circuit inside, and is capable of adjusting the speech quality by controlling them with an arithmetic processing unit In
It has multiple sound quality modes corresponding to call option devices,
With hands-free detector,
When use of a hands-free kit having a microphone and a speaker is detected by the hands-free detection circuit, the sound quality mode is set to the sound quality mode for the hands-free kit,
By controlling the digital equalizer, both reception and transmission are flat frequency characteristics,
The noise suppression circuit sets the noise suppression amount on the transmission side to be larger than the suppression amount during a call on the terminal body ,
The echo cancellation circuit, and setting Wrapping as possible the reception sound voices of antiphase many transmitting end,
The communication terminal according to claim 1, wherein the side-tone adding circuit sets a wraparound amount of the transmitted voice to the receiving side to zero. In addition to the hands-free detection circuit, further comprising an earphone detection circuit,
When the use of the earphone microphone is detected by the earphone detection circuit, the sound quality mode is set to the sound quality mode for the earphone,
By controlling the digital equalizer, both reception and transmission are flat frequency characteristics,
In the noise suppression circuit, the noise suppression amount on the receiver side is set to a noise suppression amount equivalent to that during a call on the terminal body ,
The communication terminal according to claim 1, wherein the side tone adding circuit sets a wraparound amount of the transmitted voice to the receiving side to zero.   Data for adjusting the call quality in the digital signal processing unit is frequency characteristics, noise suppression, echo removal, and side sound addition, and those data are stored in a memory and used for each handsfree kit or earphone microphone to be used. The communication terminal according to claim 1, wherein the communication terminal is read out.

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