JP3611515B2 - Mobile communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile communication device, and more particularly to a mobile communication device with improved recognition of the end of an audio signal of a mobile communication device that transmits and receives audio using a digitally modulated wave.
[0002]
[Prior art]
FIG. 1 shows an example of a signal format using a digital modulation method in a mobile communication system.
FIG. 1A shows an example of a framed signal format. As described above, normally, data obtained by encoding speech by dividing time into frames and non-speech data are transmitted. FIG. 1B shows an example of a signal format in each frame (# N + 1 in this example).
[0003]
In FIG. 1B, the synchronization signal, the error correction bit, and the rising / falling ramp time and guard time necessary for the digital modulation method are omitted because they are not directly related to the present invention. is there. Here, assuming that a transmission amount is obtained by excluding the necessary number of bits from a total transmission amount of 9600 BPS with a frame length of 20 ms, an example of a transmission amount including an error detection code of one frame is 66 bits. Yes. In the following description, it is assumed that one frame is all 66 bits.
[0004]
The D / V bit is a data attribute bit indicating either voice (D / V = 1) or non-voice (D / V = 0). Thus, the attribute of whether the data to be transmitted is voice or non-voice is determined by control data (D / V bit) placed at a predetermined position in the frame. For the 48-bit speech / non-speech data field, the AMBE (Advanced Multi-Bands Excitation) method, which is currently generally used as a speech coding method, is assumed.
[0005]
In AMBE, audio signals are processed in units of audio frames every 20 ms, and as a result, 48-bit audio data is generated. As described above, in general, a mobile communication device using digital modulation / demodulation transmits not only audio signals but also non-audio data. However, in the present invention, since it relates to audio transmission, the non-audio data except for the necessary parts will be described later. A description of the data is omitted.
[0006]
The next 1-bit End bit changes according to the transmission switch operation of the mobile communication device, and in the following explanation, End = 0 when the transmission switch is on, and End = 1 when it is off. As a result, the receiving side determines that the received frame when the End bit changes from “0” to “1” is the last frame. In addition, an error detection code generated according to a predetermined error detection code generation rule such as CRC (Cyclic Redundancy Check) is inserted into the 16-bit error detection field at the end of the frame.
[0007]
FIG. 2 shows a configuration example of a mobile communication device.
In FIG. 2, the transmission switch 6 is turned on at the time of transmission, the audio signal input through the microphone 1 is AMBE encoded by the audio encoder 3, the encoded data is digitally modulated by the digital modulator / demodulator 7, and Amplified by the transmission / reception unit 8 and transmitted from the antenna 9. At this time, the control unit 5 sets D / V = 1 (voice) and End = 0 (non-final frame) in the transmission frame, and an error for detecting an error on the receiving side according to a predetermined error detection code generation rule. Insert detection code. At the end of the transmission, the control unit 5 detects that the transmission switch 6 is turned off, and after that, the final frame set to End = 1 is transmitted, and then the transmission is stopped.
[0008]
On the other hand, in the mobile communication device on the receiving side, the transmission switch 6 is in an off state, and a reception frame error is detected by the error detection code in the reception frame. As a result, there is no reception error and D / V = 1 (voice) If so, the received 48-bit audio data portion is output to the audio decoder 4. The signal subjected to AMBE decoding by the audio decoder 4 is power amplified and output from the speaker 2. The control unit 5 recognizes that the continuation of the reception state has ended by receiving the last frame (End = 1).
[0009]
[Problems to be solved by the invention]
By the way, when the reception electric field becomes weak and an error is included in the signal, the error is detected on the reception side. As a result, when the End bit of the frame to be discarded is “1”, the end of the voice is not recognized on the receiving side. In this case, for example, in a system in which the end of the received voice is detected and an automatic response is made, the final frame cannot be recognized and the transmission efficiency is significantly reduced. As described above, the normal reception electric field strength largely fluctuates due to fading or the like, and there is a problem that the transmission efficiency is deteriorated because the end of voice cannot be recognized in a mobile communication system having a very bad transmission environment.
[0010]
In addition, in a conventional mobile communication device using an analog FM signal, a squelch “buzz” sound is generated at the end of reception, so that the operator can easily confirm the end of voice transmission by his / her ear. . On the other hand, in mobile communication using digital modulation, when the received electric field strength is strong and stable and there is no signal error, the “crisp” sound caused by the conventional FM signal does not occur, and the operator does not transmit voice. There is also a problem peculiar to mobile communication using digital modulation, in which it is difficult to recognize the end, resulting in a slow response and a decrease in system operation efficiency.
[0011]
Therefore, in view of the above problems, an object of the present invention is to provide a mobile communication device with improved recognition of voice end even when reception conditions are deteriorated. Thereby, it aims at improving the transmission efficiency of the whole system using a mobile communication apparatus.
It is another object of the present invention to improve ease of use by improving the operator's recognition of the end of voice transmission even in mobile communication using digital modulation. As a result, it aims at improving the operational efficiency of the communication system.
[0012]
[Means for Solving the Problems]
According to the present invention, there is provided a mobile communication device that encodes speech and wirelessly transmits the signal by digital modulation, and includes speech encoding means that encodes speech data in units of frames, and end detection means that detects the end of speech transmission. The frame is configured as a super frame composed of a plurality of frames, and when the end detection means detects the end of voice transmission, during at least one super frame period after detection Simultaneously with the encoded audio signal There is provided a mobile communication device having transmission frame generation means for setting a predetermined bit of each frame to a “voice transmission end state”.
[0013]
The predetermined bits include a plurality of bits including a predetermined pattern indicating “speech transmission end state” and a predetermined tone pattern encoded by the voice encoding means. The end of the voice communication is recognized when it is detected at least once as “end state”, and when the received predetermined pattern is compared with the predetermined reception reference pattern and a predetermined number of bits or more match, Recognize the end. Further, the end of the voice communication is recognized also when the radio wave being received cannot be received. Also, when the end of voice communication is recognized, the reception synchronization state is forcibly released.
[0014]
The mobile communication device further includes a display unit and / or an end sound generation unit that notifies the operator of the end of the voice communication when the end of the voice communication is recognized, and the end sound generation unit includes the voice communication. Only when the end of the voice communication is recognized, the operator is notified of the end sound or when the end of the voice communication is recognized except when the end of the voice communication is recognized Notify end sound.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 shows an example of the structure of a superframe which is a signal format according to the present invention.
In audio signal transmission, audio signals are conventionally transmitted in units of frames (see FIG. 1A), but in this example, each frame is further transmitted in units of superframes that are grouped into a plurality of frame groups. . Here, an example is shown in which a superframe consisting of four frames is defined as a transmission unit of a voice signal, and End = 1 is set for all frames in the superframe when the end of voice is detected according to the present invention.
[0016]
FIG. 4 shows an example of a first control flow in the mobile communication device of the present invention.
This example performs frame transmission / reception control, and starts and ends for each frame. That is, in the superframe example of FIG. 3, a CPU interrupt or the like is generated in the mobile communication device for each frame 0 to 3, and the processing of FIG. 4 is executed for each frame 0 to 3. Here, the frame number i is set to 0 to 3, and the flag Tx indicating the transmission state of the mobile communication device is set to the transmission state when Tx = 1, or to the other state when Tx = 0. Note that (A) mod 4 indicates that modulo 4 operation is performed on A in parentheses.
[0017]
First, this control flow is started by transmitting or receiving any one of the frames 0 to 3. First, in step S101, it is determined whether or not it is the first frame 0 (i = 0) of the superframe. If the frame is not the first frame 0, the transmission state flag Tx is determined next. If Tx = 0, the reception process is executed and the process ends (S114 to S116).
[0018]
In the case of the transmission state Tx = 1 (S114), D / V = 1 and End = 0, which are voice data, are set in the data from the voice encoder 3, and an error detection calculation value is further set for one frame. Transmission is performed (S108 to 111). The value of the End bit is set in step S109 as set in step S104 or 106 described later. A reception subroutine (S115) for executing the reception process will also be described later (see FIG. 6).
[0019]
Next, the determination processing in steps S112 and 113 is performed in relation to the reception processing described later, but these are not related to the processing on the transmission side, and the transmission processing other than the frame 0 is substantially ended in step S111. If the transmission data is other than voice, D / V = 0 and End = 0 are set (S108 and 109).
[0020]
Returning to step S101, in the case of the first frame 0 of the superframe, it is further determined whether or not the transmission switch 6 is turned on / off (S102). If it is on, transmission has started or is being transmitted. Therefore, End = 0 and Tx = 1 are set. Thereafter, similarly to the above-described transmission state Tx = 1 (S114), transmission for one frame is performed according to the difference in voice or data (S108 to 111).
[0021]
On the other hand, when the transmission switch 6 is off, the transmission status flag Tx is further determined (S102 and 103). As a result, the same reception process as in step S115 is executed (S105). Conversely, when Tx = 1, End = 1 indicating the end of transmission is set (S103 and 104). As a result, End = 1 is set from the first frame 0 transmitted after the transmission switch is turned off. Thereafter, transmission of frame 0 (End = 1) is performed in steps S108 to S111 as before.
[0022]
At this time, the transmission state Tx is still 1, and the increment process of step S116 and the processes of steps S101, 114, and 108 to 111 are repeatedly executed, which is the transmission of the last frame 3 (i = 3) of the superframe. Forced to complete. When transmission of the final frame 3 is completed, Tx = 0 is set (S112 and 113), and transmission of audio data ends.
[0023]
As a result, if the super frame according to the present invention is used, it is guaranteed that the receiving side always receives four consecutive frames including End = 1 indicating the end of voice in this example. Therefore, even when the reception condition is deteriorated, it is possible to improve the recognition degree of the end of the voice. In addition, since the present invention guarantees continuous reception of frames including End = 1 on the receiving side only at the end of voice transmission, this increases the redundancy of the voice transmission data somewhat. Detection rate is significantly improved, and transmission efficiency is improved as a whole system.
[0024]
FIG. 5 shows a second control flow example of the present invention.
In this example, in order to further improve the recognition rate of the voice end compared to the first control flow example, the voice data of the frame for notifying the end of voice transmission is set to a predetermined pattern. This example is also processed by an interrupt for each frame. First, on / off of the transmission switch 6 is detected (S201). Steps S207 to S212 that are processed when the transmission switch 6 is on are the same as steps S106 to S111 in FIG. 4 and are not described here. When the transmission switch 6 is off and Tx = 0, it is in the reception state, so the reception process is executed as it is (S206).
[0025]
On the other hand, when the transmission switch 6 is off and Tx = 1, End = 1 and Tx = 0 are set to indicate that transmission has ended (S203 and 204). In this example, a predetermined end recognition pattern is inserted in the 48-bit audio / non-audio data field instead of the audio data (S205). Here, a predetermined pattern meaning the end of voice is inserted in only one frame, but a predetermined pattern may be arranged in all superframes as in the first control flow example. As a modification, the End bit may be eliminated and only a predetermined pattern may be provided.
[0026]
The predetermined pattern may be a fixed pattern that can be easily recognized on the receiving side, such as all “1”, or may be recognized as a special sound by an operator via a voice decoder, for example, a single tone. Such a sound pattern may be used. In the latter case, even if the end side cannot be recognized by detecting an error on the receiving side, that is, even if the end of speech cannot be recognized as a mobile communication device, if the speech data is input to the speech decoder while containing the error, a single tone Therefore, the operator can recognize the end of the voice.
[0027]
FIG. 6 shows a third control flow example of the present invention.
This example is executed in the reception processing subroutine (S105 and 115) of FIG. 4 described above. First, when an error is detected in the received data, nothing is performed when an error is detected, and even when there is no error and non-voice data (D / V = 0), the receiving process is terminated without any action ( S301-303). On the other hand, if there is no error and the voice data (D / V = 1), the voice data is sent to the voice decoder 4 and the end of the voice is detected (End = 1), and the reception process is terminated as it is (S302˜). 305). Here, when End = 1, voice communication end processing (S306) is executed.
[0028]
In this example, as described above, all the voice / non-voice data or non-voice data in which an error is detected is rejected and not processed. Note that since the speech decoder 4 has a function of interpolating between normal speech decoded data even if there is a lack, normal speech is restored if no errors are detected continuously. At the final stage, End = 1 of the frame is detected. Here, when End = 1 is detected at least once among the frames 0 to 3 in the superframe to be received, the audio data of the subsequent frame is converted into an audio decoder by audio communication end processing (see FIG. 9) described later. Do not send to 4.
[0029]
In the example on the transmission side in FIG. 4, since the audio signal is sent for one superframe even after the transmission switch is turned off, there is no problem in detecting End = 1. As a result, the speech end detection rate is improved and an efficient speech decoding process is also achieved. Further, unnecessary continuation of the voice end tone of FIG. 5 is prevented.
[0030]
FIG. 7 shows a fourth control flow example of the present invention.
This example is executed in the reception processing subroutine (S206) of FIG. 5 described above. In this example, even when a reception error is detected, the audio data is sent to the audio compounder 4 while containing the error. For this processing, a flag Vrx indicating a voice reception state is newly provided inside the mobile communication device, and it is defined that voice reception is performed when Vrx = 1 and voice non-reception is performed when Vrx = 0.
[0031]
First, if an error is detected in received data and there is no error, the process is terminated for non-voice data (D / V = 0) (S402 and 403), and the voice data (D / V = 1) is further ended. Bit determination is performed, and a flag Vrx = 1 indicating that a voice is being received is set for a frame other than the voice end (End = 0) (S403 to 405). Thereafter, the audio data is sent to the audio encoder 4 for reproduction (S406). In the case of a voice end frame (End = 1), a voice non-reception state (Vrx = 0) is set after a voice communication end process (S410; see FIG. 9) described later is executed.
[0032]
On the other hand, even if an error is detected in the received data, if the voice is being received (Vrx = 1), the voice data is sent to the voice encoder 4 and reproduced (S406). At that time, the voice data and the predetermined voice end pattern are determined to match, and if the number of bits is equal to or greater than the predetermined number of bits, in this example, 40 bits or more in 48 bits, it is determined that the voice is ended and voice communication end processing ( S410) is executed (S401, 407 to 410). Thereafter, the voice non-reception state (Vrx = 0) is set, and the reception process ends. If the match determination is not satisfied, the voice reception state (Vrx = 1) is continued.
[0033]
In this way, even if an error is detected in the voice data in this example, it is reproduced in principle, and the voice end pattern is more highly probable using multi-bit coincidence detection or other majority logic as in this example. Since it can be detected, the end detection capability is enhanced by both the operator and the device. For example, when the voice end pattern is a sound pattern such as a single tone as described above, the operator can restore the single tone even if the voice data is less than 40 bits and matches the voice transmission end pattern. Is more likely to recognize the end of speech.
[0034]
FIG. 8 shows a fifth control flow example of the present invention.
This example is also executed in the reception processing subroutine (S206) of FIG. 5 described above, and corresponds to a modification of the above-described fourth control flow example. In this example, it is assumed that the reception electric field when the super frame is received is very weak and the end of voice cannot be detected inherently. In such a case, the voice communication is forcibly ended. . For this reason, an error counter (Errn) for newly calculating the number of reception errors is provided inside the mobile communication device, and processing steps S506, 510, and 511 for that purpose are added. Other than that, it is the same as the fourth control flow, and therefore only the differences will be described below.
[0035]
If no error is detected in the received data and there is no error and the frame is voice data (D / V = 1) and a frame other than the voice end (End = 0), a flag Vrx = 1 indicating that the voice is being received is set (S501). ~ 505). In this example, when the audio data is normally received in this way, the error counter is cleared (Errn = 0) (S506). On the other hand, even if an error is detected in the received data, if the voice is being received (Vrx = 1), the voice data is sent to the voice encoder 4 and reproduced (S502, 508, and 509). In this example, in this case, the error counter is incremented by 1 (S510).
[0036]
In the previous fourth control flow example, the voice data and the predetermined voice end pattern are subsequently determined to match. In this example, the error counter value is set to a predetermined threshold before this, and in this example, 10 (times). It is determined whether or not the voice communication has been reached, and the voice communication end process (S513) is executed when the predetermined threshold value or more is reached. The subsequent steps are the same as the previous fourth control flow example. As described above, according to this example, for example, when the vehicle enters the tunnel and it is impossible to receive the voice data itself, or other control bits due to error detection error due to loss of synchronization or incomplete error detection code. When an error frame is continuously received a predetermined number of times in the case of an abnormality in the voice communication, a voice communication end process (S513) is executed to forcibly end the voice communication. This process will be described with reference to FIG.
[0037]
FIG. 9 shows a sixth control flow example of the present invention.
This example shows a flow example executed in the voice communication end processing subroutine (S306, 410, and 513) of FIGS. 6, 7 and 8 described above. In general, when receiving a continuous signal having a frame structure, the timing of the synchronization symbol of the next frame to be received cannot be confirmed from the timing of the synchronization symbol received previously, or fading or the like as in the fifth control flow example. When the synchronization point cannot be confirmed continuously, synchronization protection is used in which the synchronization point is estimated by estimating the synchronization point from the previous normal reception frame until a predetermined number of error frames.
[0038]
In this case, for example, if synchronization protection is applied for 20 frames, even if an audio signal transmitted from the second station is received immediately after reception of the audio communication transmitted by the first station is completed, While synchronization protection is applied to one station, the signal transmitted from the second station cannot be synchronized and a problem arises in that it cannot be received immediately. In this example, this time is a maximum of 400 ms (20 frames × 20 ms). In order to solve this problem, the synchronization protection is forcibly released in the voice communication end processing subroutine (S601). As a result, synchronization is quickly established even for audio signals transmitted from a plurality of different stations at different timings, and reception is possible early.
[0039]
FIG. 10 shows a configuration example of a mobile communication device according to the present invention.
According to the configuration of the present invention described so far, only the single tone is notified to the operator of the voice end (see FIG. 5). Therefore, here, a display function and a notification sound generation function are provided in order to enhance the notification function for the operator and improve the recognition degree of the operator. For this reason, in this example, an end sound generation unit 11 and / or a voice receiving display unit 10 for reproducing and outputting the single tone are newly provided.
[0040]
The end sound generation unit 11 may use a sound output function originally provided in the mobile communication device, or may generate and output a sound of a different tone instead of the received single tone. It may be configured. Further, the display unit 10 during voice reception may output a predetermined message to an LCD display or the like on the mobile communication device, or may be configured to blink a separately provided LED or the like. For example, the voice receiving display unit 10 displays “voice receiving” on the LCD display when the value of the voice receiving flag Vrx is “1”.
[0041]
FIG. 11 shows a seventh control flow example of the present invention.
This example corresponds to a modification of the control flow example shown in FIG. 9, and the processing of this example is added after step S601. That is, after sending a forced synchronization cancellation signal to the digital modulator (S701), an end sound generation signal is sent to the end sound generation unit 11, and then the voice receiving display unit 10 is instructed to turn it off (S702 and 703). ). Such control is performed based on, for example, the value of the voice reception flag Vrx described above, a flag for display control during voice reception, and the like. As a result, the degree of recognition of whether or not voice communication is being performed by the operator is improved, and the operational efficiency of the communication system is improved.
[0042]
FIG. 12 shows an eighth control flow example of the present invention.
If the control flows of FIGS. 8 and 11 described above are applied as they are, error detection is frequently detected continuously for a certain number of times when the received electric field fluctuates drastically. In this case, if the sound end sound is sounded every time, the operator is uncomfortable. In order to improve the processing of FIG. 9, in this example, a voice communication abnormal termination processing routine (S815) applied only at the abnormal termination is added to the control flow of FIG. The other steps S801 to 814 in this example are all the same as steps S501 to 514 in FIG.
[0043]
FIG. 13 shows a ninth control flow example of the present invention.
This example shows an example of the voice communication abnormal end process (S815) of FIG. 12, and here, when the error counter (Errn) exceeds a predetermined value, a forced synchronization release signal is sent to the digital modulator (S901). Here, display off is set to a flag for the purpose of display control during voice reception (S902). As described above, in the voice communication end process of FIG. 11, an end voice generation signal is transmitted (S702). However, since there is no corresponding process in the voice communication abnormal end process of this example, error frames are continuously detected. The end notification sound is not output at abnormal termination. Therefore, the operator does not feel bothered by the frequent end notification sound.
[0044]
14 and 15 show tenth and eleventh control flow examples of the present invention.
These correspond to the compromises shown in FIGS. 11 and 13, and an end notification sound is output at the time of abnormal end of voice communication, but the occurrence frequency of the end notification sound is controlled by controlling the notification time interval with a timer. It is. FIG. 14 shows an example of a control flow from detection of abnormal end of voice communication to timer activation. As processing contents, the timer T1 is activated after the processing of FIG. 11 (S1001 to 1004). Therefore, a temporary end notification sound is output when the voice communication abnormal end is first detected.
[0045]
FIG. 15 shows an example of a control flow after the timer T1 is started, and no end notification sound is output for a voice communication abnormal end that occurs again within the set time after the timer T1 is started (S1102 and 1103). ), The timer T1 is restarted by detecting the voice communication abnormal end that occurred again (S1105). In this way, by utilizing the fact that the voice communication normally has a length of several seconds or more, at the time of abnormal end, it is configured to notify only when the elapsed time from the end of the previous voice communication has abnormally elapsed for a certain time. As a result, it is possible to accurately notify the operator of the end of the voice communication without frequently generating an end notification sound at the abnormal end.
[0046]
【The invention's effect】
As described above, according to the present invention, there is provided a mobile communication device with improved recognition of the end of speech even when reception conditions deteriorate, thereby improving the transmission efficiency of a system using the mobile communication device. Furthermore, by improving the operator's recognition of voice transmission completion in mobile communication using digital modulation, the operational efficiency of the entire mobile communication system can also be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a signal format in a mobile communication system.
FIG. 2 is a diagram illustrating a configuration example of a mobile communication device.
FIG. 3 is a diagram illustrating a configuration example of a superframe according to the present invention.
FIG. 4 is a diagram showing a first control flow example of the present invention.
FIG. 5 is a diagram showing a second control flow example of the present invention.
FIG. 6 is a diagram showing a third control flow example of the present invention.
FIG. 7 is a diagram showing a fourth control flow example of the present invention.
FIG. 8 is a diagram showing a fifth control flow example of the present invention.
FIG. 9 is a diagram showing a sixth control flow example of the present invention.
FIG. 10 is a diagram showing a configuration example of a mobile communication device of the present invention.
FIG. 11 is a diagram showing a seventh control flow example of the present invention.
FIG. 12 is a diagram showing an eighth control flow example of the present invention.
FIG. 13 is a diagram showing a ninth control flow example of the present invention.
FIG. 14 is a diagram showing a tenth control flow example of the present invention.
FIG. 15 is a diagram showing an eleventh control flow example of the present invention.
[Explanation of symbols]
1 ... Microphone
2 ... Speaker
3 ... Speech encoder
4 ... Speech decoder
5. Control unit
6 ... Transmission switch
7. Digital modulator / demodulator
8 ... Transmitter / receiver
9 ... Antenna
10 ... Display section during voice reception
11 ... End voice generation unit

Claims (10)

A mobile communication device that encodes voice and wirelessly transmits the digital modulation.
Audio encoding means for encoding audio data in frame units;
End detection means for detecting the end of voice transmission;
When the frame is composed of a plurality of frames and the end detection unit detects the end of the voice transmission, at least one superframe period after the detection, the encoded bits are simultaneously transmitted with the predetermined bit of each frame. A transmission frame generating means for setting the voice transmission end state to
A mobile communication device characterized by comprising: The predetermined bit is composed of a plurality of bits including a predetermined pattern indicating the “voice transmission end state”, and is determined as the “voice transmission end state” by detecting coincidence of a plurality of bits by comparison with a predetermined voice end pattern. The mobile communication device according to claim 1. The mobile communication device according to claim 2, wherein the predetermined pattern is a predetermined tone pattern encoded by the voice encoding means. A mobile communication device for receiving radio waves transmitted from the mobile communication device according to claim 1,
A mobile communication device characterized by recognizing the end of voice communication as "voice communication end" detection when detecting that the predetermined bit is "voice transmission end state" at least once. A mobile communication device for receiving radio waves transmitted from the mobile communication device according to claim 2 or 3,
A mobile communication device characterized by comparing the received predetermined pattern with a predetermined reception reference pattern and recognizing the end of voice communication as "voice communication end" detection when a predetermined number of bits or more match. Furthermore, the mobile communication device according to claim 4 or 5, which recognizes the end of voice communication even when the radio wave being received cannot be received. Furthermore, the mobile communication device according to any one of claims 4 to 6, wherein when the end of voice communication is recognized, the reception synchronization state is forcibly canceled. The mobile communication device according to any one of claims 4 to 7, further comprising display means and / or end sound generation means for notifying an operator of the end of voice communication when the end of voice communication is recognized. . Furthermore, it has a display means and / or end sound generation means for notifying the operator of the end of voice communication,
The mobile communication device according to claim 4 or 5, wherein the end sound generation means notifies the operator of the end sound only when the end of the voice communication is recognized upon detection of "end of voice communication". Further, when the end sound generation means recognizes the end of the voice communication other than the detection of “end of voice communication”, the end sound generation means notifies the operator of the end sound for a certain time elapsed from the previous end. The mobile communication device according to claim 9.

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