JP4453598B2 - Mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system comprising a base station and a plurality of mobile stations, and more specifically, a function of direct communication between mobile stations using radio, and an indirect communication function of performing radio communication via the base station It is related with the receiving part of the mobile station provided with.

  2. Description of the Related Art Conventionally, as shown in the block diagram of FIG. 5, a digital mobile communication system using radio includes a base station 80 and a plurality of mobile stations 85, 86, 87. The base station 80, each mobile station, Wireless communication and wireless communication between mobile stations are possible. For example, when used in a fire department, the base station 80 and all mobile stations in the jurisdiction are connected to a communication system, for example, a base station transmission / reception unit 81 provided in the base station 80 and a mobile station transmission / reception unit 88 provided in each mobile station. It is necessary to share field information via

  In general, a base station includes a high-performance antenna and a high-power radio transmitter (not shown). However, since mobile stations are mainly on-vehicle, their capabilities are lower than those of base stations. For this reason, in the case where mobile stations located at locations distant from each other cannot directly communicate with each other, indirect communication in which relaying is performed by the base station 80 is performed.

  Therefore, in the communication system shown in FIG. 5, the above-described indirect communication function is realized by using two frequencies, frequency FH (second radio wave) and frequency FL (first radio wave). For this reason, each mobile station 85, 86, 87 converts a voice input from a microphone into a digital voice signal, and uses this voice signal to modulate a radio wave of frequency FL and transmit it (not shown). And a mobile station transmission / reception unit 88 integrated with a receiving unit (see FIG. 4) that simultaneously demodulates radio waves of frequency FH and frequency FL and selectively outputs voice. Further, the base station 80 can transmit a digital audio signal at the frequency FH and receive a digital audio signal at the frequency FL by the base station transmission / reception unit 81.

  Accordingly, simplex communication (simplex) using the frequency FL is possible between the mobile stations, and the base station 80 that has received the radio wave of the frequency FL transmits (relays) this signal using the radio wave of the frequency FH. Accordingly, for example, the mobile station C can intercept wireless communication between the mobile station A and the mobile station B. When the mobile station C interrupts the communication between the mobile station A and the mobile station B, it is possible to communicate via the base station 80 in addition to the method of directly communicating with each mobile station.

  FIG. 4 is a block diagram showing a receiving unit in the mobile station transmitting / receiving unit 88 provided in the mobile station. The receiving unit receives an antenna 97, an antenna shared unit 98 that receives and separates and outputs a received radio wave from the antenna 97, and a radio wave of frequency FL separated by the antenna shared unit 98 for high frequency amplification and intermediate Received signal amplifying unit 90 for performing frequency amplification, demodulating unit 92 for demodulating the signal amplified by received signal amplifying unit 90, and receiving radio waves of frequency FH separated by antenna sharing unit 98 for high frequency amplification and intermediate The received signal amplifying unit 91 for performing frequency amplification, the demodulating unit 92 for demodulating the signal amplified by the received signal amplifying unit 91, and the audio signal demodulated by each demodulating unit 92 are switched, and any one of the audios is switched. A switching unit 94 that outputs a signal, an audio amplifier 95 that inputs and amplifies the switched audio signal, a speaker 96 that outputs the amplified audio signal as audio, and an audio amplifier 5 is input from the loudspeaker 99 for inputting the voice signal 5, the loudspeaker switch 100 for turning on / off the voice signal to the loudspeaker 99, the received signal amplifying unit 90, and the received signal amplifying unit 91. An AGC (automatic gain control) signal, which is a signal related to the frequency, is input and the magnitudes of the reception levels are compared, and the audio signal having the higher reception level at the frequency FH and the frequency FL is output to the audio amplifier 95. As described above, the reception level comparison unit 93 that outputs a selection signal to the switching unit 94 via the OR circuit 101, the signal from the reception level comparison unit 93, and the broadcast signal from the demodulation unit 92 are input and input. The OR circuit 101 is configured to output either one of the signals as a selection signal of the switching unit 94.

  As shown in FIG. 4, a speaker 96 installed in a mobile station (not shown) such as a fire truck and a loudspeaker 99 installed outside the fire truck output the same sound. Further, the loudspeaker switch 100 is configured so that the sound from the loudspeaker 99 can be turned off as necessary when the fire truck is moving. The reason for outputting the sound from the loudspeaker 99 is to make it possible to always listen to the communication contents even when there are members outside the fire truck due to digestion work or the like at the site.

  Next, the operation of the receiving unit will be described with reference to FIG. The radio wave having the frequency FL input from the antenna 97 is amplified by the reception signal amplification unit 90, further demodulated into an audio signal by the demodulation unit 92, and input to one terminal of the switching unit 94. On the other hand, the radio wave having the frequency FH input from the antenna 97 is amplified by the reception signal amplification unit 91, further demodulated into an audio signal by the demodulation unit 92, and input to the other terminal of the switching unit 94.

  The AGC signals output from the reception signal amplification unit 90 and the reception signal amplification unit 91 are compared by the reception level comparison unit 93, and the reception level 93 outputs a signal corresponding to the radio wave having the higher reception level. . This signal outputs a logical value “0” when a system of frequency FL is selected, and a logical value “1” when a system of frequency FH is selected. Further, the switching unit 94 switches according to this logical value.

  Therefore, when the logical value of the broadcast signal output from the demodulator 92 is “0”, that is, when the broadcast signal is not broadcast, the signal output from the reception level 93 passes through the OR circuit 101 as it is, and the switching unit. A selection signal is given to 94. As a result, the speaker 96 always outputs the sound having the higher radio wave reception level at the frequency FH and the frequency FL, that is, the relay radio wave from the base station and the transmitted radio wave of the mobile station. Mobile stations can perform wireless communication continuously (for example, refer to Patent Document 1).

  Note that the audio signal data demodulated by the demodulator 92 is addressed to which mobile station is transmitted from the header information demodulated at the same time, which mobile station or base station is transmitted, Since it is possible to identify whether all mobile stations should receive broadcast data as common information, the communicating station selects only the same voice data between the base station and the mobile station, as well as the data addressed to itself. Can be converted into an audio signal. Further, if the received data is broadcast data, that is, if the logical value of the broadcast signal output from the demodulator 92 is “1”, each mobile station outputs the logical value “OR”. 1 ", and the voice (voice from the base station) corresponding to the radio wave of the frequency FH is selected unconditionally.

  By the way, when a fire engine or the like is dispatched to the site and starts digestion work, it is switched by the loudspeaker switch 100 as described above, and the received voice is output from the loudspeaker 99 (on-site mode). In such a case, when a certain fire engine and a base station (not shown) start communication wirelessly, the sound emitted by the commander of the base station and the sound transmitted from the fire engine are transmitted from the base station as broadcast data. , Received by another fire engine and output from the loudspeaker 99. Whether broadcast data or individual communication data is determined by the operation of the mobile station transmission / reception unit 88 of the calling member, except for the case where the confidentiality of communication contents is intended, General communication is processed as a broadcast mode.

  However, in the case of a digital mobile communication system, the radio wave received by the base station at the frequency FL is demodulated and temporarily stored as digital audio data at the base station, and this audio data is converted for transmission, After waiting for a predetermined transmission timing, the radio wave having the frequency FH is modulated and transmitted. Therefore, a delay of several hundred milliseconds may occur depending on the processing method of the communication system from reception of radio waves of frequency FL to transmission at frequency FH.

  For this reason, when one of the mobile stations dispatched to the site starts communication with other mobile stations using radio waves of frequency FL in the broadcast mode, the content of the communication is transferred to the base station as the broadcast mode. It is relayed and retransmitted as a radio wave of frequency FH. As a result, it is very difficult for mobile station members who are transmitting on-site to make a call because the sound emitted from the loudspeaker of an adjacent mobile station is delayed by several hundred milliseconds and is heard with loud sound. There was a problem.

JP 2001-320313 A (page 4-5, FIG. 2)

  The present invention solves the above-described problems, and prevents a delay in voice due to relaying of a base station even when a plurality of mobile stations are close to each other in the field and the contents of communication in a broadcast mode are received. Thus, an object of the present invention is to provide a mobile communication system including a mobile station reception unit that facilitates communication with members of the site who are transmitting.

In order to solve the above-described problems, the present invention includes a plurality of mobile stations and a base station that performs radio communication with the mobile stations, and the mobile station transmits a first radio wave modulated with an audio signal. receiving as well as to receive the second radio wave modulated by the audio signal, and outputs the audio signal received in the loudspeaker, the base station, receiving the first radio wave transmitted from the mobile station and, the received signal and, or in a mobile communication system comprising a simultaneous broadcast function of the voice command personnel transmitted in the second radio which communicates with each mobile station, the mobile station, the mobile station said there a mode switch for setting that are present in dispatch site, an audio selection means for outputting a sound signal obtained by demodulating to the loudspeaker, the sound selection means includes a state of the mode switch Source via the base station Enter the source information included in the transmitted said second radio wave from the mobile station, a state status of the mode switch is present in dispatch site, and is transmitted from the previous SL other mobile stations transmission source information by the first radio wave, if via the base station is identical to the sender information transmitted by said second radio wave by the simultaneous broadcast function, transmitting from the previous SL other mobile stations select the first audio signal obtained by demodulating the radio waves, and wherein the benzalkonium be output to the loudspeaker.

  Further, the base station receives the state of the mode switch of each mobile station and creates the position information corresponding to the state of the mode switch.

By using the above means, according to the mobile communication system of the present invention,
According to the first aspect of the present invention, in the receiving unit, a mode switch for setting that the mobile station is present at the dispatch site, a state of the mode switch, transmission source information included in the second radio wave, and a base When the location information received from the station is input and the first radio wave transmitted from another mobile station existing at the dispatch site is transmitted by the broadcast function via the base station, the second radio wave is transmitted. By providing voice selection means for switching to output the first radio wave and the voice corresponding to the first radio wave transmitted from another mobile station existing at the dispatch site to the loudspeaker instead of the voice corresponding to the second radio wave. ,
Compared with the case of receiving via the base station, the delay of voice can be reduced, and it is possible to make it easier for the members of the field who are transmitting to talk.

In the invention according to claim 2, the base station receives the state of the mode switch of each mobile station, and creates position information corresponding to the state of the mode switch,
Even if an expensive GPS (Global Positioning System) device is not installed in the mobile station, the system can be configured at low cost.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings. In addition, the same number is given about the block of FIG. 3 demonstrated by background art, and detailed description is abbreviate | omitted.

  The receiving unit of the mobile station shown in FIG. 1 receives an antenna 97, an antenna sharing unit 98 that receives and separates the received radio wave from the antenna 97, and a radio wave of frequency FL separated by the antenna sharing unit 98. The reception signal amplification unit 90 that performs high frequency amplification and intermediate frequency amplification, the demodulation unit 92 that demodulates the signal amplified by the reception signal amplification unit 90, and the radio wave having the frequency FH separated by the antenna sharing unit 98 is received. The reception signal amplification unit 91 that performs high frequency amplification and intermediate frequency amplification, the demodulation unit 92 that demodulates the signal amplified by the reception signal amplification unit 91, and the audio signal demodulated by each demodulation unit 92 are switched. The switching unit 94 that outputs any one of the audio signals, the audio amplifier 95 that inputs and amplifies the switched audio signal, and the speaker 96 that outputs the amplified audio signal as audio. , Output from the loudspeaker 99 for inputting the voice signal of the voice amplifier 95, the loudspeaker switch 100 for turning on / off the voice signal to the loudspeaker 99, the reception signal amplification unit 90, and the reception signal amplification unit 91. The AGC (auto gain control) signal, which is a signal related to the signal magnitude, is input and the reception level is compared, and the audio signal having the higher reception level at the frequency FH and the frequency FL is output to the audio amplifier 95. As described above, the reception level comparison unit 93 that outputs a switching signal to the switching unit 94 via the voice selection unit 1, and the position information storage unit 2 that stores the position information of each mobile station received by the radio wave of the frequency FH, , The mode switch 3 for setting that the mobile station is in the field, the received data from the demodulator 92 on the side for demodulating the signal from the reception level comparator 93 and the signal from the base station Voice selection for inputting the header information, the mode selection signal indicating the state of the mode switch 3 and the position information of each mobile station in the position information storage means 2 and outputting the selection signal of the switching unit 94 according to the determination result of the input signal And means 1.

Next, the operation of the receiving unit according to the present invention will be described with reference to FIG.
First, if the mobile station equipped with the receiving unit in FIG. 1 is located outside the site, that is, if it is moving or is still in the fire station, a member (not shown) boarding the mobile station is manually operated. Thus, the loudspeaker switch 100 is operated to switch the direction to disconnect the loudspeaker 99. Further, the mode switch 3 is turned off to set that the own vehicle (mobile station) exists outside the site. Hereinafter, this state is referred to as a non-site mode.

  In this non-site mode, the radio wave of frequency FL input from the antenna 97 is amplified by the reception signal amplifying unit 90, further demodulated into an audio signal by the demodulating unit 92, and input to one terminal of the switching unit 94. . On the other hand, the radio wave having the frequency FH input from the antenna 97 is amplified by the reception signal amplification unit 91, further demodulated into an audio signal by the demodulation unit 92, and input to the other terminal of the switching unit 94.

  Further, the AGC signals output from the reception signal amplification unit 90 and the reception signal amplification unit 91 are compared by the reception level comparison unit 93, and the reception level 93 is output from the audio signal having the higher reception level to the audio amplifier 95. As described above, a selection signal is output to the voice selection means 1.

  Since the voice selection means 1 receives the state of the mode switch 3, that is, the mode selection signal, it can be determined that the voice selection means 1 is in the non-site mode. The voice selection means 1 outputs the selection signal input in the non-site mode as it is to the switching unit 94 as a switching signal.

  Therefore, the speaker 96 always outputs the voice having the higher radio wave reception level at the frequency FH and the frequency FL, that is, the relay radio wave from the base station and the radio wave transmitted from the mobile station. Mobile stations can perform wireless communication continuously.

  On the other hand, when the mobile station having the receiving unit of FIG. 1 is on site, a member (not shown) boarding the mobile station (fire truck) operates the loudspeaker switch 100 by manual operation, Switch to the direction in which the loudspeaker 99 is connected. Next, the mode switch 3 is turned on to set that the own vehicle (mobile station) exists at the site. Hereinafter, this state is referred to as a field mode.

  In this field mode, the radio wave having the frequency FL input from the antenna 97 is amplified by the reception signal amplifying unit 90, further demodulated into an audio signal by the demodulating unit 92, and input to one terminal of the switching unit 94. On the other hand, the radio wave having the frequency FH input from the antenna 97 is amplified by the reception signal amplification unit 91, further demodulated into an audio signal by the demodulation unit 92, and input to the other terminal of the switching unit 94.

  Further, the AGC signals output from the reception signal amplification unit 90 and the reception signal amplification unit 91 are compared by the reception level comparison unit 93, and the reception level 93 is output from the audio signal having the higher reception level to the audio amplifier 95. As described above, a selection signal is output to the voice selection means 1.

  Since the voice selection means 1 inputs the state of the mode switch 3, that is, a mode selection signal, it can be determined that the mode is the field mode. In this case, when the demodulator 92 demodulates the signal received from the base station, that is, the signal received at the frequency FH, the voice selection unit 1 inputs header information of the demodulated voice data. In FIG. 1, the header information is extracted from the frequency FH system, but may be extracted from the frequency FL system or from both systems.

  The voice selection means 1 determines the contents of the header information when the received voice data is transmitted in the broadcast mode, and the voice data following the header is called from the mobile station. Yes, and if it is transmitted from the vicinity of the site where the mobile station exists, the radio wave of the frequency FL, that is, the radio waves that other mobile stations existing in the vicinity of the site are receiving directly become. (Determination of the location of another mobile station using the header will be described later.)

  Therefore, the voice selection means 1 outputs a selection signal to the switching unit 94 and connects the voice amplifier 95 with the voice corresponding to the radio wave of the frequency FL that is called by another mobile station existing around the site. In other words, radio waves emitted from other mobile stations are directly received and sound is output from the loudspeaker 99, so that voice delay can be reduced as compared with the case of receiving via the base station, This makes it easier for members to talk.

  The voice selection means 1 outputs a selection signal to the switching unit 94 when receiving a radio wave transmitted in a broadcast mode from a mobile station or base station other than the site, and a frequency FH transmitted from the base station. The corresponding audio data is output as it is. It should be noted that, instead of outputting the voice data corresponding to the frequency FH transmitted from the base station as it is, when the communication of the mobile station other than the site is received, the radio wave having the higher reception level is received between the mobile station and the base station. You may select and output the audio | voice corresponding to this radio wave. Thus, reliable reception can be performed even when the radio wave of the base station is weak.

  Further, when the voice selecting means 1 receives radio waves other than the broadcast mode at the site, for example, radio waves in the individual communication mode or the direct communication mode, the processing in the broadcast mode described above is performed even in the site mode. Priority is given to reception processing according to the received mode. When receiving in the individual communication mode, the lamp on the transceiver panel (not shown) illuminates so that reception in the individual communication mode can be confirmed by the operator. The switch can be turned off so that the communication content is not output from the loudspeaker 99.

  FIG. 3A shows a format of communication data in which the mobile station and the base station in this embodiment perform voice communication, and represents data transmitted and received in one communication frame. Therefore, data is periodically exchanged using this format. FIG. 3B is a dynamic table of each mobile station stored in the mobile station.

  In FIG. 3A, one frame of communication data is composed of a header portion composed of a destination ID, a caller ID, and a communication mode, followed by a voice data portion. Audio data is obtained by digitally converting audio from a microphone (not shown) and compressing the data in a predetermined unit time.

  On the other hand, the header indicates the type of the audio data, and stores information on the destination and calling source (transmission source) for the mobile station and base station indicated by the ID, and communication mode indicating the handling of the audio data. Yes. In the communication mode, it is possible to select a broadcast mode for transmitting to all stations, an individual communication mode in which a call can be made only with a specific station, and a direct communication mode without relaying a base station. These destinations and modes can be specified on the caller side, for example, specified by a destination switch or a communication mode switch provided on a transceiver panel (not shown).

  Therefore, if the header of the received data is analyzed, for example, when the destination ID is 1, the caller ID is 2, and the communication mode is the broadcast mode, the mobile station 2 is the data transmitted to the mobile station 1. It is also found that the broadcast mode is via the relay of the base station.

  In addition, the dynamic table of each mobile station in FIG. 3B is a table in which the position information data sent from the base station as needed is stored in the position information storage means 2 in a table format. Although a detailed description is not given in this embodiment, in recent mobile communication systems, each mobile station is equipped with a GPS (Global Positioning System), and each mobile station sequentially receives the current position and dynamic information ( The mobile station's work status) is transmitted to the base station, and the base station collects the location information and dynamic information of each mobile station together as data, and displays it as a map on a large display device in the base station command room. (Not shown above).

  Each mobile station sequentially receives the dynamic information (including position information) in the form of a table from the base station using radio waves of frequency FH and stores them in the position information storage means 2. This dynamic information is transmitted / received using another data communication format different from that shown in FIG. For example, referring to the dynamic information table shown in FIG. 3B, mobile stations 1 to 4 have arrived at the site, mobile stations 1 and 2 are under water, and mobile station 5 is moving. It turns out that there is.

  Therefore, which mobile station exists in the field from the station ID of the activity information table, and the mobile station can be identified from the caller ID of the header information of the received data. In other words, it is possible to determine whether the voice data currently being received is data transmitted from a mobile station in the field, or data transmitted from a mobile station that is not in the field, that is, a mobile station that is moving or waiting in the station. .

Note that the position information of a mobile station not equipped with a GPS function may use the state of the mode switch 100, that is, a mode selection signal. For example, each mobile station sequentially transmits a mode selection signal to the base station, and the base station confirms the transmission source ID of the mobile station that is in the field mode when the mode switch 100 is pressed. Can be determined at least whether or not there is in the field. The base station creates a dynamic information table (position information) based on this information and distributes it to each mobile station.
This makes it possible to configure the system at a low cost without mounting an expensive GPS device on the mobile station.

  FIG. 2 is a flowchart showing the processing contents of the voice selecting means 1. The voice selection means 1 operates as a part of task program of the transmission / reception unit controlled by a plurality of multitask programs. In the figure, ST represents a step, Y represents Yes, and N represents No.

  First, when the processing of the voice selecting means 1 is started, the state of the mode switch 100 is checked to determine whether it is the on-site mode (ST1). If it is not the on-site mode (ST1-N), the selection signal of the reception level comparison unit 93 is input, and is directly output as the switching signal of the switching unit 94 (ST6), and jumps to ST1.

On the other hand, if it is the field mode (ST1-Y), the header information of the received data corresponding to the frequency FH is input (ST2), and it is determined whether the received data is sent in the broadcast mode (ST3). If it is not the broadcast mode (ST3-N), the process jumps to ST6.
In this way, when not in the broadcast mode, even if it is in the field mode, even if radio waves are received in the individual communication mode or the direct communication mode, the reception in accordance with the received mode takes precedence over the processing in the broadcast mode. It is configured to perform processing.

  On the other hand, if the broadcast mode is selected (ST3-Y), it is next confirmed whether the calling mobile station is in the field at the location of the dynamic information table (ST4). If the calling mobile station is not on-site (ST4-N), a switching signal is output to the switching unit 94 so as to output the voice corresponding to the frequency FH to the voice amplifier 95 (ST7), and the process jumps to ST1.

If the calling mobile station is on-site (ST4-Y), a switching signal is output to switching section 94 so as to output the voice corresponding to frequency FL to voice amplifier 95 (ST5), and the process jumps to ST1.
As mentioned above, when communication of a mobile station other than the site is received, the radio wave with the higher reception level is selected between this mobile station and the base station, and the sound corresponding to this radio wave is output, In order to perform reliable reception even when the radio wave of the base station is weak, the process of ST7 is the same as ST6, that is, the selection signal of the reception level comparison unit 93 is input, and is directly output as the switching signal of the switching unit 94 It is good to do.

  In this embodiment, the base station uses the frequency FH and the mobile station uses the frequency FL. However, the present invention is not limited to this. The base station uses the frequency FL and the mobile station uses the frequency FH. May be.

The same effect can be obtained by using an RSSI value (Received Signal Strength Indication) representing the electric field strength of the received radio wave instead of the AGC signal.
Further, although the loudspeaker switch is manually operated, the present invention is not limited to this, and the loudspeaker may be automatically turned on / off according to the mode determined by the mode switch.
In this embodiment, the mode switch is directly connected by the voice selection means. However, the present invention is not limited to this, and the state of the mode switch input by another control unit, for example, a control unit for receiver control (not shown) You may make it use with a selection means.

In addition, the mode switch is not configured by a mechanical mode switch. For example, when the position of the mobile station by GPS indicates that it has reached the vicinity of the site, the mode switch may be automatically set to the site mode. A configuration may be adopted in which the on-site mode is automatically set by command data from the station.

  In this embodiment, the two audio signals demodulated by the demodulator are switched. However, the feature of the present invention is to switch the signals received by the two systems. It is not limited to switching. Therefore, the same effect can be obtained by providing the switching unit 94 in the demodulation unit 92 or by providing the voice selection unit 1 and the position information storage unit 2 in the reception level comparison unit 93.

It is a block diagram which shows the Example of the receiving part of the mobile station of the mobile communication system by this invention. It is a flowchart explaining the process of the audio | voice selection means by this invention. It is explanatory drawing explaining this invention, (A) shows the format of communication data, (B) shows the content of a dynamic information table. It is a block diagram which shows the receiving part of the mobile station of the conventional mobile communication system. It is a block diagram explaining the communication mode of the conventional mobile communication system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Voice selection means 2 Position information storage means 3 Mode switch 80 Base station 90 Reception signal amplification part 91 Reception signal amplification part 92 Demodulation part 93 Reception level comparison part 94 Switching part 95 Voice amplifier 96 Speaker 97 Antenna 98 Antenna share part 99 Loudspeaker 100 loudspeaker switch

Claims (2)

A plurality of mobile stations, and a base station that performs radio communication with the mobile stations,
The mobile station is configured to send and receive first radio wave which is modulated by the audio signal, receiving a second radio wave modulated by the audio signal, and outputs the audio signal received in loudspeaker,
The base station receives the first radio wave transmitted from the mobile station and transmits the received signal and / or the voice of a command member communicating with each mobile station using the second radio wave in the mobile communication system comprising comprising a function,
The mobile station
A mode switch that sets that the mobile station exists at the dispatch site ,
Voice selection means for selectively outputting a voice signal obtained by demodulation to the loudspeaker;
The voice selection means inputs the state of the mode switch and transmission source information included in the second radio wave transmitted from another mobile station as a transmission source via the base station, and the mode switch state is the state is present in the dispatch site, and pre-Symbol source information according to the first radio waves transmitted from another mobile station, the second by the simultaneous broadcast function via the base station when in the radio wave is the same as the transmitted source information, the pre-Symbol said first radio wave transmitted from other mobile stations by selecting the audio signal obtained by demodulating the output to the loudspeaker mobile communication system, wherein the to Turkey. 2. The mobile communication system according to claim 1, wherein the base station receives a mode switch state of each of the mobile stations, and creates the position information corresponding to the mode switch state.

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