JP4661585B2 - Audio transmission system - Google Patents

Description

  The present invention relates to an audio transmission system that transmits an audio signal via a signal line.

Conventionally, as an audio transmission system that transmits an audio signal via a signal line, for example, a lobby interphone installed at a common entrance of an apartment house and a dwelling unit installed in each dwelling unit via a signal line There is an intercom system that transmits and receives audio signals (see, for example, Patent Document 1). In such a conventional system, the lobby interphone and each dwelling unit are connected by two lines of a signal line for transmitting an audio signal and a signal line for call control. And in the dwelling unit called from the lobby intercom, the notification sound and the voice message previously held inside are output from the speaker to inform the resident of the call from the lobby intercom.
JP 2005-260359 A

  However, in the conventional system as described above, a large number of terminal devices (dwelling units) must store and hold notification sounds and voice messages in a memory or the like, leading to an increase in cost of the terminal devices.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a voice transmission system in which a voice output terminal device does not need to hold a notification sound and a voice message, and cost can be reduced.

In order to achieve the above object, the first aspect of the present invention provides one or more voice input terminal devices including at least voice input means for inputting voice and one or more voice output means for outputting voice at least. A voice input terminal device, a voice input terminal device, and a main device connected to the voice output terminal device via a signal line and performing call control between the voice input terminal device and the voice output terminal device. An audio transmission system that transmits an audio signal to an audio output terminal device via a signal line, the audio input terminal device comprising: the audio input unit; and an encoding unit that encodes audio input from the audio input unit; A modulation means for modulating the encoded voice data, and a transmitter for storing the voice signal including the modulated voice data in the assigned time slot and transmitting the voice signal via the signal line. And a control signal transmission / reception means for frequency-division-multiplexing the control signal for call control with the voice signal via the signal line, and the voice output terminal device receives the voice signal transmitted via the signal line. Receiving means, demodulating means for demodulating the audio signal received by the receiving means, decoding means for decoding the demodulated audio data, the audio output means for outputting the decoded audio, and a signal line Control signal transmission / reception means for frequency-division multiplexing and transmission / reception of a control signal for call control with a voice signal, and the main device transmits a synchronization signal for defining the time slot to each terminal device via a signal line. Required when receiving a call establishment request control signal from any of the voice input terminal devices, a synchronization signal transmitting means for transmitting to the control signal, a control signal transmitting / receiving means for transmitting / receiving a control signal for call control via a signal line A call control means for transmitting a call establishment request control signal to a destination voice output terminal device and notifying a request source voice input terminal device and a request destination voice output terminal device of time slot allocation; Storage means for storing the notification sound and voice message output from the voice output means of the output terminal device, encoding and modulating the notification sound or voice message stored in the storage means, and storing them in an unused time slot Sound data transmission means for transmitting to the voice output terminal device, the transmission means of the voice input terminal device and the reception means of the voice output terminal device store the voice signal in a time slot allocated from the main device, and transmit / receive, The voice output terminal apparatus receives the notification sound or voice message signal transmitted from the main apparatus by the receiving means and recovers by the demodulation means. The modulated and demodulated notification sound or voice message is decoded by the decoding means, and the notification sound or voice message is output from the voice output means . In the main unit, the synchronization signal transmitting means always transmits the synchronization signal and the sound. The data transmission means stores a specific notification sound or voice message signal in a specific time slot and constantly transmits it.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the sound data transmission means of the main unit selects the encoding method and the number of time slots to be used according to the type of the notification sound and the voice message. To do.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the sound data transmitting means of the main device stores the specific notification sound or the voice message signal in a plurality of specific continuous time slots, and always stores them. It is characterized by transmitting.

According to the first aspect of the present invention, since the notification sound and the voice message output from the voice output means of the voice output terminal device are transmitted from the main device, it is not necessary for the voice output terminal device to hold the notification sound and the voice message. Cost can be reduced. Also, for example, a highly urgent notification sound or voice message is always transmitted from the main device in a specific time slot, and the voice output terminal device receives the specific time slot as necessary to A high notification sound or voice message can be output from the voice output means, and a specific notification sound or voice message can be output quickly and stably because the call control by the main apparatus is not performed.

  According to the invention of claim 2, since the encoding method and the number of time slots to be used are selected according to the type of the notification sound or voice message, the transmission efficiency in the transmission of the notification sound or voice message is improved.

According to the invention of claim 3 , since a specific notification sound or voice message signal is stored in each of a plurality of specific continuous time slots and constantly transmitted, the specific notification sound or voice message is reliably and stably transmitted. It can be output from the audio output means.

  As shown in FIG. 1, the audio transmission system according to the present embodiment is connected to a plurality of terminal devices 2 that transmit and receive audio signals via a signal line Ls, and to the terminal devices 2 through signal lines Ls. And a main apparatus 1 for transmitting a synchronization signal SY for defining a time slot TSi (i = 1, 2,..., N) described later. Here, a balanced line such as a pair line is used as the signal line Ls, but an unbalanced line such as a coaxial line may be used. Further, a pair of enhanced category 5 or category 6 LAN cables or a pair of CPEV cables may be used for the signal line Ls.

  As shown in FIG. 1, the terminal device 2 includes a microphone 20a and a speaker 21a, a microphone amplifier 20b that amplifies the output of the microphone 20a, a speaker amplifier 21b that amplifies the input to the speaker 21a, and the output of the microphone amplifier 20b. An A / D converter 20c that converts the signal into a signal; a D / A converter 21c that converts the digital signal output from the call control unit 22 into an analog signal and inputs the analog signal; and the voice converted into the digital signal An encoding / decoding unit 22 that performs encoding and decoding, and an audio signal that is generated by modulating the audio data encoded by the encoding / decoding control unit 22 and that is captured from the signal line Ls Modulator / demodulator 23 that demodulates audio data from the signal, and transmission amplifier that amplifies the audio signal output from modem 23 4a, a receiving amplifier 24b that amplifies the audio signal input to the modem unit 23, a control unit 25 that controls each unit with the CPU as a main component, and a control signal via the signal line Ls. The control signal transmission / reception unit 26 for transmission / reception, the audio signal output from the transmission amplifier 24a and the control signal output from the control signal transmission / reception unit 26 are frequency-division multiplexed and transmitted to the signal line Ls, and the audio captured from the signal line Ls A demultiplexing unit 27 that separates the signal and the control signal and outputs the audio signal to the reception amplifier 24 b and outputs the control signal to the control signal transmitting and receiving unit 26 is provided. That is, since the terminal device 2 in the present embodiment includes both a voice input unit (microphone 20a) for inputting voice and a voice output unit (speaker 21a) for outputting voice, the terminal device 2 is a voice input terminal device. At the same time, it is a voice output terminal device. However, the configuration of the terminal device 2 is not limited to this, and a voice input terminal device having voice input means and no voice output means, or voice having voice output means and no voice input means. It may be configured as an output terminal device. Each terminal device 2 is given a unique identification code (ID), and each terminal device 2 can be identified by this identification code.

  The main device 1 modulates control data having a CPU as a main component, a control signal transmission / reception unit 11 for transmitting / receiving control signals to / from the terminal device 2, and synchronization data (described later) provided from the control unit 10. Then, the modulation unit 12 that generates the synchronization signal SY, the synchronization signal SY modulated by the modulation unit 12 and the control signal output from the control signal transmission / reception unit 11 are frequency-division multiplexed and transmitted to the signal line Ls and the signal line Ls The demultiplexing and multiplexing unit 13 that separates the control signal captured from the signal and outputs the control signal to the control signal transmitting / receiving unit 11, the memory unit 14 that stores a notification sound and a voice message described later, and the notification sound that is read from the memory unit 14 by the control unit 10 And an encoding unit 15 that encodes a voice message by a method selected by the control unit 10 from among several types of audio encoding methods. Note that the notification sound or voice message stored in the memory unit 14 is, for example, a ringing sound or notification message that rings at the terminal device 2 that is a call destination in call control described later, or an evacuation recommendation when a disaster such as a fire or earthquake occurs. Notification sound or voice message for evacuation guidance.

  The control unit 10 controls the memory unit 14 to transfer the notification sound and voice message data stored in the memory unit 14 to the encoding unit 15. The encoding unit 15 encodes the notification sound and voice message data transferred from the memory unit 14 using the encoding method designated by the control unit 10 and outputs the encoded data to the modulation unit 12. The encoding unit 15 can perform encoding with three types of encoding schemes of PCM (Pulse Code Modulation), ADPCM (Adaptive Differential Pulse Code Modulation), and CELP (Code Excited Linear Prediction). The CELP method is designated for those with a small amount of data, and the PCM or ADPCM method is designated for those with a large amount of data such as voice messages. Further, the modulation unit 12 modulates and outputs the notification sound and voice message encoded by the encoding unit 15 by the digital modulation method specified by the control unit 10. The modulation unit 12 can perform modulation with four types of modulation schemes of BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and 64QAM, and has a small amount of data like a notification sound. BPSK and QPSK systems are specified for things, and 16QAM and 64QAM systems are specified for those with a large amount of data such as voice messages.

  The synchronization signal SY is composed of a header part and a data part as shown in FIG. The header part includes a preamble, a packet type, a modulation method, a data length, and an error correction code. On the other hand, the data part is composed of synchronous data (actually empty) and an error correction code. As shown in FIG. 2B, the audio signal is also composed of a header part and a data part. The header part includes a preamble, an identification code (ID) indicating the terminal device 2 that is the transmission source, a packet type, a modulation method, a data length, and an error correction code. On the other hand, the data part is composed of audio data and error correction codes.

  In the main apparatus 1 and the terminal apparatus 2, as shown in FIG. 3, a period until a next synchronization signal SY rises with a time when a predetermined time has elapsed from the fall of the synchronization signal SY as a start time of the first time slot TS1. A plurality (n) of time slots TS1, TS2,..., TSn are arranged within (signal transmission period). Here, in the present embodiment, n time slots TSi are arranged within the signal transmission period, so that a maximum of n / 2 terminal apparatuses 2 can transmit and receive audio signals on a one-to-one basis.

  Next, the operation of the present embodiment when a one-to-one call (individual call) is performed between the two terminal devices 2 will be described with reference to FIG. In the following, a case where two devices, terminal device A and terminal device B, make an individual call will be exemplified.

  First, when a call button (not shown) is operated in the terminal device A, the control unit 25 generates a call (call establishment) request for calling the partner terminal device B, gives it to the control signal transmission unit 26, and performs control. The signal transmission unit 26 sends the call request, its own identification code, and the other party's identification code to the signal line Ls via the demultiplexing unit 27 by a control signal.

  On the other hand, in the main apparatus 1, a control signal transmitted via the signal line Ls is received by the control signal transmission / reception unit 11, and a call request, a caller (requester) identification code included in the received control signal, a callee The identification code of (request destination) is passed to the control unit 10. The control unit 10 causes the control signal transmission / reception unit 11 to transmit a control signal including allocation of a time slot TSi in which data of a call request and notification sound (calling sound) is stored with the identification code of the call destination as a destination. Further, the control unit 10 gives the synchronization data (actually empty) to output the synchronization signal SY from the modulation unit 12 and send it to the signal line Ls, and the ring tone data read from the memory unit 14 is encoded. It designates and gives to the encoding part 15. The encoding unit 15 encodes the ringing tone data by the encoding method specified by the control unit 10 (for example, CELP method) and outputs the encoded data to the modulation unit 12, and the modulation unit 12 specifies the modulation method specified by the control unit 10. The ringing tone data encoded by is modulated. Then, the voice signal including the ringing tone data modulated by the modulation unit 12 is stored in the time slot TSi designated by the control unit 10 and transmitted. Here, the control unit 10 assigns only one time slot TSi when encoding is performed according to the CELP method, and two when the data is encoded according to the ADPMC method, according to the amount of data after encoding. A time slot TSi is allocated, and when encoding is performed by the PCM method, three time slots TSi are allocated.

  The control signal transmission / reception unit 26 of the called terminal device B receives the control signal transmitted from the main device 1 and controls the allocation of the time slot TSi for storing the call request and ringing tone data included in the received control signal. When passed to the unit 25, the control unit 25 demodulates the signal stored in the assigned time slot TSi by the modulation / demodulation unit 23, decodes it by the encoding / decoding unit 22, and converts it to an analog signal by the D / A converter 21c. After conversion, a ringing tone is generated from the speaker 21a. When a response button (not shown) is operated in the terminal device B, the control unit 25 generates an affirmative response indicating that the individual call with the terminal device A that is the call source is accepted, and the control signal transmission unit 26, the control signal transmitter 26 sends an acknowledgment and its own identification code to the signal line Ls via the demultiplexer 27 by the control signal.

  In the main apparatus 1, the control signal transmitted / received via the signal line Ls is received by the control signal transmission / reception unit 11, and the acknowledgment included in the received control signal and the identification code of the call destination (request destination) are transmitted to the control unit 10. The control unit 10 causes the control signal transmission / reception unit 11 to transmit a control signal including a call establishment notification with the caller identification code as the destination. Further, the control unit 10 transmits, from the control signal transmission / reception unit 11, a control signal for notifying each of the terminal devices A and B of the call source and the call destination of the allocation of the time slots TS1 and TS2 each storing the voice signal. Let

  Then, in the call source terminal device A and the call destination terminal device B, the audio signal collected by the microphone 20a, encoded by the encoding / decoding unit 22, and modulated by the modulation / demodulation unit 23 is transmitted from the main device 1 to itself. Stored in the time slot TS1 or TS2 assigned to the signal and transmitted via the signal line Ls, and the voice signal stored in the time slot TS2 or TS1 assigned to the other party is captured and demodulated by the modem 23 and the voice The encoding / decoding unit 22 decodes the data, and the other party's voice is sounded from the speaker 21a. In this way, the two terminal apparatuses A and B can transmit and receive voice signals using the different time slots TS1 and TS2, thereby enabling individual calls. Here, since two time slots are occupied in an individual call, if there are a total of n time slots, a maximum of n / 2 sets of terminal devices 2 can simultaneously make individual calls.

  Next, the operation of the present embodiment when a many-to-many call (simultaneous call) is performed between the three terminal devices 2 will be described with reference to FIG. In the following, a case where three devices, terminal device A, terminal device B, and terminal device C, make a simultaneous call will be exemplified.

  First, when a general call button (not shown) is operated in the terminal device A, the control unit 25 generates a general call request for calling other terminal devices B and C all at once and gives it to the control signal transmission unit 26. Then, the control signal transmission unit 26 sends a simultaneous call request and its own identification code to the signal line Ls via the demultiplexing unit 27 by the control signal.

  On the other hand, in the main apparatus 1, the control signal transmitted / received via the signal line Ls is received by the control signal transmission / reception unit 11, and the general call request and the caller identification code included in the received control signal are passed to the control unit 10. . The control unit 10 causes the control signal transmission / reception unit 11 to transmit a control signal including the allocation of the time slot TSi for storing the data of the call request and the notification sound (calling sound) with the identification code of the general call destination as the destination. Further, the control unit 10 gives the synchronization data (actually empty) to output the synchronization signal SY from the modulation unit 12 and send it to the signal line Ls, and the ring tone data read from the memory unit 14 is encoded. It designates and gives to the encoding part 15. The encoding unit 15 encodes the ringing tone data by the encoding method specified by the control unit 10 (for example, CELP method) and outputs the encoded data to the modulation unit 12, and the modulation unit 12 specifies the modulation method specified by the control unit 10. The ringing tone data encoded by is modulated. Then, the voice signal including the ringing tone data modulated by the modulation unit 12 is stored in the time slot TSi designated by the control unit 10 and transmitted.

  A time slot TSi in which the control signal transmission / reception unit 26 of the terminal devices B and C of the general call destination receives the control signal transmitted from the main device 1 and stores the data of the general call request and the ringing tone included in the received control signal. Is transferred to the control unit 25, the control unit 25 demodulates the signal stored in the assigned time slot TSi by the modulation / demodulation unit 23, decodes it by the encoding / decoding unit 22, and D / A converter 21c. Then, it is converted into an analog signal and a ringing tone is generated from the speaker 21a. Then, when a response button (not shown) is operated in the terminal devices B and C, the control unit 25 generates an affirmative response indicating that the simultaneous communication is accepted, and gives it to the control signal transmission unit 26 to control the control signal. The transmitter 26 sends an acknowledgment and its own identification code to the signal line Ls via the demultiplexer 27 by the control signal.

  In the main device 1, the control signal transmitted through the signal line Ls is received by the control signal transmission / reception unit 11, and the acknowledgment included in the received control signal and the identification code of the general call destination are passed to the control unit 10, The control unit 10 causes the control signal transmission / reception unit 11 to transmit a control signal including a call establishment notification with the caller identification code as a destination. Further, the control unit 10 transmits, from the control signal transmission / reception unit 11, a control signal for notifying each terminal device A, B, C of the call source and the call destination of the allocation of the time slot TSi for storing the voice signal. Then, the synchronization signal SY is output from the modulation unit 12 by sending the synchronization data (actually empty), and sent to the signal line Ls. Here, in the case of a simultaneous call, time slots TS1, TS2, TS3 for transmission (transmission) and time slots TS4, TS5, TS6 for reception (reception) are assigned to each terminal device A, B, C. It is done.

  In each of the terminal devices A, B, and C, the main device 1 assigns the audio signal collected by the microphone 20a, encoded by the encoding / decoding unit 22, and modulated by the modulation / demodulation unit 23 to itself. The data is stored in the transmission time slots TS1, TS2, TS3 and transmitted via the signal line Ls. Here, in the main apparatus 1, the audio signal stored in the transmission time slots TS1, TS2, and TS3 is taken into the control unit 10, and the audio obtained by combining the audio data transmitted from the terminal apparatuses B and C by the control unit 10 is used. A signal is generated and stored in the reception time slot TS4 assigned to the terminal device A, and a voice signal obtained by combining the voice data transmitted from the terminal devices A and C is generated and assigned to the terminal device B. And a voice signal obtained by combining the voice data transmitted from the terminal devices A and B is generated and stored in the reception time slot TS6 assigned to the terminal device C.

  Therefore, the terminal devices A, B, and C take the audio signals stored in the reception time slots TS4, TS5, and TS6, demodulate them by the modem unit 23, and decode the audio data by the encoding / decoding unit 22. The terminal device A can hear the sound transmitted from the other terminal devices B and C, and the terminal device B can hear the sound transmitted from the other terminal devices A and C. In C, since voices transmitted from other terminal apparatuses A and B can be heard, simultaneous communication is possible.

  As described above, according to the present embodiment, since the notification sound and the voice message output from the speaker 21a of the terminal device 2 are transmitted from the main device 1, it is not necessary for the terminal device 2 to hold the notification sound and the voice message. Cost can be reduced. In addition, since the encoding method and the number of time slots TSi to be used are selected according to the type of the notification sound or voice message, there is an advantage that the transmission efficiency in the transmission of the notification sound or voice message is improved.

  By the way, when transmitting a highly urgent notification sound or voice message from the main device 1 to the terminal device 2, such as a notification sound or voice message for evacuation advisory or evacuation guidance in the event of a disaster such as a fire or an earthquake, It is conceivable that the terminal device 2 will not be able to output it quickly and stably if it is transmitted in the procedure of call control as in the case of individual calls or simultaneous calls. Therefore, the notification sound or voice message with high urgency as described above is assigned in advance with a specific time slot TSi and is always transmitted together with the synchronization signal SY from the main device 1, and the control unit 25 of the terminal device 2 is necessary. Accordingly, if the specific time slot TSi is received and a highly urgent notification sound or voice message is sounded from the speaker 21a, the emergency control can be promptly and stably performed without the call control by the main device 1. High-quality notification sounds and voice messages can be output (sounded) by the terminal device 2. At this time, a specific notification sound or voice message (for example, the above-mentioned highly urgent notification sound or voice message) is stored in each of a plurality of continuous time slots TSi in the control unit 10 as sound data transmission means of the main device 1. Thus, if it is always transmitted, it is possible to prevent the reception error of the specific notification sound or voice message, and to make it ring from the speaker 21a of the terminal device 2 reliably and stably.

  In this embodiment, the assignment of the time slot TSi to the terminal device 2 is notified by the control signal. However, the assignment of the time slot TSi to the terminal device 2 can be notified by the synchronization signal SY instead of the control signal. It is. For example, it is only necessary to transmit data associating the identification code of each terminal device 2 with the allocation of the time slot TSi as the synchronization data constituting the data portion of the synchronization signal SY. If the synchronization signal SY is used to notify the assignment of the time slot TSi in this way, the procedure for transmitting the control signal to notify the assignment of the time slot TSi becomes unnecessary.

  Here, as shown in FIG. 6, by simply connecting the connector of the functional module 108 to the connection port of the gate device 103, the power path and the information path of the functional module 108 can be secured at the same time. There is a wiring system that can be connected also to the gate device 103 and is excellent in workability. In this wiring system, one or a plurality of switch boxes 102 embedded and disposed at appropriate positions in a building are provided, and a power line 110 and an information line 111 that are wired in advance in a wall surface between the switch boxes 102 are sent and wired. At the same time, with respect to the switch box 102 at the starting end, a field line 110 drawn indoors through the main breaker MB and the branch breaker BB drawn into the wiring board 101, and a gateway 120 ( Information line 111 connected via a router and a hub is connected. It is also possible to incorporate the audio transmission system according to the present invention into such a wiring system.

It is a system configuration figure showing an embodiment of the present invention. (A) is explanatory drawing of the synchronizing signal same as the above, (b) is explanatory drawing of the audio | voice signal same as the above. It is a time chart of a synchronous signal and a time slot in the same as the above. It is operation | movement explanatory drawing at the time of the individual call in the same as the above. It is operation | movement explanatory drawing at the time of the simultaneous call in the same as the above. It is a system configuration diagram of a wiring system incorporating the same.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main apparatus 2 Terminal apparatus 10 Control part 11 Control signal transmission / reception part 12 Modulation part 14 Memory part 15 Coding part 20a Microphone 21a Speaker 25 Control part 26 Control signal transmission / reception part 27 Separation multiplexing part Ls Signal line

Claims (3)

One or more voice input terminal devices provided with at least voice input means for inputting voice, one or more voice output terminal devices provided with voice output means for outputting at least voice, voice input terminal devices, and voice output terminals A main apparatus that is connected to the apparatus via a signal line and performs call control between the voice input terminal apparatus and the voice output terminal apparatus, and transmits a voice signal from the voice input terminal apparatus to the voice output terminal apparatus via the signal line An audio transmission system,
The voice input terminal device includes: the voice input unit; a coding unit that codes the voice input from the voice input unit; a modulation unit that modulates the coded voice data; and the modulation in an assigned time slot. A transmission means for storing a voice signal including the received voice data and transmitting the signal via a signal line; and a control signal transmission / reception means for frequency-division multiplexing and transmission / reception of a control signal for call control with the voice signal via the signal line. And
An audio output terminal device includes: a receiving unit that receives an audio signal transmitted via a signal line; a demodulating unit that demodulates an audio signal received by the receiving unit; and a decoding unit that decodes demodulated audio data; The voice output means for outputting the decoded voice, and the control signal transmission / reception means for frequency-division multiplexing and transmission / reception of the control signal for call control via the signal line with the voice signal,
The main apparatus includes a synchronization signal transmitting means for transmitting a synchronization signal for defining the time slot to each terminal apparatus via a signal line, and a control signal transmitting / receiving means for transmitting and receiving a control signal for call control via the signal line When a call establishment request control signal is received from any of the voice input terminal devices, the call establishment request control signal is transmitted to the request destination voice output terminal device and the request source voice input terminal device and request The call control means for notifying the previous voice output terminal device of the time slot assignment, the storage means for storing the notification sound and the voice message output from the voice output means of the voice output terminal device, and the storage means Sound data transmitting means for encoding and modulating a notification sound or a voice message, storing it in an unused time slot, and transmitting it to a voice output terminal device; ,
The transmission means of the voice input terminal device and the reception means of the voice output terminal device store the voice signal in a time slot allocated from the main device, and transmit / receive it.
The voice output terminal device receives the notification sound or voice message signal transmitted from the main device by the receiving means, demodulates the signal by the demodulation means, and decodes the demodulated notification sound or voice message by the decoding means to output the voice. Output a notification sound or voice message from the means ,
In the main apparatus, the audio transmission is characterized in that the synchronization signal transmission means always transmits the synchronization signal, and the sound data transmission means always stores the specific notification sound or voice message signal in a specific time slot and transmits it. system.   2. The audio transmission system according to claim 1, wherein the sound data transmission means of the main unit selects the encoding method and the number of time slots to be used according to the type of the notification sound and the voice message. The sound data transmitting means of the main device, voice transmission according to claim 1 or 2, characterized in that constantly transmitted by each stored signal of the specific notification sound or a voice message to a plurality of successive time slots specific System .

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