JP4629633B2 - Real-time communication device - Google Patents

Description

  The present invention relates to a real-time call device for a real-time call system that makes a call in real time.

  Conventionally, as a device related to this type of technology, a real-time audio reproduction device that is connected to an asynchronous communication network such as Ethernet (registered trademark) and reproduces audio in real time, a digital interface unit that manages an interface with the asynchronous communication network, Received by a reception buffer that temporarily stores digital audio data received by the digital interface unit, a buffer accumulation amount control unit that monitors and controls the amount of digital audio data accumulated in the reception buffer, and a buffer accumulation amount control unit A D / A converter that converts digital audio data read from the buffer into an analog signal, a control target value determiner that determines a control target value for ensuring the quality of conversation, and the status and reception of the asynchronous communication network Missing actual audio due to loss of audio to be played due to buffer status The voice loss rate measurement unit that measures the voice and the analog interface unit that controls the interface with analog telephones and public lines, and the buffer accumulation amount control unit is within the maximum voice loss rate of conversation establishment. Some of them have a configuration that is acceptable.

  Then, the control target value determination unit that determines the control target value for ensuring the quality of conversation establishes the maximum delay time that is established as a conversation (maximum delay time for conversation establishment) and the conversation that is established in advance. Control target so that it falls within a predetermined callable area based on the maximum voice drop rate (maximum voice drop rate for establishing a conversation) and the actual voice drop rate sent from the voice drop rate measurement unit. In order to determine the value and converge to the control target value, the buffer storage amount control unit changes the buffer storage amount and performs feedback control so that the control target value is reached. By allowing the (missing rate) to be within the maximum voice missing rate of conversation establishment, it is possible to control the voice delay to be within the maximum delay time of conversation establishment and to ensure the overall conversation quality ( example For example, see Patent Document 1).

JP 2002-223247 A

  In the conventional device as described above, the maximum delay time established as a conversation (maximum delay time of conversation establishment), the maximum voice loss rate established as a conversation (maximum voice loss rate of conversation establishment), Considering the actual voice loss rate, determine the control target value so that it falls somewhere within the predetermined callable area, and change the buffer storage amount by the buffer storage amount control unit to converge to the control target value And control the feedback to achieve the control target value and allow the voice loss rate (actual voice loss rate) to be within the maximum voice loss rate of conversation establishment. There is a problem that it is necessary to perform complicated processing at all times.

  In addition, the conversation quality is ensured by the control only by the arithmetic processing of the device. For example, when the amount of audio data to be reproduced is extremely large, the control cannot be ensured by the control only by the arithmetic processing to the extent that the content can be understood. There were problems such as cases.

  The present invention controls the buffer amount without unnecessarily increasing the buffer amount by simpler control, and further informs the caller of an abnormality in the buffer amount and encourages consideration of the manner of conversation. An object is to provide an apparatus.

The present invention provides a telephone having a microphone and a speaker for calling, and converts an analog audio signal from the microphone into digital audio data and transmits the digital audio data via a communication line, and is transmitted via the communication line. A communication device that receives the received digital audio data and converts it into an analog audio signal and then inputs the digital audio data to the speaker to generate sound. A data buffer circuit that temporarily stores digital voice data from the communication line, a buffer initial value that is set in the data buffer circuit at the start of a call, and a remaining buffer amount in the data buffer circuit becomes zero, resulting in insufficient buffer amount A memory that stores the buffer increment to be added to the buffer initial value each time it occurs, and the above at the start of a call The buffer initial value and when the remaining buffer amount becomes zero in the data buffer circuit and the buffer amount is insufficient, each time the remaining buffer amount becomes zero, the buffer increment value is sequentially added to the buffer initial value. possess a buffer controller for controlling the buffer amount of the data buffer circuit by performing the initialization is set to the buffer circuit, and the memory, the buffer amount threshold indicating an upper limit of a buffer amount of the data buffer circuit Further, the buffer control unit compares the buffer amount of the data buffer circuit with the buffer amount threshold stored in the memory, and when the buffer amount of the data buffer circuit exceeds the buffer amount threshold, a buffer status alarm A signal is generated, and the communication device is operated according to a buffer status alarm signal from the buffer control unit. In real-time communication device, characterized by further comprising a buffer status alarm indicator for performing multi-address display.

  Also, a telephone set provided with a microphone and a speaker for calling, and an analog audio signal from the microphone is converted into digital audio data and transmitted via a communication line, and sent via the communication line. A communication device that receives digital audio data and converts it into an analog audio signal and then inputs it to the speaker to generate sound, and performs real-time audio communication, wherein the communication device communicates A data buffer circuit that temporarily stores digital voice data from the line, and a buffer initial value that is set in the data buffer circuit at the start of a call and when the remaining buffer amount of the data buffer circuit becomes zero and a buffer amount shortage occurs The remaining buffer amount threshold indicating the lower limit of the remaining buffer amount in the data buffer circuit, and the above-mentioned threshold for important calls. Set the buffer initial value in the data buffer circuit at the start of the call and when the remaining buffer amount becomes zero in the data buffer circuit and the buffer amount is insufficient. If the important buffer signal is input when the remaining buffer amount becomes zero and the buffer amount is insufficient in the data buffer circuit, the buffer important call value is set in the data buffer circuit and the initialization is performed. A buffer control unit that compares the remaining buffer amount of the data buffer circuit with the remaining buffer amount threshold value stored in the memory and generates a buffer status alarm signal when the remaining buffer amount of the data buffer circuit falls below the remaining buffer amount threshold value; And the telephone handset displays an alarm according to a buffer status alarm signal from the buffer control unit. And Cormorant buffer status alarm indicator, in real-time communication device characterized by having a the importance call switch for generating a critical call signal to the buffer control unit according to the operation of the operator.

  In the present invention, it is possible to control the buffer amount without unnecessarily increasing the buffer amount by simpler control, and it is also possible to notify the caller of an abnormality in the buffer amount and to consider the manner of conversation.

  In the following description, for example, when a passenger is canned in an elevator car, an explanation will be given for a case where it is applied to an elevator real-time call system that makes a call between the inside of the car and the outside of the car such as an elevator monitoring center. However, the present invention is not limited to this, and can be generally applied to a real-time call device for a real-time call system.

Embodiment 1 FIG.
FIG. 1 shows the configuration of a real-time call system for an elevator using a real-time call device according to an embodiment of the present invention. In FIG. 1, a real-time call system for an elevator includes an elevator-side real-time call device 100 and an external-side or center-side real-time call device 200. Although the external side or center side real-time call device 200 is a real-time call device according to the present invention, the elevator-side real-time call device 100 can also be constituted by the real-time call device according to the present invention.

  An elevator-side real-time communication device (hereinafter referred to as an elevator-side communication device) 100 is provided in an elevator car, and a car call device 1 in which a caller who is a passenger makes a call, generally an elevator control panel (not shown), etc. It consists of the elevator side communication apparatus 2 provided together. An external-side or center-side real-time communication device (hereinafter referred to as a center-side communication device) 200 is connected to an elevator-side communication device 2 via a communication line 5 so as to be communicable with a center-side communication device 3 provided in an elevator monitoring center. It consists of a center-side telephone 4 on which a caller who is a supervisor of the center-side elevator makes a call. The communication line 5 may be wired, wireless, or a combination of these including a dedicated line, a general public telephone line, a PHS line, an Internet line, or the like.

  The in-car telephone 1 includes an in-car microphone 6 and an in-car speaker 7. The elevator-side communication device 2 includes an A / D conversion circuit 8 connected to the car microphone 6, a data transmission circuit 9 connected to the A / D conversion circuit 8, a data reception circuit 10 connected to the communication line 5, and data The data buffer circuit 11 connected to the receiving circuit 10, the data buffer circuit 11 and the D / A conversion circuit 12 connected to the car speaker 7, the buffer control unit 13 connected to the data buffer circuit 11, and the buffer control unit 13 A memory 14 storing a connected buffer initial value 14a is provided.

  The center side telephone 4 includes a microphone 15 and a speaker 16. The center side communication device 3 includes an A / D conversion circuit 17 connected to the microphone 15, an A / D conversion circuit 17, a data transmission circuit 18 connected to the communication line 5, and a data reception circuit 19 connected to the communication line 5. The data buffer circuit 20 connected to the data receiving circuit 19, the D / A conversion circuit 21 connected to the data buffer circuit 20 and the speaker 16, the buffer control unit 22 connected to the data buffer circuit 20, and the buffer control unit 22 A memory 23 storing the connected buffer initial value 23a and buffer increase amount 23b is provided.

  The buffer control units 13 and 22 are constituted by a microcomputer or the like that operates by reading data stored in the memory.

  FIG. 2 shows a basic flow of voice communication processing in this type of real-time call system, and shows a case of a call from the microphone 6 in the car to the speaker 16 of the center side caller 4. The sound that enters the car microphone 6 becomes an analog sound signal and is input to the A / D conversion circuit 8. In the A / D conversion circuit 8, the analog audio signal (audio 1) is digitized and converted into digital audio data (data 1) at regular time intervals T. The digitized digital audio data (data 1) is transmitted from the data transmission circuit 9 to the communication line 5. In the communication line 5, a delay occurs depending on the state of the communication path, and the digital audio data (data 1) is delayed and received by the data receiving circuit 19. The received digital audio data (data 1) is sent from the data receiving circuit 19 to the data buffer circuit 20.

  Each time communication is started, the buffer control unit 22 initializes the data buffer circuit 20, and sets the buffer amount Td in the data buffer circuit 20 with the buffer initial value (Td) 23a stored in the memory 23 as an initial value. To do. The data buffer circuit 20 buffers the digital audio data for the set buffer amount Td, and outputs the digital audio data (data 1) to the D / A conversion circuit 21 at regular time intervals T.

  The delay of the digital audio data varies, and the time from the completion of reception of data 1 to the completion of reception of data 2 is “T + T1”, and the time from the completion of reception of the next data 2 to the completion of reception of data 3 is “T + T2”. " Since the buffer amount Td is buffered from the data buffer circuit 20, the data buffer circuit 20 starts transmission of data 1 after the buffer amount Td from the completion of reception of data 1, and the next data 2 starts from transmission start of data 1. Transmission starts after a certain time T, and is transmitted from the data buffer circuit 20 to the D / A conversion circuit 21 at every certain time T, converted into an analog audio signal by the D / A conversion circuit 21, and output from the speaker 16 as sound. .

  Here, if there is a large delay in data communication in the communication line 5 and the data 4 is delayed and the data buffer circuit 20 has reached the time to transmit, if the data 4 is not completely received, the data buffer circuit 20 Since the data 4 cannot be transmitted to the D / A conversion circuit 21 at a certain time T (buffer amount is insufficient), the D / A conversion circuit 21 cannot output an analog audio signal to the speaker 16, and the sound is interrupted. Become.

  The above occurs when the delay exceeds the buffer amount Td and “T + T1” + “T + T2” + “T + T3”> T + T + T + Td.

When the delay exceeds the buffer amount Td in the data buffer circuit 20 as described above, the buffer control unit 22 initializes the data buffer circuit 20 again and sets the buffer initial value 23a as the initial value to the data buffer circuit 20. A buffer amount Td is set.
The above operation is continued until the call is finished.
The above operation is an explanation of the case where the sound of the car microphone 6 is sent to the center speaker 16, but the same is true when the sound of the center microphone 15 is sent to the car speaker 7.

  When the communication line 5 having an unstable delay time is used, it is necessary to increase the buffer amount Td so that the sound is not interrupted. Since the buffer amount Td is large, the delay in the data buffer circuit 20 is large. It becomes difficult to talk. Conversely, if the buffer amount Td is reduced, the audio delay is reduced, but the buffer amount becomes insufficient and the audio is easily interrupted.

  Therefore, in the present invention, the buffer increase amount 23b is stored in the memory 23 as shown in FIG.

  FIG. 3 is an operation flowchart of the buffer control unit 22 of the center-side communication device 3 of the center-side communication device 200 according to this embodiment. Hereinafter, based on the operation flowchart, audio from the in-car microphone 6 is transmitted to the center-side speaker. The operation of the buffer control unit 22 when sending to 16 will be described. When a call from the in-car microphone 6 is started and communication for sending the call to the center side speaker 16 is started, the data buffer circuit 20 receives the digital audio data from the data receiving circuit 19, and the buffer control unit 22 When the data buffer circuit 20 receives the digital audio data, it detects the start of a call (step S1).

  When detecting the start of a call, the buffer control unit 22 initializes the data buffer circuit 20, and sets the buffer amount Td in the data buffer circuit 20 using the buffer initial value (Td) 23a as an initial value (step S2). The data buffer circuit 20 buffers the digital audio data for the set buffer amount Td, and outputs the digital audio data (data 1) to the D / A conversion circuit 21 at regular time intervals T.

  The remaining buffer amount t shown in FIG. 2 represents the time from the completion of data reception by the data buffer circuit 20 to the start of data transmission from the data buffer circuit 20. When this remaining buffer amount t disappears, i.e., becomes zero, the buffer amount becomes insufficient and the sound is interrupted.

When the buffer control unit 22 detects that the buffer amount is insufficient in the data buffer circuit 20 during the call (step S3) (step S4), the buffer control unit 22 initializes the data buffer circuit 20 and An amount obtained by increasing the buffer increase amount (Tp) 23b with respect to the buffer amount Td is set as a new buffer amount Td + Tp (increase buffer value) (step S5). As a result, the data buffer circuit 20 buffers the digital audio data corresponding to the newly set buffer amount Td + Tp, and outputs the digital audio data (data 1) to the D / A conversion circuit 21 every predetermined time T. If the buffer amount becomes insufficient, a buffer increase amount Tp is newly added (Td + Tp + Tp + Tp (increased buffer value)), and the buffer amount is increased (steps S3 to S5).
The above continues until the call ends.

  With the above operation, a buffer amount shortage occurs in the data buffer circuit 20 due to the delay of the communication line 5, and even if the sound is interrupted once, the buffer amount increases thereafter, so that the buffer amount shortage does not easily occur. Also, the amount of buffer is unnecessarily increased so that the audio is not delayed.

Embodiment 2. FIG.
FIG. 4 shows a configuration of a real-time call system for an elevator using a real-time call device according to another embodiment of the present invention. The same or corresponding parts as those of the above-described embodiment shown in FIG. The memory 23 further stores a buffer amount threshold 23c indicating the upper limit value of the buffer amount of the data buffer circuit 20, and the center side communication device 4 is provided with a buffer status alarm display 24.

  FIG. 5 shows an operation flowchart of the buffer control unit 22 of the center side communication device 3 of the center side communication device 200 according to this embodiment. In the following, the operation when the sound from the car microphone 6 is sent to the center speaker 16 will be described based on the operation flowchart. When a call from the in-car microphone 6 is started and communication for sending the call to the center side speaker 16 is started, the data buffer circuit 20 receives the digital audio data from the data receiving circuit 19, and the buffer control unit 22 When the data buffer circuit 20 receives the digital audio data, it detects the start of a call (step S1).

  When detecting the start of a call, the buffer control unit 22 initializes the data buffer circuit 20, and sets the buffer amount Td in the data buffer circuit 20 using the buffer initial value (Td) 23a as an initial value (step S2). The data buffer circuit 20 buffers the digital audio data for the set buffer amount Td, and outputs the digital audio data (data 1) to the D / A conversion circuit 21 at regular time intervals T.

  During a call (step S3), the buffer control unit 22 sets the buffer amount Td set in the data buffer circuit 20 in the memory 23 in advance and compares it with the stored buffer amount threshold value (Tth) 23c. (Step S6), a buffer status alarm signal is sent to the buffer status alarm indicator 24 of the center side telephone 4, and the buffer amount Td of the data buffer circuit 20 is set to the buffer status alarm indicator 24. (Tth) An alarm is displayed indicating that the value exceeds 23c (step S7).

  The remaining buffer amount t shown in FIG. 2 represents the time from the completion of data reception by the data buffer circuit 20 to the start of data transmission from the data buffer circuit 20. When this remaining buffer amount t disappears, i.e., becomes zero, the buffer amount becomes insufficient and the sound is interrupted.

During a call, when the buffer control unit 22 detects that a buffer amount shortage has occurred in the data buffer circuit 20 (step S4), the buffer control unit 22 initializes the data buffer circuit 20 to the current buffer amount Td. On the other hand, an amount obtained by increasing the buffer increase amount (Tp) 23b is set as a new buffer amount Td + Tp (step S5). As a result, the data buffer circuit 20 buffers the digital audio data corresponding to the newly set buffer amount Td + Tp, and outputs the digital audio data (data 1) to the D / A conversion circuit 21 every predetermined time T. If the buffer amount becomes insufficient, a buffer increase amount Tp is newly added (Td + Tp + Tp + Tp...), And the buffer amount is increased (steps S3 to S5).
The above continues until the call ends.

  In this way, every time a buffer amount shortage occurs in the data buffer circuit 20 of the center side communication device 3, the buffer amount is set to be increased by a certain amount, and the buffer amount (Td + Tp + Tp + Tp) set in the data buffer circuit 20 is set. ...) exceeds a predetermined buffer amount threshold value Tth, by displaying that the buffer amount exceeds the buffer amount threshold value Tth on the buffer status alarm indicator 24 provided in the center side telephone 4. Since the caller's center elevator supervisor is aware that the buffer volume has increased and the audio volume has been delayed due to the increase in the buffer volume, the conversation has to be carried out according to the amount of audio delay. be able to.

  For example, when the buffer amount (Td + Tp...) Is equal to or less than the buffer amount threshold value (Tth) 23c and no alarm is displayed on the buffer status alarm indicator 24, the center side talker performs a normal conversation. However, when the buffer amount (Td + Tp...) Exceeds the buffer amount threshold value Tth and the alarm indication is displayed on the buffer status alarm indicator 24, the caller asks the conversation from the center side into the car in the question format. This makes it possible to have a conversation even if there is a voice delay.

Embodiment 3 FIG.
FIG. 6 shows the configuration of a real-time call system for an elevator using a real-time call device according to still another embodiment of the present invention. The same or corresponding parts as those in the above embodiment are denoted by the same reference numerals and the description thereof is omitted. The center side communication device 4 is provided with an important call switch 25 operated by a caller who is a supervisor, and the memory 23 has a buffer initial value (Td) 23 a and a lower limit of the remaining buffer amount in the data buffer circuit 20. A remaining buffer amount threshold value (Trth) 23d indicating a value and a buffer important call value (Tinp) 23e described later are stored.

  FIG. 7 shows an operation flowchart of the buffer control unit 22 of the center side communication device 3 of the center side communication device 200 according to this embodiment. In the following, the operation when the sound from the car microphone 6 is sent to the center speaker 16 will be described based on the operation flowchart. When a call from the in-car microphone 6 is started and communication for sending the call to the center side speaker 16 is started, the data buffer circuit 20 receives the digital audio data from the data receiving circuit 19, and the buffer control unit 22 When the data buffer circuit 20 receives the digital audio data, it detects the start of a call (step S1).

  When detecting the start of a call, the buffer control unit 22 initializes the data buffer circuit 20, and sets the buffer amount Td in the data buffer circuit 20 using the buffer initial value (Td) 23a as an initial value (step S2). The data buffer circuit 20 buffers the digital audio data for the set buffer amount Td, and outputs the digital audio data (data 1) to the D / A conversion circuit 21 at regular time intervals T.

  During a call (step S3), the buffer control unit 22 compares the remaining buffer amount t of the data buffer circuit 20 with the remaining buffer amount threshold value (Trth) 23d previously set and stored in the memory 23, and falls below the threshold value. (Step S8), a buffer status alarm signal is sent to the buffer status alarm indicator 24 of the center side telephone 4, and the remaining buffer amount t of the data buffer circuit 20 is set to the buffer status alarm indicator 24. An alarm display indicating that the value has fallen below the threshold is displayed (step S9).

  The remaining buffer amount t shown in FIG. 2 represents the time from the completion of data reception by the data buffer circuit 20 to the start of data transmission from the data buffer circuit 20. When this remaining buffer amount t disappears, i.e., becomes zero, the buffer amount becomes insufficient and the sound is interrupted.

  Then, when the buffer control unit 22 detects that the buffer amount is insufficient in the data buffer circuit 20 during a call (step S4), the buffer control unit 22 initializes the data buffer circuit 20 and operates as a caller. When the important call switch 25 of the center side telephone 4 is pushed by the person and an important call signal is input from the important call switch 25 to the buffer control unit 22 (step S10), the buffer important call value in the memory 23 is stored. (Tinp) 23e is selected, and the value is set in the data buffer circuit 20 as the buffer amount (step S11).

On the other hand, if the important call switch 25 of the center side telephone 4 is not pressed in step S10, no important call signal is input, so the buffer control unit 22 selects the buffer initial value (Td) 23a in the memory 23. Then, the value is set as a buffer amount in the data buffer circuit 20 (step S12). The data buffer circuit 20 buffers the digital audio data corresponding to the newly set buffer important speech value Tinp or buffer initial value Td, and converts the digital audio data (data 1) into a D / A conversion circuit 21 at a predetermined time T. Output to. As shown in step S <b> 13, the buffer control unit 22 may always send a buffer amount signal indicating the buffer amount of the data buffer circuit 20 to the buffer state alarm indicator 24 for display.
The above continues until the call ends.

  Thus, when the remaining buffer amount t of the data buffer circuit 20 falls below the remaining buffer amount threshold value (Trth) 23d, it is displayed on the buffer status alarm display 24 provided in the center side telephone 4. The caller of the elevator on the center side can recognize the shortage of the remaining buffer amount, and can be aware of the interruption of the call when the remaining buffer amount is insufficient.

  For example, if the remaining buffer amount t is not less than the remaining buffer amount threshold (Trth) 23d and the buffer status alarm indicator 24 is not displaying an alarm, the center-side talker performs a normal conversation.

  Further, when the remaining buffer amount t is below the remaining buffer amount threshold value (Trth) 23d and a warning is displayed on the buffer status alarm indicator 24, the center side caller hears an important matter from the car. In the case where it is desired, the buffer important call value larger than the buffer initial value (Td) 23 a normally set in the data buffer circuit 20 after the buffer amount shortage occurs by pressing the important call switch 25 of the center side telephone 4. (Tinp) 23e can be set as the buffer amount.

  Further, the fact that the remaining buffer amount t of the data buffer circuit 20 is insufficient is displayed on the center side telephone 4, so that the center side caller can recognize the shortage of the remaining buffer amount t, and the important conversation In this case, the buffer amount to be set can be set large to the buffer important call value Tinp.

  For example, when the remaining buffer amount is large and the delay of the communication line 5 is stable, and the mutual exchange of calls between the car and the center side is necessary, the buffer amount is equal to the initial value Td. And keep the audio delay as small as possible. Further, when the remaining buffer amount t is small and the delay of the communication line 5 is unstable, and when it is desired to hear important matters from the car, the buffer amount is set to the buffer important call value Tinp having a large value, Once the buffer amount becomes insufficient, it is possible to make it difficult for the sound to be interrupted.

It is a figure which shows the structure of the real-time call system for elevators which uses the real-time call apparatus by one Embodiment of this invention. It is a figure for demonstrating the basic flow of the voice communication process in this kind of real-time telephone system. It is an operation | movement flowchart of the buffer control part of the center side communication apparatus in the center side call apparatus of FIG. It is a figure which shows the structure of the real-time call system for elevators which uses the real-time call apparatus by another embodiment of this invention. 5 is an operation flowchart of a buffer control unit of a center side communication device in the center side call device of FIG. 4. It is a figure which shows the structure of the real-time telephone call system for elevators which uses the real-time telephone apparatus by another embodiment of this invention. It is an operation | movement flowchart of the buffer control part of the center side communication apparatus in the center side call apparatus of FIG.

Explanation of symbols

  1 in-car communication device, 2 elevator side communication device, 3 center side communication device, 4 center side communication device, 5 communication line, 6 in-car microphone, 7 in-car speaker, 8, 17 A / D conversion circuit, 9, 18 Data transmission circuit, 10, 19 Data reception circuit, 11, 20 Data buffer circuit, 12, 21 D / A conversion circuit, 13, 22 Buffer control unit, 14, 23 Memory, 14a Buffer initial value, 15 Microphone, 16 Speaker, 23a Buffer initial value (Td), 23b Buffer increase amount (Tp), 23c Buffer amount threshold value (Tth), 23d Remaining buffer amount threshold value (Trth), 23e Buffer important call value (Tinp), 24 Buffer status alarm indicator, 25 Important call switch, 100 Elevator side real-time communication device, 200 External side or center side real tie The communication device.

Claims (4)

A telephone set provided with a microphone and a speaker for calling, and an analog voice signal from the microphone is converted into digital voice data and transmitted via a communication line, and a digital voice sent via the communication line A communication device that receives data and converts it into an analog voice signal and then inputs it to the speaker to generate sound, and performs voice communication in real time,
The communication device
A data buffer circuit for temporarily storing digital audio data from the communication line;
A memory storing a buffer initial value set in the data buffer circuit at the start of a call, and a buffer increase amount to be added to the buffer initial value each time the remaining buffer amount in the data buffer circuit becomes zero and a buffer amount shortage occurs ,
When the call starts, the buffer initial value is increased. When the remaining buffer amount is zero in the data buffer circuit and the buffer amount is insufficient, the buffer increment is sequentially added to the buffer initial value each time the remaining buffer amount becomes zero. have a, a buffer control unit which controls the buffer amount of the data buffer circuit by the buffer value respectively set to the data buffer circuit is initialized,
The memory further stores a buffer amount threshold value indicating an upper limit of a buffer amount of the data buffer circuit;
The buffer control unit compares the buffer amount of the data buffer circuit with a buffer amount threshold value stored in the memory, and generates a buffer status alarm signal when the buffer amount of the data buffer circuit exceeds the buffer amount threshold value. ,
The real-time communication device, wherein the telephone further includes a buffer status alarm indicator that displays an alarm in accordance with a buffer status alarm signal from the buffer control unit . A telephone set provided with a microphone and a speaker for calling, and an analog voice signal from the microphone is converted into digital voice data and transmitted via a communication line, and a digital voice sent via the communication line A communication device that receives data and converts it into an analog voice signal and then inputs it into the speaker to generate sound, and performs voice communication in real time,
The communication device
A data buffer circuit for temporarily storing digital audio data from the communication line;
Buffer initial value set in the data buffer circuit when the call starts and when the remaining buffer amount of the data buffer circuit becomes zero and the buffer amount is insufficient, and the remaining buffer amount threshold value indicating the lower limit of the remaining buffer amount in the data buffer circuit A memory storing a buffer important call value larger than the buffer initial value for the important call,
At the start of a call and when the remaining buffer amount becomes zero in the data buffer circuit and the buffer amount becomes insufficient, the above buffer initial value is set in the data buffer circuit and initialization is performed, and the remaining buffer amount becomes zero in the data buffer circuit. If an important call signal is input when the buffer amount is insufficient, the buffer important call value is set in the data buffer circuit and initialization is performed, and the remaining buffer amount of the data buffer circuit and the remaining amount stored in the memory are initialized. A buffer control unit that compares the buffer amount threshold value and generates a buffer state alarm signal when the remaining buffer amount of the data buffer circuit falls below the remaining buffer amount threshold value,
The above phone is
A buffer status alarm indicator for displaying an alarm according to the buffer status alarm signal from the buffer control unit;
A real-time call device, comprising: an important call switch that generates an important call signal in the buffer control unit in accordance with an operation of an operator. The real-time call device according to claim 1 , wherein the real-time call device is a real-time call device for a real-time call system that makes a call between an elevator car and the outside. The real-time call device according to claim 3 , wherein the real-time call device is provided on the outside of the elevator.

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