JPS6410158B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a communication method in telephone communication that allows subscribers to freely select various types of audio encoding/decoding in consideration of economic efficiency, quality, etc. It is.

<Background Art> Digitalization of communication networks is currently progressing, and in the future it will become possible to communicate using one digital link between subscribers. When a digital 1 link between subscribers is achieved, an encoder converts audio into a digital signal, and a decoder converts it vice versa.
(referred to as a CODEC) will be installed in the subscriber's premises. As the audio encoding method in this case, PCM having a logarithmic companding characteristic of approximately 64 Kb/s, the so-called logPCM audio encoding method, is considered to be used for the time being from the viewpoint of economy and quality.

However, in addition to the above-mentioned logPCM audio encoding method, audio encoding methods include (i) a method that obtains sufficient quality at a lower transmission speed; (ii) a method capable of conveying meaning at a very slow transmission rate but with poor quality;
(iii) A method that can transmit high frequency information of 4KHz or higher (music information, etc.) at approximately 64Kb/s is considered.

Therefore, when it becomes possible to set up digital 1-link communication channels with various transmission speeds, and when the cost of audio CODEC is achieved using the high-efficiency audio encoding method, it is thought that the following service requests will arise.

(a) Inexpensive long-distance voice communication system (b) High-quality communication system for music, etc. To realize these services, select the one suitable for the situation from among arbitrary audio encoding systems and use it for communication. It is desirable to configure future communication networks so that

<Purpose of the Invention> The present invention enables subscribers to freely select an audio encoding method for telephone communication in consideration of economic efficiency and quality, and also to flexibly respond to the future development of audio CODECs. This is what I did. A detailed explanation will be given below with reference to the drawings.

<Configuration of Embodiment> FIG. 1 shows the configuration of a system in the communication system of the present invention. A terminal 1 is accommodated in an exchange 2 through a digital subscriber line transmission line 3, and the exchanges 2 and 2 are mutually connected through a digital relay transmission line 4. A digital communication network is constructed by connecting the As will be explained below, each part of this communication network is configured so that a subscriber can communicate by selecting an appropriate audio encoding method in consideration of economy and quality.

FIG. 2 shows the external appearance of the terminal 1, and the handset 5 and dial button 6 can be similar to those of existing telephones. For example, five audio CODEC selection buttons 7 are provided, and each button 7
Letters or symbols indicating the audio encoding method are attached near the button, and the subscriber can freely select the desired audio encoding method by pressing one of the buttons. The inconsistency indicator lamp 8 is an indicator for notifying the originating subscriber by blinking when the receiving terminal does not have the processing function for voice encoding desired by the originating subscriber. Audio CODEC selection display lamps 9 are provided in close proximity to each audio CODEC selection button 7, and the selected audio encoding method is lit and the audio encoding processing function desired by the calling subscriber is displayed on the receiving terminal. This is an indicator that blinks to indicate the available audio encoding methods of the called terminal when the number is not available. Figure 2 shows the audio CODEC at the terminal.
As written at the bottom of selection button 7, approximately
64Kb/S logPCM audio encoding method, approximately 64Kb/S
s high-quality APC-AB (Adaptive Predictive Coding - Adaptive Bitrate) audio coding system, 32Kb/s
ADPCM (adaptive differential PCM) audio encoding method,
16Kb/s APC audio encoding method, 8Kb/s
This is an example in which the PARCOR audio encoding method can be selectively used. There are many documents regarding the quality of these audio encoding systems, so a description thereof will be omitted here.

FIG. 3 shows an example of the internal configuration of the terminal 1, in which the composite audio CODEC 10 is used to record audio using the various audio encoding methods mentioned above.
Circuit that enables CODEC processing, signal control circuit 1
1 is a circuit for transmitting and receiving signals with the exchange 2 in FIG. 1, transmitting and receiving signals with the other terminal signal control circuit 11, and controlling each circuit in FIG. Signal channels and composite audio
The communication channel from the CODEC 10 is combined and supplied to the line termination circuit 13, or conversely, the communication of the line termination circuit 13 is separated into a signal channel and a communication channel. The line termination circuit 13 is a transmission interface circuit interposed between the digital subscriber line transmission line 3 and the multiplex conversion circuit 12, and performs clock synchronization extraction and regeneration and transmission of digital transmission waveforms. The signal tone generation circuit 14 is controlled by the signal control circuit 11 and generates a dial tone, a ringing tone, and an audio CODEC.
An audible signal such as a mismatched sound is generated and supplied to the synthesis circuit 15. The synthesis circuit 15 combines the audible signal from the signal tone generation circuit 14 and the received and decomposed composite voice.
It combines the communication signal from the CODEC 10 and supplies it to the handset 5. The switch section 16 is an on/off switch for the handset, a dial button switch, and an audio
The operating state of each switch is input to the signal control circuit 11. The display unit 17 includes a mismatch indicator lamp 8 and an audio CODEC selection indicator lamp 9, and is controlled to turn on and off by the signal control circuit 11.

FIG. 4 shows a configuration example of the exchange 2, in which a line termination device 18 is connected to one end of the subscriber line transmission line 3, and is a transmission interface device and multiplexer that performs the same processing as the line termination circuit 13 in FIG. The conversion device 19 is disposed between a plurality of line termination devices 18 and a communication path switch 20, and is a device for multiplexing and separating a plurality of signal channels and communication channels, and the communication path switch 20 is composed of a memory switch. , (8×N)Kb/
Central controller 21 is a device that connects communication channels of various transmission speeds of s (N is 12345678...) between the multiplex converter 19 and the digital relay transmission line 4.
is a device that controls the communication path switch 20, monitors the line, etc., and the signal transmitter/receiver device 22 is a device that transmits and receives signals to and from terminals and other exchanges. By configuring the exchange as described above, it is possible to set communication channels of various transmission speeds in accordance with the requests of terminals.

<Operation of Embodiment> The operation of the communication system according to the present invention will be described below with reference to FIG. FIG. 5 shows the signal flow and terminal operation procedure. The calling subscriber is
After pressing the desired audio CODEC selection button 7 in FIG. 2, pick up the handset 5. After this operation,
The operation of the audio CODEC 10 in FIG. 3 is switched to the desired functional operation of the audio CODEC corresponding to the pressed button 7, and the result
This is displayed on the CODEC selection display lamp 9, and a "calling signal" is sent from the calling terminal 1a to the exchange 2 in FIG. The calling terminal 1a receives the "outgoing signal" from the exchange 2, and the calling subscriber, after hearing it as a signal tone from the signal tone generating circuit 14 in FIG. 3, dials the other party's telephone number. In response to the dialing operation, the calling terminal 1a sends a "selection signal" representing the other party's telephone number and a "speed designation signal" representing the transmission speed necessary for communication using the desired voice CODEC to the exchange 2 in FIG. do.

The exchange 2 receives the "selection signal" and the "speed designation signal" and reserves the communication channel of the designated speed between the terminals, and also sends the "speed designation signal" to the destination terminal 1b to determine how to use the communication channel. Notify. After receiving the "speed designation signal", the receiving terminal 1b sends a "provisional response signal" to the transmitting terminal 1a. After receiving the "provisional response signal", the originating terminal 1a sends out an "audio CODEC selection signal" representing the type of the desired audio CODEC. The receiving terminal 1b receives this signal and outputs the voice desired by the calling party.
Determine whether it has CODEC function. In some cases, the called terminal 1a, after switching to the necessary voice CODEC function operation, emits a ringing tone and sends a "ringing signal" to the calling subscriber. The calling subscriber hears a ringing signal and
Thereafter, the subscriber's response is known by the ringing tone disappearing, and the call can be made.

If the called terminal 1b does not have the audio CODEC function desired by the calling terminal 1a, the called terminal 1b
sends an "available audio CODEC instruction signal" indicating the audio CODEC function it possesses to the originating terminal 1a. After receiving the "available audio CODEC instruction signal", the originating terminal 1a flashes the mismatch indicator lamp 8 in FIG. 2, generates an audio CODEC mismatch sound, and flashes the audio CODEC selection indicator lamp 9. The calling subscriber must confirm that the called party does not have the desired audio CODEC function and that the available audio
The CODEC function can be known by blinking the selection display lamp 9. The calling subscriber selects the desired audio CODEC function again from the flashing audio CODEC selection display lamp 9.
Press CODEC selection button 7. As a result, if it is necessary to change the transmission speed, a "speed designation signal" is sent from the originating terminal 1a to the exchange 2, and the transmission speed of the suspended communication channel is changed. The originating terminal 1a sends an "audio CODEC selection signal" to the receiving terminal. Thereafter, a telephone call can be made in the same manner as described above.

In the above description of the operation of the present invention, the signal transmission and reception is performed using the signal control circuit 11 in FIG. 3 at the terminal.
In the exchange, the signal transmitting/receiving device 22 shown in FIG. 4 is used.

As explained above, the present invention provides an exchange with a means for changing the communication channel at any time according to the "speed designation signal" issued from the calling terminal. audio
Even though I wanted to use the CODEC function,
When you are forced to use the audio CODEC function of the 8Kb/s PARCOR audio encoding method due to the equipment condition of the receiving side, you can now change the transmission speed of the communication channel used from the initial setting of 16Kb/s to 8Kb/s. In addition, the terminal has operating means for selecting the audio CODEC according to the needs of the calling subscriber, automatic switching means for the operation of the audio CODEC function according to the operation, and if the receiving terminal does not have the desired audio CODEC function. By providing a means for automatically notifying the calling side terminal of the voice CODEC available on the called side and a means for notifying the calling side subscriber of the matching voice CODEC function of the calling side and the called side, each subscriber can This enables communication using various audio CODEC functions.

In addition, in order to further improve the operability of the communication system of the present invention, it is possible to
The CODEC function is the voice that every device owns.
In the case of a basic voice CODEC function, which is a CODEC function, the handset is picked up and the call is made by dialing only, and the calling terminal does not receive a provisional response signal, etc., and after sending out a "speed designation signal", suddenly "calls". It is possible to communicate by receiving a medium signal.

<Example of configuration of composite audio CODEC 10> Next, an example of the configuration of the composite audio CODEC 10 shown in FIG. 3, which is an important circuit for making the present invention possible, will be described with reference to FIG. 6. The terminals 23 and 24 are used to receive and receive analog audio signals from the handset 5.
The terminals 23 and 24 are connected to an analog-to-digital conversion circuit and a digital-to-analog conversion circuit 28, and the circuit 28 is connected to a bus 30 through an interface 29. Digital audio input/output terminals 25 and 26 are connected to the bus 30 through a transmission interface circuit 31 with the multiplex conversion circuit 12, and further a CPU 32 and a random access memory 3 are connected to the bus 30.
3, read only memory 34, and other types of high speed digital processing circuits 35, 36 are also connected to bus 30.

The digital signal processing required for the audio CODEC function is carried out by read-only memory (read-only memory) 34.
This is done by the CPU reading out the program written in it, decoding it, and executing it. The read-only memory 34 contains programs for the basic audio CODEC function as well as various audio files required by the subscriber.
Programs for CODEC functions are available,
The selection of this program is made by the control signal from the signal control circuit 11 in FIG.
This is done by an interrupt through 7. Basic audio
When operating as an audio CODEC with a small amount of digital signal processing like a CODEC, the digital signal processing required for encoding and decoding is performed by the CPU 3.
2 or a code conversion table in the read-only memory 34. In particular, when operating as an audio CODEC that requires high-speed calculation, a dedicated high-speed digital signal processing circuit 35 or 36 is used.
Use. As explained above, the signal control circuit 1
1, a composite audio CODEC that can operate as an audio CODEC as required can be constructed.

Furthermore, the CPU 32 in the composite audio CODEC and the CPU for communication control processing built in the signal control circuit 11
It is also possible to use both.

<Effects> As explained above, the switching equipment is provided with a means to change the transmission speed of the communication channel in accordance with the request of the terminal, and the terminal is provided with the means to change the transmission speed of the communication channel in accordance with the request of the terminal. By providing a function consistent with the voice CODEC function, subscribers can
By using the CODEC function properly, you can transmit low-speed audio over long distances.
In addition to enabling low-cost telephone communications and high-quality telephone communications using CODEC through unified terminal operations, consistency can be achieved by exchanging control signals between terminals without prior knowledge of the voice CODEC function of the other party's terminal. It becomes possible to make calls using the voice encoding method, and it becomes possible to flexibly respond to future voice CODECs, such as by making it easier to introduce new voice CODECs as technology advances.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a system configuration in a communication system according to the present invention, FIG. 2 is a diagram showing an example of the external appearance of terminal 1 in FIG. 1, and FIG. 3 is a configuration inside terminal 1 in FIG. FIG. 4 is a block diagram showing an example of the configuration of the exchange shown in FIG. 1, and FIG.
The figure shows an example of a signal flow and a terminal operation procedure in the communication system of the present invention, and FIG. 6 is a block diagram showing an example of the configuration of the composite voice CODEC 10 in FIG. 3. 1: Terminal, 2: Exchange, 3: Digital subscriber line transmission line, 4: Digital relay transmission line, 5: Handset, 6: Dial button, 7: Audio CODEC selection button, 8: Mismatch indicator lamp, 9: audio
CODEC selection indicator lamp, 10: Composite audio
CODEC, 11: Signal control circuit, 12: Multiplex conversion circuit, 13: Line termination circuit, 14: Signal tone generation circuit, 15: Synthesis circuit, 16: Switch section, 17:
Display section, 18: Line termination device, 19: Multiplex conversion device, 20: Communication path switch, 21: Central control device, 22: Signal transmitting/receiving device, 23, 24: Analog audio signal input terminal and output terminal, 25, 26 :
Digital audio signal input terminal, output terminal, 2
7: Control signal input terminal, 28: Linear CODEC section,
29: Interface circuit, 30: Common bus, 3
1: Interface circuit, 32: CPU, 33:
Random access memory, 34: Read only memory, 35, 36: High speed digital processing circuit.

Claims (1)

[Claims] 1. In a digital communication network, an exchange is equipped with a means to change the transmission speed of a communication channel at any time according to a speed designation signal sent from a calling terminal, and a terminal is equipped with multiple types of voice encoding and decoding means. , a selection operation means for selecting the voice encoding/decoding means, and a voice encoding/decoding selection signal representing the voice encoding/decoding means desired by the calling subscriber from the calling terminal; Means for automatically switching the voice encoding/decoding means to the desired voice encoding/decoding means, and voice encoding/decoding means usable when the desired voice encoding/decoding means is not present in the receiving terminal. means for automatically notifying the originating terminal from the terminating terminal, and means for notifying the originating subscriber that the terminating terminal does not have the desired voice encoding/decoding means. A voice encoding method automatic switching communication system characterized in that a voice encoding method is automatically switched for communication by selectively using various voice encoding/decoding means as necessary.