JPS61128642A - Compound media communicating system - Google Patents

Abstract

PURPOSE:To eliminate the unnaturalness of a sound communication and to decrease a cost by inserting the packeted data information after a silent section of the sound is recognized. CONSTITUTION:When a compound media control device 3 receives data information sent from an HDLC control circuit 8 and detects a flag pattern F, in an F pattern continuous sending circuit 11, further plural flag patterns F are added, a format constitution is corrected, inverted by an inverter 17, inserted through a buffer circuit 10 to a silent section of a digital sound signal and transferred. When the silent section is released while the packeted data are sent, the sound equivalent to a head part of the continuous conversation will not be transferred and the time length not transferred is coincident to data transfer time at the worst.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to
Related to a composite media communication system that transmits or receives digitized audio information and packetized data information from a second terminal device that handles non-audio media via a common digital transmission path. It is.

For example, a service called Sketchphone is known. A sketch phone is a device that connects to the other party using a telephone and then writes characters or figures on a drawing pad with a ballpoint pen, etc., and the audio signal and drawing image signal are simultaneously transmitted to the other party over the telephone line. The image signal is separated from the image signal, and the audio is sent to telephone K.

This is a service in which the drawn image signal is sent to a display and displayed.

There are various other services that are based on the premise that voice information and data information can be sent and received at the same time, but the present invention is useful for providing services such as Sketchphone. The present invention relates to a composite media communication system that can be suitably used.

[Conventional technology]

Conventionally, the following forms have been considered as this type of communication system.

(b) A method in which simultaneous communication is performed using two mutually independent channels: one channel for voice and one channel for data.

Naka) A method that uses only one channel, but in order to make it possible to distinguish between voice and data, both voice and data are transferred in packet transfer format.

According to the method (a) above, there is a drawback that two channels are used, which increases communication fees and subscriber equipment. (transfer format using the HDLC procedure), it is possible to distinguish between voice and data, but the immediacy that characterizes voice communication cannot be fully realized.

In other words, if voice is packetized and transferred, transmission delays will increase as the voice is transferred via storage devices such as terminals, various control devices, and network devices, so problems such as those that occur in "international calls" will be avoided. The disadvantage is that the voice communication has a natural tone and tone. In order to solve this drawback, it is necessary to reduce transmission delay, which requires a high-speed transmission line, and also requires control to limit the number of relay stages. , network equipment becomes expensive.

[Problem that the invention seeks to solve]

Therefore, the problem to be solved by the present invention is to realize a composite media communication system without making voice communication unnatural and at low cost.

Therefore, it is an object of the present invention to provide a composite media communication system realized as described above.

[Means and operations for solving the problems] In order to achieve the above object, the present invention provides digitalized audio information from a first terminal device that handles audio media and a second terminal device that handles non-audio media. In a composite media communication system that transmits and receives packetized data information from and through a common digital transmission path,
means for detecting a silent section of audio information sent to the digital transmission path;
A transmitting side is provided with means for inserting and transmitting a flag pattern indicating the start of a data frame according to DLC (High Level Data Link Control Procedure) K after consecutively inserting it several times in vI,
The receiving side includes means for detecting the flag pattern, and identifies received information as voice information or data information depending on whether or not the flag pattern is detected, and distributes the received information between the first terminal device and the second terminal device. It is characterized by comprising a means for receiving the information.

〔Example〕

The present invention will now be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing a schematic configuration of an embodiment of the present invention. In the figure, 1 is a telephone device, 2 is a data terminal device, and 3 is a composite media control device.

FIG. 1 is a block diagram showing details of one embodiment of the present invention. In the figure, 4 is a transmitter, 5 is a receiver, 6 is an encoder (A/D converter), 7 is a decoder (D/A converter), and 8
is an HDLC (high level data link control procedure) control circuit, 9 is a silence detection circuit, 10 is a buffer circuit, 11 is F
12 is an F pattern (inverted pattern of F pattern) detection circuit; 13 is a buffer circuit; 14 is a pattern continuous sending circuit;
15 is a gate, 16 is a silent pattern generation circuit, and 17 and 18 are inverters (inversion circuits).

Next, the circuit operation will be explained.@First, in the telephone device 1, the voice is converted into an analog electrical signal by the transmitter 4, and then converted into a 64 kb/s digital voice signal by the encoder 6. This digital audio signal is transferred to the composite media control device 3. In the composite media control device 3, the silence detection circuit 9 constantly monitors the digital audio signal transferred from the telephone device 1, and when it is detected that the audio amplitude is below a certain amplitude for a certain period of time, the period is marked as silent. The data terminal device 2 determines that it is a section.
Metern continuous transmission circuit 11, inverter 17, buffer circuit 1
0, it is inserted into the silent section of the audio and sent.

Here, the data information is the HDL in the data terminal device 2.
The C control circuit 8 takes a frame configuration as shown in FIG. 3 and sends it to the control device 3.

By the way, the high-level data link control procedure (HDLC) enables highly efficient data transmission between data terminal devices via a data transmission line, and allows arbitrary data transmission without depending on any coding system. This is known as a pit-transparent synchronous transmission control procedure that can transmit bit strings.

In this oHDLC procedure, arbitrary bit string information and link control information are transmitted using seven frames, which are a transfer unit. The start of frame 7 and 18T are indicated by flag pattern F (01111110).

FIG. 3 is an explanatory diagram showing a 7-frame configuration of such HDLC procedure. That is, between the flag pattern F indicating the start of the 7th frame and the same pattern F indicating the end, there are 8 bits for address (A), 8 bits for control (C), and 16 bits for data and frame check (Fe2). is located.

When the control device 3 receives the data information sent from the HDLCHJ@circuit 8 and detects the above-mentioned 7-lag pattern F, the F-pattern continuous sending circuit 11 adds a plurality of 7-lag patterns F to the 4. After correcting the format configuration as shown in Figure 4, invert 1 to O and O to 1 with inverter 17), buffer 7 circuit 1
0, the digital audio signal is inserted into the silent section of the digital audio signal and transferred.

Here, the reason why a plurality of flag patterns F are added to the beginning of the data information as shown in FIG. 4 is to make it easy and reliable for the receiving side to identify the data information from the audio information. . In other words, the number of flag patterns FO to be added depends on the aforementioned identification ability on the receiving side.

For example, assume that the audio encoder uses the .mu.-1ow method, which is currently standardized by the CCITT recommendations. The flag pattern F is composed of an 8-bit pattern of "01111110", but in correspondence with the μmJow law, if the value indicated by the pattern F is close to the maximum amplitude of the audio signal according to the μmJgow law, the detection ability of the pattern F is increases, so the pattern FOfiiL can be reduced.

In other words, in voice communication, the bit pattern of the voice digital signal obtained by digitizing the sample value of the analog voice signal is a value close to the maximum amplitude of the voice signal according to the μmlow law (note that it is not the maximum amplitude). In practice, a bit pattern that takes such a value almost never appears, so if a bit pattern that takes this value is selected as the aforementioned 7-lag pattern F, it becomes possible to distinguish data information from audio information. It becomes easy.

However, the 7 lag pattern F”01111 according to the μm10w rule
110'' is a value close to the minimum amplitude rather than the maximum amplitude if it is left as is, so if it is inverted by the inverter 17 and made into a two's complement number, that is, '10000001'', this bit pattern becomes the maximum amplitude mentioned above. Since the bit pattern has a similar value, this is sent. Therefore, all data information is inverted, and 0 is inserted into the silent section of the digital audio signal and transferred in two's complement format.On the receiving side, the digital signal sent from the other party is received by the buffer circuit 13, and this The parallel output from the buffer circuit 13 is guided to the F pattern detection circuit (inversion pattern O detection circuit of flag pattern F) 12 to detect the inversion flag pattern F.

When a plurality of inversion flag patterns F are detected by the circuit 12, the detection force opens the gate 14, reads the data information following the pattern from the buffer circuit 13, inverts it in the inverter 18, and returns it to the original state. The signal is guided through the gate 14 to the receiving side of the HDLC control circuit 8 in the data terminal device 2.

At the same time, the gate 15 is controlled using the detection forces of several inversion patterns Fm in the circuit 12, and thereafter,
The silence pattern created by the silence pattern generation circuit 16 is sent to the telephone device 1 via the gate 15.

In the circuit 12, when one inverted flag pattern F is detected after a plurality of inverted flag patterns F have continued,
Since it is the end of the frame of data information, it uses its detection power to close gate 14 and
5, the audio information read out from the buffer circuit 13 is guided through the gate 15 to the decoder 7 of the telephone device l, in place of the silence pattern from the silence pattern generation circuit 6, where it is decoded. and then send it to receiver 5.

In the above method, it is considered that it is sufficient to repeat the sending of the flag pattern Fo three to four times.

Additionally, silent sections of audio are used as sections for inserting packetized data information into the digital audio signal, and after recognizing this silent section, packetized data information is inserted, but this Generally, the maximum packet data length is 256B3'te, or about 2000 bits, and can be transferred in about 3 Qms using a 64 kb/s digital transmission path.

With the insertion of this data information, if a silent period is canceled during the transmission of packetized audio data, the audio corresponding to the beginning of the following conversation will not be transferred. At worst, the length of time during which data is not transferred matches the data transfer time.

This phenomenon is similar to the cutting off at the beginning of a line (the beginning of a line is cut off and becomes inaudible) when measures are taken to prevent howling in a loudspeaker telephone. This episode's opening time is the worst 15
It is designed as 0m5 and maintains a certain level of audio quality.

7 Therefore, if the same level of voice quality as a public address telephone is to be maintained, a maximum of 5 packets of data (5k
bit) can be transferred.

〔Effect of the invention〕

As explained above, according to the present invention, there is an advantage that a multimedia communication system can be realized at low cost without making voice communication unnatural.

[Brief explanation of the drawing]

#! FIG. 1 is a detailed block diagram showing an embodiment of the present invention, FIG. 2 is a book diagram showing a schematic configuration of an embodiment of the present invention,
FIG. 3 is an explanatory diagram showing the frame structure of the HDLC procedure, and FIG. 4 is an explanatory diagram showing the frame structure used in the present invention. ...Data terminal device, 3...Composite media control device, 4...
...Telephone, 5...Telephone receiver, 6...Encoder (A/D converter), 7...Decoder (D/A
converter), 8...HDLC control circuit, 9...
... Silence detection circuit, 10... Buffer circuit,
11...F pattern continuous delivery path, 12...
...F pattern detection circuit, 13...Buffer circuit, l11-...Gate, 15...
Gate, 16... Silence pattern generation circuit, 17
・・・・・・Inverter, 18・・・・・・Inverter

Claims (1)

[Claims] 1) Common digital transmission of digitized audio information from a first terminal device that handles audio media and packetized data information from a second terminal device that handles non-audio media. In a multi-media communication system in which audio information is transmitted or received via a digital transmission channel, means for detecting a silent section of audio information sent to the digital transmission channel; The data information is
The transmitting side includes means for inserting and transmitting a plurality of consecutive flag patterns indicating the start of a data frame by DLC (High Level Data Link Control Procedure), and the receiving side detects the flag pattern. and means for identifying received information as audio information or data information depending on whether or not the flag pattern is detected, and distributing and receiving the received information between the first terminal device and the second terminal device. A multimedia communication system characterized by: 2) In the composite media communication system according to claim 1, when the packetized data information is inserted into a silent interval and transmitted, at least the flag pattern indicating the start of the data frame is inverted. A composite media communication method characterized in that it is transmitted (as a two's complement number). 3) In the composite media communication system according to claim 1 or 2, the number of packetized data information sent at one time is limited to a certain number or less after detecting a silent section. Multimedia communication method.