JPH05103116A - Communication terminal device - Google Patents

Abstract

PURPOSE:To receive also the data based on a HDLC by switching the data from a line interface part so that it may bypass a multiplexing means when a high level transmission control HDL flag is detected. CONSTITUTION:When a HDLC flag pattern is detected in a flag detection circuit 22c, the circuit 22c controls switching circuits 22b, 22d and bypasses the data from a line interface part 21 from the circuit 22b to the circuit 22d. Thus, even the data transmitted by a procedure of an HDLC can also be received as data. When the HDLC flag pattern is not detected in the circuit 22c, the circuit 22c controls the circuit 22b so that data may be inputted in a multiplexing circuit 22a. The circuit 22a continues to detect a bit pattern which is a synchronizing signal for multiplexing and divides it into each sub-channel of sound data and non-sound data. Thus, the discrimination of data can be performed in an earlier time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal device connected to a digital communication network.

[0002]

2. Description of the Related Art An analog communication network such as a public telephone line is originally not designed for data communication because it is originally designed for voice signal transmission. Therefore, in order to make up for the drawbacks of such analog communication networks, digital communication networks (for example, I
SDN and integrated service digital network) are becoming popular.

ISDN is a two-channel (B
Channel) and one channel (D channel) for additional information, and each of the B channels is 64 Kbps (bit / s).
It has the data transmission capability of ec). IS like this
Since the DN is sufficiently faster than the analog network, there are various terminal devices that utilize the high speed. These terminals include terminal devices that simultaneously transmit voice and data. In this case, communication of the terminals is generally based on having one channel for voice and one channel for data, that is, two B channel lines.

In addition, the H.264 standard, which is a standard for data multiplexing. 221 attempts to multiplex voice and document data and the like on a B channel 1 line. This H. The 221 standard is a framing standard, and the frame can be synchronized by detecting a specific bit pattern in the framing. As a result, it becomes possible to multiplex on one B channel line, and to change the communication speed during communication.
It is expected to be applied to various terminal devices in the future.

FIG. 4 shows a conventional H.264 standard. 22 shows a multiplexing terminal according to the 221 standard.

That is, the received data enters the multiplexing unit 12 via the line interface unit 11, where the voice data,
It is separated into sub-channels such as non-voice data or high level transmission control (HDLC) procedure data. Here, when the data of the HDLC procedure typified by G4 facsimile enters the multiplexing unit 12, the multiplexing unit 12 can detect the bit pattern of the multiplexing synchronization signal.
When the flag of the LC procedure is transmitted, it cannot be detected. Therefore, assuming that all 64 Kbps data is voice data, it is connected to the voice data channel and the data is not received.

[0007]

SUMMARY OF THE INVENTION As described above, H.264. 22
In the terminal conforming to the H.1 standard, the H.264 standard is used. When data that does not have 221 frames is received, that is, H.264 is received within a predetermined time. If 221 frames are not detected, it is determined to be a voice signal, and all B channel signals are connected to the voice subchannel.
And H. The receiving terminal side having the multiplexing unit 221 of 221 forcibly enters the communication state as all voice data, and therefore, if all the data is data, this cannot be received.

Therefore, the present invention is based on H.264. It is intended to provide a communication terminal device capable of receiving data even when data having no 221 frame is received.

[0009]

According to the present invention, a communication terminal device includes a line interface section for interfacing with a telephone line, and a frame synchronization signal for multiplexing from data applied from the line interface section. Means for separating the voice data and the non-voice data from each other and extracting them, an HDLC flag detecting means for detecting an HDLC flag for a high level transmission control procedure from the data from the line interface section, and the HDLC When the HDLC flag is detected by the flag detecting means, there is provided a switching means for switching the data from the line interface section so as to bypass the above-mentioned multiplexing means.

[0010]

The bit pattern of the synchronizing signal for multiplexing is detected by the multiplexing means, and the voice data and the non-voice data are separated and extracted. On the other hand, the data transmitted by the HDLC procedure is transmitted by the HDLC procedure because the flag detection means of the HDLC detects this and switches the data from the line interface unit so as to bypass the multiplexing means. The received data can also be detected and received as data.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are explanatory views for explaining respective data flows based on an HDLC flag pattern in this embodiment.

In FIG. 1, reference numeral 21 is a line interface section, and 22 is a multiplexing section. The multiplexing unit 22 includes a multiplexing circuit 22a, a switching circuit 22b, and a flag detection circuit 2
2c and a switching circuit 22d, and switching circuits 22b and 22d and a flag detection circuit 22c are added to the conventional multiplexing unit.

The flag detection circuit 22c includes an 8-bit shift register latched by a data clock,
The shift register is composed of a comparator or the like that generates an output indicating that the data output from the shift register is true when the HDLC flag pattern is "01111110", and is a flag detection unit dedicated to the HDLC flag pattern.

In such a structure, when the HDLC flag pattern is not yet detected by the flag detection circuit 22c, the data flow is as shown by the thick line in FIG. When the HDLC flag pattern is continuously detected by the flag detection circuit 22c for a predetermined time or longer, the flag detection circuit 22c controls the switching circuit 22b and the switching circuit 22d, and the data from the line interface unit 21 is changed as shown in FIG. The switching circuit 22b is bypassed to the switching circuit 22d. As a result, the data transmitted by the HDLC procedure can be received as all data.

On the other hand, in the flag detection circuit 22c, HD
When the LC flag pattern is not detected, the flag detection circuit 22c controls the switching circuit 22b so as to input the data to the multiplexing circuit 22a, as shown in FIG. The multiplexing circuit 22a continues to detect a bit pattern which is a synchronizing signal for multiplexing, and H.264 / AVC. In accordance with the H.221 standard, for example, audio data and non-audio data are divided into subchannels.

In the conventional multiplexing method, all the data is compulsorily transmitted as voice data when the bit pattern for detecting the synchronizing signal for the multiplexing is not transmitted. Therefore, there is an inconvenience that the data of the HDLC procedure cannot be received. However, since the flag detection circuit 22c for detecting the flag pattern of the HDLC and the multiplexing circuit 22a which is the bit pattern detection unit for obtaining the synchronization signal for multiplexing are both provided as in the present embodiment, the multiplexing is performed. It is possible to distinguish whether the data sequence is a converted data sequence or a data sequence according to the HDLC procedure at an early time when the communication line is connected.

Further, in the conventional method, when the data of the HDLC procedure is used, all of the data has entered into the communication as voice data, but since the detection unit of the flag of the HDLC is provided, the communication with the terminal supporting only the HDLC procedure is also performed. can do.

[0018]

As described above in detail, according to the present invention, a line interface section for interfacing with a telephone line and a frame synchronization signal for multiplexing are extracted from data applied from this line interface section. Means for separating audio data and non-voice data from each other and extracting them, HDLC flag detecting means for detecting an HDLC flag for a high level transmission control procedure from the data from the line interface section, and this HDLC flag detection When the HDLC flag is detected by the means, switching means for switching the data from the line interface section so as to bypass the above-mentioned multiplexing means is provided. Even when data having no 221 frame is received, the data can be received. That is, it is possible to determine whether the data is a multiplexed data string or data according to the HDLC procedure at an early point in time when the communication line is connected. As a result, when a specific bit pattern is not transmitted as in the conventional case, communication is forcibly performed because it is all voice data, and HDL is used.
The inconvenience that data cannot be received by the C procedure can be eliminated. It also becomes possible to communicate with a terminal device that supports only the HDLC procedure.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a data flow when an HDLC flag pattern is detected in FIG.

FIG. 3 is an explanatory diagram illustrating a data flow when an HDLC flag pattern is not detected in FIG. 1.

FIG. 4 is a block diagram showing a general example of a communication terminal device.

[Explanation of symbols]

 21 line interface unit 22 multiplexing unit 22a multiplexing circuit 22b, 22d switching circuit 22c flag detection circuit

Claims (1)

[Claims] 1. A line interface unit for interfacing with a telephone line, and a frame synchronization signal for multiplexing is taken out from data applied from the line interface unit to separate voice data and non-voice data from each other. Multiplexing means for extracting and HDLC for high-level transmission control procedure from data from the line interface section
HDLC flag detecting means for detecting a flag, and the HDL
A communication terminal device, comprising: switching means for switching the data from the line interface section so as to bypass the multiplexing means when the HDLC flag is detected by the C flag detecting means.