JPS5974791A - Subscriber circuit for digital telephone set - Google Patents

Abstract

PURPOSE:To ensure effective a D/A conversion and an A/D conversion with a miniature device for a telephone subscriber circuit which connects a subscriber and a digital telephone circuit or an exchange by performing the transmission and reception of information between the telephone subscriber circuit and the digital telephone circuit, etc. with a burst. CONSTITUTION:A code multiplexer 29 supplies a code burst signal and also a service signal as a control bit signal via a coder 27 and then sends these signals a 2-wire/4-wire cnverter 31 following a frame synchronizing signal. The converter 31 transmits the output of a multiplexer 29 to a subscriber line 33 and transmits a code burst signal transmitted from the subscriber side in a gap period of said burst signal to a code separator 30. Then an information burst signal is separated from the control bit signal. This separated information burst signal is converted and delivered by a reception buffer memory 26 and synchronously with the exchange side. While the separated control bit signal is converted into a service signal by a decoder 28.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a subscriber circuit for a digital telephone set for connecting a digital telephone line or a digital exchange or the like to a subscriber line.

Digital telephone lines or digital exchanges generally have a four-wire configuration, and subscriber lines have a two-wire configuration. For this reason, subscriber circuits for digital telephones are limited to having a 4-wire to 2-wire conversion function.

FIG. 1 is a block diagram showing an example of a conventional digital telephone subscriber circuit, and FIG. 2 is a time chart showing the code structure and arrangement of signals in each part. In FIG. 1, the left side of the figure is connected to a digital telephone line or digital exchange, and the cloth side of the figure is connected to a subscriber line. Then, from the information input terminal 1 to the terminal 1 shown in FIG.
Input information 101 configured in series in units of frame 8 bits
is input and stored in the transmission buffer memo IJ (SBM) 5. In addition, the signal input terminal 3 has a service signal 10.
3 is input, and is converted by the encoder (COD) 7 into a control bit signal 107 as shown in FIG. 2(b). The control bit signal 107 corresponds to one frame of the input information 101.
Consists of bits. The stored contents of the transmission backup memory 5 are read out from the code multiplexer (M1) 9 as an 8-bit continuous information burst signal 105 as shown in FIG. 2(C). The code multiplexer 9 sends out the above-mentioned 8-bit information burst signal after sending out the frame synchronization signal F, and finally a code burst signal 109'e with a control bit signal 107 added thereto. Send to 11.

The code burst signal 109 output from the code multiplexer 9 is the second
As shown in Figure (d), there is a gap between the signal corresponding to the first frame and the signal corresponding to the second frame. This gear is a gap for carrying a second code burst signal in the opposite direction on the subscriber line. The code signal (-st signal 109, for example, is converted by the 2-wire to 4-wire converter 11) into an Ibora format transmission line burst signal 111 and sent to the subscriber line 13 via the 2-wire terminal 12. On the subscriber line 13, a similar transmission line burst signal sent from the subscriber terminal is carried at the gap position (see FIG. 2(e)). The 2-wire to 4-wire converter 11 converts the transmission line burst signal sent from the subscriber terminal into a second
It is converted into a second code burst signal 110 having a logic level as shown in FIG.

The second code burst signal consists of a frame synchronization bit F and a second information burst signal of eight bits and a second control bit signal R of one bit.

The signal is converted into a second information burst signal 106 by a code separator (DMPX) 1'0 as shown in FIG.
The control bit signal 108 and the control bit signal 108 are separately output.

The second information burst signal 106 is transmitted to the receive buffer memory (
The second control bit signal 108 is inversely converted into a service signal by a decoder (DEC) 8. The contents of the reception buffer memory 6 are output from the information output terminal 2 as continuous output information 102 of 8 bits per frame as shown in FIG. A service signal 104 outputted from the signal output terminal 4 is outputted from the signal output terminal 4. As described above, conventional subscriber circuits for digital telephones time-compress input information as burst signals for 2-wire to 4-wire conversion, creating gaps between burst signals, and filling these gaps with the subscriber's side. Since it is configured to carry a burst signal sent from the oscilloscope, it has the disadvantage that the configuration is complicated and it is difficult to miniaturize it.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks and to provide a subscriber circuit for a digital telephone that has a simple structure and is advantageous for downsizing.

The subscriber circuit of the present invention is a subscriber circuit for a digital telephone that connects a digital telephone line or a digital exchange and a subscriber line. an encoder that inputs a service signal and converts the service signal into a control pit signal; and a code multiplexer that sends out the input information burst signal and control bits output from the encoder successively to a frame synchronization signal. , a second code burst signal output from the code multiplexer is sent to the subscriber line, and a second code burst signal sent from the subscriber side during the gap period of the code burst signal is supplied to the code separator. a line converter, a code separator that separates and outputs a second information burst signal and a second control bit signal from the second code burst signal, and stores a second information burst signal output from the code separator. and a reception buffer memory that converts and outputs received information into a synchronized burst signal to the exchange side, and a decoder that converts the second control bit signal into a service signal, and transmits and receives information with the digital telephone line or the digital exchange. is characterized by being performed in bursts.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the present invention.
FIG. 4 is a time chart showing the states of signals of each part in this embodiment. In this embodiment, a burst information signal is input from the information output terminal 21 on the digital telephone line or digital exchange side. That is,
The input information is an information burst signal 201 as shown in FIG. 4(a).

If the digital telephone line or digital exchange itself operates in the format of the information burst signal 201 described above, it is sufficient to input that signal as is, but if the exchange operates with continuous frame signals, the common part The information may be stored in a buffer memory and converted into an information burst signal and output. The common parts on the exchange side are shared by many subscriber circuits, so even if such a buffer memory is provided, it requires much less hardware than when it is provided for each subscriber circuit as in the past. The amount makes me feel tired. On the other hand, a service signal 203 is input from the signal input terminal 23 and is converted by an encoder (COD) 27 into a control bit signal 207 as shown in FIG. 4(b). A code multiplexer (MPX) 29 sends out a frame synchronization bit FK, followed by an information burst signal 105, and a code burst signal 209 with a control bit 207 added to the final bit on line 2-4.
The signal is sent to a line converter (CONV) 31. code burst signal 2
09, a gap is formed between the signal corresponding to the first frame and the signal corresponding to the second frame, as shown in FIG. 4(C). The code burst signal 209 is converted into, for example, a bipolar transmission line burst signal 211 by a 2111j-4-wire converter 31 and sent to the subscriber line 33 via a 2-wire terminal 32.

On the subscriber line 33, a similar transmission path burst signal sent out from the subscriber terminal is carried at the gap position (see FIG. 4(d)). The 2-wire to 4-wire converter 31 converts the transmission line burst signal sent from the subscriber terminal into a fourth
It is converted into a second code burst signal 210 having a logic level as shown in FIG.

The second code burst signal 210 includes a frame synchronization bit (F) and an eight-pit second information burst signal (1).
The second control bit signal R of the bits. The signal is
A code separator (DMPX) 30 separates the signal into a second information burst signal 206 and a second control bit signal 204 as shown in FIG. The second information burst signal 206 is stored in the receive buffer memory (RBM) 26 and the received information burst signal 202 as shown in the figure (ω) is stored in the receive buffer memory (RBM) 26.
is converted and output. That is, it is read out in synchronization with the frame on the exchange side and sent out from the information output terminal 22.

Further, the second control bit signal 204 is transmitted to a decoder (DEC).
28, it is inversely converted into a service signal 204 and output from the signal output terminal 24. When a continuous frame signal is required on the exchange side as in the conventional case, it can be handled by converting the common part or by changing the reading speed from the reception buffer memory 26.

As described above, in the present invention, since information is exchanged with the exchange or the transmission line side using an information burst signal, a transmission buffer memory or the like is required on the subscriber circuit side to create the information burst signal. It has the effect of being provided at a low cost with a simple configuration. It is also advantageous for downsizing the device. Since a subscriber circuit is provided for each subscriber, and a large number of subscriber circuits are installed in exchanges, etc., the effects of the present invention are extremely significant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional digital telephone subscriber circuit, FIG. 2 is a time chart showing various signals in the conventional example, and FIG. 3 is a block diagram showing an embodiment of the present invention. FIG. 4 is a time chart showing signals of various parts in the above embodiment. In the figure, 1.21 river information input terminal, 2, 22...
Information output terminal, 3.23...Signal input terminal, 4゜24
...Signal output terminal, 5...Transmission backup memory, 6
．． 26... Receive pan amemo IJ, 7.27... Encoder, 8.28... Decoder, 9.29... Code multiplexer, 10.30... Code separator, 11.31.・・２
Line-4-wire converter, 12.32...2-wire terminal, 13.3
3...N subscriber line. Agent Patent Attorney 1) Toshi Sou

Claims (1)

[Claims] In a digital telephone subscriber circuit that connects a digital telephone (b) m-i or digital exchange and a subscriber line,
an encoder inputting an information burst signal having a gap between frames and a service signal corresponding to the information burst signal, and converting the service signal into a control pit signal;
a code multiplexer that transmits the input information burst signal and the control bits output from the encoder following a frame synchronization signal; and a subscriber side that transmits the code burst signal output from the code multiplexer to a subscriber line. a 2-wire-4# converter that supplies a second code burst signal sent out during the gap period of the code burst signal from the second code burst signal to the code separator; a code separator that separates and outputs the second control bit signal; a reception buffer memory that stores the second information burst signal output from the code separator and converts it into a received information burst signal synchronized with the exchange side; 1. A subscriber circuit for a digital telephone, comprising: a decoder for converting a control pit signal of No. 2 into a service signal, and transmitting and receiving information to and from the digital telephone line or the digital exchange in a burst manner.