JP4144158B2 - ISDN terminal device with built-in DSU - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ISDN (Integrated Digital Communication Network) terminal device incorporating a DSU (Home Line Termination Device).
[0002]
[Prior art]
In order to connect the ISDN and the terminal device, a DSU (Digital Service Unit) having a function of forming a user / network interface is used. The DSU has a U point connection terminal for connection to ISDN and an S / T point connection terminal for connection to a terminal device.
[0003]
In addition, in an ISDN terminal device with a built-in DSU such as a terminal adapter with a built-in DSU, the terminal is connected to the DSU inside the device. 3 and 4 show block diagrams of a conventional ISDN terminal device incorporating a DSU. In FIG. 3, a driver 33 and a receiver 34 are provided in the in-device terminal 23 and connected to the outside of the S / T point transformers 26 and 27 of the DSU 22, that is, the S / T connection point side via the S / T point transformers 24 and 25. It is a block diagram of a transformer connection type DSU built-in ISDN terminal device. FIG. 4 is a configuration diagram of a digital connection type DSU built-in ISDN terminal device in which the in-device terminal 43 is directly connected to the front side (terminal side) of the line termination unit 49 inside the DSU 42 by TTL or the like.
[0004]
[Problems to be solved by the invention]
In the above-mentioned conventional ISDN terminal device with a built-in DSU, the transformer connection type ISDN terminal device of FIG. 3 requires components such as a driver, a receiver, and two transformers, which increases the number of components and needs to drive the driver and receiver. For this reason, there are problems such as high power consumption and low price because it is necessary to use a relatively expensive component such as a transformer.
[0005]
In the digital connection type ISDN terminal device shown in FIG. 4, since the so-called uplink signal sent from the in-device terminal 43 to the ISDN via the DSU 42 is not output from the TA / TB terminals at the S / T connection point, There was a problem that this could not be monitored and maintenance was poor.
[0006]
It is an object of the present invention to provide a DSU built-in ISDN terminal apparatus having a simple configuration and capable of monitoring an upstream signal of an in-device terminal.
[0007]
[Means for Solving the Problems]
The present invention relates to a DSU built-in ISDN terminal device having an S / T connection point for connecting a terminal device, a DSU including an S / T point transformer connected to the S / T connection point, and an in-device terminal. , A downlink signal line for inputting a downlink signal input to the DSU to the in-device terminal without going through an S / T point transformer, and an uplink signal input to the DSU from the in-device terminal to the S / T connection point and the S / T And an in-device terminal transformer to be supplied between the point transformer.
[0008]
As described above, a so-called downlink signal input from the DSU to the in-device terminal is directly input via a TTL connection or the like without going through the S / T point transformer, thereby reducing the number of components and reducing power consumption and cost. . Also, by inputting so-called uplink signals input from the in-device terminal to the DSU from outside the S / T point transformer through a transformer connection, the uplink signals output from the in-device terminal can be monitored from the outside. The maintainability increases.
[0009]
The present invention relates to a DSU built-in ISDN terminal device having an S / T connection point for connecting a terminal device, a DSU including an S / T point transformer connected to the S / T connection point, and an in-device terminal. ,
A downlink signal line that inputs the downlink signal input to the DSU to the in-device terminal without passing through the S / T point transformer, and an uplink signal that is output from the in-device terminal to the DSU without passing through the S / T point transformer. An upstream signal line to be input, an upstream signal output from an in-device terminal, supplied between the S / T connection point and the S / T point transformer and input to the DSU, and the in-device terminal And switch means for turning on / off the supply of the upstream signal to the transformer.
[0010]
As described above, the upstream signal of the in-device terminal is input to the DSU by both digital connection and transformer connection, and the switching means can turn on / off the supply of the upstream signal via the transformer. The user turns on the signal supply only when monitoring the upstream signal, and turns off the signal supply through the transformer otherwise. As a result, the upstream signal can be monitored and the normal power consumption can be suppressed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a DSU built-in ISDN terminal apparatus according to an embodiment of the present invention. The ISDN terminal device 1 includes U connection points L1 and L2, S / T connection points RA, RB, TA, TB, DSU2, an in-device terminal 3, and an in-device terminal S / T point transformer 4.
[0012]
The DSU 2 is connected to the U connection points L1 and L2 via the U point transformer 11, and is connected to the S / T connection points RA, RB, TA and TB via the S / T point transformers 5 and 6. The U point transformer 11 and the S / T point transformers 5 and 6 are connected via a transmission line termination unit 10, a line termination unit 9, a driver 7, and a receiver 8. The transmission line termination unit 10 is a circuit unit that shapes the waveform of the signal received from the ISDN and sends the signal received from the line termination unit 9 to the ISDN. The line termination unit 9 is a circuit unit that performs format conversion and sequence control of the signal on the terminal side (S / T point side) and the signal on the ISDN side (U connection point side).
[0013]
The downstream signal input from the ISDN is input to the in-device terminal 3 via the line C between the line termination unit 9 and the driver 7. An upstream signal output from the terminal in the apparatus to ISDN is input via the line B between the receiver 8 and the line termination unit 9. The signal output from the receiver 8 and the signal input from the line B are added and synthesized by the adder 12 and then input to the line termination unit 9.
[0014]
The in-device terminal 3 has a built-in transformer driver 13 and inputs an upstream signal to the in-device terminal S / T point transformer 4 via the driver 13. The intra-device terminal S / T point transformer 4 is connected to the S / T connection point of the upstream signal, and the signal output from the intra-device terminal 3 passes through the upstream signal S / T point transformer 6. Are input to the receiver 8 of the DSU 2 and output from the S / T connection points TA and TB.
[0015]
With this configuration, the signal output from the in-device terminal 3 is output from the S / T connection points TA and TB via the in-device terminal S / T point transformer 4 and can be monitored from the outside. The line termination unit 9 receives the uplink signal of the in-device terminal input from the line B and the in-device terminal uplink input via the S / T point transformer 4 and the S / T point transformer 6 for the in-device terminal. Signals are superimposed and input, but the same signal is input with almost no time difference, so there is no problem in processing.
In the above embodiment, the adder 12 is an adder that performs a logical addition (OR operation) of digital signals, and is input via the S / T point transformer 4 and the S / T point transformer 6 for in-device terminals. Even if the uplink signal from the in-device terminal 3 overlaps with the uplink signal from the device fixed terminal 3 input via the signal line B, the level is doubled as in the case of addition synthesis of analog signals. There is nothing. The upstream signal line B and the adder 12 are not essential in this embodiment.
[0016]
FIG. 2 is a diagram showing a configuration in which the switch 14 for turning on / off the driver 13 of the in-device terminal 3 is provided in the ISDN terminal device 1 with built-in DSU of the above embodiment. In this figure, parts having the same configuration as in FIG. The switch 14 is normally a switch that switches the signal amplification operation between active and inactive by turning on / off the power supply of the driver 13 or turning on / off the bias voltage. The switch 14 is normally switched to the off side. As a result, the driver 13 does not operate and does not consume power. At this time, the upstream signal of the in-device terminal 3 is not output to the TA and TB terminals. On the other hand, when the switch 14 is turned on, the driver 13 operates to output the upstream signal of the in-device terminal 3 via the S / T point transformer 4 for the in-device terminal, which is input to the DSU 2 via the S / T point transformer 6. At the same time, it is output from the TA and TB terminals at the S / T connection point, and can be monitored from the outside.
[0017]
This ISDN terminal device with a built-in DSU is generally realized as a terminal adapter or a router, but the embodiment is not limited to this.
[0018]
【The invention's effect】
According to the present invention, the configuration can be simplified and the power can be saved, and the uplink signal of the in-device terminal can be monitored from the outside. Further, by providing the switch means, it is possible to further save power.
[Brief description of the drawings]
1 is a block diagram of a DSU built-in ISDN terminal apparatus according to an embodiment of the present invention; FIG. 2 is a block diagram of a DSU built-in ISDN terminal apparatus according to another embodiment of the present invention; Block diagram of the device [Fig. 4] Block diagram of a conventional ISDN terminal device with a built-in DSU
DESCRIPTION OF SYMBOLS 1 ... ISDN terminal device with built-in DSU, 2 ... DSU, 3 ... In-device terminal, 4 ... S / T point transformer for in-device terminal, 5, 6 ... S / T point transformer, 13 ... Driver, 14 ... Switch, TA, TB: Up line terminal of S / T connection point, B: Up signal line from in-device terminal to DSU, C: Down signal line to in-device terminal

Claims (2)

An S / T connection point for connecting the terminal device;
A DSU having an S / T point transformer connected to the S / T connection point;
In an ISDN terminal device with a built-in DSU having an in-device terminal,
A downlink signal line for inputting the downlink signal input to the DSU to the in-device terminal without passing through the S / T point transformer;
An in-device terminal transformer for supplying an upstream signal input from the in-device terminal to the DSU between the S / T connection point and the S / T point transformer;
ISDN terminal device with built-in DSU. An S / T connection point for connecting the terminal device;
A DSU having an S / T point transformer connected to the S / T connection point;
In an ISDN terminal device with a built-in DSU having an in-device terminal,
A downlink signal line for inputting the downlink signal input to the DSU to the in-device terminal without passing through the S / T point transformer;
An upstream signal line for inputting an upstream signal output from the in-device terminal to the DSU without going through the S / T point transformer;
An in-device terminal transformer for supplying an uplink signal output by the in-device terminal between the S / T connection point and the S / T point transformer and inputting the uplink signal to the DSU;
Switch means for turning on / off the supply of the upstream signal to the in-device terminal transformer;
ISDN terminal device with built-in DSU.

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