JPS58101543A - Terminal interface - Google Patents

Abstract

PURPOSE:To transmit signals between a subscriber's line terminator and a terminal, by superimposing a DC signal on an interface line for signal transmission without increasing the number of interface lines for the transmission of a DC loop signal, a DC level signal or a DC power. CONSTITUTION:In applying a positive voltage on a line B and a negative voltage on a lone A at waiting, a diode bridge 25 is turned on, a power supply circuit 22 is operated and a DC voltage is applied to an incoming call detection circuit 28. In calling, a call switch 27 is turned on, and the calling is informed to a DSU (subscriber's line terminator)3, then a loop switch 26 is turned on, the power supply circuit 22 starts operation and the DSU 3 is operative. Thus, the feeding control for each call can be done without increasing the number of interface lines.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a terminal interface that connects a digital subscriber line terminal unit (hereinafter referred to as DSU) to a terminal.

Conventionally, CCIT TX21 recommendation and the like are known as this type of circuit. This interface is an interface that assumes that both the DSU and the terminal are powered on even when not communicating. However, from the viewpoint of power saving, it is desirable that the power of the DSU and terminal be turned on each time communication is required. Specifically, when a call is made, the power of the DSU is automatically turned on by the calling signal from the terminal, and when a call is received, the power of the DSU is automatically turned on by the incoming call signal from the station, and furthermore, the power of the DSU is automatically turned on by the calling signal from the terminal, and then It is desirable that the power is turned on automatically. To this end, Recommendation X 21
In addition to the interface lines specified in the above, it is sufficient to newly install call activation and incoming call activation lines, but this has the disadvantage that the number of interface lines increases. Furthermore, in order to guarantee operation even in the event of a power outage, it is desirable for digital telephone terminals to be powered by power supplied from the switching center. If a power supply line is provided at this point, the problem arises that the number of interface lines will further increase.

In order to solve these problems, the present invention superimposes a DC signal on the interface wire for signal transmission, and transmits a DC loop signal, DC level signal, or DC power between a DSU and a terminal without increasing the number of interface lines. It is something that can be done.

Figure 1 shows an overview of the digital subscriber system.
2 is a switching center, 2 is a subscriber line, 3 is a DSU, 4 is a terminal, 5 is an interface circuit of the DSU @, 6 is an interface circuit on the terminal side, and 7 is an interface cable.

FIG. 2 schematically shows the configuration of the interface section between the DSU 3 and the terminal 4 in the present invention.

In the same figure, 8 and 9 are cable drivers, 10° and 11
is a cable receiver, 12.13 is a cable (interface line), 14.15 is an AC/DC superimposition circuit, 16.1
7 is an AC/DC separation circuit, 18 is a call switch 9 placed in the terminal 4, and 19 is a call switch 1 placed in the DSU 3.
A subscriber line loop switch 20 is controlled by a current flowing through 8, and 20 is an incoming call activation circuit or circuit in DSU 3 which generates a DC voltage or forms a DC loop in response to an incoming call signal from the exchange. a circuit that generates voltage,
Reference numeral 21 denotes an incoming call detection circuit placed in the terminal 4, which detects a DC voltage or a DC loop to turn on the power of the terminal, or an electronic circuit that operates upon receiving voltage from the circuit 21.

Fig. 3 shows an example of an AC/DC superimposition circuit or an AC/DC separation circuit for a balanced transmission system, and Fig. 4 shows an example of an AC/DC superimposition circuit or an AC/DC separation circuit for an unbalanced transmission system. .

FIG. 5 is a diagram showing an embodiment of the present invention. 22 is a power supply circuit that generates the voltage required by the DSU 3 for each call in order to supply power from the exchange; 23. 24 is a DC separation circuit that separates the DC component from the digital signal transmitted through the subscriber line, and 25 is a diode bridge that detects the polarity of the power supply from the station and supplies power to the power supply circuit 22 when the B line is positive. , 26 is a subscriber line loop switch, and when it is turned on, power is supplied to the power supply circuit 22 even if the A line has positive polarity. Reference numeral 27 is a call originating switch placed in the terminal, and when this is turned on, the subscriber line loop switch 26 is also turned on. Then, the power supply circuit 22 operates, and DC voltage is applied to the terminal 4, making it possible to supply power. Reference numeral 28 denotes an incoming call detection circuit which turns on the power of the terminal upon receiving a DC level signal, or an electronic circuit operated by power supplied from the power supply circuit 22.

Next, this operation will be explained. When on standby, turn to A line, Bll
A negative voltage is applied from the station, and the diode bridge 25 is turned on, but the subscriber line loop switch 26 is turned on.
rr, the power supply circuit 22 does not operate, no DC voltage is applied to the incoming call detection circuit 20, and the terminal is in a stopped state.

Here, when a negative voltage is applied to the A line and a positive voltage to the B line due to power supply from the station due to an incoming call, the diode bridge 25 is turned on, and the power supply circuit 22 operates regardless of the 0N10FF state of the subscriber line loop switch 26. Then, DC voltage is applied to the incoming call detection circuit 28 or power supply is started.

In the case of a call, the call switch 27 is turned on to notify the DSU 3 of the call, and the switch 26 is turned on, the power supply circuit 22 starts operating, and the DSU becomes operational. As described above, power supply control can be performed for each call without increasing the number of interface lines. The present invention can be implemented in the same way even if the incoming call from the station does not require polarity reversal.

FIG. 6 shows another embodiment of the present invention, in which departure and arrival are both activated by the loop 0N10FF.

In the case of an incoming call, the power supply circuit 22 is activated by the incoming call, and the output of the photocoupler 29 is turned on, thereby forming a DC loop. The incoming call detection circuit 28 detects this DC loop and turns on the power of the terminal. In the case of a call, the output side of the photocoupler 32 becomes conductive when the call switch 27 is turned on, and the subscriber line loop switch 26 in FIG.
is turned ON, a subscriber line loop is formed, and local power supply to the DSU is started. In this way, power supply control for each call becomes possible. In addition, the signal transmission and reception system is also a photocup J30.31.
A feature of this interface is that it is possible to separate the interface circuit and the 7-path system of the DSU main body by connecting the two.

The above embodiments are examples in which four interface lines are used, but FIG. 7 is an example in which two interface lines are used. Transmission and reception of signals is performed bidirectionally by means such as time division, frequency division, and directional coupling.

The operation is as follows. When making a call, when the call switch 27 is closed, the output side of the photocoupler 32 is turned on, forming a subscriber line loop, and activating the DSU. On the other hand, in the case of an incoming call, the photo coupler 29
When the output side of is turned on, the photocoupler 33 is turned on and the incoming call detection circuit 28 is activated. The above enables power feeding control for each call.

In the above embodiments, since the signal transmission system has DC cutoff characteristics, it is desirable to use a balanced code such as an AMI code or a CMI code as the transmission code.

The laB diagram is a configuration example to avoid this condition,
Diode 34 is connected between the output terminal of the line receiver and
was inserted to regenerate the DC component.

As explained above, according to the present invention, a DC level signal, a DC loop signal, or DC power can be transmitted between a DSU and a terminal without increasing the number of interface lines, and power supply control for each call can be easily performed. be able to.

[Brief explanation of the drawing]

FIG. 1 is an outline of a digital subscriber system, FIG. 2 is an embodiment of the system, FIG. 6 is another embodiment of the present invention, and FIG. 7 is an embodiment of the present invention in which there are two interface lines. FIG. 8 is a diagram showing each DC regeneration circuit. 1... Exchange, 2... Subscriber line, 3... DSU14...
...Terminal, 5 ......DSU @ interface circuit, 6 ......Terminal side interface circuit, 7 °°° ...Interface cable, 8 .9 ・・・・・・・・・Cable driver, 10. 11... Cable receiver, 12.13... Cable (interface line), 14.15... AC/DC superimposition circuit, 16.17... ...AC/DC separation circuit, 18... Calling switch, 19...
...Subscriber line loop switch, 20...
...Incoming call activation circuit (or a circuit that generates voltage due to incoming calls), 21...Incoming call detection circuit (
or electronic circuit), 22... power supply circuit,
23.24・・・・・・DC separation circuit, 25
......Diode bridge, 26...
...Subscriber line loop switch, 27...
...Call switch, 28...Incoming call detection circuit. Figure 1 Figure 3

Claims (1)

[Scope of Claims] (Li) In a terminal interface that connects a home line termination device and a terminal via an interface line for signal transmission, an alternating current that superimposes an alternating current and a direct current is applied to each of the home line termination device and the terminal. An interface circuit is provided which includes a DC superimposition circuit and an AC/DC separation circuit that separates AC and DC.For each call, the DC level is transmitted between the home line termination equipment and the terminal via the interface circuit. Alternatively, a means for forming a DC loop and a means for controlling power supply in response to the control signal such as the DC level and the DC loop are provided, so that the control signal and the DC power can be controlled without increasing the number of interface lines. A terminal interface characterized in that transmission can be performed on a call-by-call basis. (2) In a terminal interface that connects a home line terminating device and a terminal via an interface line for signal transmission, the home line terminating device Each of the device and the terminal is provided with an interface circuit including an AC/DC superimposing circuit for superimposing alternating current and direct current and an AC/DC separating circuit for separating alternating current and direct current, and a calling switch is provided in the terminal, This is connected to the DC side terminal of the AC/DC superimposing circuit of the terminal, a subscriber line loop switch is provided in the home line terminating device, and the control terminal of the subscriber line loop switch is connected to the AC/DC side terminal in the home line terminating device. connected to the DC side terminal of the separation circuit, and when ON information of the calling switch is transmitted to the subscriber line loop switch via the interface line,
A terminal interface characterized in that a power supply control means is provided for controlling power supply when a call is made in response to the power supply. (3) In a terminal interface that connects a home line termination device and a terminal via a signal transmission interface line, each of the home line termination device and the terminal includes an AC/DC superimposing circuit that superimposes alternating current and direct current; It is equipped with an AC/DC separation circuit that separates AC and DC.In addition, an interface circuit is provided to separate AC and DC.
A power supply circuit for N10 FF is provided, and the output of the power supply circuit is connected to the DC side terminal of the AC/DC superimposing circuit of the residential line termination device, and the DC level transmitted from the power supply circuit to the terminal via the interface line is A terminal comprising an incoming call detection circuit for detecting an incoming call, and an input terminal of the incoming call detection circuit and a power supply terminal of an electronic circuit in the terminal are connected to a DC side terminal of a DC separation circuit in the terminal. interface.