JPS63181547A - Subscriber's line interface circuit for telex network - Google Patents

Abstract

PURPOSE:To omit an outgoing starting circuit for the world by making it possible to apply a normal incoming current in case of answering to an incoming signal after passing through a local state once when the incoming signal is detected and moreover using an outgoing starting current generation means both for the internal country and the outgoing starting current for the world. CONSTITUTION:A series circuit consisting of an incoming current adjustment circuit 16 which sets the incoming current IR (dotted line) in a certain value and an incoming detection circuit 17 which converts the existence of the incoming current IR into 1, 0 and outputs them is connected through one terminal (a) and a common terminal (c) of a relay 18. A current adjustment circuit 19 which limits a transmission reception current ITR (alternate long and short dash line) and the outgoing starting current IR (alternate long and two short dashes line) in a certain value is connected to two contacts (a) and (b) of the second relay 22 through a release signal generation circuit 20 (release circuit) and a reception circuit 21, where the output from the circuit 19 branched into two passes through, namely one of them passes through the circuit 20 and the other passes through the circuit 21, and connected to the terminal (b) of the first relay 18 through the series circuit consisting of the transmission circuit 23 and a disconnection circuit 24. The relays 18 and 22 are controlled by a control circuit 25 and a switch 26 for selecting which line for the internal country or for the world is made to correspond is added to the control circuit 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a subscriber line interface circuit for an international subscriber telecommunication network, particularly to a subscriber line interface circuit for an international subscriber telecommunication network, which is compatible with international subscriber telecommunication networks.

[Prior art]

There are differences between the subscriber line interface circuits of the domestic subscriber telephone network and the domestic subscriber telephone network, and they have conventionally been handled by separate devices.

FIG. 2 is a block diagram showing an outline of a conventional subscriber line interface circuit for an international telecommunications network.

In the same figure, Ll and L2 are connection terminals for the connected telecommunications network, and L2 is connected to the common terminal C of the relay switch 1, and the contact A of the relay switch 1 is connected to the terminal for adjusting the incoming current. A circuit 2 and an incoming call detection circuit 3 are inserted, and a transmission starting current adjustment circuit 4, a reception circuit 5, a transmission/reception circuit 6, and a disconnection circuit 7 are connected in series between the terminal of the relay switch 1 and the L+. When connected, one of the two closed loops is connected to the subscriber telecommunication network by operating the relay switch 1.

To briefly explain the functions of each of the above parts, the incoming current adjustment circuit 2 and the outgoing starting current adjusting circuit 4 both adjust the magnitude of the incoming current (7) and the outgoing starting current (1) flowing from the subscriber telegraph group to predetermined values. In addition, the incoming call detection circuit 3 converts the presence or absence of the incoming current (8) into logical values "0" and "1" and outputs it as an incoming signal, and also blocks current in the opposite direction to the incoming current (8). It is something to do. Furthermore, the reception circuit 5 detects the transmission starting current (7) and outputs a logical value of "0" due to its presence, and also outputs the transmission/reception current IT! 1 to nothing to logical value "0"l" and outputs it as received data, and the transmitting/receiving circuit 6 functions to intermittent the transmitting/receiving current ITR in accordance with the transmitting data to be transmitted, Furthermore, the disconnection circuit 7 interrupts the conduction between the transmitting/receiving current ITII and the transmission starting current (1) A as necessary.

Note that the transmitting/receiving current ITII (one-dot chain line) and the outgoing starting current A (two-dot chain line) have the same current value, but the incoming current (
(dotted line) is different from the current value.

The operation of the above configuration will be explained.

(1) Line open state In the line open state, a voltage is applied from the exchange (not shown) connected via the subscriber line so that L2 becomes (+) polarity, and in this state, If the terminal of the relay 1 is brought into contact with the terminal a, no current flows through the subscriber line interface circuit and the standby state is established.

(2) If the transmitting operation relay 1 is operated and brought into contact with the terminal, and the operation of the disconnection circuit 3 is prohibited, the transmitting starting current IA (two-dot chain line) flows, and the switching equipment When a chain line) is detected, the voltage polarity between L+ and Lz is inverted. As a result, the outgoing starting current it (double-dashed line) changes to
A reverse transmission/reception current ITR (dotted chain line) flows, and the receiving circuit 5 outputs a logic level O as received data, completing line capture. Next, the dial number expressed with a logic level of 0.1 is input to the transmitting circuit 6, and the transmitting/receiving current is
□ is sent to the exchange intermittently, and then the data transmission/reception operation begins.

(3) Incoming call operation When a call arrives, the line is open, the polarity of the voltage from the exchange that was added between Output as a signal. When an incoming signal is detected, operate relay l and touch the terminals, and the transmitting/receiving current ■A,
I (dotted chain line) flows, a logic level 0 is output from the reception circuit 5, and data transmission/reception operation begins.

(4) Data transmission and reception operation Transmission and reception are performed alternately. Transmission data is input to the transmission circuit 6 as logic levels 0 and 1, and the transmission and reception current IT
It is sent to the other party as an intermittent R (dashed line). Data sent from the other party as an intermittent transmission/reception current ■A R (dotted chain line) is converted to logic level 0, ■ by the receiving circuit 5, and output as received data. When there is no transmitted/received data, the transmitted/received current ITII (dotted chain line) flows, and the received data is at a logic 1 level.

(5) Line restoration operation When the line is restored by itself, the switching circuit 7 is operated to cut off the transmitting/receiving current (2) for a predetermined period of time, and then the relay 1 is connected to the terminal a side to return to the line open state.

In addition, if the transmitting/receiving current ■a sent from the other party does not exist for a predetermined time, the received data output from the receiving circuit 5 becomes logic 1 during that time, and from this, the relay 1 is driven and the terminal a side is set. , the line automatically returns to the open state.

In either case, the exchange changes the voltage polarity between L+ and Lz to the line open state, that is, when L2 is (+).
It switches to become a pole.

FIG. 3 is a block diagram illustrating the outline of a conventional international telecommunications network layer subscriber line interface circuit.

The circuit configuration of this device is that a current adjustment circuit 8 for adjusting the sending and receiving current is connected to the subscriber's telecommunication network end, and the output end of the current adjusting circuit 8 is connected to the other terminal L2 of the subscriber's telecommunication network. A transmission starting circuit 9 consisting of a relay RL and an amplifier AMP is connected between them.

Furthermore, a series circuit of a local state control circuit 10 and a recovery signal generation circuit 11 is connected in parallel with the transmission activation circuit 9, and an incoming call detection circuit 12 is connected in parallel with the local state control circuit 10.
, a transmitting circuit 13, and a receiving circuit 14 are connected in series.

This circuit is different from the domestic subscriber telecommunications network interface shown in FIG. It has a function of generating a local current IL, and is equipped with a recovery signal generation circuit (release circuit) 11 that reduces the transmission/reception current 1A to restore the line, and the other circuits are as shown in FIG. Since it has almost the same function as the one shown in , the explanation will be omitted.

Note that currents in the opposite direction to the currents shown in FIG. 3 cannot flow through the other circuits except the current adjustment circuit 8. Also, the transmitting/receiving current I
TR (dashed line), outgoing starting current I;

(two-dot chain line) and the incoming currents ■, l (dotted line) have the same current value, but the current value of the local current IL (three-dot chain line) is different from these.

The operation of the above configuration will be explained.

(1) Line open state In the line open state, a voltage of (+) polarity is applied to L2 from the exchange connected via the subscriber line. At this time, the relay RL in the transmission activation circuit 9 is open, and no current flows through the subscriber line interface circuit.

(2) Transmission operation By closing the relay RL, the transmission starting circuit 9
The outgoing starting current ■A (double-dashed line) flows through. When the exchange detects this outgoing starting current JT (double-dashed line), it reverses the voltage polarity between , L, and L.

As a result, the transmitting/receiving current ITN (dotted and dashed line) flows instead of the transmission starting current [T (double-dotted line), and the receiving circuit 1
A logic level 1 is output from 4, and relay RL is opened to complete line capture. Next, the dial number expressed as a logic level of 0.1 is input to the transmitting circuit 13, and the transmitting/receiving current is turned on and off to be sent to the exchange, and then data transmitting/receiving operation begins.

(3) Incoming call operation When a call arrives, the polarity of the voltage from the exchange that was applied between Ll and 52 in the open line state is reversed, incoming currents I and I (dotted line) flow, and logic level 1 is output from the incoming call detection circuit 12. Output as an incoming signal. When an incoming signal is detected, a predetermined period of time later, data transmission/reception operations begin. On the other hand, if an incoming call cannot be answered, the local state control circuit 10 and the transmitting circuit 13 are switched to the local state. If the current IL (dotted line) flows, the local current IL (three-dot chain line) flows from the local state control circuit IO, and after a predetermined time,
The exchange detects no response and returns to the line open state.

(4) Data transmission and reception operation Transmission and reception are performed alternately. Transmission data is input to the transmission circuit 13 at a logic level of 0.1, and the transmission and reception current is 1.
It is sent to the other party as an intermittent y* (dotted chain line). Data sent from the other party as an intermittent transmission/reception current ItR (dotted chain line) is converted to a logic level of 0.1 by the receiving circuit 14 and output as received data. When there is no transmitted/received data, the transmitted/received current Ia (dotted chain line) flows, and the received data is at the logic 1 level.

(5) Line restoration operation When the line is restored by itself, the restoration signal generation circuit 11 (release circuit) is operated to reduce the transmission/reception current ITR (dotted chain line) to a predetermined current value. The exchange transmits and receives current IT, I
(dotted chain line) detects that the flow is reduced, L, ,
The voltage polarity between L and L is returned to the line open state, and no current flows and line restoration is completed.

Further, when it is detected that the transmitting/receiving current 1r* (dotted chain line) is interrupted for a predetermined period of time because the received data is at the logic O level during that time, it is assumed that the line has been restored. Incidentally, the exchange returns the voltage polarity between .

[Problem that the invention seeks to solve]

However, in conventional subscriber line interface circuits, L is used for domestic or international use.

, the directions of the outgoing starting current, transmitting/receiving current, and incoming current for L2 are reversed, the current values of the outgoing starting current and the transmitting/receiving current are the same, but the current value of the incoming current is different, and Because of the need for local state control and the need to reduce the transmitting and receiving current when restoring the line, it is not possible to use one circuit for both domestic and international use. Since this is necessary, there are problems in that the circuit itself becomes larger and costs increase.

[Means and effects for solving the problems] The present invention has the following features:
This was done in view of the above, and in order to create an interface that can be used for both domestic and international use with one subscriber line interface circuit, LI, L2
Since the current values of the incoming current for domestic use and the local current for international use are the same, the local control circuit for international use also serves as the incoming call detection circuit for domestic use. In such a case, when the incoming signal is outputted, if the incoming call is accepted after going through the local state, a control means is provided to control the normal incoming current to flow, and a recovery signal generating means is provided.
Furthermore, by using the transmission starting current generation means for domestic use as the starting current for international use, the calling start circuit for international use can be omitted, and a subscriber line interface circuit that can be used for both domestic and international use with one circuit can be created. Configure.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, a subscriber line interface circuit for a subscriber telecommunications network according to the present invention will be explained in detail based on the illustrated embodiment.

FIG. 1 is a block diagram showing an embodiment of a subscriber line for a subscriber telecommunications network and an interface circuit according to the present invention.

In the figure, 15 is a line polarity switching circuit that connects a-c and b-d for domestic use, and a-d and b-c for international use. This switches the line polarity.

Further, the following circuit is connected to the device side terminal C1d of the line polarity switching circuit 15.

That is, one is an incoming current sub-regulating circuit 16 for making the incoming current ■R (dotted line) a constant value, and an incoming current 1. An incoming call detection circuit 1 converts the presence or absence of the signal into logic levels “1” and “0” and outputs the result.
7 is connected via one terminal a of the relay 18 and the common terminal C.

The other one is a current adjustment circuit 19 that limits the transmitting/receiving current ITR (one-dot chain line) and the transmission starting current r, (two-dot chain line) to a constant value, and the output of this circuit is branched into two, one of which is connected to a recovery signal generation circuit 20. , the other is connected to the second relay 2 via the receiving circuit 21.
It is connected to the two contacts a and b of the first relay 18 through the common terminal C of the relay 22, and through a series circuit consisting of a transmitting circuit 23 and a disconnection circuit 24 to the b terminal of the first relay 18.

Further, the two relays 18 and 22 are both controlled by a control circuit 25.
The control 101 line 25 is provided with a switch 2 for selecting which domestic or foreign line is to be used.
6 is added, and the incoming signal from the incoming call detection circuit 17 is branched and inputted.

Note that the transmitting circuit 23 can always flow the transmitting starting current (double-dashed line), but the disconnecting circuit 24 does not flow the transmitting/receiving current (dotted chain line) and the transmitting starting current (double-dotted chain line) during operation, and this is prohibited from operating. Under these conditions, these currents can flow. Furthermore, the incoming call detection circuit 17 can flow an incoming current (dotted line) or a local current (dotted line), but has a function of blocking current in the opposite direction.

The operation of the above configuration will be explained.

When used for A9 international subscriber telecommunication network The line polarity switching circuit 16 is set to the a-c and b-d sides.

The control circuit 25 is set for domestic use by a switch 26, and at this time, the relay 22 is identified to the terminal a side.

(1) Line open state In the line open state, L2 is (+
) A polar voltage is applied, but if the relay 18 is in contact with terminal a at this time, no current will flow through the subscriber line interface circuit and the line will be in an open state.

(2) When the transmitting operation control circuit 25 operates the relay 18 to bring it into contact with the terminal, and also prohibits the operation of the disconnection circuit 24, the transmitting starting current IA (double-dashed line) flows, and when the exchange detects this, L+ , Lz. As a result, the transmitting/receiving current ■□ (dotted chain line) flows instead of the transmission starting current ■A (double-dotted line), and the receiving circuit 21 outputs a logic level 1, completing the line acquisition. Next, the dial number expressed at a logic level of 0.1 is manually input to the transmitting circuit 23, and after the transmitting/receiving current (dotted chain line) is turned on and off and sent to the exchange, a data transmitting/receiving operation begins.

(3) Incoming call operation At the time of receiving a call, when the polarity of the voltage from the exchange that was added between L+ and Lz with the line open is reversed, the incoming current IR (
(dotted line) flows, and the incoming call detection circuit 17 outputs a logic level l as an incoming signal.

When the control circuit 25 detects the arrival 3 signal, it operates the relay 18 and contacts the terminal, thereby reducing the transmission/reception current I.
T (dotted chain line) flows, logic level 1 is output from the reception circuit 21, and data transmission/reception operation begins.

(4) Data transmission and reception operation Transmission and reception are performed alternately. The transmission data is input to the transmission circuit 23 with a logic level of 0.1, and the transmission/reception current I
It is sent to the other party as an intermittent TR (dotted chain line). Conversely, data sent from the other party as intermittent transmission/reception current (dotted chain line) is converted to logic level 0, ■ by the receiving circuit 21, and output as received data. When there is no transmitted/received data, the transmitted/received current (dotted chain line) flows, and the received data is at the logic 1 level.

(5) Line restoration operation When the line is restored by itself, the disconnection circuit 24 is activated to cut off the transmitting/receiving current (dotted chain line) for a predetermined period of time, and then the control circuit 25 restores the relay 18 and makes contact with terminal a. and return to the line open state. In addition, the transmitting and receiving current (dotted chain line)
When it is detected that the relay 18 has been cut off for a predetermined period of time because the received data is at a logic 0 level during that period, the control circuit 25 restores the relay 18 and brings it into contact with the terminal a.
Return to line open state. At this time, the converter also returns the voltage polarity between Ll and L2 to the line open state.

In the case of a B0 international subscriber telecommunication switching network, the line polarity switching circuit 15 is set to the ad and bc sides, and the switch 26 attached to the control circuit 25 is switched to the international one.

(11 lines open When the line is open, the exchange sends L to L2.

A voltage is applied that makes the polarity (+).

At this time, relay 18 and relay 22 are in contact with terminal a, and no current flows through the subscriber line interface circuit.

(2) When the relay 18 is operated by the transmission operation control circuit 25 to bring it into contact with the terminal and the operation of the disconnection circuit 24 is prohibited, the transmission starting current IA (two-dot chain line) flows. When the exchange detects the outgoing starting current (double-dashed line), it reverses the voltage polarity between L2. As a result, the transmitting/receiving current (dotted chain line) flows instead of the transmitting starting current (dotted chain line), and the receiving circuit 21
A logic level 1 is output, and line acquisition is completed. Next, the dial number expressed at logic level O11 is sent to the transmitting circuit 2.
3, the transmitting/receiving current (dotted chain line) is sent to the exchange intermittently, and data transmitting/receiving operation begins.

(3) Incoming call operation When a call is received, the line is open and the polarity of the voltage from the exchange that was applied between (regarding the incoming current as a local current) flows, and the incoming call detection circuit 17 outputs a logic level 1 as the incoming 1g signal. When the control circuit 25 detects an incoming signal,
Before the exchange assumes a non-response and returns to the open state, the relay 18 is operated and the terminals are brought into contact, causing a transmission/reception current (dotted chain line) to flow, and after the receiving circuit 21 outputs a logic 1, data transmission/reception is started. Get into action. As described above, when a call is received, the device goes through the local state once and then enters the call receiving operation. On the other hand, if the incoming call cannot be answered, the control circuit 25 ignores the incoming call signal, continues to flow the local current (dotted line), and remains in the local state. After a predetermined time,
The exchange detects this local current, assumes there is no response, and returns to the line open state.

(4) Data transmission and reception operation Transmission and reception are performed alternately. The transmission data is input to the transmission circuit 23 as a logic level O11, and the transmission and reception current (
It is sent to the other party as an intermittent line (dotted chain line). Conversely, data sent from the other party as intermittent transmission/reception currents (dotted and dashed lines) is converted to logic level O1■ by the receiving circuit 21 and output as received data. When there is no transmitted/received data, the transmitted/received current (dotted chain line) flows, and the received data is at the logic 1 level.

(5) Line restoration operation When the line is restored by itself, the control circuit 25 controls the relay 2
2 is brought into contact with the terminal, the receiving circuit 21 is switched to the recovery signal generating circuit 20, and the transmitting/receiving current (dotted chain line) is reduced to a predetermined current value. When the exchange detects that the transmitting/receiving current (single-dot chain vA) has been reduced, it returns the voltage polarity between Ll and Lz to the line open state. Since the recovery signal generation circuit 20 blocks currents in the opposite direction to the transmission and reception currents, neither current flows, and the control circuit 25 turns on the relay 18 after a predetermined period of time.
Then, the line is returned to the open state by controlling the relay 22 to contact the terminal a.

In addition, when it is detected that the transmitting/receiving current (dotted chain line) has been cut off for a predetermined period of time because the received data is at the logic 0 level during that time, it is assumed that the line has been restored, and the control circuit 25 sets the relay 1 day to the terminal. A is controlled to make contact with a, and the line returns to the open state. In addition, the exchange will perform 1. after the above predetermined time.
Return the voltage polarity between + and Lz to the line open state.

〔Effect of the invention〕

As explained above, according to the subscriber line interface circuit according to the present invention, since the line polarity switching means for switching L+ and Lx, the incoming current for domestic use, and the local current for international use are the same, The local control circuit for domestic use also serves as the incoming call detection circuit for domestic use, and in the case of international use, when an incoming signal is detected, the normal incoming current can be passed if the incoming call can be accepted after going through the local state. By providing a control means and a recovery signal generating means for controlling the output signal so as to cause the transmission to start, and by using the transmitting starting current generating means for domestically using the transmitting starting current for international use, the transmitting starting circuit for international use can be omitted. Since one circuit can be used for both domestic and international use, the subscriber line interface circuit itself can be downsized and costs can be further reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a subscriber line interface circuit according to the present invention, FIG. 2 is an explanatory diagram showing the configuration of a conventional subscriber line interface circuit for an international subscriber telephone network, and FIG. FIG. 1 is an explanatory diagram showing the configuration of a conventional subscriber line interface circuit for an international subscriber telephone network. Explanation of symbols 15...Line polarity switching circuit 16...Incoming current adjustment circuit 17...Incoming call detection circuit 18.22...Relay 19...Current adjustment circuit 20...Recovery signal generation circuit 21. ... Receiving circuit 23 ... Transmitting circuit 24 ... Cutting circuit 25 ... Control circuit 26 ... Suinochi

Claims (1)

[Claims] In a subscriber line interface circuit that is connected to a domestic subscriber telecommunications network and performs network control such as originating, receiving, and line restoration, a line polarity switching means for switching subscriber line connection terminals L_1 and L_2, and an international subscriber telecommunications network. When a call arrives at the network subscriber line interface, the local state control circuit that notifies the exchange of non-response also serves as the incoming call detection circuit, and includes a control means that once passes through the local state when the call is received, and then the call is received, and a recovery signal generation. 1. A subscriber line interface circuit for a subscriber telecommunication network, characterized in that it is configured so that it can also be used for an international subscriber telecommunication network by adding means.