KR950012585B1 - Direct inward outward dialing circuits - Google Patents

Abstract

The circuit consists of Zener diodes which is to protect a system against the overflow of voltage, a transformer which converts the level of transmission signals received, a central processing unit (CPU) which controls the whole system, a switching circuit which switches to connect subscribers, a dialling circuit, a detecting circuit which detects tone signals between the dialling circuit and the switching circuit, an interfacing unit which interfaces the signal network among the CPU, the switching circuit, and the dialling circuit, a high/low impedance generating unit which generates high or low impedance, a switch which selects high or low impedance, Direct Inward Outward Dialling (DIOD) signals detecting/transmitting circuit which detects and transmits DIOD signals, a current limiting circuit which limits the flow of forward or reverse current, and a relay drive circuit which controls a coil to limit the switching of the switch.

Description

Two-way dialing trunk interfacing circuit

1 is a block diagram of a conventional private exchange.

2 is a detailed circuit diagram of the DIOD trunk circuit 90 of FIG.

3 is a private exchange circuit diagram according to the present invention.

4 is a specific circuit diagram of the DIOD signal detection / transmission circuit 101 of FIG.

The present invention relates to a trunk interfacing circuit in an electronic exchange, and more particularly to a direct inward ourward dialing (DIOD) circuit for bidirectional dialing trunk interfacing.

In general, one method of trunk interfacing of private exchanges is direct inward dialing (DID). This is a calling method in which a specific subscriber (caller) accommodated in a trunk line of a national exchange directly dials a predetermined extension of a private exchange in which a DID trunk is accommodated. In order to call the extension of the private exchange, a part of the dialed CO line subscriber's number is recognized inside the private exchange to give a ring signal directly to the corresponding subscriber, that is, the caller. In other words, this feature means that an incoming call to an extension within a private exchange can be called without an operator. And the outgoing of the extension of the private exchange which accommodates the DID trunk key means when the extension requests to take the trunk line, and it is not possible to directly catch the trunk line through the DID trunk. In other words, this trunk is accepted by the DID trunkron private exchange and can only receive incoming dialing. Therefore, a predetermined extension subscriber of the private exchange cannot perform outgoing cal1 through the DID line. there was.

In the case of the Loop Start Trunk, the incoming call cannot be handled in the private exchange, so when the operator makes an incoming call (a ring signal is detected), the answering party answers the call. Say the "extension number" or "subscriber name" you want and give them the corresponding extension number. Therefore, since the automatic switching of the incoming call by the loop start trunk interfacing method is not possible in the private exchange, an operator is required, and for the outgoing, the operator can dial through the loop start trunk.

In order to implement the DID and loop start trunk interfacing methods, there is a problem in that the two types of trunks are accommodated as described in US Pat. No. 3,748,396, and the corresponding functions are selectively applied as necessary.

In order to solve the above-mentioned problem, the first PMI has been applied to the European PTT ALS-70 system by a circuit configured as the second PART. In the configuration as shown in FIG. 2, the coils L1 and L2 having a large impedance must be used, and thus the size is increased. And there was a problem that the volume spreads.

Accordingly, an object of the present invention is to provide a direct inward outward dialing (DIOD) trunk.

Another object of the present invention is to provide a circuit that can be called (incoming) and outgoing (outgoing) by direct dialing without the operator's service, and can be both incoming and outgoing by direct dialing.

It is still another object of the present invention to provide a circuit capable of selecting a called party by incoming and outgoing dialing.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a circuit diagram of a private exchange according to the present invention, a Zener diode (ZD1 to Zd2) for protecting the system from transient voltages between the tip and ring ends of the trunk line, and a transmission signal transmitted and received through the trunk line. CPU 10 for controlling the transformer T1 and T2 for converting the level of the circuit and the entire private exchange, and a switching circuit 50 for switching from a CO line to a call and an extension subscriber through the control of the CPU 10. ), A call signal 102 connected to the switching circuit 50 and the transformer T1 to conduct a call, and a tone signal detecting a tone signal between the call circuit 102 and the switching circuit 50. A private exchange having a detection circuit 104 and a signal transmission between the CPU 10, the switching circuit 50, and the call signal 102, and having an interface unit 130, the high or low impedance to the trunk line. Generated and provided A high / low impedance generating means, a switch SW1 connected to the transformer T1 to select and provide the generated high or low impedance, and a reference for generating a high or low impedance of the high / low impedance generating means And a DIOD signal detection and transmission circuit 101 for detecting a low or impedance value provided to the trunk line and detecting a forward or reverse polarity inversion signal and a busy signal from the polarity inversion signal of the trunk line, and the DIOD signal detection and transmission. The current limiter circuit 121 for limiting the current flow in the forward or reverse direction in the circuit 101 and the impedance generated by the high or low impedance impedance according to the switching of the switch SW1 are provided to the trunk line. Relay drive circuit 107 for controlling the signal and the busy signal from the DIOD signal detection and sending circuit 101 And an interface unit 30 which decodes the tone signal detection signal from the polarity polarity inversion signal, the high impedance detection signal, and the tone signal detection circuit 104 to control the communication circuit 102 and transmit it to the CPU 10. .

That is, the impedance matching transformers T1 and T2 are connected from the tip and ring ends connected to the trunk line, and at the same time, the high / low impedance detection terminals 5 and 6 of the DIOD signal detection and transmission circuit 101 are connected to each other. The current limiting current of the limiter circuit 121 is connected to the current limiting input / output terminals 2 and 3 of the DIOD signal detection and sending circuit 101, and the coil L1 is controlled by the relay drive circuit 107. The switch SW1 is selected to generate a high or low impedance signal by driving. When the switch SW1 is in the ① position through the high / low impedance generation reference stage 4 of the DIOD signal detection and transmission circuit 101, a high impedance is generated through the diode D1 and the resistor R1, resulting in a transformer T1. It is provided to the trunk line, and when the switch SW1 is in the ② position, the low impedance is generated based on the high / low impedance generation reference terminal 4 and is transmitted to the trunk line.

The high impedance detection output through the high impedance output terminal 14 of the DIOD signal detection and sending circuit 101 is processed by the control circuit 109 and input to the CPU 10 through the buffer circuit 110, and the DIOD signal The forward polarity inversion signal terminal 11 of the detection and sending circuit 101 is connected to the power supply terminal Vcc through the resistor R7, and the reverse polarity inversion signal terminal 10 is connected to the latch circuit 106. The reverse polarity inversion signal is connected to the CPU 10 through the latch circuit 106 through the control circuit 109 and the buffer circuit 110. The board protection stage 13 of the DIOD signal detection and transmission circuit 101 is connected to the control circuit 109, and the call interruption 12 is connected to the latch circuit 108 so that the busy signal is received by the latch circuit 108. Through the buffer circuit 110 through the input through the CPU 10 and the control circuit 109 is configured. The communication circuit 102 is connected to the secondary sides of the transformers T1 and T2.

A capacitor C6 is connected to one output terminal of the call circuit 102 to thereby connect the tone signal detection circuit 104 through the resistors R3 and R4, and the input / output terminal of the tone signal detection circuit 104. It is connected to the latch circuit 105 and configured to be applied to the CP U 10 through the control circuit 109 and the buffer circuit 110.

The relay driver circuit 107 excites the relay coil L1 by the driving of the relay driver circuit 107 according to the output of the control circuit 109 to generate the low or high impedance signal generating means by the driving of the switch SW1. It is configured to select high or low impedance to supply to trunk line.

4A and 4B are specific circuit diagrams of the DIOD signal detecting and transmitting circuit 101. The resistors R11 and R12 and the photocoupler are connected to the current limiting input terminal 3 of the current limiter circuit 121. Connect the light emitting diode cathode of PT1, PT2, the anode of diodes D11 and D13 to the current limiting output terminal 2 of the current limiter circuit 121, and the connection terminal 1 from the transformer T2. ) Connects the cathode of diode D11 and the anode of diode D12 to the anode of diode D24 and the anode of diode D13 from the high / low impedance generation reference terminal 4. The light emitting diodes of the photocouplers PT1 and PT2 are connected to the diodes D12 and D24.

Resistor R13, R14 and R15, R16 are connected to the anodes of the phototransistors of the photocouplers PT1, PT2, respectively, and pass through the inverters N11, N12 from the resistors R14, R15. The polarity inversion signal is detected.

The signal of the board protection stage 13 and the signal through the inverter N15 are output through the AND gate AN15, and the AND gate AN12 is output from the outputs of the inverters N11 and N12 through the AND gate AN11. The call interruption 12 is connected.

4B is a high impedance detection circuit in the DIOD signal detection / transmission circuit 101. Inverting the operational amplifier OP1 through the resistors R25 and R26 from the tip and ring ends of the trunk line. And non-inverting terminals (-, +) are connected, and the resistors R24, R19, R20, and R23 are connected from the -48V power supply terminal 9, and the resistors R19, capacitors C13, A base of the transistor Q12 is connected, a power supply terminal Vcc of the operational amplifier OP1 is connected to an emitter of the transistor Q12, and a diode D14 and a resistor are connected to an output terminal of the operational amplifier OP1. R18 is connected, and the base of the transistor Q11 is connected from the resistor R18.

The light emitting diode of the photocoupler PT3 is connected to the collector of the transistor Q11, the resistor R22 and the capacitor C15 are connected to the collector of the phototransistor of the port coupler PT3, and then the inverters N13 and N14 are connected. It is configured to detect high impedance.

Briefly, first, the outline of the present invention, the DIOD trunk circuit 90 from the CO line in the high impedance state instead of the ring signal in the existing loop start trunk when the side of the private exchange from the main line CD (Seizure) By inverting the polarity of the supplied 48V power supply, the CPU 10 is notified of the incoming call, and the switching circuit 50 is controlled to open the call path through the switching circuit 50 so that the call can be made through the corresponding subscriber circuit 40. Let's do it. That is, when the DTMF signal is recognized, the passage of the call path as described above should be connected, and the ringback tone or busy tone in the tone supply circuit 60 is provided as in the DID interfacing method. Here, since the call path is already open, there is no need to notify the CO line side of the busy or free state separately. However, for the billing process, the incoming station hooks off the signal to the trunk line.

In conventional European private exchanges, metering pulses are also used for billing processing, so they do not need to be recognized by private exchanges. They count metering pulses and send high impedance to the trunk line when all DTMF signals are received. When this signal is received, the DTMF signal transmission is stopped. In the case of origination, the DIOD trunk circuit 90 is similar to the loop start operation that it adopts and uses only the advantages of the functions of the loop start.

One embodiment of the present invention will be described in detail with reference to FIGS. 4A and 4B, which are specific circuits of the DIOD signal detection and transmission circuit 101 of FIG. When calling subscribers subscribed to, the high impedance polarity reversal signal is sent from the CO line first. Since the transmitted signal is a high impedance polarity inversion transmission signal, a detection signal whose input impedance is close to infinity is required.

The high impedance detection circuit uses an operational amplifier OP1 to perform a differential amplification function by comparing inputs of a tip and a ring, as shown in FIG. 4B, and the output of the operational amplifier OP1. Compares the input of the tip terminal and the ring terminal so that the base of the transistor Q11 is applied through the diode D14 and the resistor R18, and when the output of the operational amplifier OP1 is " low " The collector of the transistor Q11 becomes "high" to drive the port coupler PT3, and becomes "low" in response to the driving of the port coupler PT3, thereby the resistor R and the inverters N13 and N14. The output of detection of the "high" impedance signal is generated, and the -48V voltage is turned on by the voltage divider by the resistors R19 and R20 to turn on the transistor Q12 to the voltage terminal Vcc of the operational amplifier OP1. -24V is applied. Of the voltage polarity normally applied to the tips and ring ends 5 and 6, the tip end 5 is [-] and the ring end 6 becomes [+] so that there is no output of the delay operation amplifier OP1. Since it is turned off, the operation of the photocoupler PT3 is turned off. Therefore, the outputs of the inverters N13 and N14 become " high " state and are in the idle state.

But if you want to caesar private exchanges, Tip. If the tip end 5 of the polarity of the power applied to the ring stages 5 and 6 is positive, and the ring end 6 becomes negative, the input polarity of the operational amplifier OP1 is changed. Since the output polarity of the operational amplifier OP1 is changed, the output polarity of the operational amplifier OP1 is in a "low" state, and the transistor Q11 is turned on. At this time, the emitter side ground power supply of the transistor Q11 flows to the -48V terminal 9 through the port coupler PT3. Therefore, the port transistor is turned on when the light emitting diode D16 of the photocapillar PT3 is turned on so that the collector becomes "low". The " low " signal is output as " low " through the inverters N13 and N14, and is input to the control circuit 109 as shown in FIG. 3, and is sensed by the CPU 10 through the buffer circuit 110. As shown in FIG. 1, the tone supply circuit 60 is controlled through the interface unit 30 under the control of the CPU 10, and the switching circuit 50 is controlled so as to generate a dial tone and attach the DIOD trunk circuit 90. After passing through the switching circuit 50 receives the DTMF signal from the DTMF receiving circuit 70 to the CPU (10). However, if the DTMF signal from the CO line is received according to the designated extension number or if it is an unacceptable number, the control circuit 109 is executed by the CPU 10 by the received signal for the number. The high impedance signal is sent to the trunk line under the control of the relay drive circuit 107.

That is, in the above case, when the control circuit 109 controls the relay driver circuit 107 to drive the coil L1, the switch SW1 is switched to the position of ①, whereby the resistor R1 and the diode D1. This is because a high impedance signal is generated. At this time, the resistor R1 connected to the high / low impedance generation reference terminal 4 of FIG. 4A and the diode D1 are connected to switch lines SW1 and transformers T1 and T2 to have high impedance. It will send a signal. That is, it passes from the tip terminal Tip through the resistor R1 and the diode D1 through the high / low impedance generation reference terminal 4 and through the diode D24 of FIG. Then, the port coupler PT2 is driven, and the current flowing through the current limiting input terminal 3 of the current limiter circuit 212 is limited.

The limited current is output through the current limiting output terminal 2 of the current limiter circuit 121 through the diode D11 to the connection terminal 1 and high through the transformer T2 to the ring terminal connected to the trunk line. Impedance signal is sent out. This is because when the private exchange receives all the digits from the CO line via the DIOD trunk circuit 90 or receives the unwanted or impossible number from the CO line, it does not need to receive any more digit information. Circuit.

Before the high impedance signal transmission state, the relay driver circuit 107 is driven in the incoming state so that the switch SW1 for selecting the high / low impedance transmission for the low impedance loop shape is in the position of ②. This state means that the CPU 10 is in the detection state of the DTMF signal under the control of the DTMF receiving circuit 70.

When the CPU 10 does not need to receive the DTMF signal any more, the switch SW1 for the high / low impedance transmission selection is placed at the FH position by turning off the relay drive circuit 107 so that the resistor R1 and the diode D1 are located. A high impedance loop is formed by) to transmit a high impedance signal to the trunk line.

This signal is maintained until the corresponding subscriber 120 hears the ring generating tone of the ring generating circuit 110 and hangs off, as in the first diagram. At this time, the incoming call sound provided by the tone supply circuit 60 is converted from the transformers Tl and T2 through the call circuit 102 of the DIOD trunk circuit 90 through the switching circuit 50 to which the call path is connected and transmitted to the trunk line. do. Looking at the transmission relationship of the high / low impedance signal in the DIOD signal detection and transmission circuit 101 in detail, according to the position (1) or (2) of the switch (SW1) for high / low impedance transmission selection, the diode (D24), The current flowing in the current limiting circuit 121 through the resistor R12 is limited. The limited current passes through the diode D11 to the trunk line through the connection terminal 1. At this time, the current flows below about 3mA, and the CO line recognizes this to start charging and connects the call path at the CO switch side. This high impedance state is the moment when the normal return of this signal to the incoming call tone transmission state is the moment when the call is started.

The low impedance signal is fed to the DIOD link circuit 90 or forms a call path when the DIOD link circuit 90 is calibrated for outgoing dialing in a private exchange. When the power flows through the DIOD trunk circuit 90, it is in a low impedance state.

3, the diode D24 and the port when the state of the switch SW1 for selection according to the high or low impedance signal transmission to the excitation of the coil L1 of the relay drive circuit 107 is in the position of ②. The current flowing in the current limiter circuit 121 through the current limiting output stage 2 through the coupler PT2 is limited to 30 mA. The current limited in the current limiter circuit 121 transmits a low impedance state signal through the diode D11 through the transformer T2 to the trunk line side ring end. In addition, the low impedance polarity inversion signal is converted from the transformer T1 through the team tip Tip to the high / low impedance of the DIOD signal detection / transmission circuit 101 through the stage ② of the switch W1 as opposed to the transmission. When input to the reference (4) has a photocoupler (FT2) through the diode (D24). The signal passing through the port coupler PT2 is limited in the current limiter circuit 121 through the current limiting output terminal 3, and then converted from the transformer T2 through the diode D11 through the current limiting input terminal 2. do.

The signal through the transformer T2 causes current to flow through the trunk line side ring. As the port couplers PT1 and PT2 are driven, the state of the emitter of each port transistor is inverted in the inverters N11 and N12 through the resistors R14 and R15 and is reversely reversed to the reverse polarity reverse stage 10. Is detected and forward battery signal to jar 11 is detected. When either of the two signals is received, a low state is output from the AND gate AN11 to generate a BUSY signal from the AND gate AN12. That is, it is generated regardless of the state of the board protection stage 13 and the output of the AND gate AN13 generated from the signal through the inverter N15.

As described above, the low impedance signal is sent to the trunk line side, and the trunk line side detects it and connects the call path at the trunk line exchange. Looking at the relationship between DTMF and tone signal transmission and detection according to the call path, the tone and DTMF transmission and detection are enabled by only turning on / off the time switch in the switch circuit 50 regardless of the state of the loop relay. The tone signal detection circuit 104 of FIG. 3 executes the functions of the DTMF transmission / reception circuits 70 and 80 and the tone supply circuit 60 of FIG.

As described above, it is possible to provide a DIOD trunk function capable of bidirectional dialing, but there is an advantage of facilitating interfacing with an existing trunk bridge, improving reliability, and facilitating installation work.

Claims (3)

Zener diodes (ZD1 to ZD2) for protecting the system from transient voltages between the tip of the trunk line and the ring ends (Tip, ring), transformers (T1 and T2) for converting the level of transmission signals transmitted and received to the trunk line, CPU 10 for controlling the entire private exchange, a switching circuit 50 for switching from a trunk line to a call and an extension subscriber under the control of the CP U 10, the switching circuit 50 and A call circuit 102 connected to the transformer T1 to conduct a call, a tone signal detection circuit 104 for detecting a tone signal passing between the call circuit 102 and the switching circuit 50; A private switch having an interface unit 30 for interfacing a signal network between the CPU 10, the switching circuit 50, and the communication circuit 102, the high switching device generates a high or low impedance for providing the trunk line. Low impedance generating means, and A switch SW1 connected to a transformer T1 to select high or low impedance generated by the high / low impedance generating means to the trunk line, and a reference for generating high or low impedance of the high / low impedance generating means; And a DIOD signal detection and sending circuit 101 for detecting a low or high impedance value provided to the trunk line and detecting a forward or reverse polarity inversion signal and a busy signal from a polarity inversion signal of the trunk line, and detecting the DIOD signal. And a current limiter circuit 121 for limiting the current flow in the forward or reverse direction in the output circuit 101 and the relay drive circuit 107 for controlling the coil L1 to control the switching of the switch SW1. Two-way dialing trunk interfacing circuit, characterized in that configured. The method of claim 1, wherein the high / low impedance generating means connects the resistor R1 and the diode D1 in series from the ① position of the switch SW1 so that the anode side of the diode D1 detects the DIOD signal. Bidirectional dialing trunk interfacing circuitry, characterized in that it is connected to a terminal (4) of the transmission circuit (101) and directly to the terminal (4) from the ② position of the switch (SW1). 2. The DIOD signal detection / transmission circuit 101 of claim 1 is in order. The diodes D11 to D13 and D24 which limit the input or output from the reverse application terminals 1 and 4 by the current limiter circuit 121 and convert the polarity inversion signals according to the outputs of the diodes D12 and D24. Photocouplers PT1 and PT2 for detecting, Filter means for removing noise from the polarity inversion signal output from the photocouplers PT1 and PT2, and Inverters 10 and 11 for inverting output from the filtering means. And AND gates (AN11, AN12, AN15) for detecting a busy signal by the output of the inverter (10, 11) and the output of the board protection stage 13, the trunk line side tip, ring (Tip, Ring) A high frequency band to remove high-frequency noise from the output of the operational amplifier OP1, the port coupler PT3 driven by the output of the operational amplifier OP1, and the output of the caprocoupler PT3. A high impedance phase by inverting the filter means and the output of the high pass filter means. Bidirectional dialing trunk interfacing circuit, characterized in that consisting of inverters (N13, N14) for outputting the state.