JPS61269488A - Subscriber circuit - Google Patents

Abstract

PURPOSE:To obtain a large detection level for origination, resetting, a dial pulse signal, etc., by using two resistances whose resistance values are nearly equal to each other between the output of the 1st entire-area passing circuit having a switched capacitor and the output of the 2nd entire-area passing circuit of nearly the same constitution with the 1st circuit, and outputting dial pulses, etc., from the connection point of the two resistances. CONSTITUTION:The base potential of a transistor (TR) 1 is set by a resistance 4 and a Zener diode 2 at a subscriber current circuit part and the collector current of the TR 1 is determined by the resistance 3 to supply a constant speech current to a subscriber. A speech signal from the subscriber side is applied between communication line connection terminals 41 and 41 in opposite phase relation with earth points 26 and 35, so no output appears at a subscriber signal output terminal 44 where a subscriber signal averaged by resistances 38 and 39 appears. Therefore, the speech signal from the subscriber is led out to a speech signal output terminal 43. An operational amplifier 36 which is connected between grounding in terms of DC and grounding to the chassis, on the other hand, is applied with the variation of the speech line connection terminal 42 to the ground, so the variation in DC voltage due to the connection and disconnection of a subscriber side loop is detected at the subscriber signal output terminal 44.

Description

[Detailed description of the invention] [Industrial field of use] The present invention relates to subscriber circuits for electronic exchanges.

〔overview〕

The present invention supplies each communication line with a potential obtained by dividing the voltage of a 1TL1 current supply source, one end of which is connected to the earth, into two equal parts with respect to the earth, and separates incoming voice signals and pulse signals. In a common circuit, an all-pass circuit having a Swiss capacitor is connected to one input terminal via a capacitor, and an all-pass circuit having the same configuration as this all-pass circuit is connected to the other input terminal. A reactance element is inserted between the potential and the ground, and two almost equal resistances are inserted between the outputs of the two all-pass circuits, and a pulse signal is extracted from the connection point of these resistors, and the pulse signal is extracted from the connection point of the two all-pass circuits. By extracting the audio signal from either one of the outputs, it is possible to increase the amount of unbalanced attenuation to the ground, and it is also possible to extract a large detection level of the pulse signal from the subscriber. .

[Prior Art] The configuration of a conventional subscriber circuit is shown in FIG.
A resistor 7 of a power supply circuit that includes transistors 1 and 9, resistors 3 to 8, Zener diodes 2, operational amplifiers 12 and 13, a power supply 10, and resistors 14 to 17 and supplies communication current to subscribers. It detects the voltage change applied to the subscriber, extracts signals such as call origination, recovery, and dial pulses from the subscriber and outputs them from the subscriber signal output terminal 44, and also connects capacitors 45 and 46, resistors 47 to 50, and an operational amplifier. 51 detects the imm multiplied signal between the communication line connection terminals 41 and 42 and outputs it from the communication signal output terminal 43.

That is, the resistor 4 and the Zener diode 2 set the heath potential of the transistor 1, the resistor 3 determines the collector current of the transistor 1, and supplies a constant communication current to the subscriber.
Further, the impedance of the voltage of the voltage a10, which is divided into two by the resistors 5 and 6, is lowered by the operational amplifier 12 to make it a reference potential. The operational amplifier 13 compares a reference voltage with the potential obtained by averaging the potentials of the communication line connection terminals old and 42 with the resistors 14 and 17 having the same resistance value, and calculates the difference between the potentials of the communication line connection terminals old and 42 with the resistors 15 and 17.
6 is amplified according to the value of transistor 9 via resistor 8.
control the Heas potential of Therefore, the voltage applied between the resistor 3 and the collector and emitter of the transistor 1 is
The voltages applied between the resistor 7 and the collector and emitter of the transistor 9 become equal. The call signal from the subscriber is
When all resistance values of resistors 47 to 50 are made equal,
Between the communication line connection terminal 42 and the earth and the communication line connection terminal 41
is taken out from the operational amplifier 51 as the difference between
The call signal is output from the call signal output terminal 43. Call origination, recovery, and dial pulse signals from the subscriber are generated by the intermittent communication current caused by the opening and closing of the DC loop on the subscriber side.
The voltage drop is taken out at the subscriber signal output terminal 44 and detected.

[Problem that the invention seeks to solve]

In such a conventional subscriber circuit, variations in characteristics of transistors 1 and 9, variations in capacitors 45 and 46 and resistors 48 to 50,
Due to the control ability of the operational amplifier 13, etc., the impedance between the communication line connection terminal 42 and the ground 11 is not equal, and the unbalanced attenuation to the ground is poor. At the time of detection, the resistance value of the resistor 7 cannot be set to a large value due to the relationship between the communication current and the distance to the subscriber, so the detection level is low and, therefore, there is a drawback that detection is difficult.

SUMMARY OF THE INVENTION The present invention aims to eliminate such drawbacks and to provide a subscriber circuit which can detect subscriber call origination, recovery and dial pulse signals to a large extent.

Means for Solving Problem C] The present invention generates a first potential and a second potential that are obtained by dividing the voltage of a communication current supply source whose one end is connected to the ground into approximately two equal parts with respect to the ground. a first input terminal to which the first potential is applied and connected to one communication line; and a second input terminal to which the second potential indicated by -1- is applied and connected to the other communication line. A subscriber circuit comprising a second input terminal, a first output terminal that outputs a signal related to 1m talk information included in the call current, and a second output terminal that outputs a signal generated by intermittent communication current. , as a means for solving the above-mentioned problems, a first all-pass circuit having a capacitor having one end connected to the first input terminal, and a switched capacitor having an input connected to the other end of the capacitor. and a second all-pass circuit whose input is connected to the second input terminal and whose configuration is substantially the same as that of the first all-pass circuit, and a common potential of the second all-pass circuit and the ground voltage of the communication current supply source. a reactance element inserted between the two resistors, and two resistors connected in series between the output of the first all-pass circuit and the output of the second all-pass circuit and having substantially equal resistance values;
Output of the first full range pass circuit or second full range 1tl
a first circuit means for connecting either one of the outputs of the overpass circuit and the first output terminal; and a second circuit means for connecting the connection point of the two resistors and the second output terminal. It is characterized by

[For production]

Signals generated by intermittent current flow include signals associated with call origination, recovery, and dialing by a subscriber.

First, when the subscriber DC loop is open, the DC component is blocked by the capacitor connected to the first input terminal and is not output from the first output terminal that outputs signals related to call information, and the second all-pass circuit Since the potential of the second input terminal is at the ground potential, the DC output of the DC output becomes the ground potential which is the same potential as the potential connected to the reactance element, and this is the second output that outputs the signal generated by the intermittent communication current. It becomes the output of the terminal.

Next, when the subscriber side DC loop is closed, no output is output from the first output terminal whose DC component is blocked by the capacitor, but the potential of the second input terminal is inverted in the second all-pass circuit section. Therefore, the output of the second output terminal becomes a potential averaged by the two resistors inserted between the output of the first all-pass circuit and the output of the second all-pass circuit.

Further, the audio signal applied between the first input terminal and the second input terminal is outputted from the all-pass circuit in an opposite phase. By the way, since the first all-pass circuit and the second all-pass circuit have the same configuration, no output is applied to the second output terminal that is averaged by the two resistors.

That is, the subscriber's voice signal is taken out from the first output terminal, and the subscriber's call origination, recovery, and dial pulse signals are taken out from the second output terminal.

〔Example〕

Hereinafter, a circuit according to an embodiment of the present invention will be explained based on the drawings.

FIG. 1 is a circuit connection diagram showing the configuration of a circuit according to an embodiment of the present invention. First, the configuration of this embodiment circuit will be explained based on FIG.

This embodiment circuit includes a capacitor 1B that blocks direct current,
the first full range) WU overcircuit section, the second full range pass circuit section, the ground 25, 26, 34 and 35 of the first full range pass circuit section and the second full range pass circuit section, and the ground air 11 and 40, resistors 38 and 39 that connect between the outputs of the two all-pass circuits, a call signal output terminal 43, a subscriber signal output terminal 44, and a subscriber current supply circuit section. Equipped with Here, the first area il passage section includes switches 22 to 24 and capacitors 19 to 21.
The second all-pass circuit section includes switches 31-33, capacitors 28-30, an operational amplifier 36, and grounds 34 and 35, and the second all-pass circuit section includes The supply circuit section includes transistors 1 and 9, resistors 3 to 8, Zener diode 2, operational amplifiers 12 and 13, power supply 10, and resistor 14.
~17.

Next, the operation of this embodiment circuit will be explained based on FIG.

First, in the subscriber current circuit section, the base potential of the transistor 1 is set by the resistor 4 and the Zener diode 2, the collector current of the transistor 1 is determined by the resistor 3, and a constant communication current is supplied to the subscriber. The voltage of the power supply 10 is divided into two parts by the resistors 5 and 6, and becomes a low impedance reference voltage via the operational amplifier 12. In the operational amplifier 13,
The potential of the communication line connection terminals 41 and 42 is averaged by the resistors 14 and 17, which have the same resistance value, and the reference voltage is compared, and the difference is amplified according to the values of the resistors I5 and 16, and is applied to the resistor 8. It is supplied as the base potential of the transistor 9 through the transistor 9. Therefore, the voltage applied between both ends of the resistor 3 and the collector and emitter of the transistor 1 is equal to the voltage applied between both ends of the resistor 7 and the collector and emitter of the transistor 9.

Now, the subscriber's call origination, recovery and dial pulse signals are generated by the intermittent communication current of 50 m accompanying the opening and closing of the DC loop on the subscriber side. First, when the subscriber side DC loop is opened, transistors l and 9 are in a saturated state, so the potential of the communication line connection terminal 41 becomes the voltage side potential of the power supply 10, and the communication line connection terminal 42 becomes the voltage side potential of the power supply 10. Becomes the earth potential. The switches 22-24 and 31-33 of the first and second all-pass circuit sections operate synchronously from the state shown in FIG. Switch 2 of the first all-pass circuit section
The electrical characteristics of capacitor 19 and capacitor 19 are equivalent to resistance for frequency components sufficiently lower than the switching frequencies of switches 22 and 23, and capacitor 1
Since the DC component is blocked by the terminal 8, no DC output appears at the call signal output terminal 43, which is at ground potential. Further, the DC output of the second all-pass circuit is connected to the communication line connection terminal 42.
Since this is the earth's potential, the ground potential is the same as that of the ground 35 connected by the coil 37.

Therefore, the output of the subscriber signal output terminal 44 becomes the ground potential.

Next, when the subscriber side DC loop is closed, transistors 1 and 9 are in an unsaturated state, so the potential of the communication line connection terminal 41 rises from the battery 10 side to the earth side, and the communication line connection terminal The potential of 42 falls toward the earth side battery 10 side. The DC potential of the call signal output terminal 43 becomes ground potential because the DC component is blocked by the capacitor 18. The output DC potential of the second area i1 passage section is the communication line connection terminal 4.
The potential of 2 is inverted and output. Therefore, the output of subscriber signal output terminal 44 has a potential averaged across resistors 38 and 39.

Next, the audio signal from the subscriber side is transmitted through the communication line connection terminals 41 to 41.
42, and is applied to the communication line connection terminals 41 and 42 in opposite phase with respect to earths 26 and 35, so that the first full-range im passing circuit output and the second full-range passing circuit output have opposite phases. Since each element value of the first and second all-pass circuit sections is equal, the output voltages are equal, and no output appears at the subscriber signal output terminal 44 averaged by the resistors 38 and 39. Therefore, the voice signal from the subscriber is extracted from the call signal output terminal 43, and the subscriber output terminal 44
Signals such as subscriber call origination, recovery and dialing pulses are extracted from the .

The audio signal between the communication line connection terminal old and 42 is connected to the switch 22.
．． 23. When 31 and 32 are in the state shown in Figure 1, the voltage is divided by capacitors 18, 19 and 28 in inverse proportion to their capacitances, but if the capacitances of capacitors 19 and 28 are made equal, the charges stored in capacitors 19 and 28 will be become equal. Therefore, the audio signal output to the terminal 44 can be easily suppressed, and since the coil 37 is inserted between the ground and the earth, unbalanced components of the audio signal from the transistors 1 and 9 with respect to the earth can be suppressed. is attenuated.

On the other hand, since there is a direct current connection between the ground and the earth's atmosphere, changes to the earth's air at the communication line connection terminal 42 are applied to the operational amplifier 36, so that the subscriber side loop is interrupted at the subscriber signal output terminal 44. It is possible to detect changes in DC voltage caused by

〔Effect of the invention〕

As explained above, the present invention has the effect of increasing the amount of ground unbalance attenuation, and also has the effect of increasing the detection level of subscriber call origination, recovery, dial pulse signals, etc. Furthermore, since the coil can be equivalently configured with a semiconductor, it is possible to configure a circuit suitable for miniaturization such as an integrated circuit.

[Brief explanation of the drawing]

FIG. 1 is a circuit connection diagram showing the configuration of a circuit according to an embodiment of the present invention. FIG. 2 is a circuit connection diagram showing the configuration of a conventional circuit. 1.9...Transistor, 2...Zena diode, 3~8.14~17.38.39.47~50...
Resistance, 10...Power supply, 11.52...Earth air, 12.
13.27.36.51...Operation amplifier, 18-2
1.28~30.45.46...Capacitor, 22~
24.31-33...Switch, 25.26.34.
35... Earth, 37... Coil, 40... Earth air, 41.42... Call line connection terminal, 43... Call signal output terminal, 44... Subscriber signal output terminal.

Claims (1)

[Claims] (1) A communication current supply circuit having means for generating a first potential and a second potential which are obtained by dividing the voltage of a communication current supply source, one end of which is connected to the earth, into approximately two equal parts with respect to the earth; A first input terminal to which one potential is applied and connected to one communication line; a second input terminal to which the second potential is applied and connected to the other communication line; In a subscriber circuit comprising a first output terminal for outputting a related signal and a second output terminal for outputting a signal generated by intermittent communication current, a capacitor having one end connected to the first input terminal. a first all-pass circuit having an input connected to the other end of the capacitor and having a switched capacitor; and a second all-pass circuit having an input connected to the second input terminal and having substantially the same configuration as the first all-pass circuit. an all-pass circuit; a reactance element inserted between the common potential of the second all-pass circuit and the earth of the communication current supply source; and an output of the first all-pass circuit and the second all-pass circuit. two resistors that are connected in series with the output and have approximately equal resistance values; and either the output of the first all-pass circuit or the output of the second all-pass circuit and the first output terminal. A subscriber circuit comprising: first circuit means for connecting the connection point of the two resistors and the second output terminal.