JPS6232860B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a subscriber monitoring circuit for a telephone exchange or the like.

Generally, the incoming call indication to the called party is
A sine wave so-called bell signal with a frequency of 16 Hz and an effective value of 75 V is applied to the B line of the telephone line, and -48 V is applied to the B line of the telephone line.
This is accomplished by applying a DC voltage of 1, respectively, and causing the called party's magnetic bell to ring using the AC power of the bell signal.

When the called party answers and the DC loop is closed, an alternating current is applied between the A and B lines of the communication line together with the alternating current caused by the bell signal to the B line of the communication line.
A DC voltage of 48V causes a DC current determined by the value of the loop resistance to flow.

Therefore, in order to monitor the called party's response when sending a bell signal, it is necessary to separate the alternating current and direct current caused by the bell signal by some means and then detect the presence or absence of this direct current. It won't happen.

Conventionally, this so-called ring trip circuit, which monitors the response of the called party, slows down the operation time by providing a copper sleeve on the magnetic core, and has a slow-slow operation that is not affected by the alternating current power of the bell signal. A type of wire spring relay was used.

On the other hand, in order to send a dial pulse from a calling subscriber, according to switching equipment rules, -48V DC voltage is applied to the A line of the communication line, and a DC voltage of -48V is applied to the B line of the communication line, respectively.
As a result, the direct current flowing between the A line and the B line of the communication line is caused to flow intermittently at a predetermined speed by the telephone of the calling subscriber.

Therefore, the dial pulse from the calling subscriber is received by detecting the interruption of the direct current between the A line and the B line on the exchange side.

In general, the intermittent speed of the dial pulse is usually either 10 pps or 20 pps depending on the type of telephone, so that the dial pulse can be received at a speed that is not affected by the 16 Hz bell signal. It has been difficult to share slow-acting wire spring relays.

For this reason, conventionally, in addition to the wire spring relay for response monitoring, intermittent DC current flowing between wires A and B was detected using a dial pulse of 10 pps or 20 pps, and the dial pulse was received. .

As described above, subscriber monitoring in conventional exchanges has been carried out by providing a plurality of monitoring circuits such as response monitoring circuits and dial pulse receiving circuits, and selecting and using the monitoring circuits depending on the situation.

Therefore, since multiple monitoring circuits are required for one subscriber, the amount of hardware is large and it is very uneconomical, and the location that the central processing circuit scans is separated for each monitoring circuit, making it difficult to perform a replacement processing program. It made it complicated.

An object of the present invention is to provide a subscriber monitoring circuit that can be used in all cases such as response monitoring and dial pulse reception, has a simple circuit configuration, and does not require complicated software.

According to this invention, there is provided a circuit for detecting the voltage or current between the A line and the B line of the communication line, a switched capacitance low frequency device whose input is connected to the output of the detection circuit, and a switched capacitance low frequency device having an input connected to the output of the detection circuit. The input is connected to the output of the bandpass filter, and the output is connected to the input of the central processing circuit, respectively, and consists of a voltage comparator circuit having a predetermined threshold voltage, and a plurality of clock generation circuits having different frequencies. There is obtained a subscriber monitoring circuit characterized in that a switch element is further added for selectively connecting any one of the plurality of clock generation circuits to the clock input of the switched capacitance low frequency device in accordance with the above.

FIG. 1 is a diagram showing an example of a conventional subscriber monitoring circuit. According to FIG. 1, the conventional subscriber monitoring circuit has a first terminal 100 connected to a movable contact.
relay contact 101 and this first relay contact 1
A first relay winding 102 whose one end is connected to one fixed contact of 01, and a bell signal source 103 inserted between the other end of this relay winding 102 and the earth.
, a second relay winding 104 wound around the same magnetic core as the first relay winding, and this relay winding 1
A first storage battery 105 has a negative terminal connected to one end of 04 and a positive terminal connected to the ground.
and a second relay contact 106 connected between the other end of the second relay winding 104 and the earth;
a third relay contact 108 with a movable contact connected to the terminal 107 of the third relay contact 108;
A resistor 109 has one end connected to one fixed contact of this third relay contact 108, a negative terminal is connected to the other end of this resistor 109, and a positive terminal is connected to the ground. Second storage battery 1
10 and a third relay winding 111 having one end connected to the other fixed contact of the first relay contact 101.
The other end of the third relay winding 111 is connected to a negative terminal, and the other end of the third relay winding 111 is connected to a positive terminal connected to the third storage battery 112. One end is connected to the other fixed contact of the third relay contact and the other end is connected to the ground, and one end is connected to one end of the fourth relay winding 113 and the third relay winding 111 connected to the third relay contact. A first DC blocking capacitor 115 has its other end connected to the terminal 114 of the fourth relay winding 113, and a first DC blocking capacitor 115 has its other end connected to the fourth terminal 116, respectively. 2 DC blocking capacitor 117, the fifth terminal 118 and the sixth terminal 11
9 and a fifth relay contact 123 connected between a seventh terminal 121 and an eighth terminal 122.

The subscriber's A line is connected to the first terminal 100 shown in FIG. 1, and the subscriber's B line is connected to the second terminal 107. 1 relay winding 102-first
to the magnetic bell of the called party through the path of relay contact 101 - first terminal 100 - called party's telephone - second terminal 107 - third relay contact 108 - resistor 109 - second storage battery 110. Supplied.

The first relay winding 102, the second relay winding 104, the first relay contact 101, the second relay contact 106, the third relay contact 108, and the fourth
The relay constituted by the relay contact 120 is a slow-slow action type relay that is not affected by the alternating current generated by the bell signal.

Now the called party answers and the first terminal 10
When a DC loop is closed between 0 and the second terminal 107, the DC current from the second storage battery 110 flows through the same path as the AC current from the bell signal,
First relay winding 102 is energized.

As a result, when the second relay contact 106 operates, a direct current from the first storage battery 105 flows through the second relay winding 104, forming a self-holding circuit.

Along with this, the first relay contact 101 and the third
relay contact 108 operates, and the first terminal 100
and the second terminal 107 to the switched circuit connected to the third terminal 114 and the fourth terminal 116.

Furthermore, at the same time, the fourth contact 120
Since the terminal is closed, the subscriber's response can be detected by monitoring the conduction state between the fifth terminal 118 and the sixth terminal 119 by a central processing circuit (not shown).

On the other hand, when receiving a dial pulse from a calling subscriber, the first and third relay contacts 101 and 108 shown in FIG. 1st by
For the calling subscriber telephone connected between the terminal 100 and the second terminal 107 of the Subscriber telephone - first terminal 10
DC current is supplied through a path of 0-first relay contact 101-third relay winding 111-third storage battery 112. When the DC current thus supplied is interrupted in response to the dialing of the calling subscriber,
Accordingly, the fifth relay contact 123 controlled by the third and fourth relay windings 111 and 113 opens and closes. Therefore, a dial pulse from a calling subscriber can be received by monitoring the continuity state between the seventh terminal 121 and the eighth terminal 122 by a central processing circuit (not shown). I can do it.

In this way, in conventional subscriber monitoring circuits, slow-slow action relays (first and second
relay windings 102, 104, first, second, third
and fourth relay contacts 101, 106, 10
8, and 120. ) for receiving dial pulses, a relay (consisting of third and fourth relay windings 111, 113 and fifth relay contact 123) is used to receive dial pulses. ), and the subscribers are monitored by switching between these two monitoring circuits depending on the situation.

For this reason, the conventional subscriber monitoring circuit is complicated and expensive, and the central processing circuit (not shown) scans two locations, making the replacement processing program complicated.

FIG. 2 shows the switch type used in this invention.
FIG. 3 is a diagram illustrating an example of a circuit of a capacity low-frequency wave device.

According to FIG. 2, the switched-capacity low-frequency device includes a switch element 201 with one fixed contact connected to an input terminal 200, one end connected to a movable contact of this switch element 201, and the other end connected to the ground. A first capacitor 202 having a capacitance value of _C1 is connected to the first capacitor 202, an operational amplifier has an inverting input connected to the other fixed contact of the switch element 201, a non-inverting input connected to the ground, and an output connected to the output terminal 203, respectively. 204, one end is connected to the inverting input of this operational amplifier 204, the other end is connected to the output, and C ₂
and a second capacitor 205 having a capacitance value of .

IEEE Journal SC-12, No. 6, Dec 1977,
P600 and other documents, when the switch element 201 shown in FIG. 2 is switched at the frequency fc, the signal e _io applied to the input terminal 200 and the signal e _put obtained at the output terminal 203 are The following equation holds true between them.

That is, the switched-capacity low-pass filter shown in FIG. 2 provides a low-pass filter whose cut-off frequency can be continuously controlled by the switching frequency fc of the switch element 201.

FIG. 3 is a diagram showing an embodiment of the subscriber monitoring circuit according to the present invention.

According to FIG. 3, the subscriber monitoring circuit according to the present invention includes a first resistor having one end connected to one fixed contact of a first switch element 301 having a movable contact connected to a first terminal 300. 302 and this first
A bell signal source 303 is connected between the other end of the resistor 302 and the earth, a second switch element 305 has a movable contact connected to the second terminal 304, and a second resistor 306 whose one end is connected to one fixed contact;
A first storage battery 307 whose negative terminal is connected to the other end of the resistor 306 and a positive terminal connected to the ground, and a first inductor 308 whose one end is connected to the first terminal 300. The other end of the first inductor 308 has a negative terminal connected to the ground, and the second storage battery 309 is connected to the other end, and the second terminal 304 has one end connected to the ground, and the other end is connected to the ground. connected second inductor 31
0, one end to one end of the first inductor 308, the other end to the third terminal 311, one end to the first DC blocking capacitor 312 connected to one end of the second inductor 310, and a fourth terminal 3 of
A second DC blocking capacitor 314 whose other end is connected to 13, a differential amplifier 315 whose non-inverting input is connected to the first terminal 300, an inverting input to the second terminal 304, and this differential Amplifier 3
A switched-capacity low-pass filter 316 whose input is connected to the output of the fifth switch, one input to the output of the switched-capacity low-pass filter 316, and the other input to the reference voltage generation circuit 317.
A third switch element 320 has a movable contact connected to a voltage comparator circuit 319 and a clock input of the switched capacitance low frequency converter 316, respectively, and a third switch element 320 has an output connected to a terminal 318 of the switch.
The first clock generating circuit 321 has an output connected to one fixed contact of the switch element 320 and has a frequency f ₁ , and the output is connected to the other fixed contact of the third switch element and has a frequency f ₂ . and a second clock generation circuit 322 having a second clock generation circuit 322.

The first terminal 300 shown in FIG.
The subscriber's B line is connected to the second terminal 304.
The alternating current generated by the bell signal is
bell signal source 303 - first resistor 302 - first switch element 301 - first terminal 300 - called subscriber telephone - second terminal 304 - second switch element 305 - second resistor 306 - the magnetic bell of the called party is supplied in the path of the first accumulator 307; At this time, the first terminal 300 and the second terminal 304
The voltage applied between the differential amplifier 315 and
At the output, an AC voltage corresponding to the bell signal supplied to the called party and a DC voltage corresponding to the activation force of the first storage battery 307 are obtained.

Here, the clock frequency f ₁ of the first clock generation circuit 321 is set to a value that allows the switched capacitance low frequency amplifier 316 to sufficiently remove the alternating current voltage caused by the bell signal output from the differential amplifier 315. selected. Therefore, the voltage comparison circuit 31
Only a DC voltage corresponding to the electromotive force of the first storage battery 307 is applied to one input of the storage battery 9 .

When selecting a bell signal, the first terminal 300
and the second terminal 304 can be considered to be in an open state in terms of direct current, so the differential amplifier 3
A DC voltage equal to the electromotive force of the first storage battery 307 is applied between the inverting input and the non-inverting input of the battery. Here, when the called party answers and a DC loop is closed between the first terminal 300 and the second terminal 304, the DC current from the first storage battery 307 becomes the AC current from the bell signal. The DC voltage flowing through the same path and thus applied between the inverting and non-inverting inputs of the differential amplifier 315 is reduced by the voltage drop across the first resistor 302 and the second resistor 306. .

Therefore, by monitoring changes in this DC voltage using the voltage comparator circuit 319, the response of the called party can be detected. When a central processing circuit (not shown) detects a subscriber response by scanning the fifth terminal 318, it moves the first switch element 301 and the second switch element 305, respectively, in opposite directions from that shown. the first terminal 30
0 and the second terminal 304 is switched to the switched circuit connected to the third terminal 311 and the fourth terminal 313.

Generally, a sine wave having a frequency of 16Hz is used for the bell signal, so the first clock generation circuit 3
The frequency f ₁ of 21 is selected so as to set the cutoff frequency of the switched capacitance low frequency filter 316 to about several Hz.

On the other hand, when receiving a dial pulse from a calling subscriber, the first, second and third switch elements 301, 305 and 320 shown in FIG.
are tilted in the opposite direction to that shown.

As a result, the first terminal 300 and the second terminal 3
04 to the calling subscriber connected between
inductor 310 - second switch element 305
A direct current is supplied in the path: - second terminal 304 - calling subscriber telephone - first terminal 300 - first switch element 301 - first inductor 308 - second storage battery 309.

Here, when the DC current is interrupted by the calling subscriber's dial, the DC voltage applied between the inverting input and the non-inverting input of the differential amplifier 315 is applied to the first inductor 308 and the second inductor. It varies by the voltage drop due to the DC resistance of the inductor 310.

Therefore, by monitoring this DC voltage fluctuation by the voltage comparator circuit 319, it is possible to receive dial pulses from the calling subscriber.

At this time, the frequency of the second clock generation circuit 322
f ₂ has a switched capacity low frequency filter 3.
16 is selected so that the dial pulse waveform obtained at the output of the differential amplifier 315 can be sufficiently transmitted to the voltage comparator circuit 319.

Dial pulses generally include
Since 10pps or 200pps is used, the frequency _f2 of the second clock generation circuit 322 is such that the cutoff frequency of the switched capacitance low frequency filter is
It is usually selected to be 30Hz or higher.

As described above, the subscriber monitoring circuit according to the present invention focuses on the fact that the cut-off frequency of the switched-capacity low-band transmitter can be easily controlled by the clock frequency, and conventionally, the subscriber monitoring circuit and the dial pulse receiving circuit can be used in common with each other. Since it is difficult to do this, the subscriber monitoring circuits that had been individually provided are unified into one, thereby simplifying the hardware configuration.

Furthermore, according to the subscriber monitoring circuit of the present invention, there is an advantage that the exchange processing program can be simplified because the central processing circuit scans only one location.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional subscriber monitoring circuit, FIG. 2 is a diagram showing an example of a switched-capacity low-band filter used in the present invention, and FIG. 3 is a diagram showing an example of an embodiment of the present invention. It is a figure which shows an example. In addition, in the figure, 101, 106, 108,
120 and 123 are relay contacts, 102, 10
4, 111 and 113 are relay windings, 103 and 303 are bell signal sources, 201, 301, 30
5 and 320 are switch elements, 204 is an operational amplifier, 308 and 310 are inductors, 315
316 is a switched capacitor low frequency amplifier, 319 is a voltage comparison circuit, 317 is a reference voltage generation circuit, and 321 and 322 are clock generation circuits.

Claims (1)

[Claims] 1. A circuit that detects the voltage or current between the A line and B line of the communication line, a switched-capacity low-frequency wave generator whose input is connected to the output of the detection circuit, and the output of the switched-capacity low-frequency wave generator. and a voltage comparator circuit with a predetermined threshold voltage, the input of which is connected to the input of the central processing circuit, and the output of which is connected to the input of the central processing circuit. A subscriber monitoring circuit further comprising: a switch element for selectively connecting any one of the plurality of clock generation circuits to a clock input of the switched capacitance low frequency device.