JPS59161196A - Subscriber's terminal supervising system - Google Patents

Abstract

PURPOSE:To use only one supervising circuit and a loop forming resistance with respect to plural terminal equipment by converting the digital information from the control device of a switchboard to a voltage value, and generating a desired detecting threshold. CONSTITUTION:A titled system is provided with a circuit 1 for supplying a DC current to a subscriber terminal equipment 11 connected in parallel to a telephone set 15, a supervising circuit 5 for discriminating the state of the telephone set 15 and the equipment 11 by the variation quantity of the DC current, a communication circuit 3 to the telephone set 15 and the equipment 11, and a D/A converter 16 for generating a detecting threshold of the supervising circuit 5 basing on the terminal classifying digital information sent out of the control device of a switchboard. In this state, in accordance with the instruction of the control device, a detecting threshold corresponding to a classification of a terminal is generated by the digital information and the converter 16, and by this detecting threshold, a state of the telephone set 15 and the equipment 11 is discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention 1- The present invention relates to a system for monitoring subscriber circuits, particularly for monitoring systems such as telemeters, facsimiles, and data terminals that start up without ringing a bell. The present invention relates to a subscriber terminal monitoring system that allows a non-ringing call terminal device to be connected in parallel to a telephone set.

(2) Conventional technology and problems Silent calling requires high voltage alternating current (16Hz, 75Vrms)
) A method different from the method used for receiving calls to a telephone, such as ringing the bell due to signal 1, is used.

A silent ring is executed by receiving an in-voice band signal (referred to as an activation signal) in an off-hook state (a state in which the DC current loop is not closed to the terminal device).

A subscriber circuit made of conventional electromagnetic components can send out this activation signal even under an on-hook condition with no bias of a direct current of 0 mA.

However, subscriber circuits made of semiconductors such as LSIs are required to operate under such non-bias conditions.

The most efficient way to implement this technique is to form a loop that allows DC current to flow through the subscriber's circuit even when the terminal device is on-hook.

This can be easily achieved with a single loop-forming resistor and a switch, as shown in FIG.

A conventional monitoring system for a silent call terminal device 1ζ of an electronic subscriber circuit will be explained with reference to FIG.

1 is a power supply circuit that performs DC supply and 2-wire 4-wire conversion;
2 is a 48V power supply for DC supply, 3 is a PC-M fist C0D
IC, 4 is a PCM highway, 5 is a monitoring circuit for direct current sent from the power supply circuit, 6 is a terminal that outputs the monitoring result of the monitoring circuit, 7 is a resistor used to form a loop in the circuit,
8 is a switch for connecting (inserting) this resistor; 9.
10 is a direct current resistance of the subscriber line, 11 is an interface section of a FAX and data terminal of the silent call terminal device,
Reference numerals 12 and 13 indicate a capacitor for DC cut, 14 a transformer for connecting an activation signal receiver, and 15 a telephone set.

3- When it is recognized from the information from the control device that the incoming call is not from the telephone 15 but from the silent calling terminal, first close the switch 8 and insert Rp7. The value of Rp is set so that the power supply circuit 1 can operate.

Next, the activation signal input from PCM Highway 4 is
The signal is sent to the interface unit 11 of the FAX and data terminal via the M-C0DEC 3, the power supply circuit 1, and the DC resistors 9 and 10. FAX, data terminal interface section 11
has a capacitance of 12°13 for DC cutting, which cuts the DC current and passes only the start signal.

This activation signal is further inputted to a receiver (not shown) via the transformer 14 to complete activation. Resistance 7 at this time
A monitoring circuit 5 monitors the direct current flowing through the.

However, in this method, the DC current sent out from the power supply circuit 1 increases by the DC current flowing into the loop forming resistor, and it is necessary to change the detection threshold value for identifying the state of the terminal device.

Alternatively, it is necessary to prepare multiple monitoring circuits. seek

Furthermore, the detection threshold value can be changed at
It is necessary to carry out the process according to e, and a plurality of loop forming resistors must be prepared. This is because the current value supplied to the terminal during a silent call differs depending on the terminal, from several mA for telemeters to OmA for data.

In other words, in order to connect a telephone set and a silent call terminal device to the same electronic subscriber circuit, it is necessary to prepare multiple detection threshold generation circuits, multiple monitoring circuits, and furthermore, multiple loop forming resistors. .

(3) Purpose of the Invention The present invention solves the above-mentioned drawbacks of the conventional technology, and the present invention provides information on whether the terminal device to which the call is being received is a telephone only or a silent ring terminal device. By recognizing digital information and converting this information into a voltage value by means of a digital-to-analog converter and creating the desired detection threshold, it is possible to monitor multiple terminals with one and the same 5-way and only one A monitoring scheme is provided that can use loop-forming resistors.

(4) Structure of the Invention According to the present invention, the object of the present invention is to provide a power feeding circuit for supplying direct current to a telephone and a subscriber terminal device connected in parallel with the telephone; In a subscriber circuit equipped with a monitoring circuit for identifying the state of a subscriber terminal device, and a circuit for communicating with the telephone and the subscriber terminal device, digital information indicating the type of terminal is sent from a control device of an exchange. is equipped with a digital-to-analog converter for creating a detection threshold for the monitoring circuit based on the digital information and the digital-to-analog converter according to the instruction of the control device. This is achieved by providing a subscriber terminal monitoring method characterized in that the states of the telephone and the subscriber terminal are categorized based on the detection threshold.

(5) Examples of the invention 6- Hereinafter, embodiments of the present invention will be described in detail with reference to drawing ζ.

FIG. 2 is a circuit diagram showing an example of the monitoring system according to the present invention. In FIG. 2, 51 is a current-voltage converter that detects direct current and converts it into voltage, and 52 is a comparator.
51 and 52 form the monitoring circuit 5. 16 is a digital-to-analog converter, which creates a plurality of detected values for identifying the status of the terminal device.

As explained in FIG. 1, when it is recognized from the information from the control device that the incoming call is not from the telephone 15 but from the silent ring terminal, first the switch 8 is closed and the DC resistor R
Insert p. The value of Rp is set so that the power supply circuit l can operate.

Next, the activation signal input from PCM Highway 4 is
M@C0DF: Sent to the silent calling terminal device interface section 11 via C3, the feeder circuit 1, and the DC resistance 9.10 of the subscriber line. The interface unit 11 of the FAX and data terminal of the silent call terminal device cuts direct current with capacitors 12 and 13 and passes only the activation signal. This starting signal 7- is inputted to a receiver (not shown) via a secondary transformer 14, and the starting is completed.

At this time, the DC current of the power supply circuit 1 flowing through the resistor 7 is controlled by the monitoring circuit 5, which is composed of a current-voltage converter 51 and a comparator 52, and is converted into a digital-to-analog converter so that an output of 10'' is sent from 6. The detection threshold value created by the device 16 and determined from the detection threshold value 17 is determined.

When this activation is completed, the interface section 11 operates a DC closing circuit (not shown) to bring the telephone 15 into a state equivalent to the off-phi hook state. 11 has transitioned to off-hook, the monitoring circuit 5 composed of 51 and 52 outputs "
It is recognized by sending 1″ from 6. Here,
Output 10'' of the monitoring circuit 5 indicates that 11 and 15 are on hook, and output ``1'' indicates that φ hook is off.

Next, an example of the circuit configuration of the digital-to-analog converter 16 will be explained with reference to FIG.

19 is a register that receives and stores various digital information sent from a control device (not shown);
is an operational amplifier, which together with resistors 21 and 22°8-23 constitutes a digital-to-analog converter.

24, 25, 26 are logic gates, 18 is a second
Terminal 2 that outputs the detection threshold output, connected to 17 in the figure.
8 is a terminal connected to the terminal 6 which outputs the detection output shown in FIG. 2, and 27 is a terminal which outputs a signal for controlling the switch 5 (8) shown in FIG.

19 SDl and sD1+t are digital information indicating the type of subscriber terminal device to which the call is received, and SD, = "1" +
SD+++ = “O” is an incoming call to the phone, SD.

=SD+++=“l” is the silent calling terminal (in this example, F
AX, data terminal).

The output voltage (Vo + ) of 18 when receiving a call to the telephone is:
Vo+=(RF/R1)XV+ −−−−−−−(
1), and the output voltage (V, a) of 18 at the time of incoming call to the silent calling terminal is 0'', so Vow
= (RF/R1) XV+ + (RF/R1+1
) ・Vt ++・・・・・・・・・・・・・(2) Both vl l and Vll1 are outputs of 19, and in order to represent them with the logic level Ve, +1), (21
The formula is vo+=(RF/H,)xve −−・−=・=
...--(a)9- VO! =RF (”/Rt + ”/R1+I) X
Ve-=(4).

When the telephone is connected, the switch 8 in FIG. 2 is open, and the direct current ILI is ILI :E/(RL+RT+
R11) ・・・・・・・・・・・・
...(5). RL indicates a resistance value of 9.10, RT indicates an internal resistance value of the telephone 15, R111I indicates an internal resistance value of the power supply circuit 1, and E indicates a voltage value of 2.

Equation (5) is RL=1500Ω, RT=220Ω+R+a
r"440+15J, it shows the minimum value when E=43V (7) and becomes about 20mA. The output of the current-voltage converter 51 in FIG. 2 when IL+=20mA is assumed to be vl1. 21 and 23 in FIG. is determined so that the output vol from 18 is a value somewhat lower than Vll.The difference between V.1 and Vll at this time is the detection margin, which is used to ensure the detection operation of the monitoring circuit. be.

Next, when the FAX/data terminal device 11 is connected, the gate 25 outputs 1", and since 28 is @om, the output of the gate 26 becomes 1". This 1" operates the switch 8 in Figure 2 through 27, and a direct current flows through the resistor 7. The value Rp of 7 operates the switch 8 in Figure 2 so that the decide.

Now, assuming that Rp is 2 and Ω, the current ■8 flowing through the resistor 7 at this time is Is = E/(Rp + R + mt) ...
...(6).

This value is K-48V, RIs 1 == 440Ω
The standard value is approximately 20 mA.

In this state, when the FAX/data terminal 11 connects (responses) a DC closing circuit equivalent to the telephone 15, the DC current 11
g is iL proverb =”/(Rp/(Rz+Rt)+R+□t]...
...(7). The minimum value of IL2 is approximately 30mA. Current-voltage converter 5 in Figure 2 when IL2 = 30mA
Let the output from 1 be VIH. Rl+1 is the output (Vat) from 18 vs! Set it to a slightly lower value.

As a result, when the FAX/data terminal 11 is on-hook, 0'' is output as shown in FIG. 2, and when the FAX/data terminal 11 is off-hook, 1'' is output.

Further, when 6 in FIG. 2 becomes 1'', this is transmitted to 28, and the switch 8 in FIG. 2 is restored in order to shift the output of gate 26 to O''. At the same time, the output of gate 24 is also
o' and 18 output is also vo.

will be restored.

The digital information (
SD++SD+'++), the detection threshold can be easily and flexibly changed. Therefore, this is a delay circuit prepared for monitoring purposes. After the control of the switch S by the gate 26 is completed based on the detection output from the comparator 52 shown in FIG. 2, stabilization is achieved by inputting the aforementioned detection output to the gate 24.

Therefore, the delay time of the delay circuit 29 is set in consideration of the operating time of the switch S and the stabilization time of the input potential of the power supply circuit 1.

2 and 3, the present invention has been explained in the case where the silent calling terminal is a fax or data terminal that requires a DC current of 0 mA when receiving a call, but it is applicable to a telemeter that requires several mA of DC current when receiving a call. , and other subscriber terminal devices with different detection thresholds can be dealt with in a similar manner.

(6) Effects of the Invention As explained in detail above, the subscriber terminal monitoring system of the present invention creates various detection thresholds by setting the relationship between the resistance value of the converter and the sign of digital information. In addition, fine threshold settings can be easily handled by adjusting the resistance value, so multiple subscriber terminal devices with different detection values can be connected to the same subscriber circuit without changing the monitoring circuit at all. can be accommodated. In other words, it has a great effect of flexibly and easily expanding the range to which subscriber circuits can be accommodated.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional subscriber terminal monitoring system when connecting a silent calling terminal to an electronic subscriber circuit, FIG. 2 is a block diagram of a subscriber terminal monitoring system according to the present invention, and FIG. 3 is a block diagram of a subscriber terminal monitoring system according to the present invention. Second
FIG. 2 is a specific configuration diagram of the digital/13-analog converter shown in the figure. In the drawing, 1 is a power supply circuit, 2 is a power supply, and 3 is a PCMφ
C0DFC, 4 is PCM highway, 5 is monitoring circuit, 7
is a resistance, 8 is a switch, 9.10 is a DC resistance, 11 is F
AX, data terminal interface section; 15 is a telephone;
16 is a digital-to-analog converter, 51 is a current-voltage converter, 52 is a comparator, 19 is a register, and 20 is an operational amplifier. 14-

Claims (1)

[Claims] A power supply circuit that supplies direct current to a telephone and a subscriber terminal connected in parallel with the telephone; a monitoring circuit that identifies the state of the telephone and subscriber terminal according to the amount of change in the direct current; In a subscriber circuit equipped with a circuit for communicating with a subscriber terminal device, a digital circuit for creating a detection threshold of the monitoring circuit based on digital information indicating the type of terminal sent from a control device of the exchange. It is equipped with an analog converter, and according to instructions from the control device, a detection threshold according to the type of terminal is created using the digital information and the digital-to-analog converter, and the detection threshold is used to send an order to the telephone and the subscriber terminal. A subscriber terminal monitoring method characterized by identifying the state.