JPS59115652A - Detecting system of disconnection for subscriber - Google Patents

Abstract

PURPOSE:To obtain an inexpensive wire disconnection system by flowing a minute current being a degree not detected by a conventional telephone exchange without interrupting the current at the end of call and providing a means monitoring this minute current. CONSTITUTION:A resistor Rs=40kOMEGA is connected in parallel with a subscriber (telephone set or the like) TEL in Figure and a current as small as 1mA is flowed thereto at all times. A contact C is a contact of a telephone exchange and closed normally. A relay L is a call detecting relay of the telephone exchange, restored normally and operated at the closing of a subscriber loop. Resistors RF1, RF2 and capacitors CF1, CF2 of a noise absorbing circuit FIL constitute a low pass filter, which absorbs a noise voltage such as AC induction induced in a subscriber line and gives only the change in a DC potential to an open wire detector DET through a diode DF. If a subscriber wire is opened, the DC potential of said subscriber line is dropped to a power supply voltage -48V. When any subscriber line potential in a subscriber group is lower than a reference potential, a current flows to a resistor RD1 through the diode DF and its terminal potential is made lower than the reference potential. Since the resistance of the L relay is 1kOMEGA, the change in the subscriber line potential depending on the presence of the Rs=40kOMEGA is nearly 1V. The result of detection is given to a controller CONT.

Description

[Detailed description of the invention] Concerning how to identify adults.

If an emergency communication device, security device, etc. is installed in the home of a single person, it will not be effective if the subscriber line is disconnected due to negligence or failure when an emergency call is made. Therefore, υ disconnection monitoring calls are always received from the central office side, and the telephone capacity between the communication lines is measured to determine whether it is normal or not. Since it takes more than an hour to test all subscribers (10,000 terminals), it is impossible in terms of test time to shorten the periodic test interval to meet the above objective. (because the number of incoming calls would be extremely large).

As a countermeasure to this problem, a device that constantly monitors subscriber lines is required. As a disconnection test method, the conventional method of measuring the capacity of a telephone between communication lines is used, but it is an object of the present invention to provide a disconnection monitoring method.

A common way to monitor disconnections is to constantly apply current and detect current interruptions using relays, etc. However, in the case of telephone lines, if current flows, a call cannot be made; , it is not possible to detect a disconnection based only on the presence or absence of current.

Therefore, in the present invention, a means is provided to cut off the current at the end of the call, to flow a minute current that cannot be detected by conventional telephone exchanges, and to monitor the minute current.The minute current is 1 mA.
Considering the extent, this value is equivalent to the leakage current due to the insulation resistance of 40 Ω between the subscriber lines, and the conventional telephone exchange determines that the current is interrupted, and does not interfere with its operation in any way. . On the other hand, it is difficult to find a means to detect this minute current.

That is, a current of 1 mA has a current of 1 mA.
A means is provided to simultaneously monitor minute currents (which are small compared to 10 mA of AC induced noise and are called lightning strikes), and if a disconnection of any subscriber in the subscriber group is detected,
A method of sequentially testing subscribers within a subscriber group using a conventional disconnection testing device to identify disconnected subscribers is adopted. If about 100 subscribers are selected as the subscriber group, a disconnected subscriber can be identified in a few minutes as shown in the block diagram of the formula. In the figure, 1 to m indicate subscribers who constantly monitor disconnections, FILI to m are noise absorption circuits installed in subscriber groups, DET1 to n are disconnection detection devices installed for each subscriber group, and ALT E is a disconnection detection device installed for each subscriber group. This is a conventional subscriber line testing device. C0NT is a control device that controls the whole, and receives disconnection detection indications from a plurality of disconnection detection devices DET1 to n, and sequentially sends the subscriber numbers in the subscriber group to the subscriber line testing device ALTE. . Subscriber line test equipment AL
The TE tests the subscriber line in question in a known manner and sends the results back to the control device C0NT. When the disconnected subscriber is found, the control device C0NT (not shown below)
The disconnected subscriber information is sent to a pre-specified location using a general telephone line or a dedicated line.

FIG. 2 shows an embodiment of the apparatus shown in FIG. In the figure, a resistor R5 = 40KΩ is connected in parallel with the subscriber (telephone, etc.) terminal, and a current of about 1mA is constantly flowing. Contact point C is
This is a contact point in a telephone exchange and is always closed. Relay L
is a call detection relay of the telephone exchange, and normally operates to close the subscriber loop after recovery. Noise absorption circuit FLL
The resistors RF1 and RF2 and the capacitors CF1 and CF2 constitute a low-pass filter, which absorbs the noise voltage before the AC induction induced into the subscriber line, and passes only the change in DC potential through the diode DF to the disconnection detection device. This is to be communicated to DbT. The resistors RD2 and RD5 of the disconnection detection device DET are circuits that divide the power supply voltage to create a reference potential for comparison with the line voltage.

The voltage division ratio is approximately resistance Ⅰ = 4oKΩ and L relay resistance I
It is a ratio of KΩ.

If all subscriber terminals in a subscriber group are connected with a resistance of 40KΩ or less, the DC potential of each subscriber line is equal to or higher than the above-mentioned reference potential (with a negative potential , its absolute value is small), so the terminal potential of resistor 1 (, Dl is higher than the reference potential).

On the other hand, when the subscriber is disconnected, the DC potential of the subscriber line drops to the power supply voltage -48V. When the potential of any subscriber line in the subscriber group becomes lower than the reference potential, a current flows through the diode I) to the resistor 11 and Dl, and the terminal potential becomes lower than the reference potential. Since the LIJ Schiller resistance is 1Ω, the change in the subscriber line potential depending on the presence or absence of the resistor (=40KΩ) is approximately 1Ω. The voltage comparator CMP detects this 1V voltage change and sends the detection result to the control device C0N.
Send to T.

The control device C0NT is composed of a general-purpose microprocessor μP, and receives the detection result of the disconnection detection device DET through an input interface circuit IN11'A.

According to the present invention, it is possible to economically and immediately detect a subscriber disconnection, thereby increasing the reliability of the emergency call system. This greatly contributes to improving the level of performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a disconnection detection system according to an embodiment of the present invention, and FIG. 2 is an implementation circuit diagram of the apparatus shown in FIG. I~m...Subscribers (telephones, etc.) FIL+~m...Noise absorption circuits DET1~n...Disconnection detection device C0NT...Control device ALTE...Subscriber line testing device EX...Telephone exchange C ... Exchange contact L ... Call detection relay R5 ... Constantly energized resistance Rk'1.2 ... Noise absorption resistance CFL, 2 ... Noise absorption capacitor DF ・
...Diode RDl ...Resistance for disconnection detection RD2.3 ...Resistance for reference voltage CMP ...Voltage comparator μP ...Microprocessor INFA ...Input interface circuit INFB
...Output interface circuit attorney Susuki 1
)P Good luck. O 1 Figure O 2 ■

Claims (1)

[Claims] 1. A disconnection detection device is provided for each subscriber group, and when the device detects a disconnection for any subscriber in the subscriber group, the disconnection identification device detects all subscribers in the subscriber group registered in advance. A subscriber disconnection detection method is characterized in that a disconnection test is performed by sequentially receiving calls from subscribers to identify disconnected subscribers.