KR950009872B1 - Line checking system for telephone - Google Patents

Abstract

The subscriber's system detects the short or the cut-off state of subscriber's line and generates an alarm signal without the help of a station. The system includes a rectifier for rectifying a signal transmitted from a station, a cut-off state detector for discriminating cut-off state by inspecting the rectified voltage level, and an alarm signal generator for generating alarm signals according to output signal of the cut-off state detector.

Description

Telephone line short circuit detection system

1 is a schematic diagram of a telephone line short circuit detection system according to the present invention.

2 is a detailed configuration diagram of each part of FIG.

* Explanation of symbols for main parts of the drawings

100: rectifier 101: telephone line detection unit

102: voltage comparison unit 103: alarm device

The present invention relates to the detection of a short circuit of a telephone cable coming from a telephone station. In particular, a telephone line of a subscriber is used to detect the abnormality of a telephone line by using a subscriber's telephone line without using a test line for a disconnection state of the telephone cable due to other disasters. The present invention relates to a telephone line short circuit detection system.

In general, the detection of telephone cable is selected from several lines of telephone cable laid from the telephone company to the subscriber area and used as a test line, and the short circuit condition of the telephone line due to local flood or other disaster of the subscriber through the test line. Is detected and transmitted to the central control officer.

In the conventional telephone line short-circuit detection technology, only the telephone line detects the subscriber's telephone line short-circuit through the test line and transmits it to the central control officer. However, since the subscriber side does not have a device for detecting the short circuit of the telephone line, There was no choice but to wait for the service, and in the absence of the service of the telephone company, it was difficult for the user of the subscriber to directly detect a short-circuit of the telephone line.

Therefore, an object of the present invention is to detect the disconnection of the telephone cable due to other disasters, without using a separate test line, by directly using the telephone line at the subscriber side, detecting the presence of abnormality in the telephone line to detect the telephone line short-circuit to alert the user. In providing a system.

Means for achieving the object of the present invention is a rectifying means for rectifying and outputting the voltage transmitted from the telephone station from the ring terminal and the tip terminal of the telephone line irrespective of the polarity of the telephone line, and rectified from the rectifying means Telephone line detecting means for detecting the abnormality of the short circuit state of the telephone line according to the input voltage and outputting the result, and comparing the voltage input from the telephone line detecting means with the reference voltage and alarming with the comparison voltage. It is achieved by the configuration of the voltage comparison means for driving the means, which will be described below in detail with reference to the accompanying drawings of the present invention.

FIG. 1 is a schematic diagram of a telephone line short circuit detection system of the present invention, and FIG. 2 is a detailed schematic diagram of each part of FIG. 1, and as shown therein, the voltage transmitted from the telephone station is independent of the polarity of the telephone line. A rectifying unit 100 made of a bridge diode BD1 that receives and receives rectification from the ring terminal R and the tip terminal T, and a short circuit state of the telephone line depending on whether or not the voltage rectified from the rectifying unit 100 is input. The telephone line detection unit 101 detects the abnormality of and outputs the resulting voltage, and the voltage comparison unit 102 compares the voltage input from the telephone line detection unit 101 with the reference voltage and outputs the comparison voltage. ), And an alarm device 103 that drives according to the output voltage of the voltage comparing unit 102 to audibly or visually inform the presence or absence of abnormalities in the telephone line.

As shown in FIG. 2, the telephone line detecting unit 101 is connected to both ends of the bridge diode BD1 configured in the rectifying unit 100 to step down a resistor R1 (R2), An amplifier 101a for amplifying and outputting a difference between voltages across the voltage drop resistor R2, and a resistor for feeding back the output voltage of the amplifier 101a to the inverting terminal of the amplifier 101a ( R4).

The voltage comparing unit 102 divides the voltage of the power supply terminal Vcc to generate a reference voltage Vref, and a reference generated by being divided by the resistors R5 and R6. Comparing the voltage (Vref) and the voltage amplified from the telephone line detection unit 101 and outputted, it is composed of a comparator (102a) for controlling the alarm device 103 with the resulting voltage.

Thus, the operation and effect of the present invention configured as described in detail with reference to FIGS. 1 and 3 as follows.

When the voltage transmitted from the telephone station is input through the ring terminal R and the tip terminal T of the telephone line, the bridge diode BD1 of the rectifier 100 is connected to the ring terminal R and the tip regardless of the polarity of the telephone line. The voltage input through the terminal T is rectified and input to the telephone line detector 101.

The telephone line detector 101 detects a short circuit condition of the telephone line according to whether the voltage rectified from the rectifier 100 is input and outputs the resulting voltage.

That is, before the telephone line is short-circuited, a loop is formed by the resistors R1, R2, and R3 of the telephone line detector 101, so that voltage is formed at both ends of the resistor R2.

Specifically, before the telephone line is shorted, the voltage transmitted from the telephone station is input through the tip terminal T and the ring terminal R, and the voltage is rectified through the rectifying unit 100 and then the telephone line sensing unit. Through the resistors R1 and R3 of 101, the resistor R2 is caught across the resistor R2.

The voltage across the resistor R2 is input to the inverting terminal (-) and the non-inverting terminal (+) of the amplifier 101a, respectively, amplified by the amplifier 101a, and then configured in the voltage comparator 102 ( It is input to the non-inverting terminal (+) of 102a).

The comparator 102a of the voltage comparator 102 compares the voltage amplified from the telephone line detector 101 with the reference voltage Vref of the power terminal Vcc divided by the resistors R5 and R6. Will be compared.

At this time, the voltage input before the telephone line is shorted is higher than the reference voltage Vref set by the resistors R5 and R6.

Therefore, the comparator 102a compares the voltage input from the telephone line detection unit 101 with the reference voltage Vref and outputs a high signal to disable the alarm device 103.

When the telephone line is shorted due to other disasters, the loop of the telephone line sensing unit 101 is not formed, so the voltage at both ends of the resistor R2 becomes zero volt (0V).

That is, if the telephone line is shorted, the voltage transmitted from the telephone station is cut off before passing through the tip terminal T and the ring terminal R, so that the output voltage of the rectifying unit 100 becomes 0V, and thus the telephone line detecting unit 101. The voltage across the resistor R2 is 0V.

The voltage across the resistor R2 is input to the inverting terminal (-) and the non-inverting terminal (+) of the amplifier 101a, respectively, amplified by the amplifier 101a, and then configured in the voltage comparator 102 ( It is input to the non-inverting terminal (+) of 102a).

The comparator 102a of the voltage comparator 102 compares the voltage amplified from the telephone line detector 101 with the reference voltage Vref of the power terminal Vcc divided by the resistors R5 and R6. In comparison, when the detected voltage from the telephone line detector 101 is lower than a predetermined level (ie, lower than the reference voltage Vref), a low signal is output to enable the alarm device 103 to cause an alarm. .

When the present invention is used for home automation, when an intruder breaks the telephone line and intrudes, it detects a short circuit of the telephone line and sounds an alarm through an alarm device, thereby preventing external intrusion and when using the telephone. By notifying the user of the abnormality of the telephone line or the telephone line, the user can quickly recognize the abnormality of the telephone line without the service of the telephone company.

Claims (3)

Rectifying means for receiving the voltage transmitted from the telephone line from the telephone line and rectifying the voltage regardless of the polarity of the telephone line, and detecting the short-circuit state abnormality of the telephone line according to the input of the rectified voltage from the rectifying means. Telephone line short circuit detection system comprising: a telephone line sensing means for outputting a voltage; and a voltage comparing means for comparing the voltage input from the telephone line sensing means with a reference voltage and driving the alarm means with the comparison voltage. . 2. The telephone line detection means according to claim 1, wherein the telephone line sensing means amplifies the difference between the voltages between the resistors R1, R2, and R3, which are connected in series with both ends of the rectifying means, to step down the voltage. And a resistor (R4) for feeding back the output voltage of the amplifier (101R) and the output voltage of the amplifier (101a) and inputting the half-stage electrons of the amplifier (101a). 2. The voltage comparing means according to claim 1, wherein the voltage comparing means is divided by the resistors R5 and R6 for generating a reference voltage Vref by dividing the voltage of the power supply terminal Vcc and the resistors R5 and R6. And a comparator (102a) which compares the reference voltage (Vref) with the amplified voltage output from the telephone line sensing means and controls the alarm device with the resultant voltage.