JP2858565B2 - Fault detection method for two-wire subscriber line and fault detection circuit using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-wire subscriber line fault detection method, which is a telecommunication line facility for connecting terminal equipment such as telephone terminals installed in subscriber premises and switching equipment. The present invention relates to a failure detection circuit to which is applied.

[0002]

2. Description of the Related Art Conventionally, when a line fault is detected in a two-wire subscriber line accommodated in a two-wire subscriber circuit of a telecommunication line facility, current measurement, potential difference measurement, etc., between the two-wire subscriber lines are performed. And a line fault is detected based on a current measurement value and a voltage value obtained by such a detection circuit.

[0003] Incidentally, as a known technique relating to the detection of such a two-wire subscriber line and its line failure, for example, a ground fault contact detection and earth detection circuit of a subscriber circuit disclosed in Japanese Patent Application Laid-Open No. Hei 4-10845 is disclosed. There is a two-wire subscriber circuit disclosed in Japanese Unexamined Patent Publication No. Hei 7-23110.

[0004]

In the case of detecting a line failure in the above-described two-wire subscriber line, a detection circuit for performing current measurement, potential difference measurement, etc. between the two-wire subscriber lines is provided. There is a problem that the circuit configuration of the two-wire subscriber circuit is complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and the technical problem is that the two-wire subscriber circuit is reduced in size and simplified with a small-scale circuit configuration to accurately and accurately. It is an object of the present invention to provide a two-wire subscriber line fault detection method capable of detecting a line fault and a fault detection circuit to which the method is applied.

[0006]

According to the present invention, there is provided a fault detecting method for a two-wire subscriber line, which is a telecommunication line facility for connecting a terminal facility installed in a subscriber's house to a switching facility. A fault for a two-wire subscriber line for detecting a line fault by detecting a loop open state and a loop closed state between the two-wire subscriber lines and monitoring the state of the generated SCN signal for equipment state monitoring. A detection method is obtained.

Further, according to the present invention, in the two-wire subscriber line fault detection method, the line fault is detected by determining whether or not the change of the SCN signal has occurred a predetermined number of times within a predetermined time. Thus, a failure detection method for a two-wire subscriber line based on the above is obtained.

On the other hand, according to the present invention, there is provided a two-wire subscriber circuit accommodating a two-wire subscriber line which is a telecommunication line facility for connecting a terminal facility and a switching facility installed in a subscriber's house; A loop detection circuit that detects a loop open state and a loop closed state between two-wire subscriber lines to monitor the state of the terminal equipment and generates an SCN signal, and an on-hook state to monitor the state of the terminal equipment based on the state of the SCN signal Or
In a fault detection circuit for a two-wire subscriber line, which is provided with an SCN signal monitoring circuit for monitoring any of an off-hook state, the SCN signal monitoring circuit detects a line failure by monitoring the state of the SCN signal. A two-wire subscriber line fault detection circuit is obtained.

According to the present invention, in the two-wire subscriber line fault detecting circuit, the SCN signal monitoring circuit determines whether or not the change of the SCN signal exceeds a predetermined number of times within a predetermined time when detecting a line fault. Is obtained on the basis of the result of the determination.

[0010]

According to the present invention, the basic function of an existing SCN signal monitoring circuit, that is, the state of an SCN signal generated by detecting a loop open state and a loop closed state between two-wire subscriber lines, is stored in a subscriber's home. In addition to the function of monitoring the on-hook state or the off-hook state of the installed terminal equipment, line failure detection is performed by monitoring the state of the SCN signal. The line failure detection here is performed based on the result of determining whether or not the change of the SCN signal is a predetermined number of times or more within a predetermined time. In addition to determining the state and the off-hook state, a state in which any of these states cannot be determined is newly positioned as a line failure state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First, the outline of the fault detecting method for a two-wire subscriber line according to the present invention will be briefly described. This failure detection method is for a two-wire subscriber line, which is a telecommunication line facility for connecting a terminal facility such as a telephone terminal installed in a subscriber's house to a switching facility, and is used for monitoring the state of the terminal facility. A line failure is detected by monitoring the state of an SCN signal generated by detecting a loop open state and a loop closed state between two-wire subscriber lines. However, line failure detection is performed based on the result of determining whether or not the change in the SCN signal has occurred a predetermined number of times within a predetermined time.

FIG. 1 shows a main configuration of a two-wire subscriber line fault detecting circuit according to an embodiment to which the fault detecting method is applied.

This fault detection circuit is a two-wire subscriber circuit which is housed in a two-wire subscriber circuit and which is a telecommunication line facility for connecting terminal equipment such as a telephone terminal installed in the subscriber's home to a switching facility. A power supply circuit 1 for supplying power to the A and B lines of the subscriber line, and a loop detection circuit 2 for detecting a loop current between the A and B lines of the two-wire subscriber line and converting and generating an SCN signal. SC that determines the state of the terminal equipment based on the SCN signal, that is, the on-hook state, the off-hook state, and the state that does not belong to any of them, as the line failure state
And an N signal monitoring circuit 3.

In this fault detection circuit, power is supplied to the A and B lines of the two-wire subscriber line by the power supply circuit 1 having a ground line and applying a negative voltage of -48 V. In the loop detection circuit 2, the current in the diode connected to the line B is supplied to the base of a switching element having one end connected to the + 5V line and the other end grounded. , B loop current is detected and S
Conversion and generation of the CN signal S1. On the basis of the SCN signal S1 from the loop detection circuit 2, the SCN signal monitoring circuit 3 sets the terminal equipment state as an on-hook state, an off-hook state, or a state that does not belong to any of these states as a two-wire subscriber line failure state. A state signal S2 indicating the result of the determination is output. That is, the SCN signal monitoring circuit 3 identifies three states: an on-hook state, an off-hook state, and a line failure state. At this time, SCN signal monitoring circuit 3 is performed based on a result of changes in the SCN signal S1 when the line fault detection is determined whether more than a predetermined number N within a predetermined time T _X.

FIG. 2 shows an example of the SCN signal monitoring circuit 3 for explaining the function of determining a line failure state.
It is a waveform diagram of CN signal S1.

[0017] Here, SCN signal monitoring circuit 3 is normal transmission operation, a predetermined Examples recognizing a change state of the SCN signal S1 not occur in the incoming operation, and the predetermined time T _X with respect SCN signal S1 for example within 30 seconds The number of ON states exceeding the threshold value (or the OFF state where the state is avoided) may be a predetermined number N of eight or more times (here, eight times).
An example is shown in which repeated occurrences occur.

In the case of this fault detection circuit, a detection circuit for performing current measurement or potential difference measurement between two-wire subscriber lines for the purpose of detecting a line fault is not provided as in the prior art. In addition to reducing the size of the user circuit, the circuit configuration becomes small, and the line failure can be detected simply and accurately.

[0019]

As described above, according to the method for detecting a fault in a two-wire subscriber line according to the present invention, a two-wire subscriber is provided for the purpose of detecting a fault in a two-wire subscriber line as in the prior art. Line fault detection is performed by monitoring the state of the SCN signal without requiring a detection circuit for detecting current measurement, potential difference measurement, and the like between the user lines (especially SC
The line failure detection is determined based on the result of determining whether or not the change in the N signal is greater than or equal to a predetermined number within a predetermined time.) In addition to the configuration, it is possible to easily and accurately detect a line failure. Also, in the fault detection circuit for a two-wire subscriber line to which this fault detection method is applied, the existing SC
Since the N signal monitoring circuit newly has a line failure detection function by monitoring the state of the SCN signal, the miniaturization of the two-wire subscriber circuit and the miniaturization of the circuit configuration can be effectively achieved.

[Brief description of the drawings]

FIG. 1 shows a main configuration of a two-wire subscriber line fault detection circuit according to an embodiment to which a two-wire subscriber line fault detection method of the present invention is applied.

FIG. 2 is a waveform diagram of an SCN signal exemplified for explaining a function of determining a line failure state in an SCN signal monitoring circuit provided in the two-wire subscriber line failure detection circuit shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply circuit 2 Loop detection circuit 3 SCN signal monitoring circuit S1 SCN signal S2 Status signal

Claims (4)

(57) [Claims] 1. A fault detecting method for a two-wire subscriber line, which is a telecommunications line facility for connecting a terminal facility and a switching facility installed in a subscriber's house, wherein said two wires are used for monitoring the status of said terminal facility. A fault detecting method for a two-wire subscriber line, comprising detecting a line fault by monitoring a state of an SCN signal generated by detecting a loop open state and a loop closed state between the subscriber lines. 2. The failure detection method for a two-wire subscriber line according to claim 1, wherein the detection of the failure in the line is based on a result of determining whether or not the change of the SCN signal is a predetermined number or more within a predetermined time. A failure detection method for a two-wire subscriber line, wherein the method is performed based on the following. 3. A two-wire subscriber circuit accommodating a two-wire subscriber line, which is a telecommunication line facility for connecting a terminal facility and a switching facility installed in a subscriber's house, and monitoring the state of the terminal facility. A loop detection circuit that detects a loop open state and a loop closed state between the two-wire subscriber lines to generate an SCN signal, and an on-hook state as a state monitor of the terminal equipment based on the state of the SCN signal. Or an SCN signal monitoring circuit for monitoring either the off-hook state or the off-hook state, wherein the SCN signal monitoring circuit monitors the state of the SCN signal by monitoring the state of the SCN signal. A fault detection circuit for a two-wire subscriber line, which performs fault detection. 4. The failure detection circuit for a two-wire subscriber line according to claim 3, wherein the SCN signal monitoring circuit determines whether or not the change of the SCN signal is greater than or equal to a predetermined number within a predetermined time when detecting the line failure. A failure detection circuit for a two-wire subscriber line, wherein the failure detection is performed based on the result of the determination.