JPS58202654A - Connection test system for subscriber line - Google Patents

Abstract

PURPOSE:To perform a connection test of each subscriber line, by connecting a test circuit containing an oscillating circuit, a filter and a monostable multivibrator with 1:1 correspondence or in common to a subscriber line circuit. CONSTITUTION:A connection test relay RLY is provided between a subscriber line TEL LINE and a subscriber line circuit LINE to perform switching between the normal and connection test modes. In a connection test mode, an oscillator OSC is connected to the line A of the line TEL LINE to transmit an AC signal of a fixed frequency. This AC signal is transmitted through a filter FIL which extracts only the component of the frequency transmitted from the line A and then supplied to a monostable multivibtator MM which has a slope several times as much as said frequency. If the output of the MM has a high level of potential, a normal connection is detected. While a non-connection or a fault such as a cut of the TEL LINE is detected if the output of the MM has a low level of potential.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a subscriber line connection test method for an automatic telephone exchange.

Conventionally, subscriber line connection testing methods for automatic telephone exchanges have involved providing test-specific detection circuits in the call trunk circuits, or activating the detection circuits by switching switches, to check the connection between the call trunk circuits and the subscriber line circuits. By connecting the lines with a telephone switch, a connection test of the subscriber line was performed using the telephone trunk circuit.

However, with this test method, it was not possible to test the subscriber line itself because the test included failures in the subscriber line circuit and call switch. Furthermore, no inexpensive method for performing such connection tests on subscriber line circuits has been proposed, and has not yet been realized.

An object of the present invention is to enable testing of the subscriber line itself in a subscriber line connection test method for an automatic telephone exchange by simply adding an inexpensive circuit to the subscriber line circuit one-to-one or in common. The objective is to provide a subscriber line connection test method.

A feature of the present invention that achieves the above object is that in a subscriber line connection test method for performing a connection test of a subscriber line of an automatic telephone exchange, an oscillator, a frequency filter, and an input terminal are connected to an output terminal of the frequency filter. The invention comprises a monostable multivibrator and means for connecting the output terminal of the oscillator and the input terminal of the frequency filter to a first conductor and a second conductor of the subscriber line, respectively.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the main part of an embodiment of the present invention, showing the positioning and contents of the subscriber line circuit and the subscriber line connection detection circuit. This figure shows another embodiment of the present invention when it is applied to a public railway line.

As shown in Fig. 1, the operation of this embodiment is as follows: By interposing a connection test relay between the subscriber line and the subscriber line circuit, it is possible to distinguish between normal operation and connection test. During a connection test, an oscillator is connected to line A of the subscriber line, and an alternating current signal of a constant frequency is sent out.

・When the subscriber's line is connected normally, the AC signal is sent back to the B line through the subscriber's telephone, but if there is a problem with the subscriber's line, it is not sent back.

In order to utilize this fact and detect the AC signal sent from the A line on the B line, first pass the AC signal through a frequency filter that extracts only the river wave number component sent from the A line.
input to a monostable multivibrator with a slope several times that frequency. If the output of the monostable multivibrator is in the lH1 state, it is detected as a normal connection.
If it is in the LI state, it is detected as a failure such as disconnection or disconnection of the subscriber line. This result is a review result (
SCAN).

Figure 2 shows a matrix switch used as a call switch in place of the connection test relay in Figure 1, and a capacitor to prevent it from affecting the subscriber line circuit during normal operation. Therefore, it becomes possible to selectively connect a plurality of subscriber lines in common to one subscriber line connection detection circuit described above. As a result, even if, for example, a fault occurs in any one of the plurality of subscriber lines and the scan result of the subscriber line connection detection circuit becomes 1L, the selection of the IJ switch will not be possible. By combining the status and the scan results, it becomes possible to immediately determine which subscriber telephone the faulty subscriber line corresponds to. Since this method directly monitors the subscriber line without any relation to other subscriber line circuits or trunk circuits, in the event of a failure, the failure is not related to the automatic telephone exchange itself, and therefore the subscriber line is directly monitored. It is determined that a fault has occurred in either the subscriber telephone or the subscriber line.

As explained above, the present invention enables the connection test of a plurality of subscriber lines by adding inexpensive circuits to the subscriber line circuits one-to-one or in common. Connection tests can be performed for each line.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main part of an embodiment of the present invention, and FIG. 2 is a block diagram of the main part of another embodiment of the invention. Placement...Subscriber telephone, Placement LINE-°-Subscriber line, A...A line, B...B line,
LINE...Subscriber line circuit, R, LY...
... Connection test relay, DET ... Subscriber line connection detection circuit, MM ... Monostable multivibrator, AND ... AND gate, O20.
...Oscillator, FIL ...Frequency filter, SW ...Matrix switch, GATE...
...Gate signal coming from the central control unit, 8C
AN...Scanning result. 61

Claims (1)

[Claims] In a subscriber line connection test method for testing the connection of subscriber lines of an automatic telephone exchange, an oscillator, a frequency filter, a monostable multivibrator whose input terminal is connected to the output terminal of the frequency filter, an output terminal of the oscillator, and the monostable multivibrator whose input terminal is connected to the output terminal of the frequency filter; and means for connecting input terminals of a frequency filter to a first conductor and a second conductor of the subscriber line, respectively.