JPH01263504A - Apparatus for measuring length of subscriber's line - Google Patents

Abstract

PURPOSE:To enable the precise measurement of the length of a subscriber's line when a terminal is not in the state of service, by determining the length of the subscriber's line on the basis of a delay time of a step voltage signal reflected by the terminal through the subscriber's line. CONSTITUTION:A terminal 1 is connected to a two-wire/four-wire conversion circuit 5 through lead-in relay contacts 31 and 32 of a subscriber's interface circuit 4 of a telephone exchange by a subscriber's wire 2. A central control circuit 9 operates a relay 3 of the circuit 4 corresponding to the subscriber's wire 2 to be measured, so as to make the subscriber's line 2 connected to a step voltage signal generator 7 and a signal processing circuit 8. Under the control of the circuit 9, the generator 7 generates a voltage signal of a step function. Monitoring the voltage signal of an output element of the generator 7, the circuit 8 measures a time difference between a step voltage signal supplied to the subscriber's line and the step voltage signal reflected by the terminal 1 and inputted through the relay contact 32, computes a distance from a delay time and reports the same to the circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a subscriber line length measuring device for measuring the line length of a subscriber line connecting a terminal to a telephone exchange.

[Conventional technology]

Conventionally, there is no device that directly measures subscriber line length.
To measure the subscriber line length, the resistance is calculated from the direct current flowing through the subscriber line and converted to the subscriber line length.

[Problem to be solved by the invention]

However, the above measurements can only be performed when the terminal is in a talking state. Also, the measurement accuracy is poor.

[Means to solve the problem]

The subscriber line length measuring device of the present invention includes a first means for connecting a subscriber line connecting a terminal to a telephone exchange, and a second means for generating a step voltage signal to be supplied to the subscriber line via the first means. measuring the time difference between the step voltage signal from the second means and the step voltage signal reflected at the terminal through the first means and the subscriber line; and third means for calculating the line length of the subscriber line.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

Referring to the figure which shows one embodiment, the terminal 1 is connected by a subscriber line 2 to a 2-to-4-wire conversion circuit 5 via drop-in relay contacts 31, 32 of a subscriber interface circuit 4 of a telephone exchange. The central control circuit 9 connects the subscriber line 2 to be measured.
The lead-in relay 3 of the subscriber interface circuit 4 corresponding to the step voltage signal generator 7 is activated, and the subscriber line 2 is
and the signal processing circuit 8. One step voltage signal generator 7 and one signal processing circuit 8 are provided for each of the plurality of subscriber interface circuits 4.

The step voltage signal generator 7 generates a step function voltage signal under the control of the central control circuit 9. Signal processing circuit 8
monitors the voltage signal at the output of the step voltage signal generator 7, and compares the step voltage signal supplied to the subscriber line 2 with the terminal 1.
The time difference with the step voltage signal reflected by and input through the retracting relay contact 32 is measured, and the distance is calculated from the delay time and reported to the central control circuit 9. Note that reference numeral 6 in the figure is a time division switch.

〔Effect of the invention〕

As explained above, according to the present invention, by determining the subscriber line length based on the delay time of the step voltage signal reflected by the terminal through the subscriber line, the subscriber line length is accurately calculated when the terminal is not in a call state. Can measure length.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Terminal, 2... Subscriber line, 3... Lead-in relay, 31.32... Lead-in relay contact, 7... Step voltage signal generator, 8... Signal processing circuit, 9 ...
Central control circuit.

Claims (1)

[Claims] first means for introducing a subscriber line connecting the terminal to a telephone exchange; second means for generating a step voltage signal supplied to the subscriber line via said first means; and said second means. measuring a time difference between the step voltage signal from the terminal and the step voltage signal reflected at the terminal through the first means and the subscriber line, and calculating the line length of the subscriber line based on this time difference; 3. A subscriber line length measuring device comprising the means of item 3.