JPH0438051A - Subscriber line maintenance system - Google Patents

Abstract

PURPOSE:To enable one person to discriminate whether or not a subscriber line is busy by providing a test signal application circuit in a subscriber line termination device of an exchange and applying/eliminating of a test signal to/from a subscriber line in response to the idle/busy state of the subscriber line. CONSTITUTION:A frequency of nearly 100Hz is set to a frequency of a sinusoidal wave outputted from a low frequency sinusoidal wave oscillator (OSC) 22 and at the outside of a band of a signal sent to an ISDN subscriber line (SUBL) 6 in order to reduce a cable loss in the SUBL 6. An output signal 32 of a termination control circuit (EXC) 31 is inputted to an SW 27, in which two switches are opened during the busy state and closed during the idle state. Thus, a low frequency sinusoidal wave propagates between lines of the SUBL 6 during the idle state and no sinusoidal wave exists during the busy state. A low frequency sinusoidal wave detector (DET) 8 connects to the SUBL 6 in this state and the presence of the sinusoidal wave is confirmed from an ISDN exchange 1 through a BPF 82 and a V 81.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a subscriber line maintenance system, and particularly to a subscriber line maintenance method that determines whether or not a digital subscriber line is in use and performs line maintenance and testing. Regarding the method.

[Conventional technology]

Traditionally, when maintenance personnel perform maintenance and testing of analog subscriber lines outdoors, etc., maintenance telephones (so-called battenski) are used.
is connected to a two-line subscriber line and listens to voice signals and modem transmission signals passing through that line to determine whether or not the line is currently in use. After confirming that no calls are in progress, maintenance and testing of the line is performed.

I SDN basic rate subscriber lines use digital 2-wire full-duplex transmission to transmit downlink signals from the subscriber line termination device to the network termination device and upstream signals in the opposite direction at the same time. Even if you try to monitor the signals on the line, there are cases where the upstream and downstream signals overlap and cannot be distinguished, and even if they do not overlap, it may not be possible to determine which is the upstream signal and which is the downstream signal. , it is not possible to extract the data strings of the uplink signal and the downlink signal, and it is not possible to tell whether the subscriber's line is busy or not.

For this purpose, it is necessary to look at the call status display of subscriber line termination equipment and network termination equipment near the equipment to determine whether a call is in progress, or to use a separate dedicated maintenance line for maintenance at the central office exchange. The maintenance/testing was carried out from a line that was not in use while calling someone to tell them the call status of the line that required maintenance/testing.

[Problem to be solved by the invention]

As mentioned above, in the past, when a maintenance person wanted to know whether or not an ISDN basic rate subscriber line was in use, if a call status display function such as a network termination device was not nearby, the maintenance worker had to do it outdoors. -The disadvantage is that you cannot do the exam alone.

Furthermore, when performing maintenance and testing outdoors, as mentioned above, support from a maintenance person at the telephone office is required, which has the disadvantage of being less efficient than maintenance and testing of analog subscriber lines.

[Means to solve the problem]

The subscriber line maintenance method of the present invention includes a test signal applying means for outputting a test signal between two subscriber lines, and a means for drawing the subscriber line connected to a subscriber line termination device into the test signal applying means. a switching means, a monitoring means for monitoring whether the subscriber line is in a call or not in a call, and controlling on/off of the switching means according to the monitoring result; and test signal detection means for selectively detecting only the test signal sent from the test signal applying means on the subscriber line, and the test signal detection means detects only the test signal on the subscriber line. The test signal is characterized by consisting of a bandpass filter that passes through the bandpass filter, and a voltmeter that measures the voltage of the test signal that has passed through the bandpass filter.

The subscriber line may also be an ISDN basic rate subscriber line, and the test signal may be a low frequency sinusoidal signal.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of the subscriber line maintenance method of the present invention, and shows an example in which a low frequency sine wave is used as a test signal for an ISDN exchange.

In FIG. 1, 1 is an ISDN exchange, 2 is a subscriber line termination device, 3 is an exchange termination device, 4 is a network termination device (hereinafter referred to as NT), 5 is a terminal (hereinafter referred to as TE), and 6 is a 2-line terminal. I
SDN subscriber line (hereinafter referred to as 5UBL), 7 is a 4-line IS
DN user/network interface line (hereinafter referred to as IFL)
2.1 is a low frequency sine wave application circuit (hereinafter referred to as LPG)
, 22 is a low frequency sine wave oscillator (hereinafter referred to as 0SC), 23.2
4 is a DC cutoff capacitor (hereinafter referred to as C), 25 and 26 are high impedance resistors (hereinafter referred to as R), 27 is a switching circuit (hereinafter referred to as SW) that connects/disconnects LFGll and 5UBL6, and two switches that draw 5UBL6 into LFG21. has. 28 is a layer 1 termination/control circuit (hereinafter referred to as DSU),
Reference numeral 29 denotes a DC power supply circuit to the subscriber line, hereinafter referred to as DCS. 31 is the "layer 3 termination/control circuit (hereinafter referred to as EXC)" 0, t, 8 is the low frequency sine wave detector (hereinafter referred to as "DET")
81 is a low frequency sine wave voltmeter (hereinafter referred to as V), 82 is 03
This is a narrow band pass filter (hereinafter referred to as BPF) that passes the frequency oscillated from C22.

Next, the operation of this embodiment will be explained.

The frequency of the sine wave output from 03C22 is 5tJBL6
Select a frequency around 100Hz outside the band of the signal transmitted above and to reduce cable loss at 5UBL6. However, to prevent the DET8 from erroneously detecting induced noise from the commercial AC power supply, the AC frequency and its harmonics should be selected. and the direct current supplied to the line.

Whether 5UBL6 is busy or not is determined by ISDN, E
Since call origination/termination is monitored by XC31, EXC
31 has a function as an output signal 32 to notify that a call is in progress, that is, a call of layer 2 or higher is set up between the ISDN exchange 1 and the TE 5. Output signal 32 is 5W2
7, the two switches can be turned off during a call and turned on when not on a call.

In this way, in this embodiment, a low frequency sine wave propagates between the lines of 5UBL6 during non-calling, and no sine wave exists during talking. Connect DET8 to 5UBL6 in this state and use BPF82. ISDN switch 1 through VS2
Check for the presence of a sine wave from the side. If a sine wave is detected, it will be confirmed that this 5UBL6 is not in a call,
If a sine wave is not detected, it is confirmed that a call is in progress.

〔Effect of the invention〕

As explained above, the present invention provides a test signal application circuit in the subscriber line terminating device of an exchange, and applies a test signal between the lines of the subscriber line depending on whether the subscriber line is in a non-call state or in a call state. By applying/removing the signal, the subscriber line maintainer can use the test signal detector without having to use a nearby switchboard or terminal, and without having to worry about the maintenance of the central office switchboard. This has the effect of allowing one person to determine whether or not the subscriber's line is busy without having to do so.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the subscriber line maintenance system of the present invention. 1...I SDN exchange, 2...Subscriber line termination device, 3...Switch termination device, 4...Network termination device (NT
), 5...Terminal (TE), 6...I SDN subscriber line (StJBL), 7...I SDN user/network interface line (IFL>, 8...Low frequency sine wave detection (DET), 21...Low frequency sine wave application circuit (
LPG), 22...low frequency sine wave oscillator (OSC),
23.24... DC cutoff capacitor (C), 25° 26... High impedance resistor (R), 27...
Switching circuit (SW), 28...Layer 1 termination/control circuit (DSU), 29...Direct I feed xo path (D
C8>, 31...Layer 3 termination/control circuit (EXC)
, 32... Output signal, 81... Low frequency sine wave voltmeter (V), 82... Narrowband band pass filter (BP
F).

Claims (1)

[Scope of Claims] Test signal applying means for outputting a test signal between one or two subscriber lines, and switching means for drawing the subscriber line connected to a subscriber line termination device into the test signal applying means. a monitoring means for monitoring whether the subscriber line is in a call or not in a call and controlling the switching means on/off according to the monitoring result; and test signal detection means for selectively detecting only the test signal sent from the test signal application means. 2. The test signal detection means is characterized by comprising a bandpass filter that passes only the test signal on the subscriber line, and a voltmeter that measures the voltage of the test signal that has passed through the bandpass filter. The subscriber line maintenance system according to claim 1. 3. The subscriber line maintenance system according to claim 1 or 2, wherein the subscriber line is an ISDN basic rate subscriber line. 4. The subscriber line maintenance system according to claim 1, 2 or 3, wherein the test signal is a low frequency sine wave signal.