JPH0226450A - Subscriber line testing system - Google Patents

Abstract

PURPOSE:To measure a subscriber line digital transmitting characteristic and to start a test from the side of an in-house equipment by providing an in-house terminal unit connected to a network terminating set, channel digital signal transmitting and receiving devices connected to the in-house terminal unit, and a channel folding device connected to the network of an exchange. CONSTITUTION:The title system is equipped with an in-house terminal unit 4 connected to a network terminating set 6, channel digital signal transmitting and receiving devices 2 and 3 connected to the in-house terminal unit 4, and a channel folding device 10 connected to the network of the exchange. When a subscriber line 7 is tested, a telephone number assigned to the channel folding device 10 is sent from the in-house terminal unit, it is activated, a digital signal sent from the channel digital signal transmitting device after a connection is completed, and folded by the channel folding device 1 is received by the channel digital signal receiving device 3, and the digital transmitting characteristic of the subscriber line 7 is measured. Thus, not only the digital transmitting characteristic of the subscriber line 7 can be measured but also the subscriber line test can be started from inside a house.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a subscriber line testing system.

[Conventional technology]

Conventionally, when testing subscriber lines, subscriber lines are selected from a test stand on the exchange side, and the insulation resistance and capacitance between the subscriber lines are measured.
In addition, analog parameters such as ground voltage were measured. This made it possible to detect subscriber line disconnections, ground faults, and contact with power lines.

[Problem to be solved by the invention]

However, the above-mentioned test method has the following problems.

Since the subscriber line is selected from the exchange side, testing cannot be started from the home equipment side during construction of the home equipment, for example.

The test items are consistent with conventional analog transmission systems, making it difficult to evaluate problems such as instantaneous interruptions in subscriber lines and noise intrusion, which are problems in digital transmission.

Therefore, there is a need for a new subscriber line testing method, especially for switching systems such as ISDN exchanges, which are based on the premise of digital transmission over subscriber lines.

[Means to solve the problem]

The subscriber test method of the present invention is applicable to a switching system in which a digital subscriber circuit of an exchange and a network termination device face each other via a subscriber line. The subscriber line includes a communication path digital signal transmitting device connected to the terminal device, a communication path digital signal receiving device connected to the home terminal device, and a communication path return device connected to the network of the exchange. During the test, the home terminal device sends a telephone number assigned to the call path return device to activate it, and after the connection is completed, a digital signal is sent from the call path digital signal transmitter and is returned by the call path return device. is received by the communication channel digital signal receiving device, and the digital transmission characteristics of the subscriber line are measured.

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

Referring to the diagram showing one embodiment, on the exchange side,
The digital subscriber circuit 8 and the call path return device 10 can be connected via a network 9 . This communication path connection is made via a control bus 12 under the command of a central controller 11. The control bus 12 is used not only to issue a call path connection command, but also to transfer the telephone number of the called party from the digital subscriber circuit 8 to the central control unit 11, and to transfer an incoming call request signal and response signal to the call loop return device 10. is also used. The call path loopback device 10 has a function of looping back up or down the call path as a digital signal. The subscriber line 7 is a subscriber line to be measured. The network termination device 6 faces the exchange through the subscriber line 7, and serves to terminate the layer 1, protect the home terminal device 4 from external surge signals, and drive the home bus 5. The home terminal device 41 is connected to the home bus 5 and provides an interface between other terminal devices and the home bus 5. In this embodiment, a communication path digital signal transmitting device 2 is connected to the upstream side of the communication path (in the direction toward the exchange), and a communication path digital signal receiving device 3 is connected to the downstream side of the communication path (in the direction from the exchange). ing. The signal inserted into the call path by the call path digital signal transmitting device 2 is transmitted as a digital signal from the home terminal device 4 to the home bus 5, and is transmitted to the network termination device 6, subscriber line 7, digital subscriber circuit 8, and network 9. It is possible to reach the channel turning device 10 via the channel turning device 10, and to return the digital signal from the channel turning device 10 to the channel digital signal receiving device 3 in the same way from the opposite direction. The telephone 1 cannot be used for making calls because the communication path digital signal transmitting device 2 and the communication path digital signal receiving device 3 are connected to the upstream and downstream sides of the communication path. used for bamboo shoots. The digital signal generated by the communication path digital signal transmitter 2 is 2n.
1 (n = 1, 2...) and has a predetermined initial value, and the channel digital signal receiving device 3 uses the pseudo-random pattern with the same period and the same initial value as the transmission pattern. Detection is possible.

In the above-described configuration, when a test of the subscriber line 7 is started, the telephone number assigned to the call path return device 1° is first sent from the telephone set 1. This telephone number is input to the digital subscriber circuit 8 on the subscriber signal channel and then to the central control unit 11 via the control bus 12. When the central control unit 11 determines that the input telephone number information belongs to the call path return device 10, it also sends an incoming call request signal to the call path return device 10. When the call path return device 10 returns a response signal,
Call path digital subscriber circuit 8 and call path return device 10
The network 9 is instructed to form a bus in order to connect the network. All of these commands and signal transmission and reception are performed through the control bus 12.

In this way, the pseudo-random pattern of the digital signal from the channel digital signal transmitting device 2 is passed through the Kadai veteran 7, turned back by the channel loopback device 10, and received by the channel digital signal receiving device 3. Since the cycle and initial value of the received pseudo-random pattern are known in advance, it is possible to know how many bit errors have occurred during transmission, and as a result, the function of the entire exchange system can be determined. Most of the errors are thought to occur in the subscriber line 7, so by measuring the error rate, it is possible to
It is possible to quantitatively measure the digital transmission characteristics of

〔Effect of the invention〕

As explained above, according to the present invention, it is not only possible to measure the digital transmission characteristics of a subscriber line, but also it is possible to start a subscriber line test from inside the premises.

equipment, experienced, ri, 1 equipment, 5...indoor bus, 6...network termination equipment, 7...subscription 8...digital subscriber circuit, 9...network 〇・
...Call path delay device, 11...Central control 12...
- Control bus.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of the present invention.

Claims (1)

[Claims] In a switching system in which a digital subscriber circuit of an exchange and a network termination device face each other via a subscriber line, a home terminal device connected to the network termination device and a telephone line digital subscriber circuit connected to the home terminal device a signal transmitting device; a channel digital signal receiving device connected to the home terminal device;
a call path return device connected to the network of the exchange; when testing the subscriber line, the in-home terminal device sends the telephone number assigned to the call path return device to activate it; and after the connection is completed, the call path return device A subscriber line, characterized in that the digital signal transmitted from the communication path digital signal transmitting device and returned by the communication path return device is received by the communication path digital signal receiving device, and the digital transmission characteristics of the subscriber line are measured. Test method.