JPH0522415A - U-point monitoring system for isdn - Google Patents

Abstract

PURPOSE:To easily perform monitoring on the U-type of an ISDN. CONSTITUTION:An LT 16 takes out a frame clock FCK and outgoing data DTD, etc., out of a transmission sign to be transmitted from a station side to a subscriber side, converts them into signals at a TTL level, outputs them to a control part 18, converts incoming data DTU from a subscriber side taken out in an LT 17 into the transmission sign of a 2B1Q and outputs it. The LT 17 takes out the frame clock and the downloading data, etc., out of the transmission sign to be transmitted from the subscriber side to the station side, converts them into the signals at TTL level and outputs them to the control part, and converts the outgoing data from the station side taken out in the LT 16 to the transmission sign of the 2B1Q and outputs them to the subscriber side. The control part separates the incoming data and outgoing data into the data for information channels B1 and B2 and a signal channel D. The data for the channels B1 and B2 are converted into analog sound signals in an A/D converter 19, outputted from a speaker 20 to be used for monitoring the calling state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ISDN U-point monitor system for digital transmission using a two-wire metallic cable.

[0002]

2. Description of the Related Art As a structure of a digital subscriber system in ISDN, a home side network terminating device is installed on a user side and a network terminating device is installed on a station side, and each network terminating device is an interface with a terminal device and an exchange. There is one that forms an interface and transmits and receives a digital signal via a subscriber line. At present, the subscriber line is a two-wire metallic cable for telephones. Therefore, in order to perform bidirectional transmission of digital signals using the two-wire metallic cable, a time division directional control transmission method (ping-pong transmission method), an echo A canceller transmission system or the like is used. The time division direction transmission method is a transmission method in which the transmission time and the reception time are divided and transmitted alternately. The echo canceller transmission method separates the upstream and downstream information signals by a hybrid circuit and circulates to the receiving side. This is a transmission method in which a transmission signal is suppressed by an echo canceller. The connection point between the network terminating device inside the home and the subscriber line is called U point, and the connection point between the network terminating device and the ISDN terminal device inside the home is called S point and T point.

[0003]

When a signal is analog-transmitted between a subscriber terminal device and a switchboard, a monitor device is connected in parallel to a subscriber line to directly take out a voice signal to determine a transmission state. You can easily look it up.

However, when the signal is digitally transmitted between the subscriber terminal device and the exchange, the information is coded, and a plurality of B channel signals and D channel signals are provided on one subscriber line. Since it is sent, it is not possible to monitor the transmission status in the same way as in the case of analog transmission.

Conventionally, when it is desired to check the transmission status of a digital subscriber system, it is necessary to read the data stored in the memory inside the exchange, convert it to D / A, and convert it into a voice signal. The person who was not familiar with the hardware and software of the exchange could not check the transmission status.

An object of the present invention is to allow a maintenance person or the like to easily monitor the transmission state of the U point of ISDN.

[0007]

FIG. 1 is a block diagram showing the principle of the present invention. In a digital communication network that performs digital transmission between a station and a subscriber using a two-wire metallic cable, the first conversion means 1 uses a predetermined transmission code sent from the station side as at least a frame synchronization signal and data. And outputs it to the control means 3 while converting the signal from the station side, which has been separated into the frame synchronization signal and the data by the second conversion means 2, into a predetermined transmission code.

The second conversion means 2 separates the transmission code sent from the subscriber side into at least a frame synchronization signal and data, and outputs them to the control means 3, and at the same time, the first conversion means.
The conversion means converts the signal from the station side separated into the frame synchronization signal and the data into a transmission code and sends it to the subscriber side.

The control means 3 converts the data extracted by the first and second conversion means 1 and 2 into a plurality of B channels,
Separate into D channel signals. The output means 4 D / A converts the B channel signal separated by the control means 3 and outputs it.

A monitor device 5 including these means.
Is installed on the U point of the subscriber line consisting of a two-wire metallic cable to monitor the transmission state.

[0011]

Now, assuming that the case where the data is transmitted from the station side to the subscriber side is down and the case where the data is transmitted from the subscriber side to the station side is up, the monitor installed on the U point of the subscriber line. The device 5 extracts the downlink data and the uplink data from the transmission code sent from the station side and the subscriber side, respectively, and further separates these data into a plurality of B channel signals and D channel signals. It Then, the B channel signal is D / A converted and output.

Thus, for example, when the terminal device on the subscriber side is a telephone terminal, the transmission quality of the line can be checked by monitoring the D / A converted voice signal.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a system configuration diagram of a subscriber system according to the embodiment of the present invention. In this embodiment, the subscriber line 10 is composed of a two-wire metallic cable, and the data transmission between the exchange and the subscriber terminal device is performed by the echo canceller transmission system. In addition, 2B1Q, which is a quaternary code, is used as the transmission code.

A network terminating device D is provided in the central office exchange (NW) 11.
An LC (Digital Line Circuit) 12 is installed, and a subscriber side has a network terminator NTE facing the network terminator 12 on the station side.
(Network Termination Equipment) 13 is installed, and the terminal device TE 14 is connected to the network termination device 13.

When the connection point between the subscriber's NTE 13 and the subscriber line 10 is a U point, a U point monitor device 15 for checking the transmission quality is inserted above the U point. Figure 3
FIG. 3 is a diagram showing a specific configuration of a U-point monitor device 15.
In the U point monitor 15, an LT 16 that functions as a slave for the station side and an LT 17 that functions as a master for the subscriber side are provided.

Now, assuming that the signal flow from the station side to the subscriber terminal is down and the signal flow from the terminal device to the station side is up, the LT 16 sends a down signal from the station side (for example, 2B1).
The frame clock FCL, the clock CK, and the downlink data DTD are extracted from (Q code data), these signals are converted into TTL level signals, and the signals are output to the control unit 18.
Further, the LT 16 sends 2B to the upstream data DTU from the subscriber side, which has been converted to the TTL level by the LT 17 described later.
It is converted to a 1Q transmission code and sent to the station side.

The LT 17 is a circuit having the same configuration as that of the LC 16, and extracts the frame clock FCK, the clock CK, and the downstream data DTD from the upstream signal from the subscriber side, converts these signals into a TTL level signal, and controls them. It is output to the unit 18. Furthermore, LT17 is TT with LT16
Downstream data DTD from the station side converted to L level,
It is converted to a 2B1Q transmission code and sent to the subscriber side.

The control unit 18 separates the upstream data DTU and the downstream data DTD into, for example, the information channels B1 and B2 and the data of the signal channel D based on the frame clock FLK and the clock CK. The B1 and B2 channel data are converted into analog audio signals by the D / A converter 19 and output from the speaker 20. Accordingly, when the subscriber terminal device is a telephone terminal, the call state can be confirmed by voice. In addition, D of the control unit 18
By connecting the protocol tester 21 to the channel output, the D channel signal can be monitored. Further, by connecting the bit error tester 22 to the B channel output of the control unit 18, the B channel transmission quality can be measured.

The control unit 18 is provided with a signal loopback function. When the transmission quality is poor, the signals from the station side and the subscriber side are looped back to determine which transmission line is used. It is possible to check whether the transmission quality of is bad.

If the above monitoring device is installed on the exit side of the exchange, the call status can be confirmed by voice, so that the maintenance person does not need to read the data from the memory inside the exchange and the line can be read. Maintenance work such as becomes easy.

If the monitor device is installed in the middle of the subscriber line, for example, at an intermediate position between the station and the subscriber terminal device, the transmission code is reproduced inside the monitor device and the transmission code is newly sent from the installation position. Therefore, the signal transmission distance can be doubled.

In the above embodiment, the present invention is applied to other transmission systems such as the ping-pong transmission system, which describes the case where the signal transmission between the station side and the subscriber side is performed by the echo canceller transmission system. it can.

[0023]

According to the present invention, a maintenance person can easily check and monitor the transmission quality at the U point of ISDN. Further, by installing the monitor device in the middle of the subscriber line, maintenance becomes easy and the transmission distance can be extended.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a system configuration diagram of a subscriber system according to an embodiment.

FIG. 3 is a configuration diagram of a U-point monitor device.

[Explanation of symbols]

 1 1st conversion means 2 2nd conversion means 3 Control means 4 Output means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Fujiwara 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (1)

Claim: What is claimed is: 1. In a digital communication network for digital transmission between a station and a subscriber using a two-wire metallic cable, a predetermined transmission code sent from the station side is at least frame-synchronized. First conversion means (1) for separating the signal and the data, and for converting the signal from the subscriber side, which is separated into the frame synchronization signal and the data, into a predetermined transmission code and sending it to the station side; A predetermined transmission code sent from the user side is separated into at least a frame synchronization signal and data, and is also separated into a frame synchronization signal and data from the station side by the first conversion means (1). A second conversion means (2) for converting the signal into the transmission code and sending it to the subscriber side, and a frame synchronization signal and data separated by the first and second conversion means (1, 2) Signals to multiple B channels,
Monitor device (5) having control means (3) for separating into D channel signals, and output means (4) for D / A converting and outputting a plurality of B channel signals separated by the control means (3) Is a U-point monitoring system of ISDN, characterized in that it is installed on the U-point of the subscriber line consisting of a two-wire metallic cable to monitor the transmission status.