JPS6221475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital subscriber line carrier system that connects subscriber telephones and digital exchanges using digital transmission lines.

Conventionally, because the interface conditions between digital switching equipment and digital subscriber line carrier systems have not been standardized, it is possible to connect digital switching equipment and digital subscriber line carrier equipment from the same manufacturer, but it is possible to connect equipment from different manufacturers. It is generally difficult to connect. One of the important things in determining interface conditions is the line concentration method. Digital subscriber line transport systems include non-concentration systems and concentration systems. The non-concentration method is a method in which a digital transmission line with a transmission capacity corresponding to the number of subscribers is prepared, and concentration switching is performed within the exchange. On the other hand, the line concentration system is a subscriber line carrier system in which line concentration switching is performed at a remote terminal station, and the transmission capacity of the digital transmission line is small compared to the number of subscribers. If a digital exchange is prepared only for an interface with a concentrator type subscriber line carrier system, it cannot be connected to a non-concentrator type digital subscriber line carrier system.

However, since the non-concentrated digital subscriber line carrier system can be effectively applied to small-scale villages where the number of subscribers per unit area is small, it is not possible to connect the non-concentrated digital subscriber line carrier system to a digital exchange. This is inconvenient.

In addition, in order to increase the operation rate of the subscriber transport system,
Conventionally, a method is known in which two systems of digital transmission lines, a working system and a backup system, are prepared, and when a failure occurs in the working system, the digital transmission path is automatically switched to the protection system.

In other words, the PCM relay transmission line (digital transmission line) of the subscriber line carrier system has a low reliability because many PCM regenerators are connected in cascade, and cable breakage accidents may occur. . Furthermore, since the PCM regenerator is installed in a manhole or on a pole, maintainability becomes poor. For these reasons, the above-mentioned automatic switching system is adopted to cover the reliability and maintainability of the PCM relay transmission line and improve the operability of the subscriber transport system.

However, this conventional switching system has drawbacks such as the switching system being configured as a separate system, which makes the device complicated and the cost high.

The present invention improves on this point by providing a master station device in which the signaling information transmission method and switching between the active system and the protection system are performed at the unipolar signal level, and which can be configured with inexpensive electronic circuits along with other circuits. This makes it possible to connect a non-concentrated digital subscriber line carrier system to the concentrator digital interface of a digital switch, and to realize a low-cost switching device for the active system and standby system of the PCM relay transmission line. The purpose is to provide a transportation method.

The present invention relates to a digital subscriber line carrier system that is comprised of a remote terminal station to which a subscriber telephone is connected via a cable, and a digital transmission line using bipolar pulses that connects this remote terminal station and a digital exchange. , converts and inversely converts a non-concentrated digital signal having path time slots corresponding to each subscriber between a digital transmission path and a digital exchange into a concentrator digital signal having a number of time slots smaller than the number of subscribers. conduct,
In addition, a master station device is installed that switches between the working system and the protection system of the digital transmission line at the unipolar signal level, and it is possible to connect a non-concentration type subscriber line carrier system to the concentrating system digital interface of the digital exchange. The system is characterized in that it is configured to automatically switch to a backup system in the event of a failure in the PCM relay transmission line of the system.

An embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram of essential parts of an embodiment of the present invention. Subscriber telephones 1 and 2 are connected to remote terminal station 3
and 4. These remote terminal stations 3 and 4 are connected via PCM relay transmission lines 5 and 6 to a master station device 7, which is a feature of the present invention.
A digital exchange 8 is connected to this master station device 7.

FIG. 2 is a block diagram of main parts of the master station device 7 shown in FIG. 1. active and standby systems
The output of the PCM relay transmission line is guided to bipolar signal unipolar signal conversion circuits (hereinafter referred to as "BU conversion circuits") 10 to 13. This B-U
The outputs of conversion circuits 10 to 13 are led to switching circuits 14 and 15. Further, the outputs of the BU conversion circuits 10 to 13 are branched and guided to monitoring circuits 16 to 19. The outputs of the monitoring circuits 16 to 19 are led to drive terminals of switching circuits 14 and 15.

The outputs of the switching circuits 14 and 15 are led to synchronization circuits 21 and 22. The outputs of the synchronization circuits 21 and 22 are sent to the microprocessor 2.
It is guided by 3. In addition, the synchronous circuits 21 and 2
The other output of 2 is led to a concentrator 24.
A control signal from the microprocessor 23 is guided to the line concentrator 24 . The outputs of the microprocessor 23 and the line concentrator 24 are led to a coupling circuit 25, respectively. The output of this coupling circuit 25 is a unipolar signal bipolar signal conversion circuit (hereinafter referred to as "U-B conversion circuit") 2.
It is guided by 6. The output of this U-B conversion circuit 26 is output to the digital exchange 8 shown in FIG.

Further, the output from the digital exchange 8 shown in FIG. 1 is led to a synchronization circuit 28 via a BU conversion circuit 27. The output of this synchronization circuit 28 is led to the microprocessor 23. The other output of this synchronization circuit 28 is led to a deconcentrator circuit 29. The outputs of the deconcentrator circuit 29 and the microprocessor 23 are led to coupling circuits 30 and 31, respectively. This coupling circuit 30 and 3
The output of 1 is the switching circuit 14 and 15, U-
It is led to the active and protection PCM relay transmission lines via B conversion circuits 32 to 35.

With this configuration, signals from the PCM transmission line are applied to the BU conversion circuits 10 to 13, and bipolar PCM signals are converted into unipolar PCM signals. The unipolar PCM signals from the BU conversion circuits 10 to 13 are applied to synchronization circuits 21 and 22 via switching circuits 14 and 15.

At this time, the monitoring circuits 16 to 19 monitor the signals from the BU conversion circuits 10 to 13 and determine whether the state of the PCM transmission line is good or bad. This monitoring circuit 16~
The output signal of 19 drives switching circuits 14 and 15, which automatically switch and connect the working system or protection system transmission line.

Since the usage rate of regular subscriber telephones is about 10% even during the busiest hours, the digital exchange 8 divides the switch configuration into a concentration stage and a distribution stage, and connects a certain number of subscribers (for example, 128) to a smaller number (for example, 128) in the concentration stage. For example, we are increasing the efficiency of using the distribution stage switch by focusing on 24). It is also possible to interface this distribution stage directly with a digital subscriber line carrier system. In order to connect a non-concentration type digital subscriber line carrier system to this interface, a master station device 7 is provided, and the master station device 7
Concentration and reverse concentration are performed. On the digital exchange 8 side, the concentrated signal, PCM relay transmission line 5
And on the 6 side, unconcentrated signals are handled.

In synchronization circuits 21 and 22, signaling information is taken out and this signaling information is input to microprocessor 23. Synchronous circuit 21
and 22 not only performs frame synchronization in a normal PCM transmission system, but also performs frame phase matching between PCM signals from two PCM transmission lines. The microprocessor 23 analyzes the signaling information, converts the information into a form that meets the interface conditions with the digital exchange 8, and sends it to the coupling circuit 2.
5. On the other hand, in the concentrator circuit 24, under the control of the microprocessor 23, two systems of phase-synchronized PCM signals are combined into one system of PCM signals. This line concentration operation is performed using a buffer memory. The PCM signal and the signaling information are combined in the combination circuit 25, converted into a bipolar signal in the U-B conversion circuit 26, and sent to the digital exchange 8.

Conversely, the signal from digital exchange 8 is B-
After being converted into a unipolar signal by the U conversion circuit 27, the signaling information is separated by the synchronization circuit 28. This signaling information is input to the microprocessor 23. The microprocessor 23 analyzes this information, converts it into signaling information on the transmission line side, and controls the line concentrator 24 and deconcentrator 29. In the reverse concentrator circuit 29,
The PCM signal is converted into 2 systems of PCM by buffer memory.
split into signals. The coupling circuits 30 and 31 are
Combine the PCM signal and signaling information. The outputs of the coupling circuits 30 and 31 are connected to the switching circuit 1
4 and 15 to the U-B conversion circuits 32 and 34
Or apply to 33 and 35. U-B conversion circuit 3
2, 34 or 33, 35 send out bipolar signals to the PCM transmission line.

As explained above, the present invention converts a bipolar signal on a digital transmission line into a unipolar signal, performs mutual conversion between a non-concentration digital signal and a concentration digital signal, and also converts a bipolar signal on a digital transmission line into a unipolar signal. We decided to use unipolar signals to switch between the system and the standby system.

Therefore, in the present invention, since the master station device operates with unipolar signals, its electronic circuit is simple.
It can be configured with common inexpensive equipment. Moreover, a non-concentration subscriber transport system suitable for a small group of subscribers can be used in a digital exchange having only a concentrator interface. Further, the master station device can automatically switch between the active transmission line and the protection transmission line without requiring a special switching system. Therefore, there is an effect that the degree of freedom in system configuration as a whole is increased and the system can be configured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of essential parts of an embodiment of the present invention. FIG. 2 is a block diagram of the main part of the master station device of the above example. 1, 2...Subscriber telephone, 3, 4...Remote terminal station, 5, 6...PCM relay transmission line, 7...Main station device, 8...Digital exchange, 10-13...B
-U conversion circuit, 14, 15...Switching circuit, 16~
19... Monitoring circuit, 21, 22... Synchronous circuit, 2
3...Microprocessor, 24...Concentrator circuit,
25...Reverse concentrator circuit.

Claims (1)

[Scope of Claims] 1. In a digital subscriber line carrier system including a remote terminal station to which a subscriber telephone is connected via a cable, and a digital relay transmission path connecting the remote terminal station and a digital exchange, A master station device is provided between the relay transmission path and the digital exchange, and this master station device has means for mutually converting bipolar signals on the transmission path and unipolar signals in the device, and a call time schedule for each subscriber. Means for converting and inversely converting a non-concentrated digital signal having slots into a concentrating digital signal having a number of time slots smaller than the number of subscribers, and switching between a working system and a protection system of a digital transmission line. A digital subscriber line transport system, characterized in that it includes means for performing.