JPS6228915B2 - - 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, since the interface conditions between digital exchanges and digital subscriber line carrier systems have not been standardized, it has been possible to connect digital exchanges and digital subscriber line carriers from the same manufacturer. However, it is generally difficult to connect devices from different manufacturers. That is, one of the important interface conditions is a signaling information transmission method, but at present there is no standard signaling information transmission method for digital subscriber line carrier systems. Therefore, users must use switching equipment and subscriber line carrier systems from the same manufacturer. For example, if a common line signaling system is used in a digital exchange, individual line signaling systems cannot be used in combination with digital subscriber line transmission systems, which limits system configuration flexibility and is expensive. It has disadvantages such as: In addition, in order to increase the operating efficiency of the subscriber line carrier system, digital transmission lines have traditionally been divided into working and standby lines.
A method is known in which the system is prepared and the digital transmission line is automatically switched to the backup system when a failure occurs in the active 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 this reason, we adopted the automatic switching method described above,
It covers the reliability and maintainability of PCM relay transmission lines and improves the operability of subscriber line carrier systems. 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. To provide a digital subscriber line system that enables connection of a digital exchange with different signaling transmission systems and a digital subscriber line transport system, and that realizes a switching device for a working system and a standby system of a digital transmission line at low cost. With the goal. 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. , between the digital transmission line and the digital exchange, there is a time slot for transmitting signaling information for call control. A master station device is provided that converts and inversely converts the signaling information into a common channel signal system that transmits signaling information in one time slot common to subscribers, and switches between the working system and the protection system of the digital transmission path at the unipolar signal level, The present invention is characterized in that the digital switch is configured so that a digital subscriber line transport system with a different signaling information transmission system can be used. This will be explained in detail based on the drawings. FIG. 1 is a frame configuration diagram of the 1.544 Mb/s system. When using a 1.544 Mb/s primary group PCM relay transmission line as a digital transmission line, the transmission of signaling information is generally LSB (Least Significant
bit) is used to transmit signaling information once every six frames (bit stay method). That is, FIG. 1 shows the bit structure of five frames every six frames, and FIG. 1 shows the bit structure of one frame every six frames. This signaling information transmission bit is provided for each of the 24 audio channels, and is generally used as an individual line signaling system for transmitting the signaling information associated with each channel. On the other hand, it is also possible to use the S bit for transmitting common channel signals. Table 1 shows examples of the use of the F bit. That is, the F bit is always "1" in frame number 1 and always "0" in frame number 3. In frame numbers 2 and 4, this F bit is used as the S bit.

[Table] If the digital exchange uses a common line signaling system and the digital subscriber line carrier system uses an individual line signaling system, there is a disadvantage that the two cannot be used in direct combination. The present invention focuses on providing a master station device that exchanges the transmission method of signaling information, using the two in combination, and also switching between the working system and the backup system of the digital transmission path with this master station device. be. FIG. 2 is a block diagram of essential parts of an embodiment of the present invention. A subscriber telephone 1 is connected to a remote terminal 2 . This remote terminal station 2 is connected via a PCM relay transmission line 3 to a master station device 5, which is a feature of the present invention. This master station device 5 has a digital exchange 6.
is connected. FIG. 3 is a block diagram of main parts of the master station device 5 shown in FIG. 2. FIG. 3 shows only an example of the configuration of the receiving side, and the configuration of the receiving side, which has a similar configuration, is omitted from the drawing. PCM relay transmission line 3 (second
The bipolar PCM signal from the circuit shown in FIG. The outputs of these BU conversion circuits 8 and 9 are
0 to the synchronous circuit 11. Also,
Signals from the PCM relay transmission line 3 (FIG. 3) are guided to monitoring circuits 12 and 13 via the BU conversion circuits 8 and 9. The outputs of the monitoring circuits 12 and 13 are led to the switching circuit 10 as drive signals. The output of the synchronization circuit 11 is led to a coupling circuit 14. Another output of this synchronization circuit 11 is led to a microprocessor 15. The output of this microprocessor 15 is led to the above-mentioned coupling circuit 14. The output of this coupling circuit 14 is sent to a digital converter 6 via a unipolar signal/bipolar signal converter circuit (hereinafter referred to as "U-B converter circuit") 16.
(Figure 2). With this configuration, the bipolar PCM signals from the two digital transmission lines are converted into unipolar PCM signals by the BU conversion circuits 8 and 9, respectively. At this time, the PCM signal monitoring circuits 12 and 13 detect a failure in the digital transmission path. The output signals of the monitoring circuits 12 and 13 are applied to the switching circuit 10, and automatic switching to the protection transmission line is performed in the event of a fault in the working transmission line. The output of the switching circuit 10 is frame-synchronized by the synchronization circuit 11, and the transmission bits of the signaling information based on the LSB bit stay are separated. The transmission bits of this signaling information are applied to the microprocessor 15, and the information is analyzed. Thereafter, it is converted into a common line signal by this microprocessor 15, and the result is output from this microprocessor 15. This common line signal is connected to the audio signal bit as S bit in the coupling circuit 14.
After being combined, the signals are converted into a bipolar signal by the U-B conversion circuit 16 and sent to the digital converter 6. Since the transmitting side can also be realized with a similar configuration, the explanation will be omitted. Furthermore, there are various other signal transmission systems in the digital subscriber line carrier system. However, all of them use either the S-bit method or the bit-stay method, or a combination of both. Therefore, in such a signal transmission system, it is necessary to input both the S bits and the bit-stalled signal bits to the microprocessor in the above example, process the signals in the microprocessor, and then output them. be. As explained above, the present invention converts a bipolar signal on a digital transmission line into a unipolar signal, performs mutual conversion between signaling information of an individual line signal transmission system and signaling information of a common line signal system, and We decided to use unipolar signals to switch between the active 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, regardless of the signaling information transmission method of the common channel signaling method employed in the digital exchange, a remote terminal station of the subscriber line carrier method can be selected. 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]

Figure 1 is a frame configuration diagram of the 1.544 Mb/s system.
FIG. 2 is a block diagram of essential parts of an embodiment of the present invention.
FIG. 3 is a block diagram of a main part of the master station device shown in FIG. 1...Subscriber telephone, 2...Remote terminal station, 3...
PCM relay transmission line, 5... Master station device, 6... Digital exchange, 8, 9... B-U conversion circuit, 10
...Switching circuit, 11...Synchronization circuit, 12, 13...
...Monitoring circuit, 14...Coupling circuit, 15...Microprocessor, 16...U-B conversion circuit.

Claims (1)

[Claims] 1. A digital subscriber comprising: a remote terminal station to which a subscriber's telephone is connected via a cable; and a digital transmission line using bipolar pulses that connects the remote terminal station and a digital exchange. In the line carrier system, a master station device is provided between the digital transmission path and the digital exchange, and the master station device includes means for mutually converting a bipolar signal on the transmission path and a unipolar signal in the device, and The individual line signal transmission system has a time slot for each subscriber line for transmitting control signaling information, but by extracting only significant signaling information and multiplexing it, a single time slot common to multiple subscribers can be created. 1. A digital subscriber line carrier system comprising means for converting and inverting into a common line signaling system for transmitting signaling information, and means for switching between a working system and a protection system of a digital transmission line.