JPH0331308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control signal transmission system within a digital exchange that accommodates digital trunk lines.

Inter-office signals transmitted via digital trunk lines accommodated in a digital exchange are sent intermittently using specific bits of each channel in a specific multi-channel frame of the multi-channel frame. Since control signals similarly use specific bits within a channel and are sent and received within the exchange, it is desirable to have a control signal transmission system within the exchange that allows them to be sent and received without being affected by interoffice signals.

[Conventional technology]

The form of a signal using a digital trunk line as a transmission path will be explained using one of the conventional examples shown in FIG.

The transmitted signal consists of multiple channel frames, each multiple channel frame having 193 bits,
24 channels from CH1 to CH24, 8 channels each
bit, and one bit of the frame identification signal S. Such a multi-channel frame consists of 5 multi-channel frames for audio followed by 1 multi-channel frame.
A multi-channel frame for signal of the frame follows, and a specific bit of each channel in the specific multi-channel frame that appears once every 6 frames, that is, the least significant bit, is used as an activation signal, a dial pulse signal,
It is allocated and used for transmitting and receiving signals between stations such as response signals.

Next, control signals within the exchange will be explained.
FIG. 3 is a block circuit diagram showing the connection between a digital exchange and a terminal device. In the figure, 1-4 is a terminal device, 5-7 is a data terminal interface device,
8 is a modem, 9 is a network control device, 10-13 is a line circuit, 14-15 is a network, 16-17
is a trunk for accommodating digital trunk lines, 18
-19 is the modem control unit and modem of the modem pool,
20-21 is a common control device, and 22 is a digital trunk line.

In the interconnection within the exchange shown in Figure 3, the terminal equipment 1
Connections between the terminal device 1 and the terminal device 2, and between the terminal device 1 and the terminal device 4 are considered. The connection between 1 and 2 requires a modem pool that exchanges digital data signals handled by the data terminal interface device with analog data signals handled by the modem; Then a modem pool is unnecessary.

Upon configuring the connection, the data terminal equipment turns on the transmission request signal RS. After receiving the transmission request signal, the data terminal interface device 5, 7 or modem 8 turns on the transmission enable signal CS after a certain period of time has elapsed. The elapsed time until the clear-to-send signal CS is turned on is the time required for the device to complete its operational preparations, and it differs between the data terminal interface devices 5 and 7 and the modem 8, and also differs between the data terminal interface devices 5 and 7 and the modem 8. 5 and the modem 19 of the modem pool.

In the case of data transmission from the terminal device 2 to the terminal device 1 in FIG. 3, in order to prevent transmission data from being lost, it is necessary to adjust the timing at which the send enable signal CS is turned on to the longer time.

FIG. 4 is a block circuit diagram showing the correlation between control signals within the exchange and interoffice signals.

In order to match the timing of turning on the clear-to-send signal CS, the data terminal interface device 5,
7 includes timers 23 and 24 with a delay time T1 and gates 26 and 27, and a modem 19 of the modem pool.
is equipped with a timer 25 with a delay time T2, the terminal interface devices 5 and 7 fix the least significant bit of the channel sent to the network 14 to 1, and the send clear signal CS of the modem 19 in the modem pool is set to the lowest bit of the channel. It is now being transmitted using

In the connection configuration between the data terminal interface devices 5 and 7, the terminal interface device turns on the ready-to-send signal CS in the time required for the terminal interface device to turn on the ready-to-send signal CS after turning on the request signal RS.

In addition, in the connection configuration between the data terminal interface device 5 and the modem 19 of the modem pool, the necessary signals are required to turn on the transmission request signal RS and the send clear signal CS of the terminal interface device 5 and the modem 19, respectively. Adjust the time to the longest part of the time.

With the above configuration, when mutual extension lines are connected, the time from when the transmission request signal RS is turned on to when the transmission enable signal CS is turned on is made to be the shortest possible time without causing any data loss.

[Problem that the invention seeks to solve]

When terminal interface devices are interconnected via digital trunk lines, interoffice signals influence control signals within the exchange. When the signal 31 from the digital trunk line 22 in FIG. 4 is given as the signal 30 to the terminal interface device 5, each of the multiple channel frames is Once every six frames, the least significant bit of the channel becomes 0, and when the send clear signal CS should be on, the least significant bit is changed from 1 to 0 and the send clear signal CS is turned off. For this reason, there is a problem in that it is no longer possible to transmit the send clear signal CS using the least significant bit when connecting the extension lines.

[Means for solving problems]

The problem described above is that the trunk accommodating the digital trunk line forcibly fixes a specific bit of each channel in a specific multi-channel frame of the multi-channel frames arriving via the digital trunk line to a constant value. This problem is solved by a control signal transmission system within an exchange according to the present invention, which is configured to send out to the digital exchange side.

[Effect]

According to the present invention, the least significant bit of each channel of a specific frame for transmitting an inter-office signal of a data signal entering the network from a digital trunk line is fixed to a fixed value of 0 or 1, and then sent to the exchange. Even if the control signal used within the exchange uses the least significant bit of the channel in the same way as the inter-office signal, the least significant bit of the channel for transmitting the control signal within the exchange may be affected by the inter-office signal. It can be done so that there is no

〔Example〕

The gist of the present invention will be explained in detail below with reference to illustrated embodiments.

Figure 1 is a block circuit diagram of a trunk that accommodates digital trunk lines, with 32-33 being a data rate conversion circuit, 34-37 being a shift register, and 38-3 being a data rate conversion circuit.
9 is a signal level conversion circuit, 40 is a multiplexing circuit, 4
1 is a timing circuit.

The data signal 64kbps from the network 14 is sent to the serial/parallel conversion register 33 and the parallel/serial conversion register 3.
4, the signal is converted to a transmission line speed of 1.544 Mbps, multiplexed by a multiplexing circuit 40, and sent to the digital trunk line 22.

On the other hand, multiple channel frames received via digital trunk line 22 are separated and converted by multiplexing circuit 39 and distributed to data rate conversion circuits 32-33 and signal level conversion circuits 38-39. The timing necessary for multiplexing and demultiplexing conversion is determined by a timing generation circuit 41. The received data signal enters the shift register 35 at a predetermined timing, is set in the shift register 36, and is then sent in bursts to the network 14. At this time, based on the present invention, the least significant bit of the shift register 37 is shifted. It is not the data of the register 36, but is fixedly set to 1. Therefore, the least significant bit sent to network 14 is fixed at one. Although the illustrated embodiment shows a case where the value is fixed to 1, it is also possible to fix it to 0.

By using the trunk containing the digital trunk according to the present invention, the least significant bit in the channel can be used to transmit the clear-to-send signal CS in the switch, and the call can be routed to the data terminal interface equipment via the digital trunk. Even when connected, the least significant bit of the data arriving via the digital trunk line is forcibly changed to a specific fixed value, so the transmission of the clear-to-send signal CS of the data terminal interface device will not be adversely affected. do not have.

According to an embodiment of the present invention, even in a system in which a digital trunk line that performs bit stealing is housed in a digital exchange, the stolen bits can be used for information transmission within the exchange without being affected by bit stealing. This allows us to improve our services.

〔Effect of the invention〕

As described above, according to the present invention, the control signals within the exchange are not adversely affected by the inter-office signals of the digital trunk line, and the exchange connection within the premises is reliably facilitated, and its effects are extremely significant.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a trunk accommodating a digital trunk line, FIG. 2 is a frame configuration diagram showing the signal form on the digital trunk line, and FIG. FIG. 4 is a block circuit diagram showing the connections; FIG. 4 is a block circuit diagram showing the correlation between control signals within the exchange and interoffice signals. In the figure, 1-4 is a terminal device, 5-7 is a data terminal interface device, 8 is a modem, 9 is a network control device, 10-13 is a line circuit, 14-15
is a network, 16-17 is a trunk for accommodating digital trunk lines, 18-19 is a modem control unit and modem of a modem pool, 20-21 is a common control device, 22 is a digital trunk line, 23, 24,
25 is a timer, 26, 27 are gates, 28, 2
9, 30 are control signals within the exchange, 31 are interoffice signals, 32-33 are data rate conversion circuits, 34-3
7 is a shift register, 38-39 are signal level conversion circuits, 40 is a multiplexing circuit, and 41 is a timing circuit.

Claims (1)

[Claims] 1. A trunk accommodating a digital trunk line forcibly fixes specific bits of each channel in a specific multi-channel frame among the multi-channel frames arriving via the digital trunk line to a constant value, and sends it to the digital exchange side. A control signal transmission system within an exchange, characterized in that it is configured as follows.