JPH0720107B2 - Transmission repeater - Google Patents

Description

The present invention relates to a communication device, and more particularly to a transmission repeater for connecting a plurality of transmission lines.

B. SUMMARY OF THE INVENTION The present invention is a transmission repeater connecting a plurality of transmission lines, including a receiver for receiving a signal from the transmission line and a transmitter for transmitting a signal to the transmission line. And an input for outputting a signal from the first transmission line which is a transmission line of the second transmission line to the second transmission line which is a one-way transmission line or a signal from the second transmission line to the first transmission line. In order to prevent the repeater from oscillating after the output signal selecting means, the signal generating means for outputting a predetermined signal, and the output signal selecting means output the signal to the transmission line, the output signal selecting means has a predetermined value. When the signals are simultaneously input from the control means for stopping the output of the signal and the first and second transmission lines for the time, the predetermined signal is selected from the output side in order to eliminate the signal collision state. Through the first and second By and control means to be outputted to the transmission path, by connecting a plurality of transmission paths are placed at a long distance, and makes it possible to communicate between the transmission lines.

C. Conventional technology Figure 9 shows an example of a bus-type network. In this network, a plurality of nodes 92 are connected by a transmission path 91 which is a bidirectional transmission path, and signals are exchanged between the nodes via this transmission path. The transmission line 91 is usually configured by a cable that electrically transmits a signal, such as a coaxial cable or a twisted pair cable.

D. Problems to be Solved by the Invention By the way, such an electric cable has problems such as large signal attenuation and easy mixing of noise. Therefore, the transmittable distance is limited, and it is impossible to perform long-distance signal transmission by simply extending this type of cable.

An object of the present invention is to provide a transmission repeater which solves such a problem and which connects a plurality of transmission lines installed at a long distance to each other and enables long-distance signal transmission.

E. Means for Solving the Problems In order to solve the above problems, the present invention relates to a transmission repeater connecting a plurality of transmission lines, in which a first transmission line which is a bidirectional transmission line and a unidirectional transmission line. A receiver for receiving and outputting a signal from a second transmission path, which is a transmission path, a transmitter for sending a signal to the first and second transmission paths, and the first or second transmission Input signal selecting means for receiving a signal from the channel through the receiver, selecting one of the signals based on the first control signal, and outputting the selected signal;
Based on a signal generator that outputs a predetermined signal and a second control signal, the signal output by the input signal selection means is output to the first or second transmission path through the transmitter, or Output signal selecting means for outputting the predetermined signal output from the signal generator to the first and second transmission lines through the transmitter, or for stopping signal transmission to the transmission line; When a signal is input from the second transmission line, the first signal is selected by the input signal selection means and output.
When a signal is input from either the first control means for outputting the control signal or the first or second transmission path, the second control signal is output to the output signal selection means, Second control means for outputting the signal output by the input signal selection means to the first or second transmission path different from the transmission path that has received the signal; and the first and second control means.
Third control means for outputting the second control signal for outputting the predetermined signal to the first and second transmission paths to the output signal selection means when signals are input from both of the transmission paths And after the output signal selecting means outputs a signal to the first or second transmission line, the second control signal for stopping the transmission of the signal to the transmission line for a predetermined time is selected as the output signal. And a fourth control means for outputting to the means.

F. Action When a signal is input from either the first or the second transmission line, the first control means outputs the first control signal and the input signal selection means is input from the transmission line through the receiver. The selected signal is selected and output. Then, the second control means outputs the second control signal to the output signal selecting means, and the signal output from the input signal selecting means is sent to the first or second transmission path different from the transmission path which has received the signal. Output through the transmitter. As a result, the signal input from one transmission line is sent to the other transmission line through the receiver, the input and output signal selection means, and the transmitter.

Further, the fourth control means outputs the second control signal for stopping the output of the signal to the transmission path for a predetermined time after the output signal selection means outputs the signal to the transmission path. Output to. This prevents the signal output from the repeater from returning to the repeater and entering an oscillating state.

When signals are input from both the first and second transmission lines, the third control means outputs a second control signal for outputting the predetermined signal to the first and second transmission lines. Output to the signal selection means. As a result, the output signal selection means sends out the above-mentioned predetermined signal to both transmission lines to eliminate the signal collision state.

G. Example Next, an example of the present invention will be described. In the block diagram of this embodiment shown in FIG. 1, receivers 1 and 2 receive signals from a bidirectional transmission line A and a unidirectional transmission line B, respectively. Further, the transmitters 11 and 12 respectively send signals from the repeater to the bidirectional transmission line A and the unidirectional transmission line B. Although only a part of the receivers and transmitters are shown in the figure for simplification, actually, the number of transmitters and receivers corresponding to the number of transmission lines for relaying is provided.

As shown in FIG. 3, the timers 3 and 4 are triggered by the output signals of the receivers 1 and 2 and thus the signal input from the transmission path (T1), and output a pulse that continues for a predetermined time. To do. These timers are retriggerable, and once triggered, they generate an output pulse, and when the next signal is input again before the output pulse falls, it is triggered again at that time (T2) and the output pulse lasts the above time. Continue further. As for the timers, only the timers 3 and 4 are shown in the figure, but in reality, the number of timers corresponding to the number of transmission lines for relaying is provided for each receiver.

The multiplexer 7 selects and outputs one of the signals from the receivers 1 and 2 based on the control signal c1.

Generally, when received data propagates through a transmission line, a slight shift occurs in the timing of each data due to signal attenuation or noise mixing. The jitter suppressor 9 is for eliminating such timing deviation, that is, jitter. The block diagram is shown in FIG. FIFO
Reference numeral 41 is a kind of memory configured by arranging a plurality of cells in series, and the data input first is output first. In addition, the writing and reading can be performed completely asynchronously. The reception data from the multiplexer 7 is written in the FIFO 41 in synchronization with the reception clock. The counter 42 counts the number of reception clocks, and when the counter 42 counts a fixed number, that is, when it is written in the reception data FIFO 41 of a fixed number, its output is set to logic "1". At this time, the transmission clock having a constant cycle is input to the FIFO 41 as a read clock through the AND gate 43, and the reception data written in the FIFO 41 is read in synchronization with this transmission clock. The read data is output as transmission data. Since the transmission data is synchronized with the transmission clock having a constant cycle, the jitter of the reception data is removed from the transmission data.

The jamming pattern generator 8 generates a jamming pattern signal and outputs it to a multiplexer 10 described later.

The multiplexer 10 performs the following three types of operations based on the control signal C2. First, the transmission data from the jitter suppressor 9 is switched to either of the transmitters 11 and 12 and output. Second, the jamming pattern signal from the jamming pattern generator 8 is output to both the transmitters 11 and 12. Third,
No signal is output to the transmitters 11 and 12 for a certain period of time, and a silent state is created.

When the silence control signal C3 is input, the silence timer 6 outputs a pulse that lasts for a fixed time.

The control unit 5 is a state machine, and is composed of a gate circuit 51 and a register 52. The gate circuit 51 has a timer 3,
4, the register 52, and the output of the silent timer 6 are input. The output of the gate circuit 51 is determined by these four inputs. The output of the gate circuit 51 is temporarily stored in the register 52, and is output as the control signals C1 to C3 and the data DO indicating the previous state. The control signals C1, C2 and C3 are input to the multiplexers 7 and 10 and the silence timer 6, respectively, and the data DO is input to the gate circuit 51.

FIG. 2 shows a repeater 100 constructed in this way, a bidirectional transmission line A and a unidirectional transmission line B which are bus type transmission lines.
Shows the connection with. It is connected to the transmission path A through the interface circuit 200, and the signal from the transmitter 11 of the repeater 100 is output to the transmission path A through the receiver 201 of the interface circuit 200. On the other hand, the signal from the transmission line A is transmitted by the transmitter 202 of the interface circuit 200 to the repeater 10
Input to receiver 1 of 0. Further, the transmission line B is the transmitter 12
And the input of the receiver 2 are directly connected.

Next, the operation of this embodiment will be described using the flow chart showing the operation of the control unit 5 shown in FIG. The control unit 5 checks whether or not the timer 3 outputs a pulse, that is, whether or not a signal is input from the transmission line A (step 50).
1). If the timer 3 does not output a pulse, it is next checked whether or not the timer 4 has output a pulse, that is, whether or not a signal is input from the transmission path B (step 502). When the timer 4 is not outputting a pulse, the output check of the timer 3 is performed again by returning to step 501.

When a signal is input from the transmission path B and the timer 4 is outputting a pulse, the control signal C1 is output and the multiplexer 7 selects and outputs the signal from the receiver 2. On the other hand, the control signal C2 is output, and the signal from the jitter suppression chamber 9 is output to the multiplexer 10 to the transmitter 11 (step 50).
3). As a result, the signal input from the transmission path B is input to the jitter suppressor 9 through the receiver 2 and the multiplexer 7, where the jitter is removed by adjusting the data timing, and then the multiplexer 10 and the transmitter 11 are used. Is transmitted to the transmission path A through The control unit 5 again checks whether or not the timer 4 has output a pulse, and if yes, maintains this state, and if no, moves to the next operation (step
504).

The control unit 5 sends control signals C1 and C2 to the multiplexers 7 and 10, and sets them in an initial state (for example, the multiplexer 7 selects the signal from the receiver 1 and the multiplexer 10 transmits the pressure of the jitter suppressor 9 to the transmitter 12). Input state). Next, the control unit 5 sends the silence control signal C3 to the silence timer 6
And a pulse that lasts for a certain period of time is input to the gate circuit 51. As a result, in the next control state, the control unit 5
Outputs the control signal C2, and the multiplexer 10
The signal is prevented from being output to the transmitters 11 and 12, and a silent state for a certain period of time is provided. Such a silent state is provided to prevent the repeater from oscillating due to stopping the relay operation. That is, the second
In the figure, when the distance between the repeater 100 and the bus type transmission line A is large, the signal transmitted by the repeater 100 is returned to its own station after the transmission is completed due to the propagation delay, and the repeater 100 oscillates. It becomes a state. Therefore, such oscillation is prevented by providing a silent state that continues for a delay time or more due to the propagation delay. After that, the control unit 5 returns to Step 501 and prepares for the next relay operation.

When the timer 3 outputs a pulse in step 501, the control unit 5 outputs the control signal C1 to cause the multiplexer 7 to select and output the signal from the receiver 1, while the multiplexer 10 controls The signal C2 is output and the output of the jitter suppressor 9 is connected to the input of the transmitter 12. As a result, the signal input from the transmission path A is input to the jitter suppressor 9 through the receiver 1 and the multiplexer 7, where the jitter is removed by adjusting the data timing, and then the multiplexer 10 and the transmitter 12 are used. Is transmitted to the transmission path B through

The control unit 5 then checks whether the timer 4 is outputting a pulse, that is, whether a signal is input from the transmission line B (step 508), and if a pulse is being output, the control signal C2 is output and the output of the jamming pattern generator 8 is input to the transmitters 11 and 12, and the jamming pattern signal is transmitted to the transmission lines A and B for a certain period of time (step
510). That is, when the timer 4 is generating a pulse in step 508, the signals are input from both the transmission lines A and B, and the signals collide. for that reason. The jamming pattern signal is sent to the transmission lines A and B to completely destroy the signal, and all stations connected to the transmission line are surely confirmed to collide with the signal to eliminate the signal collision state. After that, the control unit 5 executes the above-described operations of steps 505 and 506, and returns to step 501.

In step 508, when the timer 4 does not output a pulse, a signal collision has not occurred, so a signal is further input from the transmission line A, and it is checked whether or not the timer 3 is outputting a pulse. Therefore, proceed to step 509. Here, if the timer 3 is outputting a pulse, the process returns to step 508 and the above-described operation is repeated. On the other hand, when the timer 3 does not output a pulse, it means that no signal is input from the transmission path A, and the control unit 5
Shifts to the operation of steps 505 and 506 described above, and then returns to step 501.

As described above, the present repeater relays signals and enables transmission / reception of signals between the transmission lines A and B even if the transmission lines A and B are installed at a long distance.

6 to 8 show examples of three types of networks constructed by using this repeater.

The network shown in FIG. 6 is constructed by connecting two bus type transmission lines A1 and A2 which are installed apart from each other by two repeaters 100 of the present invention. Each transmission line and the repeater are connected via the interface circuit 200, and the repeaters are connected by the transmission line B.

In FIG. 7, two star-type transmission lines formed by three nodes 71 and a star coupler 72 are connected by a repeater 100 and a transmission line B. Since the star type transmission line is essentially the same as the bus type transmission line, the star type transmission line can be thus connected by the repeater of the present invention.

FIG. 8 shows a repeater 100 to which nodes 71 are connected.
Is an example of a network constructed by connecting three optical cables 81. The repeater of the present invention can be connected to both the bidirectional transmission line (transmission line A shown in FIG. 1) and the unidirectional transmission line (transmission line B shown in FIG. 1). It is also possible to construct a network using an optical cable that is a directional transmission line.

H. Effects of the Invention As described above, the present invention, in a transmission repeater connecting a plurality of transmission lines, includes a receiver for receiving signals from the transmission lines and a transmitter for transmitting signals to the transmission lines. And a signal from the first transmission line, which is a bidirectional transmission line, to the second transmission line, which is a unidirectional transmission line, or a second transmission line.
Input and output signal selection means for outputting a signal from the transmission line to the first transmission line, signal generation means for outputting a predetermined signal, and the output signal selection means output a signal to the transmission line. After that, in order to prevent the repeater from oscillating, the control means for stopping the output of the signal to the output signal selecting means for a predetermined time, and the signal when the signals are simultaneously input from the first and second transmission lines, In order to eliminate the collision state, the control means for outputting the predetermined signal to the first and second transmission lines through the signal selecting means on the output side is installed at a long distance. A plurality of transmission lines are connected to enable communication between these transmission lines.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a connection between the embodiment and a transmission line, and FIG. 3 is a timing chart showing the operation of a timer constituting the embodiment. 4 is a block diagram showing the jitter suppressor of the same embodiment, FIG. 5 is a flow chart showing the operation of the control unit of the same embodiment, and FIGS. 6 to 8 are constructions using the same embodiment. FIG. 9 is a block diagram showing the formed network, and FIG. 9 is a block diagram showing the bath type network. 1,2 …… Receiver, 3,4 …… Timer, 5 …… Control unit, 6 ……
Silence timer, 7, 10 ... Multiplexer, 8 ... Jiaming pattern generator, 9 ... Jitter suppressor, 11, 12 ... Transmitter, 41 ... FIFO, 42 ... Counter, 43 ... AND gate, 51 …… Gate circuit, 52 …… Register, 71 …… Node, 72 …… Star coupler, 81 …… Optical cable, 100 ……
Repeater, 200 ... Interface circuit, A, B ... Transmission line.

Claims (1)

[Claims] 1. A transmission repeater for connecting a plurality of transmission lines, which receives signals from a first transmission line which is a bidirectional transmission line and a second transmission line which is a unidirectional transmission line, respectively. A receiver for outputting, a transmitter for sending a signal to the first and second transmission lines, and a signal from the first or second transmission line, which is received through the receiver,
The input signal selecting means for selecting and outputting any one of the signals based on the first control signal, the signal generator for outputting a predetermined signal, and the input signal selecting means for the second control signal. The signal to be output is output to the first or second transmission line through the transmitter, or the predetermined signal output from the signal generator is output to the first and second transmission lines through the transmitter. Output signal selecting means for stopping the signal transmission to the transmission path, and when a signal is input from the first or second transmission path, the signal is selected and output to the input signal selecting means. When a signal is input from either the first control means for outputting the first control signal or the first or second transmission path, the output signal selecting means outputs the second control signal. Output to The second control means for outputting the signal output by the input signal selecting means to the first or second transmission path different from the transmission path that has received the signal, and the first and second transmission paths. Third control means for outputting the second control signal to the output signal selecting means, the second control signal being output to the first and second transmission paths when signals are input from both of them; After the output signal selecting means outputs the signal to the first or second transmission path, outputs the second control signal to the output signal selecting means to stop sending the signal to the transmission path for a predetermined time. A repeater for transmission, comprising: