JPH0514347A - Repeater - Google Patents

Abstract

PURPOSE:To eliminate the effect of a terminal station T without increasing distortion in a transmission signal on the occurrence of a fault or removal/ participation of/to the terminal station T in the case of the repeater R inserted on the way of transmission lines L1, L2 to connect the terminal station T. CONSTITUTION:An equalization circuit EQ is connected in a bypass P of a repeater R and when a fault takes place in the terminal station T, terminals 1, 2 connecting to transmission lines L1, L2 are switched to the bypass P from the terminal station T connecting to terminals 3, 4 by changeover circuits S1, S2 under the control of a control circuit C, after waveform distortion of a transmission signal from a preceding terminal station is corrected once by the equalization circuit EQ of the repeater R, and the result is sent to a succeeding terminal station. Thus, even when the transmission range is extended at bypass of the repeater R, the effect of distortion in the transmission signal waveform due to various characteristics of the transmission lines L1, L2 is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repeater inserted in the middle of a transmission line in a local area network (LAN) and used for connecting terminal stations.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a configuration of a conventional repeater R. The repeater R includes first and second terminals 1 and 2 connected to the transmission lines L1 and L2, third and fourth terminals 3 and 4 connected to the terminal station T, and a first terminal. A first switching circuit S1 for switching whether 1 is connected to the third terminal 3 or a transmission signal bypass path P; and a second terminal 2 is connected to the fourth terminal 4 or a transmission signal bypass Second switching circuit S2 for switching whether to connect to the path P
And a control circuit C for controlling the first and second switching circuits S1 and S2. When the terminal station T is in a normal state, the transmission signal from the transmission line L1 is transmitted to the terminal station T via the first terminal 1, the first switching circuit S1, and the third terminal 3. In addition, the signal from the terminal station T is transmitted to the fourth terminal 4 and the second terminal 4.
Is transmitted to the transmission line L2 via the switching circuit S2 and the second terminal 2.

On the other hand, a terminal station T connected to the repeater R
Conventionally, when it is necessary to bypass the repeater R due to a failure in the terminal station or due to attachment / detachment of the terminal station T, both the first and second switching circuits S1 and S2 are conventionally switched to the side of the bypass path P to The first terminal and the second terminals 1 and 2 were short-circuited. As a result, the transmission lines L1 and L2 are directly connected without passing through the terminal station T, and are not affected by the failure or attachment / detachment of the terminal station T.

[0004]

In the above-mentioned conventional example, when the terminal station T connected to the repeater R fails or is detached,
Since the terminals 1 and 2 are short-circuited and the transmission signal is not corrected even though the transmission distance is increased from the previous terminal station to the next terminal station across the faulty terminal station,
There is a problem that the distortion of the transmission signal becomes large, the reliability at the time of signal reproduction is lowered, and correct information cannot be transmitted.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a repeater for connecting terminal stations, which is inserted in the middle of a transmission line.
An object of the present invention is to make it possible to eliminate the influence of the terminal station without increasing the distortion of the transmission signal when the terminal station fails or is attached or detached.

[0006]

According to the present invention, in order to solve the above problems, as shown in FIG. 1, first and second terminals 1 and 1 connected to transmission lines L1 and L2 are provided. 2 and
Third and fourth terminals 3 and 4 connected to the terminal station T, and a first switching for switching between connecting the first terminal 1 to the third terminal 3 or the transmission signal bypass path P. Circuit S
1 and a second switching circuit S2 for switching whether to connect the second terminal 2 to the fourth terminal 4 or the bypass path P of the transmission signal, and the first and second switching circuits S1 and S2. In a repeater R including a control circuit C for controlling, an equalization circuit EQ for equalizing and compensating transmission signals on the transmission lines L1 and L2.
Is inserted in the bypass path P of the transmission signal.

[0007]

In the present invention, the equalizer circuit EQ is inserted in the bypass path P of the repeater R, and when the terminal station T fails and is bypassed, the transmission signal from the previous terminal station is transmitted. The waveform distortion is once corrected by the equalizer circuit EQ of the repeater R and then transmitted to the next terminal station. Therefore,
Even if the transmission distance is extended when the repeater R is bypassed, it is not affected by the distortion of the transmission signal waveform due to the characteristics of the transmission line.

[0008]

1 is a block diagram showing the configuration of an embodiment of the present invention. This repeater R includes first to fourth terminals 1,
It is equipped with 2, 3 and 4. The first terminal 1 is the transmission line L1
And the second terminal 2 is connected to the transmission line L2. The third terminal 3 is connected to the receiving side of the terminal station T, and the fourth terminal 4 is connected to the transmitting side of the terminal station T. The first terminal 1 is selected by the first switching circuit S1 to be connected to the third terminal 3 or the bypass path P. Further, the second terminal 2 is connected to the fourth terminal 4 by the second switching circuit S2,
Alternatively, it is selected whether to connect to the bypass path P.
The switching operation of the first and second switching circuits S1 and S2 is controlled by the control circuit C. The equalization circuit EQ is inserted in the bypass path P.

Here, the equalizer circuit EQ is a circuit for equalizing and compensating for the distortion of the waveform of the transmission signal on the transmission line, and a configuration example thereof is shown in FIG. The terminal a is connected to the input side of the transmission signal. The low-pass filter 5 first removes high-frequency noise from the signal transmitted through the transmission line.
Next, the equalization amplifier circuit 6 limits the noise of the waveform in which attenuation distortion has occurred in the transmission line, and amplifies the transmission signal. The timing generation circuit 7 generates a timing signal from the output of the equalization amplification circuit 6. Then, the identification reproduction circuit 8 samples the output of the equalization amplification circuit 6 with a timing signal to identify whether the transmission signal is 1 or 0, reproduces it as the original code pulse, and sends it out.

The normal operation of the repeater R of this embodiment is shown in FIG.
Shown in. The switching circuits S1 and S2 are switched and controlled by the control circuit C so that the terminal 1 is connected to the terminal 3 and the terminal 2 is connected to the terminal 4 during the normal operation. in this case,
The signal from the transmission line L1 is input to the receiving device of the terminal station T via the terminal 1, the switching circuit S1, and the terminal 3. Then, after the signal processing is performed in the terminal station T to correct the waveform distortion, the terminal 4 and the switching circuit S are transferred from the transmitter of the terminal station T.
2, the transmission signal is transmitted to the transmission line L2 via the terminal 2.

Next, FIG. 4 shows the operation of the repeater R of this embodiment during bypass. During the bypass operation, the switching circuits S1 and S2 are switching-controlled by the control circuit C so that both the terminal 1 and the terminal 2 are connected to the bypass path P side. In this case, the signal from the transmission line L1 passes from the terminal 1 to the terminal 2 through the equalization circuit EQ of the bypass path P,
It flows through the transmission line L2. That is, when the terminal station T fails, or when the terminal station T is removed, the terminals 3,
Since the communication loop is disconnected between four, the switching circuits S1 and S2 of the repeater R are switched to the equalization circuit EQ side so that the communication loop is not interrupted, and the transmission lines L1 and L2 are routed through the equalization circuit EQ. To connect. At the same time,
The equalization circuit EQ corrects the transmission signal so that the signal can be transmitted to the next terminal station with high reliability.

FIG. 5 shows a connection example of the repeater. LA
Terminal stations T1, T2, T3 are connected to the N controller 9 via relays R1, R2, R3. Each of the relays R1, R2, R3 has the configuration shown in FIG. 1 and also has an equalization circuit E2 for equalizing and compensating the transmission signal in the reverse direction. The equalization circuit E2 is inserted both during normal operation and during bypass, and corrects the waveform distortion of the transmission signal in the direction returning to the LAN controller 9.
The transmission lines L1 to L7 are configured in a loop so that the LAN controller 9 is a starting point and the transmission signals are returned to the LAN controller 9 via the terminal stations T1, T2 and T3.

The switching circuits S1 and S2 may be configured by using relays or semiconductor switching elements such as transistors and diodes.

[0014]

The repeater of the present invention is inserted in the middle of a transmission line, and when the terminal station is not connected to the transmission line,
The switching circuit is configured to connect the transmission line to the bypass path, and the equalization circuit that equalizes and compensates the transmission signal is inserted in this bypass path, so that the transmission signal is transmitted even when the terminal station fails or is removed. There is an effect that good characteristics can be maintained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of an equalization circuit used in an embodiment of the present invention.

FIG. 3 is a block diagram showing a connection state in a normal operation according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a connection state during a bypass operation according to an embodiment of the present invention.

FIG. 5 is a diagram showing an example of connection of a repeater of the present invention with a LAN controller.

FIG. 6 is a block circuit diagram of a conventional example.

[Explanation of symbols]

 S1 switching circuit S2 switching circuit C control circuit P bypass path EQ equalization circuit L1 transmission line L2 transmission line T terminal station R repeater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Anichi Kinokawa 1048, Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (1)

Claim: What is claimed is: 1. A first and a second terminal connected to a transmission line, a third and a fourth terminal connected to a terminal station, and a first terminal to a third terminal. A first switching circuit for switching between a connection to a transmission path and a bypass path for a transmission signal;
In a repeater including a second switching circuit that switches whether to connect the terminal of the second terminal to the fourth terminal or to connect to the bypass path of the transmission signal, and a control circuit that controls the first and second switching circuits. A repeater, wherein an equalization circuit for equalizing and compensating a transmission signal on a line is inserted in a bypass path of the transmission signal.