JPH0514348A - Transmitter-receiver - 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 of the terminal station T in the case of the repeater R inserted on the way of transmission lines L1, L2 and to send/receive the transmission signal by a terminal station T. CONSTITUTION:An equalization circuit EQ to correct distortion in a transmission signal is inserted to a bypass P to obtain a normal transmission signal in the case of the transmitter-receiver in which changeover circuits S1, S2 selecting whether transmission lines L1, L2 are connected to the terminal station T via a reception circuit RX and a transmission circuit TX or connected to the bypass P under the control of a control circuit C. When a fault takes place in the terminal station T and a transmission signal is bypassed via the bypass P, distortion of the transmission signal from the transmission line L1 is corrected by the equalization circuit EQ and sent to the transmission line L2 while the signal is reproduced as a normal transmission signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception device which is inserted in the middle of a transmission line in a communication network such as a LAN (local area network) to transmit / receive a signal between the transmission line and a terminal station. It is a thing.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of a conventional transceiver R. The transmitter / receiver R includes a receiver circuit RX, a transmitter circuit TX, switching circuits S1 and S2, and a control circuit C. The reception circuit RX is composed of a filter circuit, an equalization circuit and a signal detection circuit, and the transmission circuit TX is composed of a filter circuit and an equalization circuit for compensating for waveform distortion occurring in the transmission process to another station. . The switching circuit S1 selects whether to connect the transmission line L1 to the receiving circuit RX or to connect to the switching circuit S2 via the bypass path P according to a control signal from the control circuit C. In addition, the switching circuit S2
Selects whether to connect the transmission line L2 to the transmission circuit TX or to the switching circuit S1 via the bypass path P according to the control signal of the control circuit C. When a terminal station T in a normal state is connected to this transmitting / receiving device, the transmission line L1 is connected to the receiving circuit RX by the switching circuit S1, and the transmission line L2 is connected to the transmitting circuit TX by the switching circuit S2. The signal from the transmission line L1 is received by the reception circuit RX and input to the terminal station T, and the signal from the terminal station T is transmitted to the transmission line L2 by the transmission circuit TX. When it is necessary to bypass the terminal station T, for example, when a failure occurs in the terminal station T, the switching circuits S1 and S2 are connected to the bypass path P side, and the signal transmitted from another station is directly transmitted to another station. Was sent to.

[0003]

However, in the above-mentioned conventional example, when the switching circuits S1 and S2 are connected to the bypass path P side, the signal transmitted from another station is directly transmitted to another station. As a result, the transmission distance is about 2
It becomes twice as long, and the waveform distortion at the time of transmission becomes larger accordingly. For this reason, the transmission destination terminal station may not be able to receive the transmission signal and may not be able to determine whether or not there is a failure in the terminal station.

The present invention has been made in view of the above points, and an object of the present invention is to prevent a failure in a transmitter / receiver for inserting and receiving a transmission signal by a terminal station, which is inserted in the middle of a transmission line. The purpose of this is to reduce the influence of waveform distortion due to various characteristics of the transmission line when bypassing the terminal station in which the error occurs.

[0005]

The transmitting / receiving apparatus of the present invention comprises:
In order to solve the above problems, as shown in FIG. 1, a receiving circuit RX connected to a terminal station T to receive a received signal from the first transmission line L1, and a transmission signal connected to the terminal station T. To the second transmission line L2, a first switching circuit S1 for selecting whether to connect the first transmission line L1 to the reception circuit RX or the bypass path P, and
A second switching circuit S2 for selecting whether to connect the second transmission line L2 to the transmission circuit TX or the bypass path P
And a control circuit C for controlling the first and second switching circuits S1 and S2, an equalizer circuit EQ for correcting distortion of a transmission signal is inserted in the bypass path P. It is characterized by.

In the normal operation, the control circuit C connects the first and second transmission lines L1 and L2 to the receiving circuit RX and the transmitting circuit TX, respectively, and when a failure occurs in the terminal station T, It is preferable that the first and second transmission lines L1 and L2 are connected to the equalization circuit EQ in the bypass path P.

[0007]

In the transmitter / receiver of the present invention, since the equalization circuit EQ for correcting the distortion of the transmission signal is inserted in the bypass path P, a failure occurs in the terminal station T and the transmission signal is bypassed via the bypass path P. Even in the case of, the distortion of the transmission signal from the transmission line L1 can be corrected by the equalization circuit EQ, and can be transmitted to the transmission line L2 in a state of being reproduced as a normal transmission signal. Therefore, in the destination terminal station T, , The transmission signal can be received well.

[0008]

1 is a block diagram showing the configuration of an embodiment of the present invention. The transmitter / receiver R includes transmission lines L1 and L2.
Switching circuits S1 and S2 connected to the terminal station, a reception circuit RX and a transmission circuit TX connected to the terminal station T, and a switching circuit S1.
An equalizer circuit EQ connected between S2 and a switching circuit S1,
It is composed of a control circuit C for controlling S2. The switching circuit S1 connects the transmission line L1 to the receiving circuit RX, or
Alternatively, it is selected whether to connect to the equalization circuit EQ. Also,
The switching circuit S2 selects whether the transmission line L2 is connected to the transmission circuit TX or the equalization circuit EQ.

In normal operation, as shown in FIG. 3, the switching circuit S1 connects the transmission line L1 to the receiving circuit RX, and the switching circuit S2 connects the transmission line L2 to the transmitting circuit TX by the control circuit C. Controlled. The receiving circuit RX identifies a message from the signals received from the transmission line L1 via the switching circuit S1 and inputs a status signal or the like to the control circuit C. On the other hand, the transmission circuit TX converts a data signal or the like sent from the terminal station T into a format for line transmission, and transmits the data signal to the transmission line L2 via the switching circuit S2. The control circuit C includes a control unit that controls the switching circuits S1 and S2 and a data processing unit that processes the data signal, the status signal, and the like sent from the receiving circuit RX.

When a power failure or other trouble occurs in the terminal station T, the loop is disconnected in the terminal station T and information cannot be transmitted. Therefore, when an abnormality occurs in the power supply of the terminal station T and the terminal station T stops, the switching circuits S1 and S2 in the transmitter / receiver R corresponding to the faulty terminal station are automatically switched to the bypass path P to cause a failure. The terminal station is disconnected from the loop to prevent the loop from being disconnected. During the bypass operation, as shown in FIG. 4, the transmission lines L1 and L
2 is connected to the equalization circuit EQ via the switching circuits S1 and S2. The equalizer circuit EQ has a function of correcting a signal waveform distorted by various characteristics of the transmission line during signal transmission. The signal transmitted through the transmission line is corrected by the equalization circuit EQ and transmitted to another station.

Here, the equalizer circuit EQ may include an active element in addition to an amplifying action in addition to the passive element alone. The power supply in the case where an active element is used in the equalizer circuit EQ may be a backup power supply supplied from a system different from the power supply of the terminal station T, or may be used by extracting the power superimposed on the transmission signal. To be Further, the switching circuits S1 and S2 may be configured by using a relay, or by using a transistor or a diode.

FIG. 5 shows a configuration example of a communication network using the transmitting / receiving apparatus of the present invention. The LAN controller N is connected to a pair of upstream and downstream transmission lines,
A plurality of terminal stations T1, T2, T3 are provided in the middle of the transmission line.
…, Tn are branch outlets B1, B2, B3, respectively.
, Bn are connected. When sending a message from the terminal station T1 to the terminal stations T2, T3, ..., Tn, the switching circuits S1, S2 in the branch outlets B1, B2, B3 ,. ，
The switching is controlled by the control circuit C so that Tn is connected to the transmission line. If the terminal station T2 becomes faulty due to a power failure or the like and the terminal station T2 cannot operate, the switching circuits S1 and S2 are connected to the equalization circuit E in the bypass path.
Switch to the Q side. Thereby, the waveform distortion of the transmission signal is shaped and transmitted to the terminal station T3, so that the terminal station T1
The message from can be transmitted normally.

[0013]

According to the first aspect of the invention, the terminal station is bypassed in a transmitter / receiver which is inserted in the transmission line and includes a transmitter circuit and a receiver circuit for transmitting and receiving signals by the terminal station. In this case, the transmission line is switched and connected from the transmission circuit and the reception circuit to the bypass path by the switching circuit, and the equalization circuit for correcting the waveform distortion of the transmission signal is inserted in the bypass path. There is an effect that the waveform of the transmission signal can be kept good.

In the transmitting and receiving apparatus according to the second aspect, when the terminal station fails, the first and second transmission lines are connected to the equalizing circuit in the bypass path. In addition, there is an effect that it is possible to maintain a good compensating action for the line characteristics.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the invention described in claim 1.

FIG. 2 is a block diagram of a conventional example.

FIG. 3 is a block diagram of the invention according to claim 1 during normal operation.

FIG. 4 is a block diagram of the invention according to claim 1 at the time of bypass.

FIG. 5 is a diagram showing a connection example of a transmission / reception device of the present invention.

[Explanation of symbols]

RX receiver circuit TX transmitter circuit EQ equalization circuit S1 switching circuit S2 switching circuit L1 transmission line L2 transmission line P bypass route C control circuit T terminal station

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Anichi Kinekawa             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works             Within the corporation

Claims (2)

[Claims] 1. A reception circuit connected to a terminal station for receiving a reception signal from a first transmission line, a transmission circuit connected to the terminal station for transmitting a transmission signal to a second transmission line, and a first circuit. Switching circuit for selecting whether to connect the transmission line to the receiving circuit or the bypass path, and a second switching circuit for selecting whether to connect the second transmission line to the transmitting circuit or the bypass path. A transmission / reception device comprising a switching circuit and a control circuit for controlling the first and second switching circuits,
A transmitting / receiving apparatus, wherein an equalization circuit for correcting distortion of a transmission signal is inserted in the bypass path. 2. The control circuit connects the first and second transmission lines to the reception circuit and the transmission circuit, respectively, during normal operation, and when the terminal station fails, the first and second transmission lines are connected. The transmitter / receiver according to claim 1, wherein the transmission / reception device is configured to connect the line to an equalization circuit in the bypass path.