JPS6161534A - Optical repeater - Google Patents

Abstract

PURPOSE:To reduce a signal processing time in a repeater by outputting an error detection signal when the same level is consecutive for a prescribed time after an output signal of a photodetector changes to an H or L level. CONSTITUTION:When an output signal (a) of the photodetector 12 is normal (not including any error), since an output (b) of a control section 13 is always at an H level, the signal (a) is inputted directly to an optical transmitter 14. When the repeater of the pre-stage is faulty and light is made incident continuously on the detector 12, the signal (a) is always at H level and an erroneous signal is outputted. When the control section 13 detects that the H signal is consecutive for a prescribed time or over, the signal (b) is brought to the L signal and an error detection signal (d) is generated. Thus, the signal processing time in the repeater is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical repeater constituting a communication network using original fibers as transmission paths.

Conventional configurations and their problems In recent years, construction of office automation (OA) and factory automation (FA) has become more popular, and communication networks using optical fibers as transmission paths are being used in these systems. An optical repeater that constitutes such a network is composed of an optical receiver that receives optical signals, an optical transmitter that transmits optical signals, and a control section that controls each electrical signal.

The conventional optical repeater as described above will be explained below with reference to the drawings. FIG. 1 shows the configuration of a portion of a conventional optical repeater. In FIG. 1, 1 is an optical fiber transmission line on the receiving side, 2 is an optical receiver that converts the received optical signal into an electrical signal, 3 is a storage unit that stores a series of received signals, and 4 is a storage unit that detects errors in the received signals. The error detection section 3 and 4 constitute a control section 8. 6 is an optical transmitter that converts an electrical signal into an optical signal and sends it out; 6 is an optical fiber transmission line on the transmitting side.

The operation of the optical repeater configured as described above will be explained. The electrical signal output from the optical receiver 2 is input to the control section 8. The control unit 8 is composed of a storage unit 3 that temporarily stores a series of input signals, and an error detection unit 4 that detects errors in the stored signals. For example, the stored signal is input as is to the optical transmitter 5 and output as an optical signal. If there is an error in the stored signal (for example, due to a failure in the previous stage repeater), if a high (Hi) signal is output continuously as a signal, an error detection signal is output from the output terminal 7, and an error detection signal is output. A low (LO) signal is input from the storage unit 3 to the optical transmitter 5, and the optical fiber 6 is set in a state where there is no optical signal. As a result, the transmission line after the next stage is in a no-signal state, and a signal can be input from any repeater at the subsequent stage.

However, in the above configuration, in order to detect signal errors, the received signal is input to the temporary storage section 3 and then output again, which takes processing time, and when there are a large number of repeaters, the signal It takes a long time for the information to be transmitted over the network, and since the storage unit 3 is used, the repeater has the disadvantage of being expensive.

Purpose of the Invention In view of the drawbacks of the above-mentioned conventional examples, the present invention solves the problem of signal errors caused by failures of upstream repeaters, in other words, when a normal signal is input to a repeater in a communication network using optical fiber as a transmission path. However, due to a failure in the repeater, a state in which light is constantly being transmitted on the subsequent transmission path is detected, and
An object of the present invention is to provide an optical repeater in which signal processing time in the repeater is short.

Structure of the Invention The optical repeater of the present invention includes an optical receiver that receives an optical signal and converts it into an electrical signal, an optical transmitter that converts the electrical signal into an optical signal and transmits it, and a failure of the optical repeater in the previous stage. When light is continuously incident on the optical receiver and a Hi or Lo signal is continuously output from the optical receiver for a certain period of time or more, this is detected;
Consisting of a control unit that inputs a signal of opposite polarity to the output signal to the optical transmitter, and an error detection unit that outputs an error detection signal when the same signal continues for a longer time than the certain time, By inputting some of the output of the optical receiver directly to the optical transmitter and the other input to the control section and error detection section described above, the signal processing time at the repeater can be shortened, and after error detection, the output of the subsequent stage can be inputted. The transmission line including the repeater is placed in a no-signal state.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows the configuration of a portion of an optical repeater in an embodiment of the present invention. In FIG. 2, 11 is an optical fiber transmission line on the receiving side, 12 is an optical receiver that converts the received optical signal into an electrical signal, 13 is a control unit that controls the received signal, and 14 is a converter that converts the electrical signal into an optical signal. 15 is an error detection unit that detects errors in the received signal 7 and outputs an error detection signal from an output end 16; 17 is an output signal of the optical receiver; AN that inputs the output of the logical sum with the output signal of the control unit to the optical transmitter 14
This is the D circuit.

The operation of the optical repeater configured as described above will be explained with reference to FIG. FIG. 3 is a signal waveform diagram of each part of the embodiment of FIG. 2, where a is the output signal of the optical receiver 12, b is the output signal of the control section 13, C is the input signal to the optical transmitter 14,
d is an error detection signal output from the output terminal 16.

Now, a case will be described in which the output signal a of the optical receiver 12 corresponds to the light incident on the optical receiver 12, that is, the case where the incident light indicates the output signal a fiHi signal.

First, a part of the output signal a of the optical receiver 12 is output to the AND circuit 1.
7 and is directly input to the optical transmitter 14, and the rest is input to the control unit 13.
and is input to the error detection section 16. Optical receiver 12
If the output signal a of the controller 1 is normal and does not contain any errors, the control unit 1
Since the output signal 3 is always a Hi-fold signal, the output signal a is directly input to the optical transmitter 14 and sent to the optical fiber transmission line 18 as an optical signal. However, from time T1 in FIG. 3, for example, if the previous stage repeater fails and light continuously enters the optical receiver 12, the output signal a of the optical receiver 12 is always a Hi-multiple signal. , an incorrect signal is output. At this time, the control section 13 detects that the Hi times signal continues for a certain period of time (T2-T1) or more, and at time T2, the control section 13
3 output signal.

As a signal, the input signal C of the optical transmitter 14 is forced to Lo.
Double signal. Furthermore, if the Hi times signal continues for a time longer than time T2, an error detection signal d is generated at time T3 to notify that there is an error.

As described above, according to the configuration of this embodiment, if there is no error as described above in the output of the optical receiver 12, the output signal 19 of the optical receiver 12 is directly input to the optical transmitter 14, so that the relay The signal processing time in the device is shortened. When an error occurs in the output signal 19 of the optical receiver 12, the error detection signal 22
At the same time, the input signal 21 of the optical transmitter 14 is forcibly multiplied by the LO signal, and the transmission path after the next stage is set to a state where there is no signal, that is, there is no optical signal, and the signal is transmitted from the optional repeater at the subsequent stage to the transmission path. Make sure you can put it inside.

The optical transmitter 14 continuously transmits Hi from time T to T2.
The doubled signal is transmitted to the next stage repeater, but since the error detection ratio signal 22 is set to occur at time T3, the error detection signal is not output from the next stage repeater and an error occurs. Only the next repeater outputs an error detection signal.

In the embodiment shown in FIG. 2, a case has been described in which Hi-fold signals are consecutive as error signals. The output signal 19 may be either a Hi-fold signal or a Lo-fold signal.

In this embodiment, the explanation of extracting signals and inputting other signals to the repeater is omitted as it is a natural function.

Effects of the Invention As described above, the present invention is an optical repeater that constitutes a communication network using an optical 7-fiber as a transmission path, and is designed to prevent light from continuously entering the optical receiver due to a failure in the previous stage repeater. , a control unit that detects when the output signal of the optical receiver is a continuous Hi signal or LO double signal for a certain period of time or more and inputs a signal of opposite polarity to the output signal to the optical transmitter; and an error detection section that outputs an error detection signal when the same signal continues for a longer time than a certain period of time. With this configuration, ■ If there is no signal error in the output signal of the optical receiver due to a failure in the previous repeater, the output signal of the optical receiver can be input directly to the optical transmitter, reducing the signal processing time at the repeater. Becomes shorter.

■ If there is an error in the output signal of the optical receiver, the input signal to the optical transmitter is forced to be a signal with the opposite polarity to the output signal, so the transmission system including the repeater in the subsequent stage becomes a no-signal (no-optical) signal. (signal) and the subsequent transmission system can be used independently.

■ If there is a failure in the previous stage repeater, an error detection signal will be output, but compared to the time it takes to detect an error, the time to force the signal to have the opposite polarity is short, so the repeater in the subsequent stage In this case, no error detection signal is output, and the location of the failure can be limited.

■ Since there is no need for a signal storage unit as shown in the conventional example, the repeater can be constructed at a low cost.

It is possible to provide an optical repeater having the following effects, and its practical effects are significant.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional optical repeater, Fig. 2 is a block diagram showing an optical repeater in an embodiment of the present invention, and Fig. 3 is a signal waveform diagram of each part in the embodiment of Fig. 2. be. 11 and 18...optical fiber transmission line, 12.-
... Optical receiver, 13 ... Control section, 14 ...
. . . Optical transmitter, 16 . . . Erroneous detection unit, 16.
...Error detection signal output terminal, 17...AND
circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure? , 5' Fig. 2 Fig. 3

Claims (2)

[Claims] (1) After the electrical output signal of the optical receiver changes to high or low level, it is detected that it is continuously output for a certain period of time or more, and a signal with the opposite polarity to the signal level is input to the optical transmitter. and an error detection section that outputs an error detection signal when the same signal level continues for a period longer than the certain period of time. (2) The optical repeater according to claim 1, wherein the electrical signals that are continuously output are output in correspondence with the light that is continuously incident on the optical receiver.