JPH05133839A - Optical cable failure detection device for repeater - Google Patents

Abstract

PURPOSE:To enable abnormality of an optical fiber cable or an optical connector to be judged easily by connecting a generator which generates a specific inspection pattern to an upstream circuit of a repeater and connecting a detection circuit which performs reception check to a downstream circuit of the repeater. CONSTITUTION:A specific pattern signal is generated from a pattern generator 6 at the time of a maintenance mode in a repeater 3 at a transmission side and is output via an O/E converter 2 and an optical fiber cable 1. This pattern signal is received by a detection circuit 7 through an optical fiber cable 4 and an E/O converter 5 of the repeater 3 at a reception side. The circuit 7 judges whether a specified pattern can be received normally or not or there is any influence due to a reflection light or not and a display circuit 8 displays the result for visual inspection. In this manner, by checking influence of the reflection light or attenuation of signal for the specific pattern signal, judgment can be made when a cable, an optical connector etc., which do not satisfy specifications are used and disconnection, etc., of cable can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable defect detecting device for a repeater used for transmission equipment using an optical fiber cable.

[0002]

2. Description of the Related Art Utilizing many excellent characteristics of an optical fiber, an optical cable transmission method can not only ensure excellent economic efficiency, maintainability and reliability which cannot be realized by a conventional transmission method using a metallic cable. It is also possible to easily transmit a wideband signal such as a video. For this reason, it has a wide range of applications from relay transmission systems in the public telecommunications field to subscriber line transmission systems, and also in the field of communications for private use for video, data transmission, computer links, ships, and communications in aircraft. Has also been applied.

In general, the basic configuration of the optical cable transmission system is that an electric signal sent from a terminal such as a telephone, data, and a facsimile is converted into an optical signal by an electric-to-optical converter (the strength of the electric signal becomes the strength of the optical signal, Also, "1" and "0" of the electric signal are converted into blinking light and sent to the optical fiber. A signal propagating in an optical fiber reaches the optical partner → optical converter of the communication partner while its power becomes weaker or the waveform of the signal spreads as the transmission distance increases. The strength is converted into the strength of the electric signal, and it is returned to the original signal of telephone, data, facsimile, etc. and sent to each terminal. Electric to optical converter
It is realized by a light emitting element such as a semiconductor laser or a light emitting diode, and the light-to-electricity converter is realized by a photodiode or an avalanche photodiode.

The token access method is used as the transmission method. This is a method in which terminals are sequentially connected to form a ring, a specific signal or frame called a token is circulated on the ring, and access right to a transmission medium is given and received.A terminal that makes a transmission request circulates. Captured tokens and gain access to the ring. Next, the frame is transmitted, and after the transmission is completed, the token is transmitted to pass the access right to the downstream terminal.

When the token disappears, neither terminal can transmit. Therefore, it is monitored that the token has stopped traveling for a certain period of time, and if the state is detected, the remaining frame on the transmission medium is detected. Erase and generate a new token. Such a token disappearance monitoring function itself may be provided in any terminal, but at one point in time, only the monitoring function of one terminal is activated. Such a method may be collectively referred to as a token passing method.

The token access can be applied even if the physical shape is a bus shape if the terminals sequentially form a logical ring. This bus type is specifically called the token passing bus, or simply the token bus system. In this case, each terminal
It records the addresses of the preceding terminal that receives the token, its own terminal, and the succeeding terminal that passes the token next, receives the token from the preceding terminal, and then sends it to the succeeding terminal. Logic must be provided to dynamically change this record when a terminal is added to or removed from the ring according to power on / off.

When the physical shape is a ring, it is called a token ring system. At this time, each terminal has a regenerative repeater mechanism called a repeater. The repeater puts the bit string sent from the upstream into a FIFO register and stores it in several bits. The data is reproduced with a delay and sent to the downstream station, and at the same time, the address attached to the frame is recognized, and the frame addressed to the own station is copied and stored in the memory.

The repeater also has the ability to rewrite bits while in the FIFO. This function changes the token to a code that points to the beginning of the frame,
Continue sending data. When the sent frame makes a round and returns, it is erased (for example, changed to time fill). Further, the terminal indicated by the destination address can update the bit indicating whether the frame attached to the end of the frame is copied or the address is recognized. This function is used for flow control, recognition of an adjacent upstream terminal, detection of a duplicate address, etc. by utilizing the characteristic of the ring that a frame makes one round.

[0009]

As described above, the conventional repeater has only the function of putting the photon in the light emitting state at the time of maintenance, and the light emitting power is measured or the light receiving power is measured by the other side to obtain the transmission line. However, in the conventional method like this, it is possible to measure only the loss of the transmission line, so when using a cable or optical connector that does not meet the specifications, Even if there was a connection error in the optical connector, it was not possible to understand it, and it was not until the actual transmission occurred that a transmission error occurred.

[0010]

SUMMARY OF THE INVENTION The present invention is an O / E converter for converting an optical signal transmitted through an upstream optical fiber cable into an electric signal, and an electric signal received from an upstream station. Connected to the repeater's upstream circuit, and a repeater for transmitting again to the downstream station, an E / O converter for converting the reproduced electric signal regenerated by this repeater into an optical signal and transmitting it to the downstream optical fiber cable, and the upstream circuit of the repeater. And a pattern generator for generating a predetermined inspection pattern, and an O / E converter, an upstream optical fiber cable, a downstream optical fiber cable and an E / O connected to the downstream circuit of the repeater when the repeater is not used. A repeater including a detection circuit that receives a test pattern transmitted through a transmission circuit including a converter and determines a connection failure of the transmission circuit. A use optical cable fault detection apparatus.

[0011]

In the optical cable defect detecting device for the repeater of the present invention, the optical signal transmitted through the upstream optical fiber cable is converted into an electric signal, and the reproduced electric signal reproduced by the repeater is converted into an optical signal again. Then, the pulse generator is connected to the upstream circuit of the repeater to generate a predetermined inspection pattern. When the repeater is not used, the O / E converter and the upstream optical fiber cable are used. , The inspection pattern transmitted via the transmission circuit including the downstream optical fiber cable and the E / O converter is received, and the connection failure of the transmission circuit is determined.

[0012]

EXAMPLE An O / E converter 2 for converting an optical signal transmitted through an upstream fiber cable 1 into an electric signal,
A repeater 3 for reproducing an electric signal received from an upstream station (not shown) and transmitting it again to a downstream station (not shown), and a reproduced electric signal reproduced by the repeater 3 is again converted into an optical signal and transmitted to a downstream optical fiber cable 4. E / O converter 5, a pattern generator 6 connected to the upstream side circuit of the repeater 3 to generate a predetermined inspection pattern, and a pattern generator 6 connected to the downstream side circuit of the repeater 3, and when the repeater 3 is not used, The inspection pattern transmitted via the transmission circuit including the O / E converter 2, the upstream optical fiber cable 1, the downstream optical fiber cable 4 and the E / O converter 5 is received, and a connection failure of the transmission circuit is detected. 1 shows a repeater optical cable defect detection device including a determination detection circuit 7 and a repeater 3 using an optical fiber cable. At that time, when the optical fiber cable is connected, a circuit that sends a specific pattern in the maintenance mode and a circuit that receives the circuit and determines whether it is normal or abnormal are generated, and the specific pattern is generated from the repeater in the maintenance mode. By incorporating a generator circuit and a receiving circuit that receives a specific pattern and determines whether the cable is normal or not, this makes it easy to judge the quality of the cable in the maintenance mode when the cable is connected.

That is, in the block diagram in which the pattern generator 6 and the detection circuit 7 for receiving check are added to the conventional circuit, the repeater 3 on the transmission side generates a specific pattern signal from the pattern generator 6 in the maintenance mode. / E converter 2 and a specific pattern signal output from the repeater 3 on the transmission side is transmitted via the optical fiber cable and the E / O converter 5 of the repeater 3 on the reception side to a detection circuit. In step 7, it is determined whether the specific pattern can be received normally or there is no influence of reflected light, and the result can be visually confirmed on the display circuit.

As described above, by checking the influence of the reflected light and the signal attenuation on the specific pattern signal, it is possible to make a determination even when a cable or an optical connector that does not meet the specifications is used, and the cable You can also find disconnections.

This diagnostic circuit can be applied not only to repeaters that face each other across an optical fiber cable, but also to optical repeaters arranged in a star shape by using an optical star coupler.

[0016]

According to the present invention, when a cable or an optical connector that does not meet the specifications is used, a disconnection of an optical fiber cable or an abnormal connection of the optical connector can be easily determined, and a system test or a current adjustment is performed. You can expect to save time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a defect detection device showing an embodiment of the present invention.

[Explanation of symbols]

 2 ... O / E converter 3 ... Repeater 5 ... E / O converter 6 ... Pattern generator 7 ... Detection circuit

Claims (1)

[Claims] 1. An O / E converter for converting an optical signal transmitted through the optical fiber cable into an electric signal, and regenerating the electric signal received from an upstream station and transmitting the electric signal again to a downstream station. A repeater, an E / O converter for converting the reproduced electric signal reproduced by the repeater into an optical signal and transmitting the optical signal to a downstream optical fiber cable, and a predetermined inspection pattern connected to an upstream circuit of the repeater. Connected to a downstream circuit of the repeater and a pattern generator for generating the signal, and when the repeater is not used, the O / E converter, the upstream optical fiber cable, the downstream optical fiber cable and the E
An optical cable defect detection device for a repeater, comprising: a detection circuit that receives the inspection pattern transmitted via a transmission circuit including an I / O converter and determines a connection defect of the transmission circuit.