JPS61232733A - Optical transmitting circuit - Google Patents

Abstract

PURPOSE:To improve reliability of the titled circuit by transmitting the special signal by the same optical cable as the main signal transmission, detecting the defect of the optical cable at both edges by the transmitting receiving condition and selecting other optical cable by the optical branch selecting element of both sides. CONSTITUTION:By using optical branching filters 14a and 14b, an optical transmitting main signal 3 and optical transmitting special signals 13a and 14b are transmitted into the same optical cable 4, an optical receiving device 5 receives the main signal 3, an optical transmitting receiving device 12a transmits the special signal 13a, receives the special signal 13b, and an optical transmitting receiving device 12b transmits the special signal 13b and receives the special signal 13a. When the special signals 13b and 13a can not be received by optical transmitting receiving devices 12a and 12b, the optical transmitting receiving devices 12a and 12b respectively drive optical switches 11a and 11b, and the optical cable is changed over from 4 to 4a. Thus, the abnormality of the optical cable can be detected at a high speed and without fail, and instantaneously, the cable is changed over to the substituting cable, and therefore, the reliability is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to an optical transmission power transmission line protection relay that collects terminal information using, for example, an optical cable and implements a predetermined protection function based on this information. This refers to optical transmission circuits used in electrical equipment, etc.

[Conventional technology]

Figure 2 shows 2 For example, Electric Kyodo Research Vol. 39 No. 5 11-1
9 is a configuration diagram showing the conventional optical transmission circuit shown on page 3.
In the figure, (1) is a transmission main signal input terminal into which a main signal to be transmitted to the other party's terminal is input.

(2) is an optical transmitter that converts this main signal into an optical transmission main signal (3) and sends it out, (41 is an optical cable that guides this optical transmission main signal (3) to the other terminal, and (5) is an optical cable that guides this optical transmission main signal (3) to the other terminal. An optical receiver receives the transmitted optical transmission main signal (3).

It is composed of an optical receiving element (6), a demodulator (7), and an AGO (automatic amplification factor control) circuit (8). (9) is a reception main signal output terminal that receives and receives the reception main signal output from the demodulator (7), and 2 is a monitoring output terminal that outputs when the main reception signal is out of the control range of the AGC circuit (8).

The operation shown in FIG. 2 will be explained. When a main signal to be transmitted to a destination terminal is input to a transmission main signal input terminal (1), an optical transmitter (2) sends out an optical transmission main signal (3).

This optical transmission main signal (3) is guided to an optical cable (4).

The light reaches the optical receiver (5) of the receiving terminal of the other party.

In the optical receiver (5), the optical receiving element (6) converts the optical transmission main signal (3) into an electrical quantity, and the demodulator (7) converts the received main signal corresponding to the transmitted main signal to the received main signal output terminal. (9
). The AGC circuit (8) is an optical receiving element (6)
This device is provided to compensate for changes in the output of the optical transmitter (2) or changes in the output of the optical transmitter (2), etc., due to sensitivity changes due to temperature. ) is controlled so that its output is always constant. By the way, when the output of the optical receiving element (6) falls below its own set control range, the AGC circuit (8) disconnects the optical cable (41).

It determines that the optical transmitter (2) is defective or the optical receiving element (6) is defective, and outputs an output to the monitoring output terminal (11).In this case, the AGC circuit (8) outputs the main signal. The clock period of the optical transmitter (2) must not be increased during the no-signal period, and therefore the response speed of the AGC circuit (8) must be naturally slow. ) is necessary because it generally performs some kind of modulation.

[Problem that the invention seeks to solve]

Conventional optical transmission circuits are configured and operate as described above, so the type of main signal (duty cycle).

Depending on the presence or absence of modulation and differences in modulation methods, AGC! circuit(
8) The sensitivity and response speed will be limited.

Therefore, when this type of optical transmission circuit is applied, for example, to a power transmission line protection relay device that protects important power transmission lines and is required to operate at high speed and with high reliability.

It had fatal drawbacks such as slow response speed and no alternative method in case of cable failure.

This invention was made to solve these problems, and by quickly and reliably monitoring the status of optical cables regardless of the type of main signal, and by immediately switching to an alternative cable in the event of a cable failure, The purpose is to obtain a highly reliable optical transmission circuit.

[Means for solving problems]

An optical transmission circuit according to the present invention includes a plurality of optical cables,
An optical branching selection element is installed to select a predetermined optical cable from among these, and the predetermined optical cable is normally used for main signal transmission, and for monitoring the optical cable, it is connected to an optical transmitter/receiver for transmitting and receiving specific signals at the transmitting and receiving ends. A wave transmitter is installed, this specific signal is transmitted through the same optical cable as the main signal transmission, and a defect in the optical cable is detected at both ends based on the transmission/reception status of this specific signal, and another optical cable is selected by optical branch selection elements at both ends. This is what I did.

[Effect]

In this invention, the specific signal for monitoring the optical cable is separated from the main signal by an optical multiplexer/demultiplexer, transmitted within the same optical cable, and guided to the other terminal, and the specific signal is converted into the main signal by the optical multiplexer/demultiplexer at both ends. A defective optical cable is detected by branching from the optical fiber, and another optical cable is selected by an optical branch selection element.

[Embodiments of the invention]

FIG. 1 is a block diagram showing an optical transmission circuit according to an embodiment of the present invention. In FIG. 1, (1) to (5) and (9) are completely the same as the conventional circuit described above. In this example,
An optical switch is used as the optical branch selection element.

An example in which two optical cables are used as a plurality of optical cables is shown.

(4a) is another optical cape A/ installed in parallel with the optical cable (4), (11a), (11b) is an optical switch + that can arbitrarily switch between these two cables (4) and (4a).
(12a1(12))) is an optical transmission specific signal that is transmitted and received by the optical transceiver (12a), (14a), (14
b) is the optical transmission main signal (3) and the optical transmission specific signal (1).
3a), an optical multiplexer/demultiplexer that multiplexes and demultiplexes (i3b);
(15a) and (15b) are this optical multiplexer/demultiplexer (14
a), (14b) and the above optical switches (11a) (11
1) Main signal (3) and specific signal (13a) connecting
.

(Optical cable for guiding the multiplexed signal with 13 lights.

(L6a) is an optical cable for guiding the main signal (3) connecting the optical transmitter (2) and the optical multiplexer/demultiplexer (f4a), (1
61)) is an optical cable for guiding the main signal (3), connecting the optical receiver (5) and the optical multiplexer/demultiplexer (14'b), (
171L), (18a) is an fF constant signal (13a) that connects the optical multiplexer/demultiplexer (14a) and the optical transceiver (12a),
(13b) Light cape A/, (171))
(181)) is an optical multiplexer/demultiplexer (141)) and an optical transceiver (
12) Specific signals (13b), (15a) connecting with 1)
) is an optical cable for guiding.

Next, the operation will be explained. Light switch (11a).

Although the optical cable (4) is used according to (11b), the transmission of the main signal (3) is the same as in the conventional circuit. Here, the duty cycle of the basic clock of the main signal (3) is 50 as the specific signals (13a) and (13b).
This section describes the case where the data is sent using When transmitting different types of signals by superimposing them on the same original cable, there is a method of transmitting different wavelengths, and this method is adopted in this embodiment. The optical multiplexer/demultiplexer (14a) and (14b) are, for example, 8 as is well known.
It is possible to combine 9 lights of different wavelengths of 10 nm and 890 nm, and by using this optical multiplexer/demultiplexer, the optical transmission main signal (3) and the optical transmission specific signal can be combined in the same optical cable (4). (13a) and (13b) can be transmitted. As a result, the optical receiver (5) receives the main signal (3), the optical transceiver (12a) transmits the specific signal (13a) and receives the specific signal (131)), and the optical transceiver (12a) receives the specific signal (131)). ))) will transmit the specific signal (131)) and receive the specific signal (13a). Here, if the optical transceivers (12a), (12))) become unable to receive the specific signals (13b), (13a), the optical transceivers (12SL), (12))) switch to the optical switch (11a), respectively. ).

(11'b) and connect the optical cable from (4) to (4a
). These optical transceivers (12a), (12b
), methods of determining whether the specific signal (13b), (13a) cannot be received include pattern recognition of the specific signal, that is, a method of detecting that the pulse width deviates from a predetermined range, )))) There are various methods for detecting that the output of the AGO circuit (not shown) deviates from the gain adjustment range of the built-in AGO circuit (not shown), and any of these methods can be easily implemented and can be detected at high speed. . In other words, the response speed of the AGO circuit on the specific signal side is as follows: While the main signal sends and receives information using a collection of several tens of bits of the basic clock, the specific signal is the basic clock itself, so the response speed of the AGO circuit on the specific signal side is approximately
It becomes possible to reduce the number to one tenth.

Note that using the basic clock of the main signal as the specific signal has the effect of allowing the demodulated signal of the optical transceiver (12t) to be used as the basic clock for decoding the main signal. It is not limited to.

In the above embodiment, the main signal and the monitoring signal and the specific signal are multiplexed by wavelength multiplexing and transmitted using the same cable. By doing this and using an optical multiplexer/distributor instead of an optical multiplexer/demultiplexer, it is possible to obtain an optical transmission circuit that exhibits the same effects as the above embodiments. Further, in the above embodiment, the number of optical cables is two.

Needless to say, it is possible to have two or more.

Further, in the above description, this optical transmission circuit is used for a power transmission line protection relay device, but it is not limited to this, and it goes without saying that it can be used for other purposes as well.

〔Effect of the invention〕

As explained above, this invention provides a plurality of optical cables, and also provides an optical transmitter/receiver for optical cable monitoring separately from the one for normal signal transmission, and uses this to transmit and receive a specific signal. In addition to transmitting a specific optical transmission signal within the same predetermined cable, a defect in the optical cable is detected by sending and receiving the specific signal, and this drives the optical branch selection element to switch the optical cable to another optical cable. It is possible to provide a highly reliable optical transmission circuit that can quickly and reliably detect an abnormality in a component and switch to an alternative couple.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an optical transmission circuit according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing a conventional optical transmission circuit. In the figure, (1) is the transmission main signal input terminal, (2) is the optical transmitter, (3) is the optical transmission raw signal, (41, (4a) is the optical cable, (5) is the optical receiver, (9) is are reception main signal output terminals. (11a), (11b) are original switches that are optical branching and selection elements, (12a), (12))) are optical transceivers, (13a), (13'b) are optical transmission specific signal,
(14a) and (14b) are optical multiplexer/demultiplexers. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (3)

[Claims] (1) Multiple optical cables installed in parallel, an optical branch selection element that arbitrarily selects a predetermined optical cable from among the multiple optical cables at the transmitting and receiving ends, and converts the main signal to be transmitted to the destination terminal into an optical transmission main signal. an optical receiver that receives the optical transmission main signal via the predetermined optical cable; an optical transceiver that transmits and receives a specific signal for monitoring the optical cable provided at the transmitting/receiving end; and an optical multiplexer/demultiplexer for multiplexing or demultiplexing a specific signal and a main signal, which are provided for transmission on the same optical cable, and drive the optical branch selection element due to poor reception of the specific signal by the optical transceiver. , an optical transmission circuit characterized in that it allows selection of other optical cables. (2) The optical system according to claim 1, characterized in that an optical multiplexer/distributor is provided in place of the optical multiplexer/demultiplexer, and the main signal and the specific signal are transmitted through the same optical cable by time division multiplexing. transmission circuit. (3) The optical transmission circuit according to claim 1 or 2, characterized in that the basic clock of the main signal is used as the specific signal.