JPS6133037A - Optical transmitter - Google Patents

Abstract

PURPOSE:To reduce the probability of mistransmission without increasing the redundancy by mixing the information on the presence of external noises around a transmitter into the transmission signal. CONSTITUTION:A transmission circuit 5 of a transmitter 1 synthesizes a start bit (a), a data signal (b) sent from an input signal terminal 4, a situation transmission bit (c) sent from a noise detecting means 3 and a stop bit (d) to form an output signal frame (e) and converts it into optical signals by an E/O converter 6 to send them to an optical fiber 7. A receiver 8 converts those optical signals into original electric signals through an O/E converter 10 and sends them to a reception circuit 11. The circuit 11 always monitors the situation bit (c) among received signals and holds the preceding data after deciding that the transmitter 1 is kept under a noise mode in case a fault is detected. Thus an error of transmission can be prevented previously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical transmission device having a function of reducing transmission errors caused by external noise.

[Background technology]

One of the features of optical transmission systems is that they are susceptible to external electromagnetic noise. However, the above features are features of the optical transmission path itself, and the transmitter and receiver at both ends of the transmission path do not necessarily have the above features. Therefore, in order to ensure reliability in information transmission, it is necessary to improve the noise resistance of the transmitter and receiver.

In order to improve the reliability of the above transmitter and receiver, conventional methods include electromagnetic shielding by housing the transmitter and receiver in a conductive case, and transmitting full I, which always transmits the same information a specified number of times and receives the same information repeatedly. A method of checking whether there is an error or a method of checking for errors by adding a parity signal to the transmitted signal has been used.

However, the electromagnetic shield provided by the case has a limited noise resistance due to its structure and shape, and if erroneous transmission occurs, it is difficult to detect it. Further, if the same information is sent using heavy equipment, redundancy increases, and the method of checking by adding a parity signal has the disadvantage that it is easy to make a check mistake.

[Purpose of the invention]

The present invention has been made to improve the above points, and its purpose is to provide an optical transmission device that reduces the risk of erroneous transmission without increasing redundancy. It is in.

[Disclosure of the invention]

The present invention will be explained below based on the drawings shown as examples.

FIG. 1 is a diagram showing an embodiment of an optical transmission device of the present invention. Reference numeral 1 denotes a transmitter, which transmits whether or not there is noise using an f' register 2, an external noise detection means 3, and the output of the detection means 3, and also transmits an input signal inputted from an input signal terminal 4. a transmitting circuit 5 that converts parallel signals into serial signals;
It is comprised of an E, 10 exchange circuit 6 that converts the output of the transmitting circuit 5 into an optical signal. The optical signal is transmitted to a receiver 8 via an optical fiber 7. The receiver 8 includes a spreading body 9;
An OA conversion circuit 10 that converts the optical signal into an optical signal, a receiving circuit 11 that converts the 'i'Jt signal into the original parallel signal, and an output terminal 12 of the receiving circuit 11. configured. Further, the external noise detection means 3 includes a Ridrigger type one-shot, a Sotomulti-type Ibrator 3a,
It is composed of the high resistance 3c connected to the input terminal 3b of the seven-reticular vibrator 3a described above, and the antenna 3d whose tip protrudes outside the female body 2.

The operation of the optical transmission device constituted by the transmitter 1, receiver 8, and optical fiber 7 will be explained using an example in which the signals to be transmitted are multiple digital signals and the synchronization method is start-stop synchronization. . No. 21\1 is an example of the output signal frame configuration of the transmitting circuit 5, consisting of a start bit ■, a data signal ■, a situation transmission bit ■ and a stop bit ■.
One frame ■ is composed. The transmitting circuit 5 synthesizes the signal (N) from the input signal terminal 4 and the signal from the noise detection means 3, and outputs the output signal shown in the 21st wing. The status transmission bit (2) corresponds to the signal from the noise detection means 3. After being converted to an optical signal, 0/E
The conversion circuit 1o transforms the signal into the original city signal. The receiving circuit 11 constantly monitors the status transmission bit (3) of the above signals, and when an abnormality is detected, transmits the transmitter 1. - Prevents erroneous transmission by determining that the device is in a noise environment and retaining the previous data.

As shown in %$3M, when transmitting in both directions,
When an abnormality is detected, issue a retransmission request 4. The data sent again may be checked, and if there is no difference in the data after a specified number of retransmission requests, it may be determined that there is no abnormality, that is, there is no erroneous transmission. Note that 13 indicates a transmitter and 14 indicates a receiver.

〔Effect of the invention〕

As described above, according to the present invention, since the transmission signal includes information indicating the existence state of external noise around the transmitter, redundancy such as sending the same information a specified number of times can be increased. However, we were able to provide an optical transmission device that reduces the risk of erroneous transmission.

[Brief explanation of drawings]

VS1 is a block diagram of an optical transmission device according to an embodiment of the present invention, FIG. 2 is a block diagram of a transmission signal frame according to an embodiment of the present invention, and FIG. 3 is a block diagram of a bidirectional transmission drawing. 1... Transmitter, 3... External noise detection means, 7...
- Optical fiber, 8...receiver.

Claims (1)

[Claims] (1) In an optical transmission device comprising a transmitter, a receiver, and an optical fiber connecting the transmitter and the receiver, the transmitter is provided with an external noise detection means, and the noise detection means is An optical transmission device characterized in that the output is incorporated into a transmission signal and sent to the receiver, and the receiver determines whether to update or retain data based on the output content of the noise detection means.