JPH02234039A - Pair identification device for coated optical fiber - Google Patents

Abstract

PURPOSE:To improve reliability by using an optical signal which flickers in accordance with a previously set code as a signal for pair identification for coated optical fiber and discriminating whether or not the code obtained by decoding the optical signal coincides. CONSTITUTION:A low frequency signal generated from an oscillation circuit 11 is amplified in an AC amplification circuit 12 and switched by a switching circuit 13 which is controlled by a control circuit 14. Then, a light emitting element 15 is driven with the switched low frequency signal and the optical signal outputted from the element 15 is made incident on a coated optical fiber 16. The one end of the optical fiber 16 is temporarily bent to be the specified radius of curvature, while a bending addition device 17 is provided on the other end side of the optical fiber 16. Thus, light propagated in the optical fiber 16 is leaked to the outside without cutting the optical fiber 16. The leaked light is received by a photoelectric conversion element 18 from which an electrical signal is obtained. The electrical signal is converted 20 into a DC signal through a narrow-band AC amplification circuit 19 and transmitted to a discrimination circuit 20 after shaping the waveform thereof in a discrimination circuit 22.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an optical fiber core comparison device used during the installation and maintenance of optical fiber lines.

[Conventional technology]

Optical fiber cables usually include a large number of optical fiber cores and are long enough to reach several krn each, so when connecting them, a large number of optical fiber cores are connected at both ends of the optical fiber cable. It is necessary to compare each line one by one to find the same line at both ends. Conventionally, as an optical fiber core comparison device for this purpose,
Something like the one shown in Figure 3 was used. The light source 31 is one that generates an optical signal modulated with a low frequency signal, and this modulated optical signal is input to one end of the optical fiber 32. A bending device 33 is disposed on the other end of the optical fiber 32, thereby bending the optical fiber 32 to a predetermined radius of curvature, thereby causing leakage light. That is, by leaking the optical signal propagating through the optical fiber core 32, the light propagating in the optical fiber core 32 can be extracted without cutting it. This leaked light is received by a photoelectric conversion element 34 and converted into an electrical signal. This electrical signal is amplified by a narrowband AC amplifier circuit 35. The frequency characteristic of this AC amplifier circuit 35 is a narrow band pass filter characteristic so as to amplify only the above-mentioned modulation frequency component, so that only the above-mentioned modulation frequency component is extracted, and this is used for AC/DC conversion. It is converted into a DC signal by circuit 36. This DC signal is sent to a DC level detection circuit 37, and it is detected that the DC level has exceeded a certain value. This confirms the contrast of the optical fibers. The reason why modulated light is used here is that since the power of the received optical signal is extremely small, unmodulated light cannot provide a sufficient S/N ratio, resulting in a decrease in dynamic range and reliability. by. As the modulation frequency, 270 Hz, which is widely used as a modulation frequency of a light source in optical measuring instruments, is usually used.

[Problem to be solved by the invention]

However, in conventional optical fiber fiber comparison equipment, since the modulation frequency of the modulated light is the frequency widely used in optical measuring instruments, as mentioned above, during fiber comparison work, a separate optical measuring instrument is simultaneously used. If measurements must be made on other optical fibers due to the It is not possible to determine whether there is
There is a problem in that there is a high possibility of performing incorrect fiber comparison. In addition, since the receiving side only captures the 270Hz frequency component, it is possible that noise with that frequency component may be mistaken for a core fiber comparison signal, resulting in a lack of reliability. That's a problem. The problem is very serious because these malfunctions cause it to be determined that the core wires have been compared even though they have not. In other words, if it is determined that the wires have been matched, the core wires are often cut for connection, etc., and the wires are unnecessarily cut and cannot be undone. This invention improves the reliability of optical fiber core comparison,
It is an object of the present invention to provide an optical fiber core comparison device that can guarantee reliable and error-free core fiber comparison.

[Means to solve the problem]

In order to achieve the above object, the optical fiber core comparison device according to the present invention includes an optical transmitting means for inputting a blinking optical signal according to a predetermined code into one end side of the optical fiber core; means for extracting the optical signal propagating on the wire; means for converting the extracted optical signal into an electrical signal; means for decoding the code generated by the blinking of the optical signal from the electrical signal; It is characterized by comprising means for determining whether the code matches a predetermined code.

[For production]

An optical signal for optical fiber comparison that is incident on one end of the optical fiber is designed to blink according to a predetermined code. On the other hand, the optical signal propagating through this optical fiber is extracted at the other end and converted into an electrical signal. and,
The code of the blinking optical signal is decoded from this electrical signal, and it is determined whether the decoded code matches the above-determined code. Therefore, if the optical fiber comparison optical signal described above is propagating through the optical fiber, the extracted optical signal should blink according to the predetermined code described above. Therefore, from the blinking code of the optical signal decoded from this extracted optical signal, it is easy and reliable to determine whether it is the above-mentioned optical signal for fiber comparison or another optical signal from another source. can. Therefore, if the code represented by the blinking optical signal for fiber comparison is complicated to some extent, another optical signal from another source will not be mistaken as the optical signal for fiber comparison, and the optical fiber The comparison can be made with certainty. Furthermore, even when noise or the like is mixed in, it is erroneously determined that the code does not match the predetermined code, so there is no risk of cutting the optical fiber unnecessarily, which is another advantage.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the oscillation circuit 11 is, for example, 2
A low frequency signal of 70 Hz is generated, and after this low frequency signal is amplified by an AC amplifier circuit 12, it is switched by a switching circuit 13. This switching circuit 13 is controlled by a control circuit 14. The control circuit 14 is composed of, for example, a microcomputer, and is set to output a signal of a predetermined sign as a control signal for switching. In other words, a signal with a predetermined bit pattern is sent to the switching circuit 13, and the switching circuit 13 is turned on and off accordingly. The light emitting element 15 is driven by the low frequency signal switched in this way. In this way, the optical signal for optical fiber comparison generated by the light emitting element 15 is input to one end of the optical fiber core 16. A bending device 17 is arranged on the other end side of the optical fiber coated wire 16, and a part of the optical fiber coated wire 16 is temporarily bent to a predetermined radius of curvature. By bending in this manner, the light propagating within the optical fiber core 16 leaks to the outside without cutting it. This leaked light is received by a photoelectric conversion element 18, and an electrical signal is obtained from this photoelectric conversion element 18. This electrical signal is passed through the narrowband AC amplifier circuit 1 having bandpass filter characteristics such that the peak is at 270Hz.
9, and its output is converted into a DC signal via an AC/DC conversion circuit 20. This DC signal is sent to a DC level detection circuit 21, where the waveform is shaped depending on whether the DC level is above or below a certain value, and the signal after this waveform shaping is sent to a discrimination circuit 22 consisting of a microcomputer or the like. In this embodiment, the control signal for the switching circuit 13 output from the control circuit 14 repeats a low level and a high level according to the rl01101010J sign during one period of time (TV) as shown in FIG. 2A. When it is "1", the switching circuit 13 is turned on, and when it is "0", the switching circuit 13 is turned off. Therefore, as shown in FIG. 2B, the optical signal for optical fiber comparison that is input from the light emitting element 15 to one end of the optical fiber 16 and propagated by the optical fiber 16 is a 270 Hz modulated light having the above code. Accordingly, the light emits light and extinguishes it repeatedly in a pattern. Therefore, the optical fiber core 16 equipped with the bending device 17 is
If the optical signal for fiber comparison is incident on the core wire, the output signal of the photoelectric conversion element 18 will also be as shown in FIG.
The signal has a waveform as shown in FIG. The voltage changes between high and low voltage depending on the flashing of the voltage. In other words, the code has been decoded, and the determination circuit 22 such as a microcomputer can automatically determine whether the decoded code matches the code of the signal output from the control circuit 14. ．． Therefore, 2708 from other optical measuring instruments etc.
This means that it can be reliably distinguished from the case where z-modulated light is received. In other words, even if modulated light of the same frequency is received, it is extremely unlikely that the modulated light will repeatedly emit and extinguish in accordance with the above code, except as a signal for fiber comparison. Furthermore, since the modulated light is blinked in accordance with a predetermined code in this way, and the code is also captured in addition to extracting the modulated frequency component, reliability against noise and the like is high. In other words, even if the noise contains a 270Hz component, it is highly unlikely that its blinking pattern will be the same as the fiber comparison signal. Receives a fiber comparison signal from the light emitting element 15. If noise with a 270Hz component is mixed in when the signal is being transmitted, the decoded code will not match the above code, and it will be determined that the core wires are not matched. Therefore, malfunctions caused by noise work in a direction that prevents the core wire 16 from being cut, that is, on the safe side, and in this sense as well, reliability is high. ? Note that the above embodiment is for convenience of explanation, and the frequencies and predetermined codes are only examples, and it goes without saying that other values can be used. Generally, increasing the number of code bits in one period improves reliability, but it also increases the time it takes to make a decision.
For practical purposes, a code of several bits seems to be sufficient. Furthermore, as for the encoding method, in addition to the above-mentioned embodiments, for example, a method using a start bit as a synchronization signal may be adopted.

【Effect of the invention】

According to the optical fiber fiber comparison device of the present invention, an optical signal that blinks according to a predetermined code is used as a signal for fiber comparison, and on the receiving side, the code obtained by decoding the optical signal is the above-mentioned code. Since the signal is determined to be a fiber reference signal based on whether it matches the signal, reliability is greatly improved and the risk of misidentifying signals from other optical measuring instruments is eliminated. Moreover, since malfunctions are safe, the optical fiber is not cut unnecessarily. The optical transmitter side simply needs to add a configuration to blink the light according to the code, and the optical receiver side also decodes the extracted signal and checks whether the code matches the sent code. It is easy to configure because it only requires judgment;
It can be realized at a low cost, and especially if a microcomputer is included, it can be handled by changing the software, so it can be made easier and cheaper.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2A,
B and C are time charts for explaining the operation of the same embodiment, and FIG. 3 is a block diagram of the conventional example. 11... Oscillation circuit, 12... AC amplifier circuit, 13.
...Switching circuit, 14...Control circuit, 15...
・Light emitting element 46.32... Optical fiber core wire, 17, 3
3...Bending device, 18, 34...Photoelectric conversion element, 19, 35...Narrowband AC amplifier circuit. 20, 36・
...AC/DC conversion circuit, 21.37...DC level detection circuit, 22...discrimination circuit.

Claims (1)

[Claims] (1) An optical transmitting means for inputting a blinking optical signal according to a predetermined code into one end of the optical fiber, a means for taking out the optical signal propagating to the optical fiber, and a means for taking out the optical signal propagating to the optical fiber. means for converting an optical signal into an electrical signal; means for decoding a code based on the blinking of the optical signal from the electrical signal; and means for determining whether the decoded code matches the predetermined code. Optical fiber core comparison device.