JP3400923B2 - Optical line diagnostic device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical line diagnostic device for diagnosing the state of an optical line such as an optical fiber line, and more particularly to a simplified optical line diagnostic suitable for making a rough diagnosis of transmission loss. Regarding the device.

[0002]

2. Description of the Related Art Diagnosis of optical lines such as optical fiber lines
Conventionally, line transmission loss, return loss, break point detection,
For each item such as core wire contrast measurement, precise quantitative measurement is performed using a dedicated measuring device such as an OTDR device.

[0003]

However, in the prior art, since precise measurement is performed by a dedicated measuring device, it is not possible to easily diagnose the optical line. That is, the dedicated measuring device for each item is usually large in size, bulky and considerably heavy, and expensive. If these are brought to the installation site or the like and measured, it is impossible to easily diagnose the optical line.

On the other hand, at the laying site of the optical line, particularly at the laying site of the optical subscriber line, rough diagnosis is often sufficient even if it is not based on precise quantitative measurement. In such a field, there is a strong demand for simple diagnosis because rough diagnosis is better than strict diagnosis.

In view of the above, the present invention is a small-sized, light-weight, easy-to-carry, easy-to-carry, low-cost, simple optical line diagnostic apparatus capable of very easily measuring the transmission loss of an optical line. The purpose is to provide.

[0006]

In order to achieve the above object, in the optical line diagnosing device according to the first aspect of the present invention, a light emitting means for generating light modulated by a signal of a predetermined frequency. A light receiving means for receiving an electric light receiving signal by receiving light, and an optical branch for introducing light from the light emitting means into one end of the optical path to be diagnosed and guiding light emitted from the one end to the light receiving means. A coupling element, an amplification degree variable type amplification means for amplifying a received light signal from the light receiving means, a switching means for switching the amplification degree of the amplification means by a manual operation, and a level of an output signal of the amplification degree variable type amplification means. To a first reference level and a second reference level higher than the first reference level, and first and second references having a light reception level lower than the first reference level according to the output of the comparison means. Of level In some, higher than the second reference level, it provided a display means for displaying the three stages are a feature.

This optical line diagnosing device comprises a light emitting means, a light receiving means, and an optical branching / coupling element, and these light emitting means and the light receiving means are coupled to one end of one optical line to be diagnosed through the optical branching / coupling element. To be done. Therefore, two optical line diagnostic devices are prepared and connected to both ends of one optical line to be diagnosed.
When the light incident on the optical line from one diagnostic device is propagated through the optical line and emitted from the other end of the optical line, and the emitted light is received by the other diagnostic device and guided to the light receiving means via the optical branching coupling element. , The received light level represents the level of light transmitted in one direction through the optical line to be diagnosed. When one optical line diagnostic device is connected to only one end of one optical line to be diagnosed, the light incident from one end of this optical line is reflected at the other end and returned to this end. And is guided to the light receiving means via the optical branching and coupling element. Therefore, the received light level represents the level of light transmitted back and forth through the optical line to be diagnosed. The light receiving signal output from the light receiving means is sent to the comparing means via the amplification degree variable type amplifying means and compared with the first and second reference levels, respectively, and the light receiving level becomes the first light receiving level according to the comparison result. It is displayed in three levels, that is, lower than the reference level, between the first and second reference levels, and higher than the second reference level. When the amplification degree of the variable amplification type amplifying means is switched, the amplification degree of the light receiving level is changed with respect to the fixed first and second reference levels, and the display state is changed. Since the switching of the amplification degree is performed manually, it is known which amplification degree has been switched, so that the light reception level can be known. This received light level is
Since it is the level of light transmitted in one direction or reciprocating light through the optical path under test, it corresponds to the transmission loss of this optical path under test. It is possible to know whether there is any by manually switching the amplification degree of the amplification means and changing the display state.

In the optical line diagnostic apparatus according to the present invention, in addition to the above configuration, an input / output terminal to which an earphone and a microphone are coupled, and a microphone input via the input / output terminal are provided. A switch for switching the light emitting means to be modulated by the audio signal,
A variable amplifier for amplifying an audio signal that outputs an audio signal to the earphone through the input / output terminal, and a destination of the light receiving signal from the light receiving means, from the amplification degree variable type amplifying means whose amplification degree can be switched by the switching means, Switch to the above variable amplifier for audio signal amplification,
It is characterized in that a switch interlocking with the above switch is further provided.

From the measurement mode in which the transmission loss of the optical line to be diagnosed is diagnosed by simply switching two switches that are interlocked with each other, the one optical line to be diagnosed is used and connected to both ends of the line. It is possible to switch to a call mode in which a call is made between the two optical line diagnostic devices. When switched to the call mode, the two devices can talk with each other by using the earphone and the microphone coupled to the input / output terminals of each optical line diagnostic device. The light emitting means and the light receiving means used for diagnosing the transmission loss are also used in this call mode, and are used in both the measurement mode and the call mode.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, the optical line diagnostic apparatus according to the present invention includes an input / output terminal 11 of a headset and an adapter 12. The terminal 11 is a connector into which a jack of a headset (not shown) in which an earphone and a microphone are integrally held and can be set on the head is inserted, and an audio signal from the microphone is input. , The audio signal is output to the earphones. An optical fiber (not shown) to be diagnosed is connected to the adapter 12, an optical signal is made incident on this optical fiber, and light emitted from this optical fiber is taken out.

The audio signal input from the terminal 11 is amplified by the amplifier 21 and then sent to one input of the comparator 24 via the switch 22. A DC reference voltage from the reference DC power supply 23 is also applied to this one input. Further, through the switches 14 and 15, the oscillator 16,
The signal from 17 is also superimposed. Each of these oscillators 16 and 17 has, for example, a frequency of 270H.
Switch 1 that generates a rectangular wave of z, 17 KHz.
Either is selected by 4. The output of the comparator 24 is applied to the base of a transistor 25, and the transistor 25 drives a light emitting element 31 such as an LED.

The light emitting element 31 is integrally formed as an optical IC module 30 with light receiving elements 32 and 33 such as photodiodes and phototransistors and an optical coupler (optical branching and coupling element) 34. The light from the light emitting element 31 is incident on the optical fiber to be diagnosed via the optical coupler 34 and the adapter 12. Further, this light is also received by the light receiving element 33 for monitoring, its output is amplified by the amplifier 26, and then guided to the other input of the comparator 24. The comparator 24 compares the two inputs and supplies the output, which is the comparison result, to the transistor 25. The feedback of the light emission of the light emitting element 31 to the input side stabilizes the light emission output.

Further, the output of the monitor light receiving element 33 that has passed through the amplifier 26 is input to the comparator 27 and compared with the reference voltage Ref3. When the output of the amplifier 26 is smaller than the reference voltage Ref3 because the light output of the light emitting element 31 has not reached the predetermined value, the alarm indicator 28 lights and an alarm is generated. The alarm indicator 28 is composed of, for example, an LED.

The light emitted from the optical fiber to be diagnosed is guided to the light receiving element 32 via the adapter 12 and the optical coupler 34, and the output of the light receiving element 32 is passed through the switch 41 to the low-pass filter 37 and the audio signal amplification. It is sent to the variable amplifier 35. The variable amplifier 35 is provided with a volume adjusting volume (variable resistor) 36.

A variable amplifier 42 is also connected to the switch 41. The switch 41 sends the output of the light receiving element 32 to the low-pass filter 37 side or the variable amplifier 4 is connected.
Switching to the 2 side is made. This variable amplifier 4
Reference numeral 2 is, for example, an OP amplifier, which is configured to change the amplification degree by changing its feedback resistance, and also has a function as a low-pass filter for amplifying only low frequency components. By operating the switch of the range selector 43, the feedback resistance changes and the amplification degree changes.

The output of the variable amplifier 42 is input to two comparators 44 and 45, and the reference voltage Ref is supplied to each of them.
1, compared to Ref2. The outputs of the comparators 44 and 45 are input to the decoder 46, and three light emitting elements (for example, LEDs) 47, 48, depending on their combination,
49 is selectively driven.

The switches 14, 22, 41 are composed of relay contacts or semiconductor switches, and the mode selector 1
According to the switching operation of 3, the switches are interlocked with each other. When the mode switch 13 is switched to the measurement mode, the switch 14 is switched to the oscillator 16 side, the switch 22 is turned off, and the switch 41 is switched to the variable amplifier 42 side. At this time, if the switch 15 is turned on, a rectangular wave of 270 Hz is superimposed on the DC voltage of the reference DC power supply 23, and the light output of the light emitting element 31 is shown in FIG.
It becomes something like. When the switch 15 is turned off, the light emitting element 31 is driven in response to the DC signal from the reference DC power supply 23, and the light emission output is DC light as shown in FIG.

If such light is incident on the optical fiber to be diagnosed and the optical line diagnostic devices are connected to both ends of the optical fiber to be diagnosed, both of these optical line diagnostic devices are the optical line diagnostic devices of the other party. The light which is incident from the optical fiber and is propagated through the optical fiber to be diagnosed is received. When the optical line diagnostic device is connected to only one end of the optical fiber under test, the optical line diagnostic device propagates the light emitted by itself through the optical fiber under test and is reflected by the end face on the opposite side and returns. Will receive the light.

When the measurement mode is set, this optical line diagnostic device is usually connected to both ends of the optical fiber to be measured, and both receive light from the other. The received light signal is amplified by the variable amplifier 42 via the switch 41 and compared with Ref1 and Ref2 by the comparator 44. As shown in FIG. 3, the received light level is higher than Ref1 and R
If it is smaller than ef2, the output of the comparator 44 is H.
Then, the output of the comparator 45 becomes L. These outputs are decoded by the decoder 46, and the light emitting element 4 of “IN” is detected.
8 is driven, the light emitting element 48 is turned on, and it is displayed that the light receiving level is within the range between Ref1 and Ref2.

When the received light level is lower than Ref1,
The outputs of the comparators 44 and 45 both become L, and their outputs are decoded by the decoder 46 to generate "UNDE".
The “R” light emitting element 47 is turned on, and the light receiving level is Ref1 to Ref1.
It is displayed that the range of Ref2 is under. On the contrary, when the received light level is higher than Ref2, the outputs of the comparators 44 and 45 both become H,
These outputs are decoded by the decoder 46, and the “OVER”
The “R” light emitting element 49 is turned on and the light receiving level is Ref1 to Ref1.
It is displayed that the range of Ref2 is over.

When "over" or "under" is displayed, the range selector 43 is operated to perform switching such that the amplification degree of the variable amplifier 42 is lowered or raised. Then, the range IN is displayed at any of the amplification degrees, so that it is possible to know what the received light level is.

Therefore, by observing the light emitting states of the light emitting elements 47 to 48, the level (intensity, luminance) of the light emitted from the optical line diagnostic device of the other party and received through the optical fiber to be diagnosed, that is, The transmission loss of the diagnostic optical fiber can be known. It should be noted that such a diagnosis is performed by turning on the switch 15 and using the 270 as shown in FIG.
The same applies to the case of using the light modulated at Hz or the case of using the DC light as shown in FIG. 2A with the switch 15 turned off. However, using the modulated light causes a DC drift or the like. It is desirable because it is not affected by. Also, if the optical line diagnostic device is not connected to both ends of the optical fiber to be diagnosed but is connected to only one end, the reflected light from the other end will be received, but in that case, the reflection state will be stable. If so, it is possible to diagnose the line condition such as transmission loss of the optical fiber to be diagnosed, and it is also possible to diagnose to a certain extent what is happening at the other end due to fluctuations in the received reflected light itself. is there.

In particular, when the DC light is used, the received light level is as shown in FIG. 2C, as if the DC light was modulated by the low frequency signal due to the change of the reflection state at the other end. fluctuate. Therefore, by separately switching only the switch 41 to the low-pass filter 37, only the low-frequency component is taken out, amplified by the amplifier 35, and led to the earphone of the headset connected to the terminal 11, and the change can be heard by the ear. You can In fact, for example, if you rub the other end with your finger, you can hear the sound like "rumble", and also when you bend or shake the optical fiber, the effect on the optical line of any kind (Reflection, interference, transmission loss, etc.) occur, so it is possible to hear sounds based on them. Therefore, by listening to such a sound, the state of each optical fiber end face can be changed at the other end, and the like, which can be used for performing the core wire comparison.

When the mode switch 13 is switched from the measurement mode to the call mode, the switch 22 is turned on, the switch 14 is switched to the oscillator 17 side, and the switch 4 is operated.
1 is switched to the low pass filter 37 side. At this time, the switch 15 is turned on. Therefore, the audio signal from the microphone input from the terminal 11 is output from the reference DC power supply 23 and the oscillator 17
Is superimposed on the rectangular wave signal of 17 KHz from FIG. 2 and the optical signal as if the rectangular wave signal of 17 KHz is used as a carrier and amplitude-modulated with an audio signal as shown in FIG. It

In the call mode, since another optical line diagnostic device is connected to the other end of the optical line to be diagnosed, such modulated lights of the carrier of 17 KHz are mutually received. . The received light signal is passed through the low-pass filter 37 to remove the frequency component of the carrier and become only the audio signal component, which is guided to the earphone of the headset connected to the terminal 11. As a result, two optical line diagnostic devices connected to both ends of the optical fiber to be diagnosed can talk with each other.
At this time, the amplifier 35 has a volume 36 for volume adjustment.
Is provided, it is possible to make the voice from the other party easy to hear, and it is possible to estimate the transmission loss of the measured optical line to some extent by the position of the volume 36 at that time. .

For rough estimation of the transmission loss of the measured optical line, the switch 22 is turned off and the switch 14 is switched to the oscillator 16 side to emit the 270 Hz modulated light from the light emitting element 31. Then, this can be received by the other optical line diagnostic device. In this case, a continuous sound of a constant volume of 270 Hz can be heard by the earphones, and the transmission loss of the measured optical line can be roughly measured by the position of the volume 36.

When the switch 15 is turned off in the call mode, the direct current light is directly modulated by the audio signal, and the optical signal as shown in FIG. 2C can be generated from the oscillator 31. Since such an optical signal is received by the other optical line diagnostic device, the low-pass filter 3
7 becomes unnecessary. If an optical signal in which direct current light is directly modulated by an audio signal as shown in FIG. 2C is used, the oscillator 17 and the low pass filter 37 can be omitted from the beginning, and the manufacturing cost can be reduced. Is possible.

The above description relates to one example, and it goes without saying that the present invention is not limited to the above description. For example, the light emitting element 31, the light receiving elements 32 and 33, and the optical coupler 34 are the optical IC module 30.
However, it is not always necessary to perform such integration, and other specific configurations can be changed in various ways.

[0029]

As described above, according to the optical line diagnosing device of the first aspect of the present invention, it is easy to determine whether the transmission loss of the optical line to be diagnosed is within a certain range, high, or low. Can be diagnosed. According to the optical line diagnosing device of the second aspect, it is possible to switch between the optical line diagnosing devices connected at both ends of the optical line itself by using the optical line to be diagnosed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing respective light outputs.

FIG. 3 is a graph showing a relationship between a light receiving level and a reference voltage.

[Explanation of symbols]

11 Headset Input / Output Terminal 12 Adapter 14, 15, 22, 41 Switch 21 Audio Signal Amplifying Amplifier 23 Reference DC Power Supply 24, 27, 44, 45 Comparator 25 Driving Transistor 26 Amplifier 28 Alarm Indicator 30 Optical IC Module 31 Light emitting element 32 Light receiving element 33 Monitor light receiving element 34 Optical coupler 35 Audio signal amplification variable amplifier 36 Volume adjusting volume 37 Low-pass filter 42 Variable amplifier 43 Range switcher 46 Decoder 47, 48, 49 Light receiving level display light emitting element

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keitaka Enomoto 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) Reference Japanese Patent Laid-Open No. 3-39629 (JP, A) Kaihei 6-123704 (JP, A) Actual opening Sho 61-32948 (JP, U) Actual opening Flat 6-13912 (JP, U) Actual opening 1-158973 (JP, U) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G01M 11/00-11/08 H04B 9/00 H04B 17/00-17/02 G02B 6/00 G01R 19/00-19/32

Claims (2)

(57) [Claims] 1. A light emitting means for generating light modulated by a signal of a predetermined frequency, a light receiving means for receiving the light to obtain an electric light receiving signal, and light from the light emitting means of a diagnostic optical line. An optical branching / coupling element that guides light emitted from one end to the above-mentioned light receiving means while entering at one end, an amplification degree variable type amplification means for amplifying a light reception signal from the above light receiving means, and an amplification degree of the amplification means Switching means for switching by manual operation, comparing means for comparing the level of the output signal of the amplification degree variable type amplifying means with a first reference level and a second reference level higher than this, and depending on the output of the comparing means. hand,
An optical line, comprising: a display unit that displays in three stages: a light receiving level is lower than a first reference level, is between a first and a second reference level, and is higher than a second reference level. Diagnostic device. 2. An input / output terminal to which an earphone and a microphone are coupled, a switch for switching the light emitting means to be modulated by an audio signal from the microphone input through the input / output terminal, and the input / output described above. A variable amplifier for amplifying an audio signal, which outputs an audio signal to an earphone via a terminal, and a variable amplification type amplifying means whose amplification degree can be switched by a switching means to a destination of a received light signal from the light receiving means. The optical line diagnosing device according to claim 1, further comprising: a switch interlocking with the switch for switching to a variable amplifier for amplification.