JP2001201428A - Optical transmission line tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission line tester which can detect breaking and attenuation abnormality of an optical transmission line and detect misses of the wiring of the optical transmission line and the fitting of an optical connector, is inexpensive and small-sized, and can be used continuously for a long time in the field. SOLUTION: A power control circuit 14b supplies electric power to a light- emitting part 20 and a light-receiving part 30 according to the gate signal outputted from a timing generating circuit 12 and a signal pattern generating circuit 13 outputs a pulse signal to the light-emitting part 20 and a signal decision circuit 18 according to the gate signal outputted from the timing generating circuit 12 and a clock signal. The light-emitting part 20 generates and emits a light pulse signal to an optical transmission line in accordance with the pulse signal. The light-receiving part 30 receives and converts the light signal emitted from the optical transmission line into an electrical signal, and a signal decision circuit 18 decides the quality of the optical transmission line, according to the pulse signal outputted from the signal pattern generating circuit 13 and the electrical signal outputted from the light reception part 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission line tester for evaluating a two-core optical fiber transmission line for transmitting a transmission signal and a reception signal of an optical communication or an optical network of a computer, etc., using respective media. .

[0002]

2. Description of the Related Art FIG. 6 shows a configuration of a measuring system for implementing a general measuring method for evaluating an optical transmission line such as an optical fiber. As an evaluation method of an optical transmission line, for example,
A suitable light source 100 having a known light emission amount is connected to the optical transmission line 1 to be measured.
01, and an optical power meter 102 at the other end.
The optical power meter 102 measures the amount of light emitted from the optical transmission line 101 to be measured, calculates the attenuation, and confirms that there is no fiber breakage in the optical transmission line 101 to be measured.

[0003] Another evaluation method is an expensive OT.
There is a method of determining the quality of the laid optical transmission line by measuring the reflected light reflected at the cut point of the optical transmission line to be measured by using a DR (Optical Time Domain Reflectometer). Since each of these evaluation methods described above is a method for evaluating a single-core optical transmission line, when evaluating a two-core optical transmission line by using these evaluation methods, the above evaluation method must be performed twice. become.

[0004]

By the way, one of the most frequent causes of transmission failure due to an optical transmission line is a connector mounting error. That is, if the connector is not properly attached to the optical transmission line, when connecting the optical fibers to each other by the connector, the segments of the two fibers are misaligned, and the optical loss increases.

[0005] Another cause of transmission failure is a wiring error when connectors are connected to both ends of a two-core optical transmission line. That is, as shown in FIG. 7A, in the two-core optical transmission line 110, one optical transmission line 110a transmits light from one end A to the other end B of the optical transmission line and the other optical transmission line The path 110b is directional in transmitting light, such as transmitting light from the other end B to the one end A.
Each of the connectors 111 and 112 attached to both ends of the two-core optical transmission line 110 is provided with two terminals, and each terminal has a terminal for reception and a terminal for transmission. here,
In FIG. 7A, 111T and 112T are transmission terminals, 11T
1R and 112R are reception terminals.

When the connectors 111 and 112 are attached to one end A and the other end B, respectively, the connectors 11 and 112 are originally provided at one end A of one optical transmission line 110a.
If one transmission terminal 111T is connected to the light emitting means, the receiving terminal 112R of the connector 112 is connected to the light receiving means at the other end B, and the receiving terminal 111R of the connector 111 is connected at the one end A of the other optical transmission line 110b. Must be connected to the light receiving means, and the transmission terminal 112T of the connector 112 at the other end B must be connected to the light emitting means. However, as shown in FIG. 7B, if this correspondence is incorrect, a transmission failure occurs.

In such a case, if a single-core connector is connected to each end of the two-core optical transmission line, the connection between the plug and the receptacle can be easily changed by replacement. In the case of using the optical transmission line, it is necessary to replace the connector on the optical transmission line, which is a very time-consuming operation. However, the above-described conventional evaluation method cannot determine such a difference in the directionality of the optical transmission line.

In a measurement system such as that shown in FIG. 6, for example, the receiving sensitivity usually differs depending on the optical link including the light emitting source 100 and the optical power meter 102, and when an optical transmission line is actually laid. Since the transmission path length differs from the design value, it is necessary to calculate whether or not the level of the optical signal after passing through the measured optical transmission path 100 is within the range of the minimum reception level at which signal transmission is possible. I did not understand finally.

Further, in order to drive an optical link and peripheral circuits necessary for checking an optical transmission line, generally, 10
A current of 0 to 200 mA is required. For this reason, the time during which the battery voltage can be maintained at 1.2 V is only about 1 hour with a normal AA manganese battery and about 3 hours with an alkaline battery, and continuous operation cannot be sufficiently performed. It was not suitable.

The evaluation method using the optical OTDR is not suitable for on-site optical transmission line evaluation because the equipment is expensive and large and a large amount of power is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and detects a disconnection of an optical transmission line or an abnormal attenuation of an optical transmission line, and also detects an error in wiring or an optical connector installation in the optical transmission line. It is an object of the present invention to provide an optical transmission line tester which is inexpensive, small-sized, and capable of continuous use for a long time that can withstand use in the field.

[0012]

According to one aspect of the present invention, there is provided a light emitting device for emitting an optical signal generated by a light emitting element to one of two-core optical transmission lines. And a light receiving unit for receiving an optical signal emitted from the other transmission line of the two-core optical transmission line; a power source for supplying power to the light receiving unit and for intermittently supplying power to the light emitting unit Control means, a signal pattern generating means for generating a control signal for controlling a pulse pattern of an optical signal generated by the light emitting means, and outputting the control signal to the light emitting means, based on an optical signal received by the light receiving means An optical transmission line tester comprising: a determination unit for determining whether the two-core optical transmission line is good or not.

[0013] Here, when the determination means determines "good", it means that the two-core optical transmission line does not have a disconnection or an abnormal attenuation.

According to a second aspect of the present invention, in the optical transmission path tester according to the first aspect, the power supply control means determines that a ratio of a period for supplying power to the light emitting unit to a period for not supplying power is set. Power is supplied to the light emitting means periodically for a certain period of time so that the light emitting means has a minimum ratio at which a stable operation can be obtained.

According to a third aspect of the present invention, in the optical transmission line tester according to the first or second aspect, the signal pattern generating means transmits the control signal only while power is supplied to the light emitting means. It is characterized in that it is generated and output to the light emitting means.

[0016] The invention according to claim 4 is the invention according to claims 1 to 3.
In the optical transmission line tester according to any one of the above,
Optical transmission path length setting means for setting the length of the two-core optical transmission path to be measured, and minimum light receiving level setting means for setting the minimum light receiving level that can be received by the light receiving means,
And a current limiting means for limiting a current flowing through the light emitting element of the light emitting means based on each set value set by the light transmission path length setting means and the minimum light receiving level setting means.

According to the above-described configuration, the power supply to the light emitting means which consumes the most current is intermittently performed, and the generation of the control signal by the signal pattern generating means is generally performed. Further, the current flowing through the light emitting element of the light emitting means can be effectively limited without hindering the evaluation of the two-core optical transmission line. As a result, the current consumption of the optical transmission line tester can be reduced, and not only long-term continuous use that can withstand field use is possible, but also optical transmission timing and light emission timing are taken into consideration. The road can be evaluated reliably.

[0018] The invention described in claim 5 is the invention according to claims 1 to 4.
In the optical transmission line tester according to any one of the above,
The power control means supplies power to the light receiving means at the same timing as the light emitting means, and the signal pattern generating means outputs the generated control signal to the light emitting means and the determining means, The means compares the pulse pattern of the control signal output from the signal pattern generating means with the pulse pattern of the optical signal received by the light receiving means, and when the two pulse patterns match, the two-core optical transmission line Is determined to be good.

According to the fifth aspect of the present invention, the light emitting means and the light receiving means are connected to one end of the two-core optical transmission line, and the other end of the two-core optical transmission line is connected to the other end of the two-core optical transmission line. By connecting a loopback cable connecting both transmission paths, abnormal attenuation of the two-core optical transmission path can be checked by one optical transmission path tester.

The invention according to claim 6 is the invention according to claims 1 to 4
In the optical transmission line tester according to any one of the above,
The power supply control means constantly supplies power to the light receiving means, the signal pattern generation means outputs the control signal to the light emitting means, and receives a determination signal having the same pulse pattern as the control signal. The means outputs the optical signal to the determining means in synchronization with the timing of receiving the optical signal, and the determining means compares the pulse pattern of the signal for determination with the pulse pattern of the optical signal received by the light receiving means. When the two pulse patterns match, it is determined that the two-core optical transmission line is good.

According to the configuration of the sixth aspect, the light emitting means and the light receiving means are connected to one end of the two-core optical transmission path, and another light is connected to the other end of the two-core optical transmission path. By connecting the light emitting means and the light receiving means of the transmission path tester, it is possible to check for abnormal attenuation of the two-core optical transmission path and wiring errors of the connector attached to the two-core optical transmission path.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an optical transmission line tester according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an optical transmission line tester according to the present embodiment. In this figure, 10 controls the power supplied to the light emitting unit 20 (light emitting unit) and the light receiving unit 30 (light receiving unit), controls the optical signal emitted from the light emitting unit 20, and the light receiving unit 30 receives light. This is a control unit that determines the quality of an optical transmission path to be measured (hereinafter, simply referred to as an optical transmission path) based on an optical signal. 40 is the control unit 10
Is a power supply unit for supplying power to the control unit 10.

Next, a detailed configuration of the control unit 10 will be described. The control unit 10 includes a mode setting switch 11 (mode switching means), a timing generation circuit 12, a signal pattern generation circuit 13 (signal pattern generation means), a power supply control circuit 14 (power supply control means), and an optical transmission path length. It comprises a setting switch 15 (optical transmission path length setting means), a light receiving level setting switch 16 (minimum light receiving level setting means), a current limiting circuit 17 (current limiting means), and a signal determining circuit 18 (determining means). I have.

The mode setting switch 11 is a switch for setting a measurement mode in the optical transmission line tester according to the present embodiment. In the present embodiment, both ends measurement mode (second measurement mode) and loopback measurement One of two types of measurement modes (first measurement mode) can be selected. The configuration of the measurement system in each measurement mode will be described below with reference to FIG. In this figure, (a) shows the configuration of the measurement system in the both-end measurement mode, and (b) shows the configuration of the measurement system in the loopback measurement mode.

First, the two-end measurement mode is a mode used for checking the optical loss of a two-core optical transmission line to be measured (hereinafter simply referred to as an optical transmission line) and the connection with an optical connector. In the case of the measurement in this mode, as shown in FIG. 2A, two optical transmission line testers of this embodiment are prepared (1a, 1b in the figure), and each is connected to both ends of the optical transmission line 2. Measurement.

The loopback measurement mode is a mode used when measuring only the optical loss of the optical transmission line.
In the case of measurement in this mode, as shown in FIG. 2B, the optical transmission line tester 1 of the present embodiment is connected to one end of the optical transmission line 2 and one end of the optical transmission line 2 is connected to the other end. Transmission line 2
A loopback cable 3 for connecting a to the other transmission line 2b is connected. In this figure, reference numeral 4 denotes a relay adapter for connecting the optical transmission line 2 and the loopback cable 3.

The timing generation circuit 12 outputs a clock signal to the signal pattern generation circuit 13 and
A gate signal (described later) is output to the signal pattern generation circuit 13 and the power supply control circuit 14. The signal pattern generation circuit 13 generates a pulse train having a predetermined pattern while the gate signal supplied from the timing generation circuit 12 is at a high level. Then, in the both-end measurement mode, the generated pulse train is used as the light emitting unit 2.
It outputs to only 0 and outputs to the light emitting unit 20 and the signal determination circuit 18 in the loopback mode.

Here, the pattern of the pulse train generated by the signal pattern generating circuit 13 may be similar to the pattern of an optical signal actually flowing on an optical transmission line to be measured using a ROM or the like, or may be a simple pattern. May be repeated. In addition, as the simplest signal pattern, signals of “1” and “0” having a fixed time width may be simply repeated.

The power supply control circuit 14 supplies the light emitting unit 20 and the light receiving unit 30 from the power supply unit 50 based on the gate signal supplied from the timing generation circuit 12 and the measurement mode set by the mode setting switch 11. Control the power supply.

Here, the waveforms of the signals output from the signal pattern generation circuit 13 and the power supply control circuit 14 are as follows.
This will be described with reference to FIG. First, as shown in FIG. 3A, the power supply control circuit 14 supplies power to the light emitting unit 20 when the gate signal supplied from the timing generation circuit 12 is at a high level, and when the gate signal is at a low level, Stop supplying.

The ratio T1 / T2 of the high-level period T1 and the low-level period T2 of the gate signal is set to the minimum ratio at which the light emitting unit 20 and the light receiving unit 30 operate stably. Power can be minimized. For example, when a general-purpose optical link is used, T1 =
4 μs to 100 μs and T2 = about 30 μs to 10 ms are preferable.

As shown in FIG. 3B, the signal pattern generation circuit 13 generates a predetermined pulse train while the gate signal is at a high level (ie, a period during which power is supplied to the light emitting section 20). To the light emitting unit 20. Thereby, the light emitting section 20 emits light according to the supplied pulse train.

Further, when the loopback measurement mode is set by the mode setting switch 11, the power supply control circuit 14 supplies power to the light receiving section 30 only while the gate signal supplied from the timing generation circuit 12 is at a high level. (Refer to FIG. 3C, “Light-receiving unit energization timing”). In addition, when the both-end measurement mode is set, the power is always supplied to the light receiving unit 30 (see “Light-receiving unit energizing timing” in FIG. 3D).

Returning to FIG. 1, the optical transmission line length setting switch 15
Sets the length of the optical transmission line measured by the optical transmission line tester of the present embodiment. The light receiving level setting switch 16 is connected to the light receiving unit 3 in accordance with the specification value of the light receiving unit 30.
Set a minimum reception level of 0. The current limiting circuit 17
The current flowing through the light emitting element of the light emitting unit 20 is limited according to the values set by the light transmission path length setting switch 15 and the light receiving level setting switch 16, respectively.

In the loop-back measurement mode, the signal determination circuit 18 detects the pulse pattern output from the signal pattern generation circuit 13 (see FIG.
A comparison is made with the pulse pattern output from 0 (see “light-receiving unit signal pattern” in FIG. 3C) to determine whether the patterns of both pulse trains are the same. Then, when both patterns match, the evaluation of the optical transmission line is determined to be “good”, and when they do not match, it is determined to be “fail”.

On the other hand, in the both-end measurement mode, the signal pattern generation circuit 13 outputs a determination signal having the same pulse pattern as the pulse pattern supplied to the light emitting section 20.
The signal is output to the signal determination circuit 18 in synchronization with the timing at which the light receiving section 30 receives the optical signal (see “Determination signal pattern” in FIG. 3D). Is compared with the pulse pattern output from the CPU to determine whether or not both pulse patterns are the same. When both patterns match, the evaluation of the optical transmission path is determined to be “good”, and when both patterns do not match, the evaluation of the optical transmission path is determined to be “fail”.

Next, the configuration of the light emitting section 20 will be described. The light emitting unit 20 includes a driving circuit 21, a light emitting element 22,
And a light emitting receptacle 23. Drive circuit 21
Drives the light emitting element 22 according to the pulse train output from the signal pattern generation circuit 13 of the control unit 10. Further, the light emitting receptacle 23 is fitted to a connector attached to the optical transmission path evaluated by the optical transmission path tester of the present embodiment. In this embodiment, the light emitting element 22
It is assumed that a light emitting diode is used.

Next, the configuration of the light receiving section 30 will be described. The light receiving unit 30 includes a light receiving receptacle 31, a light receiving circuit 32, and a light receiving element 33. The light receiving receptacle 31 is fitted to a connector attached to the optical transmission path evaluated by the optical transmission path tester of the present embodiment.
Further, the light receiving circuit 32 converts the optical signal received from the optical transmission line by the light receiving element 33 into an electric signal and outputs the electric signal to the signal determination circuit 18 of the control unit 10.

Here, a method for flexibly adapting the connector on the optical transmission line tester side to the connector on the optical transmission line side will be described with reference to FIG. FIG. 4 is a diagram showing a connection example when a conversion adapter is used to flexibly match the connector on the optical transmission line tester side with the connector on the optical transmission line side. As shown in this figure, the optical connector 60 on the optical transmission line side
By appropriately using the conversion connector 61 according to the type of the light emitting unit 20, the receptacle 23 of the light emitting unit 20 and the light receiving unit 30,
31 can correspond to an optical connector 60 on an arbitrary optical transmission path side. Here, in FIG. 4, the receptacles 23 and 31 of the light emitting unit 20 and the light receiving unit 30 are both housed in the receptacle side connector 62.

The display unit 40 is a display such as a liquid crystal display or an LED, for example.
8 is displayed. The power supply unit 50 includes a battery 51 and a power supply connector 52. When power is supplied to the optical transmission path tester of the present embodiment using an external power supply,
The external power supply is connected to the power supply connector 52. In addition,
The signal output from the light receiving circuit 32 may be directly supplied to the display unit 40 so that the waveform of the optical signal received by the light receiving unit 30 may be displayed.

Next, a procedure for evaluating an optical transmission line using the above-described optical transmission line tester will be described. As described above, in the optical transmission line tester of the present embodiment, there are two types of measurement modes, (A) both-end measurement mode and (B) loopback measurement mode. The evaluation procedure will be described.

(A) Both ends measurement mode: Two optical transmission line testers are prepared, and one end is placed at each end of the optical transmission line.
Connect them one by one. With the mode setting switch 11 of the optical transmission line tester connected to both ends, the measurement mode is set to “both ends measurement mode”. As a result, the power is always supplied to the light receiving unit 30, and the signal input to the signal determination circuit 18 includes a signal output from the light receiving circuit 32 and a signal pattern generation circuit synchronized with the output from the light receiving circuit 32. 13 becomes the determination signal.

Minimum receiving level of the light receiving section 30 (specification value)
The optical transmission path length setting switch 15 and the light reception level setting switch 16 are set based on the measured optical transmission path length. As a result, the current limiting circuit 17 limits the current flowing to the light emitting element 21 of the light emitting unit 20 according to both set values. The signal determination circuit 18 compares the pulse pattern of the determination signal output from the signal pattern generation circuit 13 with the pulse pattern output from the light reception circuit 32 in synchronization with the output from the light reception circuit 32, and The optical transmission path is evaluated based on whether or not the patterns are the same, and the result is displayed on the display unit 40. Note that the signal determination circuit 18
If the optical signals emitted from the optical transmission line are the same, it is determined that the optical transmission line is normal.

The optical transmission line loss when the optical transmission line tester of this embodiment is connected to both ends of the optical transmission line to be measured, the minimum reception level of the light receiving section 30, the loss of the conversion connector, and the transmission level of the light emitting section 20. , The following equation must hold. Tp−L1-2 × L2> Rmin (1)

Here, Tp (dBm) is the light emitting element 21
(Here, a light emitting diode) is represented by I _LED (m
In the case of A), the transmission level of the optical signal emitted from the light emitting unit 20, L1 (dB) is the light including the coupling loss between the plug of the optical transmission path to be measured and the receptacle of the optical transmission path tester of the present embodiment. The transmission line loss, L2 (dB), is the loss at the conversion connector (however, if the conversion connector is not used, L2 (dB)
2 is 0), and Rmin (dBm) is the minimum reception level of the light receiving unit 30. The conversion connector loss L2 is
Normally -2dB to -3d, depending on the processing accuracy of the connector
B.

Further, in consideration of various variations and deterioration of the light emitting unit 20 and the light receiving unit 30, a loss margin (Lm (dB)) of about 3 to 6 dB is required.
Generally, equation (2) is used as the level equation for transmission and reception. Tp−L1-2 × L2> Rmin + Lm (2)

For example, without using a conversion connector, the loss margin Lm is 3 dB, and the minimum reception level Rmin is -25 d
Bm, when the optical transmission line loss L1 is 10 dB, (2)
According to the equation, transmission is possible if the transmission level Tp is -12 dBm or more. Here, the transmission level Tp is the light emitting element 21
Varies by the current I _LED flowing to, for example, when the current I _LED flowing to the light emitting element 21 is 20 mA, when the transmission level Tp is it was -15 dBm, the transmission level Tp -12
To dBm may be adjusted current I _LED flowing to the light emitting element 21 to fold 40 mA.

That is, when a light emitting diode is used as the light emitting element 21, the relationship between the current flowing through the light emitting diode and the light emission amount (transmission level) is generally as shown in the graph of FIG. As shown in FIG. 5, in the range in which the light emission amount is not saturated (the range (b) in FIG. 5), the current flowing through the light emitting diode and the light emission amount are almost proportional to each other. Current I flowing to light emitting diode
_{When the LED} is halved and the transmission level is doubled, the current I _LED may be doubled.

(B) Loopback measurement mode: The optical transmission line tester of this embodiment is connected to one end of the optical transmission line to be measured, and the other end is connected to a loopback cable (FIG. 2).
(See reference numeral 3 in (b)). The mode setting switch 11 sets the measurement mode to the loopback measurement mode. Thereby, the light emitting unit 20
The light signal emitted from the light receiving section 30 is received by the light receiving section 30 via the optical transmission path and the loopback cable. Then, in the signal determination circuit 18, the optical signal emitted from the light emitting unit 20 and the optical signal received by the
The pulse patterns are compared to determine the quality of the optical transmission path.

Here, in the loopback measurement mode, the power supply timing to the light receiving unit 30 is controlled by the light emitting unit 20.
Power supply timing. In addition, the signal pattern output from the signal pattern generation circuit 13 needs to have a timing that takes into account the delay time between the light emitting unit 20 and the optical transmission line to be measured. Specifically, a delay of 500 ns due to the optical link and a delay of 100 ns due to the optical transmission line to be measured
In consideration of s, the period of “0” and “1” of the signal pattern output from the signal pattern generation circuit 13 is set to 1 μs or more.

The minimum receiving level of the light receiving section 30 (specification value)
The optical transmission path length setting switch 15 and the light reception level setting switch 16 are set based on the measured optical transmission path length. As a result, the current limiting circuit 17 limits the current flowing to the light emitting element 21 of the light emitting unit 20 according to both set values. The signal determination circuit 18 compares the pattern of the pulse signal output from the signal pattern generation circuit 13 with the pattern of the pulse signal output from the light receiving circuit 18 and displays the determination result on the display unit 40. Note that the signal determination circuit 18
Receiving an optical signal emitted from the optical transmission line,
If the pattern of the received optical signal matches the pattern of the pulse signal output from the signal pattern generation circuit 13, the optical transmission path is determined to be normal.

Here, in the case of the loopback measurement mode, the relationship between the optical transmission line loss, the minimum link reception level, the conversion connector loss, and the transmission level must satisfy the following equation. Tp-2 × L1-2 × L2-L3> Rmin (3)

Tp is the current flowing through the light emitting element 21 as I
The transmission level of the optical signal emitted from the light emitting section 20 when the _LED is used, L1 is the optical transmission path loss including the coupling loss between the plug of the optical transmission path to be measured and the receptacle of the optical transmission path tester of the present embodiment, L2 is a loss in the conversion connector (however, L2 is 0 when no conversion connector is used);
L3 is the loss due to the loopback cable, and Rmin is the minimum reception level of the light receiving unit 30. Although the loss L2 of the conversion connector depends on the processing accuracy of the connector, it is usually -2d.
B to -3 dB.

Further, in consideration of various variations and deterioration of the light emitting unit 20 and the light receiving unit 30, the expression (3) is
Since a loss margin (Lm) of the order of dB needs to be taken, the expression (4) is generally used as the transmission and reception level expression. Tp-2 × L1-2 × L2-L3> Rmin + Lm (4)

For example, without using a conversion connector, the loss margin Lm is 3 dB, and the minimum reception level Rmin is -25 d.
When Bm, the loss L1 of the optical transmission line is 3 dB, and the loss L3 of the loopback cable is 4 dB, transmission is possible if the transmission level Tp is -12 dBm or more according to the equation (4).
Here, the transmission level Tp is the current I flowing through the light emitting element 21.
Varies with _LED. For example, when the current I _LED flowing to the light emitting element 21 is 20 mA, the transmission level Tp -15 dBm
When it was, to the transmission level Tp to -12dBm may be adjusted current I _LED flowing to the light emitting element 21 to fold 40 mA.

In the present embodiment, the mode can be switched between the two-end measurement mode and the loop-back measurement mode. However, only one of the two measurement modes may be used.

[0057]

As described above, according to the first aspect of the present invention, since the power supply to the light emitting means that consumes the most current is intermittently performed, the optical transmission line is laid. It is possible to realize an optical transmission line tester having continuous use time characteristics that can be used in the field. Specifically, when the AA battery was used, the continuous use time of the optical transmission line tester when the power control was not performed was about one hour, but the continuous use time when the power control of the present invention was performed was performed. The time was (A) 10 hours in the both-end measurement mode and (B) 14 hours in the loopback measurement mode.

According to the second aspect of the present invention, the power supply intermittently supplied to the light emitting means is such that the ratio between the power supply period and the non-power supply period is stable in the light emitting means. Since the control is performed so that the obtained ratio is the minimum, the evaluation of the optical transmission path can be reliably performed.

According to the third aspect of the present invention, the control signal for controlling the pulse pattern of the optical signal generated by the light emitting means is generated only while power is supplied to the light emitting means. In addition, the optical transmission path can be reliably evaluated in consideration of the power supply timing and the light emission timing.

Further, according to the structure of the fourth aspect, the current flowing through the light emitting element of the light emitting means is based on the measured length of the two-core optical transmission line and the minimum light receiving level of the light receiving means. Current flowing through the optical transmission line tester can be effectively reduced without hindering the evaluation of the two-core optical transmission line.

According to the fifth aspect of the present invention, the light emitting means and the light receiving means are connected to one end of the two-core optical transmission path, and the two-core optical transmission path is connected to the other end of the two-core optical transmission path. By connecting a loop-back cable that connects both transmission paths of the path, abnormal attenuation of the two-core optical transmission path can be checked by one optical transmission path tester.

Further, according to the structure of the sixth aspect,
The light emitting means and the light receiving means are connected to one end of the two-core optical transmission path, and the light emitting means and the light receiving means of another optical transmission path tester are connected to the other end of the two-core optical transmission path. Thus, in addition to the abnormal attenuation of the two-core optical transmission line, a wiring error of the connector attached to the two-core optical transmission line can be checked.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an optical transmission line tester according to the present invention.

FIG. 2 is a diagram showing a configuration of a measurement system in a two-end measurement mode and a measurement system in a loopback measurement mode using the same optical transmission line tester.

FIG. 3 is a waveform diagram showing an example of a power supply timing to a receiving unit and a light emitting unit of the optical transmission line tester, and an example of an optical signal generation timing.

FIG. 4 is a diagram showing a connection example of a conversion adapter for matching a connector on the optical transmission line tester side with a connector on the optical transmission line side.

FIG. 5 is a graph illustrating a relationship between a current flowing through a light emitting diode and a light emission amount.

FIG. 6 is a diagram showing a configuration of a measurement system when performing attenuation measurement of a conventional general optical cable.

FIG. 7 is an explanatory diagram for explaining a wiring error in an optical transmission line.

[Explanation of symbols]

 1, 1a, 1b Optical transmission path tester 2, 2a, 2b Two-core optical transmission path to be measured 3 Loopback cable 4 Relay adapter 10 Control unit 11 Mode setting switch 12 Timing generation circuit 13 Signal pattern generation circuit 14 Power supply control circuit 15 Optical Transmission path length setting switch 16 Light receiving level setting switch 17 Current limiting circuit 18 Signal judgment circuit 20 Light emitting unit 21 Drive circuit 22 Light emitting element 23 Light emitting receptacle 30 Light receiving unit 31 Light receiving receptacle 32 Light receiving circuit 33 Light receiving element 40 Display unit 50 Power supply unit 51 Battery 52 Power supply connector

Continuation of front page (72) Inventor Akimitsu Okita 4-2-1 Ushikawa-dori, Toyohashi-shi, Aichi F-term (reference) 2M086 CC06 CC07 5F073 BA01 EA15 GA04 GA12 HA10 HA11 5K002 AA05 DA04 DA05 EA04 EA06 EA07 EA32 FA01

Claims (6)

[Claims] 1. A light emitting means for emitting an optical signal generated by a light emitting element to one transmission path of a two-core optical transmission path, and receiving an optical signal emitted from the other transmission path of the two-core optical transmission path. A light receiving unit, a power supply controlling unit for supplying power to the light receiving unit and intermittently supplying power to the light emitting unit, and a control for controlling a pulse pattern of an optical signal generated by the light emitting unit. A signal pattern generating unit that generates a signal and outputs the signal to the light emitting unit; and a determination unit that determines whether or not the two-core optical transmission path is good or bad based on an optical signal received by the light receiving unit. Optical transmission line tester. 2. The power supply control unit according to claim 1, wherein a ratio between a period in which power is supplied to the light emitting unit and a period in which power is not supplied is a minimum ratio at which a stable operation is obtained in the light emitting unit. For the light emitting means,
The optical transmission line tester according to claim 1, wherein power is supplied periodically for a predetermined period. 3. The signal pattern generating unit according to claim 1, wherein the signal pattern generating unit generates the control signal and outputs the control signal to the light emitting unit only while power is supplied to the light emitting unit. Optical transmission path tester. 4. An optical transmission path length setting means for setting a length of the two-core optical transmission path to be measured; and a minimum light receiving level setting means for setting a minimum light receiving level at which the light receiving means can receive light. And a current limiting means for limiting a current flowing to a light emitting element of the light emitting means based on each set value set by the light transmission path length setting means and the minimum light receiving level setting means. Item 4. The optical transmission line tester according to any one of Items 1 to 3. 5. The power supply control means supplies power to the light receiving means at the same timing as the light emitting means, and the signal pattern generating means sends the generated control signal to the light emitting means and the judging means. The determining means compares the pulse pattern of the control signal output from the signal pattern generating means with the pulse pattern of the optical signal received by the light receiving means. The optical transmission path tester according to any one of claims 1 to 4, wherein it is determined that the two-core optical transmission path is good. 6. The power supply control means constantly supplies power to the light receiving means, and the signal pattern generating means outputs the control signal to the light emitting means, and has the same pulse pattern as the control signal. A determination signal is output to the determination unit in synchronization with a timing at which the light receiving unit receives the optical signal, the determination unit includes a pulse pattern of the determination signal,
The pulse pattern of an optical signal received by the light receiving means is compared, and when the two pulse patterns match, it is determined that the two-core optical transmission path is good. An optical transmission line tester according to any one of the preceding claims.