JPH03104434A - Method for optical reception level adjustment - Google Patents

Abstract

PURPOSE:To automatically set an optical reception level to an optimum value for each node equipment by revising an optical transmission level in response to the command from a receiver side or the setting of an optical reception level so as to adjust the optical transmission reception level. CONSTITUTION:When a proper level is not obtained only with the adjustment of an optical reception level, an adjustment command section 15 generates optical transmission level change command information requesting the change in an optical transmission level of a sender and sends the information to an optical fiber cable 31 addressed to a node equipment of the sender via a signal conversion section 13, a relay control section 14 and an optical transmission section 11. The optical transmission level change command information is detected by the signal conversion section 13 of the node equipment of the sender and informed to the adjustment command section 15. The adjustment command section 15 sends adjustment command information to an optical transmission level adjustment device section 26 of the optical transmission section 11 to adjust the optical transmission level. Thus, the proper reception level is finished by the adjustment of the optical transmission level of the sender.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention configures a network system using optical fiber transmission lines and sets the optical transmission and reception level to an appropriate value in a node device having optical signal branching and distribution functions. The present invention relates to a method for adjusting optical transmission and reception levels.

[Conventional technology]

FIG. 3 is a block diagram showing a configuration example of a network system having a loop type connection type.

In the figure, a plurality of node devices 33, 133! are connected via an optical fiber cable 31! ,...,33n are connected,
Further, each node device 33, - 33,, has transmission lines 351 to 35f different from the optical fiber cable 31, respectively.
i are connected to form a loop-like network.

Note that the transmission lines 35+ to 35. , are connected to a plurality of terminal devices, respectively.

FIG. 4 is a block diagram showing an example of the configuration of a conventional node device. In the figure, the node device 33 has an optical transmitter 4L, an optical receiver 43, a signal converter 45, and a relay controller 47.

The optical transmitter 41 converts an electrical signal into an optical signal and sends it to the optical fiber cable 31. The optical receiver 43 converts the optical signal input from the optical fiber cable 31 into an electrical signal, and the signal converter 45 extracts transmission information from the electrical signal. Depending on the transmission information extracted by the signal conversion section 45, the relay control section 47 performs processing to send it to the optical fiber cable 31 via the transmission path 35 or the optical transmission section 41, or performs processing on information input from the transmission path 35. Accordingly, processing is performed to transmit the data to the optical fiber cable 31 via the optical transmitter 41. That is, in the relay control section 47 , if the information manually input from the transmission path 35 is addressed to another terminal device on the transmission path 35 , the information is discarded, and the other information is sent to the optical transmission section 41 . Further, when the information detected by the signal converter 45 is addressed to a terminal device on the transmission line 35 connected to the node device 33, the information is sent to the transmission line 35, and other information is sent to the optical transmitter. 41.

The optical receiver 43 outputs an electrical signal that follows the optical power level (optical reception level) of the received optical signal, or outputs a predetermined electrical signal when the optical reception level exceeds a predetermined darkness value. The signal converter 45 is configured to extract predetermined transmission information from the electrical signal output according to the optical reception level.

[Problem to be solved by the invention]

By the way, even if the optical power level (optical transmission level) of the optical signal transmitted from each node device is constant,
The optical reception level may vary greatly depending on the distance between each node device.

That is, if the distance between the node devices is extremely close and the optical reception level in the receiving side node device overflows, the signal converter may not be able to extract the transmission information. Furthermore, when the distance between node devices becomes extremely long, the optical reception level is low and is buried in noise, which similarly makes it difficult to extract transmission information.

Further, even when the optical transmission level of the node device deviates significantly from a predetermined value, a similar situation occurs on the receiving side.

Therefore, when shipping node devices, measures are taken such as measuring the optical transmission level of each node device and adjusting it to a predetermined level, or replacing the optical transmitter for devices that cannot be adjusted.

In addition, when installing optical fiber cables that make up a network, the optical reception level varies greatly depending on the length of the optical fiber cable (distance between node devices), as described above, so it is necessary to use a reference light source or other source to Measures were taken to ensure the reliability of the entire network system by measuring the amount of loss and adjusting the optical reception level to ensure normal reception.

In addition, adjustment of the optical transmission and reception level for each node device is necessary not only when constructing a network system, but also when replacing a node device due to failure, or when changing the network system due to the addition or removal of node devices. It was work.

Therefore, not only does the price of the node device itself rise, but also the construction cost of the entire network system rises, and this also becomes a factor that makes it difficult to shorten the construction period.

An object of the present invention is to provide an optical transmission/reception level adjustment method that can automatically set the optical transmission/reception level to an appropriate value for each node device.

[Means to solve the problem]

FIG. 1 is a block diagram illustrating the principle of the method of the present invention.

The present invention detects the optical reception level of an optical signal received via the optical fiber transmission path in a node device that monitors a network system using an optical fiber transmission path, and also detects the optical reception level of an optical signal sent from the opposing node device. Receives the optical transmission level change instruction information, and according to the detection output of the optical reception level,
Sets the optical reception level to a predetermined level, transmits optical transmission level change instruction information to the opposing node device requesting a change in the optical transmission level, and performs optical transmission according to the received optical transmission level change instruction information. It is characterized by changing levels.

[For production]

The present invention changes the optical transmission level between the node devices that monitor the network system according to the setting of the optical reception level or the instruction from the receiving side, and adjusts the optical transmission and reception level respectively. The optical transmission and reception level of the node device can be automatically set to an appropriate level.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of a node device that implements the method of the present invention. In this embodiment, in the diagram shown for one of the plurality of node devices, the node device 10 includes an optical transmitting section l1, an optical receiving section 2, a signal converting section 13, a relay control section 14, and an adjustment instruction section. It has 15 precepts.

The optical receiver 12 includes an optical fiber fixing section 21 that fixes the optical fiber cable 31 to be connected, and an optical fiber cable 3.
The light receiving element 22 converts an optical signal incident from 1 into an electric signal, and the optical receiving level adjustment mechanism part 23 is inserted between the optical fiber fixing part 21 and the light receiving element 22 to adjust the optical receiving level.

The signal converter 13 connected to the light receiving element 22 performs a process of extracting transmission information from the input electrical signal.

Depending on the transmission information extracted by the signal converter 13, the relay control unit 14 performs a process of transmitting it to the transmission path 35 or a process of transmitting it to the optical fiber cable 3l via the transmitting unit 1l,
Also, depending on the information input from the transmission path 35, the transmitter 1
1 to the optical fiber cable 31.

The optical transmitting section 11 includes an optical fiber fixing section 24 that fixes the optical fiber cable 31 to be connected, a light emitting element 25 that converts the electrical signal sent from the relay control section 14 into an optical signal, the optical fiber fixing section 24 and the light emitting element. The optical transmission level adjusting mechanism section 26 is inserted between the optical transmission device 25 and the optical transmission level adjustment mechanism section 25 to adjust the optical transmission level.

The adjustment instruction unit 15 sends adjustment instruction information for adjusting the optical reception level to the optical reception level adjustment mechanism unit 23 according to the input signal level of the signal conversion unit 13, and further adjusts the optical transmission level of the source node device. An adjustment instruction for adjusting the optical transmission level according to the optical transmission level change instruction information that requests a change, and also according to the optical transmission level change instruction information sent from the destination node device detected by the signal converter 13. The information is sent to the optical transmission level adjustment mechanism section 26.

Here, the optical transmission level adjustment mechanism section 26 or the optical reception level adjustment mechanism section 23 used in the optical transmission section 11 or the optical reception section 12 has a mechanism realized mechanically and an electrical (
It can be divided into two types: the precepts realized optically.

In other words,. The optical level adjustment mechanism with a mechanical configuration is similar to that used in optical attenuators and other devices, and has a configuration in which the optical attenuation plate is rotated by a motor or other means to change the light transmittance, or a lens is used to adjust the light transmittance. This can be achieved by expanding the signal and changing the transmittance by changing the width of a slit inserted into the optical path using a motor or other means. Further, the light level adjustment mechanism section having an electrical (optical) configuration can be realized by using a liquid crystal or the like whose transmittance can be electrically changed.

Based on such a precept, the operating procedure of the optical transmission/reception level adjustment method according to the present invention will be explained.

Between opposing node devices in a network system, an optical signal is sent from the optical transmitter 11 of one node device to the optical receiver l2 of the other node device via the optical fiber cable 31. Here, the first optical signal sent out may be, for example, an idle signal, a pulsed optical signal with a specially set pattern, or a continuous wave having a constant optical level.

The optical signal that reaches the light receiving element 22 via the optical reception level adjustment mechanism section 23 of the optical receiving section 12 is converted into an electrical signal and sent to the signal converting section 13. The signal conversion section 13 sends information corresponding to the optical reception level obtained from the level of the input electrical signal to the adjustment instruction section 15.

Here, the signal converter 13 converts the optical reception level (voltage or current level) of the light receiving element 22 obtained from the human electric signal into analog/digital conversion and sends it to the adjustment instruction section 15, or sends it to the adjustment instruction section 15. The optical reception level of analog information may be converted into a digital quantity. In any case, the adjustment instruction unit 15 determines whether the digital amount corresponding to the optical reception level is within a predetermined range.
Alternatively, it is determined whether the optical reception level is within an appropriate range determined from a predetermined characteristic curve, and if the optical reception level needs to be adjusted, the adjustment amount or adjustment value is sent to the optical reception level adjustment mechanism section 23. The optical reception level adjustment mechanism section 23 adjusts the optical reception level according to adjustment instruction information based on the adjustment amount or adjustment value.

Note that in the initial state, the optical reception level adjustment mechanism section 23
Then, the transmittance setting may be increased from the minimum level to match the light reception level, or the transmittance may be set to an intermediate level and then the adjustment of the light reception level may be started. Further, in the optical transmission level adjustment mechanism section 26 of the optical transmission section l1,
Start adjusting the optical transmission level from the setting position where the transmittance is at the intermediate level or higher.

In this way, in the adjustment instruction section 15, the adjustment result for the optical reception level adjustment mechanism section 23 is fed back through the light receiving element 22 and the signal conversion section 13, so that the optical reception level can be adjusted to an appropriate value. However, if the appropriate level cannot be obtained only by adjusting the optical reception level, the adjustment instruction unit 15 generates optical transmission level change instruction information that requests a change in the optical transmission level of the transmission source, and The signal is sent to the optical fiber cable 3l via the signal converter l3, relay controller l4, and optical transmitter 11 to the device. This optical transmission level change instruction information is detected by the signal conversion section 13 of the transmission source node device and is notified to the adjustment instruction section 15. The adjustment instruction section I5 sends adjustment instruction information to the optical transmission level adjustment mechanism section 26 of the optical transmission section 11 in accordance with the optical transmission level change instruction information, and the optical transmission level is similarly adjusted. In this way, the optical reception level is completed by adjusting the optical transmission level of the transmitter.

Note that although the above description has shown a procedure for independently adjusting the optical reception level and the opposite side optical transmission level, it is also possible to perform each adjustment in parallel. For example, when the optical reception level is high, it is possible to lower the optical reception level of the receiving node device and simultaneously lower the optical transmission level of the transmitting node device, but such parallel adjustment is not appropriate. On the other hand, adjusting the optical transmission and reception levels to a higher level tends to cause an overflow of the optical reception level, so in such cases, it is necessary to control each of them independently. When the adjustment instruction section 15 finishes adjusting the optical transmission/reception level, the adjustment instruction section 15 transmits the received signal to the signal conversion section 13 to the relay control section l.
You may also issue an instruction to send it to 4. Further, such an instruction may be omitted, and the signal may always flow from the signal conversion section 13 to the relay control section 14. In this case,
Since the signal converter 13 does not operate intermittently, the relay controller l4 can perform continuous processing without being aware of signal interruptions. That is, even in a situation where the node device only performs relay processing of optical signals, it is possible to adjust the optical reception level in the next node device.

In this way, each node device automatically adjusts the optical transmission and reception level to an appropriate value without using any special equipment or adjusting the optical transmission level when the node device is shipped from the factory. It becomes possible to ensure a stable optical reception level, and it is possible to improve the reliability of communication.

〔Effect of the invention〕

As described above, the present invention can automatically set the optical transmission and reception levels of all node devices that monitor a network system to appropriate values.

Therefore, when constructing a network system and adding, relocating, or removing node devices, there is no need for adjustment work or personnel, making it easy to construct a highly reliable system, and reducing construction costs and construction periods. can be made possible.

Receiving section, 13... Signal conversion section, l4... Relay control section, 15... Adjustment instruction section, 21, 24... Optical fiber fixing section, 22... Light receiving element, 23... Light Reception level adjustment mechanism section, 25... Light emitting element, 26... Optical transmission level adjustment mechanism section, 31... Optical fiber cable, 33
... Node device, 35... Transmission path, 41... Optical transmitter, 43... Optical receiver, 45... Signal converter, 4
7... Relay control section.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining the principle of the present invention. FIG. 2 is a block diagram showing an embodiment of a node device that implements the method of the present invention. Figure 3 is a block diagram showing an example of the configuration of a network system with a loop-type connection format. FIG. 4 is a block diagram showing an example of the configuration of a conventional node device. 10... Node device, 1i... Optical transmitter, 12...
・Light Figure 1 Figure 2

Claims (1)

[Claims] (1) In a node device constituting a network system using an optical fiber transmission line, detect the optical reception level of an optical signal received via the optical fiber transmission line, and detect the optical reception level of an optical signal received via the optical fiber transmission line, and detect the optical reception level of the optical signal sent from the opposing node device. The optical transmitter receives transmission level change instruction information, sets the optical reception level to a predetermined level according to the detection output of the optical reception level, and requests the opposing node device to change the optical transmission level. An optical transmission/reception level adjustment method comprising: transmitting level change instruction information; and changing an optical transmission level according to the received optical transmission level change instruction information.