JP2806866B2 - Optical communication system - 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 communication system, and more particularly to a method for adjusting an optical output from a slave station in an optical communication system in which a master station and a plurality of slave stations are connected via a star-type transmission line.

[0002]

2. Description of the Related Art Conventionally, in an optical communication system of this type, in order to perform data transmission in a pulse burst by light between terminal stations connected to a star coupler, the optical output of each terminal is controlled by using a star coupler. Is distributed to all terminal stations.

In this system, if another station sends a pulse burst while the own station is sending a pulse burst, the pulse burst may be superimposed and cause a data error. To recognize the collision.

However, in the case where the own station recognizes the collision of the pulse burst, if the pulse burst transmitted from the own station returns to the own station via the star coupler, it can be distinguished from the collision due to the pulse burst from another station. Because it's gone
There is a method of easily detecting a collision of a pulse burst from each terminal station by distinguishing and detecting a collision due to a pulse burst from another station and a pulse burst returning to the own station from the star coupler. About this method,
No. 23023.

In an optical communication system in which a master station and a plurality of slave stations are connected via a star-type transmission line, in order to avoid collision of pulse bursts from the slave stations when they join at a star coupler, the master station is used. There is a method of setting the burst signal transmission timing by designating the address of each of a plurality of slave stations from the station.

In this method, the optical transmission level from each of the plurality of slave stations is adjusted so that the optical transmission level from each of the plurality of slave stations can be received at an optimum level by the optical receiver of the master station. ing.

To adjust the optical transmission level, the worker is divided into a master station side and a slave station side, the optical transmission level is measured for each slave station by the receiving section of the master station, and the maximum light reception is performed by the optical receiver of the master station. For a level exceeding the level, an optical fixed attenuator (LBO: Line Build Out network) is provided to the optical transmitter of the slave station.
rk) to adjust the level.

The measurement of the optical transmission level of each slave station in the receiving section of the master station is performed by temporarily stopping the service to the operating slave station, if any.

[0009]

In the above-mentioned conventional optical communication system, the optical transmission level of each slave station is adjusted by measuring the optical transmission level of each slave station with the optical receiver of the master station. If there is an operating slave station, it is necessary to temporarily stop the service for the operating slave station.Every time a slave station is newly added to the system, the service for other operating slave stations is temporarily stopped. There must be.

Therefore, an object of the present invention is to solve the above-mentioned problems and to adjust the optical transmission level in each slave station optimally and automatically without temporarily stopping the service to the slave station in operation. An object of the present invention is to provide an optical communication system.

[0011]

According to the optical communication system of the present invention, a master station and a plurality of slave stations are connected in a star shape via a repeater and an optical transmission line, and a transmission signal transmitted from each of the plurality of slave stations is transmitted. An optical communication system for setting a transmission timing of the transmission signal from the master station to each of the plurality of slave stations to prevent a collision at the time of joining at the repeater, wherein the transmission timing is set to the plurality of slave stations. Means for adding a preset number of branches in the repeater from outside to a first command signal for setting each, and transmitting the first command signal to each of the plurality of slave stations; and transmitting the first command signal. Measuring means for measuring a time until receiving a reply signal from each of the plurality of slave stations corresponding to the first command signal; and a second command signal including a measurement result of the measuring means, A means for transmitting to each of the slave stations is provided in the master station, and means for transmitting the reply signal to the master station at the transmission timing in response to the first command signal, and from the number of branches and the measurement result, Each of the plurality of slave stations is provided with calculating means for calculating a transmission path loss value and adjusting means for adjusting a transmission level based on the transmission path loss value.

[0012] In another optical communication system according to the present invention, in the above-mentioned configuration, the calculation means may include the transmission path loss value calculated in advance based on the number of branches and the measurement result. And means for storing the information in association with the information.

[0013] In another optical communication system according to the present invention, in the above configuration, the adjusting means calculates a current level value based on the transmission path loss value, and an optical signal of the optical signal based on the current level value. Means for adjusting the transmission level.

Still another optical communication system according to the present invention, in the above configuration, wherein the means for calculating the current level value includes a current level value previously calculated based on the transmission path loss value. And means for storing the information in association with the information.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operation of the present invention will be described below.

The master station transmits the first command signal for setting the transmission timing to each of the plurality of slave stations to each of the plurality of slave stations by adding a predetermined number of branches in the star coupler from the outside.

When a response signal corresponding to the first command signal is received, a time from when the first command signal is transmitted to when the response signal is received is measured by a timer, and a time including a measurement result of the timer is measured. 2 is transmitted from the master station to each of the plurality of slave stations.

In each of the slave stations, the transmission line loss value is read from the loss value memory unit based on the number of branches from the master station and the transmission timing value, and based on the current level extracted from the current level memory unit based on the transmission line loss value. Adjust the transmission level to the master station.

This eliminates the need to adjust the optical transmission level at the time of installing the slave station, and eliminates the need to temporarily stop the service to the operating slave station by measuring the optical transmission level of the slave station as in the conventional example.

Further, the dynamic range required for designing the optical burst receiver on the master station side can be narrowed, so that an optimal design can be realized. Therefore, it is possible to optimally and automatically adjust the optical transmission level in each slave station without temporarily stopping the service to the operating slave station.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a system configuration according to an embodiment of the present invention. In the figure, an optical communication system according to an embodiment of the present invention comprises a master station 1 and a plurality of slave stations 2-1.
To 2-N are connected in a star shape via the transmission path 3 and the star coupler 4.

Before entering a communication state with each of the slave stations 2-1 to 2-N, the master station 1 specifies the addresses "# 1" to "#N" of each of the slave stations 2-1 to 2-N. The transmission timing of the burst signal is set one by one to each of the slave stations 2-1 to 2-N, so that the burst signals transmitted from the slave stations 2-1 to 2-N collide when they are joined by the star coupler 4. Has been prevented.

FIG. 2 shows master station 1 to slave stations 2-1 to 2- in FIG.
It is a figure which shows the format of the down frame to N direction. In the figure, a UW (unique word) unit a1 for frame synchronization of each of the slave stations 2-1 to 2-N and a downstream frame a from the master station 1 in the direction of the slave stations 2-1 to 2-N,
Command slots (# 1 to # 2) used during communication
~ # N) a2-1 to a2-N and data slot a3-
1 to a3-N and a timing control slot a4 used when setting the transmission timing of the burst signal transmitted by each of the slave stations 2-1 to 2-N.

The timing control slot a4 is connected to each slave station 2
An address part a5 for designating addresses -1 to 2-N;
It comprises a branch information section a6 indicating the number of branches of the star coupler 4, and a transmission timing section a7 indicating a transmission timing value (distance information) of a burst signal transmitted by the slave stations 2-1 to 2-N.

FIG. 3 is a block diagram showing the configuration of the main station 1 of FIG. In the figure, a master station 1 includes an optical receiving unit 11, a frame synchronizing unit 12, a data separating unit 13, a response detecting unit 14, a timer 15, an operating unit 16, a command creating unit 17, an address table 18, , Current adjusting unit 19
And an LD (Laser Diode) unit 20.

The optical receiving section 11 receives optical signals from the slave stations 2-1 to 2-N and converts them into electric signals. The frame synchronization unit 12 establishes frame synchronization of signals from the slave stations 2-1 to 2-N based on the electric signal output from the optical reception unit 11.

The data separation unit 13 receives the data and the received frame signal from the frame synchronization unit 12 and separates necessary information. The response detection unit 14 is the data separation unit 13
Is detected as a response signal from the slave stations 2-1 to 2-N.

After the first command signal to the slave stations 2-1 to 2-N created by the command creation unit 17 is transmitted to the timer 15, the response detection unit 14 sets the timer 15 to each of the slave stations 2-1 to 2-N.
The time (distance information) until the response signal from N is detected is measured.

The operation unit 16 is an input device for an operator to input various data. When a slave station is registered from the operation unit 16, the command creation unit 17 sets a first transmission timing for the slave station based on the address of the slave station input at the time of registration and the number of branches of the star coupler 4. Create a command signal. At this time, the address table 18
Is registered with the address of the slave station input from the operation unit 16.

When notified that a response signal to the first command signal from the registered slave station is detected by the response detection unit 14, the command creation unit 17 includes the distance information measured by the timer 15. Create a second command signal.

The current adjusting section 19 converts the data from the command creating section 17 into a current and sends it to the LD section 20. LD part 2
Numeral 0 converts the current from the current adjusting unit 19 into an optical signal and transmits it to the slave stations 2-1 to 2-N.

FIG. 4 is a block diagram showing the configuration of the slave station 2-1 of FIG. In the figure, a slave station 2-1 is an optical receiver 21
-1, a frame synchronization unit 22-1, and a data separation unit 23
-1, an address comparing unit 24-1 and an address setting unit 2
5-1, a latch unit 26-1, and a loss value memory unit 27-
1, a current level memory unit 28-1, and a current adjustment unit 29
-1 and an LD unit 30-1.

The optical receiver 21-1 receives an optical signal from the main station 1 and converts it into an electric signal. Frame synchronization unit 22-1
Establishes frame synchronization of the signal from the main station 1 based on the electric signal output from the optical receiving unit 21-1. The data separation unit 23-1 receives the data and the received frame signal from the frame synchronization unit 22-1, and separates necessary information.

The address comparing section 24-1 is a data separating section 2
The address separated in 3-1 is set in the address setting unit 25-1.
Is compared with a preset own station address. Latch section 2
6-1 latches the branch information from the data separation unit 23-1 and the transmission timing, and outputs the result to the loss value memory unit 27-1.

The loss value memory unit 27-1 includes a latch unit 26-
The transmission line loss value retrieved from the branch information from 1 and the transmission timing is output. The current level memory unit 28-1 outputs the current level searched from the transmission path loss value from the loss value memory unit 27-1.

The current adjusting section 29-1 stores the optimum current in accordance with the current level value from the current level memory section 28-1 in the LD.
Send to section 20. The LD unit 20 converts the current from the current adjustment unit 19 into an optical signal and transmits the optical signal to the main station 1. Although not shown, the slave stations 2-2 to 2-N have the same configuration as the slave station 2-1 described above, and the operation thereof is the same as that of the slave station 2-1.

FIG. 5A shows the loss value memory unit 27- of FIG.
5 is a diagram showing a configuration example of FIG. 5, and FIG. 5B is a diagram showing a configuration example of the current level memory unit 28-1 of FIG. FIG.
In (a), the loss value memory unit 27-1 stores the branch information of the star coupler 4 (the number of branches is “1” to “16”) and the information between the master station 1 and the slave stations 2-1 to 2-N. The transmission path loss values (“a”, “b”, “x”) calculated in advance based on the transmission timing values (“0”,..., “X”) (sec) that are the distance information.
.., “L”, “m”, “n”,...) Are stored in association with the branch information and the transmission timing value.

In FIG. 5B, the current level memory section 28-1 stores the transmission line loss values ("a", "b", "c",..., "L") from the loss value memory section 27-1. ”,“ M ”,
Current level (“α”,...) Calculated based on “n”,.
“Β”, “γ”,..., “Θ”,...) Are stored in association with the above transmission path loss values.

FIG. 6 is a sequence chart showing the operation of one embodiment of the present invention. The operation of the embodiment of the present invention will be described with reference to FIGS. Hereinafter, the slave station 2- is a system composed of the master station 1 and the slave stations 2-1 and 2-2.
The operation when N is newly added will be described.

When the slave station 2-N is newly added, when the operator inputs the address "#N" of the slave station 2-N and the branch number "3" of the star coupler 4 from the operation unit 16, the master station 1 The command creation unit 17 sets the address “#N” (address of the added slave station 2-N) input from the operation unit 16 in the address part a5 of the timing control slot a4 of the downstream frame a.

The command creating unit 17 sets the number of branches “3” input from the operation unit 16 in the branch information unit a6 of the timing control slot a4 of the downstream frame a, and sets the default value “0” in the transmission timing unit a7. "Is set. In this case, since the distance between the master station 1 and the slave station 2-N is unknown in the command creation unit 17, the default value “0” is set in the transmission timing unit a7.

After setting the timing control slot a4 as described above, the command creating unit 17
As the first command signal, the current adjusting unit 19 and the LD
The data is transmitted to the slave station 2-N via the unit 20.

The slave station 2-N receives the first command signal from the master station 1 at the optical receiver 21-N (not shown), and the frame synchronizer 22-N (not shown) receives the first command signal. UW
After establishing frame synchronization from the unit a1, the data separation unit 2
After latching the timing control slot a4 by 3-N (not shown), the address part a5, the branch information part a6, and the transmission timing part a7 are separated from the timing control slot a4.

An address comparing section 24-N (not shown) compares the address section a5 separated by the data separating section 23-N with an address preset by an address setting section 25-N (not shown). If a match is detected in the comparison, the reset of the latch unit 26-N (not shown) is released. Therefore,
The branch information section a6 and the transmission timing section a7 separated by the data separation section 23-N are latched by the latch section 26-N, and sent to the loss value memory section 27-N.

As shown in FIG. 5A, the transmission line loss value is stored in advance in the loss value memory unit 27-N (not shown) corresponding to the branch information and the transmission timing value. The loss value memory unit 27-N stores transmission path loss values corresponding to the branch information unit a6 from the latch unit 26-N and the transmission timing unit a7 in the current level memory unit 28-N (not shown).
To send to. In this case, the loss value memory unit 27-N sends "c" as the transmission path loss value because the number of branches is "3" and the transmission timing is "0".

In the current level memory section 28-N, FIG.
As shown in (b), since the current level is stored in advance corresponding to the transmission path loss value, the current level memory unit 28
-N sends the current level corresponding to the transmission path loss value from the loss value memory unit 27-N to the current adjustment unit 29-N (not shown). In this case, since the transmission line loss value is “c”, the current level memory unit 28-N sends “γ” as the current level.

The current adjusting unit 29-N converts the current level “γ” from the current level memory unit 28-N into a current,
Since an optimum current is given to the LD unit 30-N (not shown), a response signal to the first command signal from the master station 1 is transmitted from the LD unit 30-N at an optical power corresponding to the current. .

In the master station 1, the response detecting section 14
-N, the timer 15 stops the timing operation started in response to the transmission of the first command signal.
The address “#N” in the address part a5 of the timing control slot a4, the number of branches “3” in the branch information part a6,
The timing result “X” of the timer 15 is added to the transmission timing section a7.
Are set respectively.

After setting the timing control slot a4 as described above, the command generator 17
As the second command signal, the current adjusting unit 19 and the LD
The data is transmitted to the slave station 2-N via the unit 20.

The slave station 2-N receives the second command signal from the master station 1 in the optical receiver 21-N,
After establishing the frame synchronization from the UW unit a1 of the downstream frame a at -N, latching the timing control slot a4 at the data separation unit 23-N, and then from the timing control slot a4 to the address unit a5 and the branch information unit a6. The transmission timing unit a7 is separated.

The address comparing section 24-N includes a data separating section 2
The address part a5 separated by 3-N is assigned to the address setting part 2
The address is compared with a preset address in 5-N, and if a match is detected in the comparison, the reset of the latch unit 26-N is released. Therefore, the data separating unit 23 is provided in the latch unit 26-N.
Branch information section a6 and transmission timing section a separated by -N
7 is latched and sent to the loss value memory unit 27-N.

FIG. 5A shows the loss value memory 27-N.
As shown in (1), since the transmission path loss value is stored in advance corresponding to the branch information and the transmission timing value, the loss value memory unit 27-N stores the branch information unit a6 from the latch unit 26-N.
And a transmission line loss value corresponding to the transmission timing unit a7 to the current level memory unit 28-N. In this case, the loss value memory unit 27-N sends "n" as the transmission path loss value because the number of branches is "3" and the transmission timing is "X".

In the current level memory section 28-N, FIG.
As shown in (b), since the current level is stored in advance corresponding to the transmission path loss value, the current level memory unit 28
-N sends the current level corresponding to the transmission path loss value from the loss value memory unit 27-N to the current adjustment unit 29-N. In this case, since the transmission line loss value is “n”, the current level memory unit 28-N sends “θ” as the current level.

The current adjuster 29-N converts the current level "θ" from the current level memory 28-N into a current,
Since the optimum current is given to the LD unit 30-N, the LD unit 30-N
From -N, a response signal to the second command signal from the main station 1 is transmitted at an optical power corresponding to the current.

Thereafter, the slave station 2-N enters an operation state, and transmits an optical signal to the master station 1 at a transmission level corresponding to the current level “θ”. In the master station 1, the slave station 2-N
When the response signal is received from, the registration completion is notified to the worker.

As described above, the number of branches in the star coupler 4 preset from the outside is added to the first command signal for setting the transmission timing to each of the plurality of slave stations 2-1 to 2-N. 1 to a plurality of slave stations 2-1 to 2-N, and when a response signal corresponding to the first command signal is received, a time from when the first command signal is transmitted to when the response signal is received. Timer 15
And a second command signal including the measurement result of the timer 15 is transmitted from the master station 1 to each of the plurality of slave stations 2-1 to 2-N. The transmission line loss value is read out from the loss value memory unit 27-1 based on the number of branches from 1 and the transmission timing value, and the main current level is read out from the current level memory unit 28-1 based on the transmission line loss value. By adjusting the transmission level to the station 1, the optical transmission level adjustment performed when the slave station is installed becomes unnecessary, so that it is not necessary to temporarily stop the service for the operating slave station by measuring the optical transmission level of the slave station as in the conventional example. Become.

Further, the dynamic range required for the design of the optical burst receiver on the side of the main station 1 can be narrowed, so that the optimum design can be achieved. Therefore, it is possible to optimally and automatically adjust the optical transmission level in each of the slave stations 2-1 to 2-N without temporarily stopping the service to the operating slave stations 2-1 to 2-N.

The present invention can take the following aspects in connection with the description of the claims.

(1) A master station and a plurality of slave stations are connected in a star shape via a star coupler and an optical transmission line, and collision is prevented when burst signals sent from each of the plurality of slave stations merge at the star coupler. An optical communication system for specifying the address of each of the plurality of slave stations from the master station and setting the transmission timing of the burst signal for each of the plurality of slave stations, wherein the transmission timing is set to the plurality of slave stations. Means for adding a predetermined number of branches in the star coupler from outside to a first command signal to be set for each, and transmitting the first command signal to each of the plurality of slave stations; and transmitting the first command signal. Measuring means for measuring the time until receiving a reply signal from the slave station corresponding to the first command signal in association with each of the plurality of slave stations; and Means for transmitting, to the plurality of slave stations, a second command signal obtained by multiplexing a fixed result in each of the plurality of slave stations, wherein the reply signal is converted to the first command signal in response to the first command signal. Means for transmitting to the main station at the added transmission timing of the own station, means for calculating a transmission path loss value to the own station from the number of branches and the measurement result, and transmission based on the transmission path loss value An optical communication system, comprising an adjusting means for adjusting a level in each of the plurality of slave stations.

(2) The calculating means includes means for storing the transmission path loss value calculated in advance based on the number of branches and the measurement result in association with the number of branches and the measurement result. (1) The optical communication system according to (1).

(3) The adjusting means includes means for calculating a current level value based on the transmission path loss value, and means for adjusting the transmission level of the optical signal based on the current level value. The optical communication system according to (1) or (2).

(4) The means for calculating the current level value includes means for storing a current level value calculated in advance based on the transmission path loss value in association with the transmission path loss value. The optical communication system according to (3).

[0063]

As described above, according to the present invention, the number of branches in the star coupler preset from the outside is added to the first command signal for setting the transmission timing to each of a plurality of slave stations. A station transmits a command signal to each of the plurality of slave stations, measures a time until a response signal corresponding to the first command signal is received from each of the plurality of slave stations, and transmits a second command signal including the measurement result to the master station. And transmitting to each of the plurality of slave stations, and adjusting the transmission level based on the transmission path loss value calculated from the number of branches from the master station and the measurement result in each of the plurality of slave stations,
There is an effect that the optical transmission level of each slave station can be adjusted optimally and automatically without temporarily stopping the service to the slave station in operation.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a system configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing a format of a downstream frame from a master station to a slave station in FIG. 1;

FIG. 3 is a block diagram showing a configuration of a main station in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of a slave station in FIG. 1;

5A is a diagram illustrating a configuration example of a loss value memory unit in FIG. 4; FIG. 5B is a diagram illustrating a configuration example of a current level memory unit in FIG. 4;

FIG. 6 is a sequence chart showing the operation of one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 master station 2-1 to 2-N slave station 3 transmission line 4 star coupler 11, 21-1 optical receiving unit 12, 22-1 frame synchronization unit 13, 23-1 data separation unit 14 response detection unit 15 timer 16 operation unit 17 Command creation unit 18 Address table 19, 29-1 Current adjustment unit 20, 30-1 LD unit 24-1 Address comparison unit 25-1 Address setting unit 26-1 Latch unit 27-1 Loss value memory unit 28-1 Current Level memory section

Continuation of front page (56) References JP-A-9-191317 (JP, A) JP-A-9-64904 (JP, A) JP-A-8-97843 (JP, A) JP-A-6-326723 (JP) , A) JP-A-1-170243 (JP, A) JP-A-62-76948 (JP, A) U.S. Pat. No. 5,036,612 (US, A) IEICE Technical Report (IEICE Technical Report VOL. 95 NO. 532) IN95-105 (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/44 H04B 10/20 JICST file (JOIS) WPI (DIALOG)

Claims (4)

(57) [Claims] 1. A master station and a plurality of slave stations are connected in a star shape via a repeater and an optical transmission line, and a collision is prevented when transmission signals transmitted from each of the plurality of slave stations merge at the repeater. An optical communication system for setting the transmission timing of the transmission signal from the master station to each of the plurality of slave stations, wherein a first command signal for setting the transmission timing to each of the plurality of slave stations is provided. Means for adding a predetermined number of branches in the repeater from outside and transmitting the plurality of slave stations to each of the plurality of slave stations; and transmitting the first command signal and then transmitting the plurality of slave stations corresponding to the first command signal. The master station has measuring means for measuring a time until receiving a reply signal from each of the slave stations, and means for transmitting a second command signal including the measurement result of the measuring means to each of the plurality of slave stations. , Means for transmitting the reply signal to the master station at the transmission timing in response to the first command signal; calculating means for calculating a transmission path loss value from the number of branches and the measurement result; An optical communication system comprising: an adjusting unit that adjusts a transmission level based on a loss value in each of the plurality of slave stations. 2. The method according to claim 1, wherein the calculating unit includes a unit configured to store the transmission path loss value calculated in advance based on the number of branches and the measurement result in association with the number of branches and the measurement result. The optical communication system according to claim 1, wherein 3. The method according to claim 2, wherein the adjusting unit includes a unit that calculates a current level value based on the transmission line loss value, and a unit that adjusts a transmission level of the optical signal based on the current level value. The optical communication system according to claim 1 or 2, wherein 4. The apparatus according to claim 1, wherein the means for calculating the current level value includes means for storing a current level value calculated in advance based on the transmission path loss value in association with the transmission path loss value. The optical communication system according to claim 3.