JP4492379B2 - Master optical transmission apparatus and optical transmission system - Google Patents

Description

  The present invention relates to a master optical transmission device and an optical transmission system, and in particular, a master optical transmission device and an optical device that transmit and receive optical signals between a pair of other nodes via a distributed optical signal transmission body (optical sheet bus). It relates to a transmission system.

  An optical transmission system that performs optical transmission between a master and a plurality of slaves via an optical sheet bus has been proposed (for example, see Patent Document 1). In such an optical transmission system, when the transmission distance (length of the optical transmission medium) from the master node to each slave node is different, how to secure the bit error rate (BER) becomes a problem. In high-speed serial data transmission using an optical fiber, an error correction code encoder / decoder is required. The BER at the physical level and the actual BER in a state where the error correction algorithm is combined must exceed the required specifications.

Therefore, considering the difference in transmission path distance, coupling loss, and variation in light loss due to individual differences in components, setting an appropriate light emission amount for each light emitting element (or appropriate for each light receiving element) It is necessary to set a proper light sensitivity. However, there is a possibility that the light emission amount once set appropriately changes due to environmental changes such as ambient temperature, and data transmission cannot be performed normally, that is, the BER falls below the required specification. In optical communication, a BER of less than 10 ⁻¹¹ to 10 ⁻¹² is generally required.

Therefore, Patent Documents 2 to 5 are disclosed as methods for returning to the state before the change when the light emission amount of the light emitting element changes.
JP 2003-244175 A JP-A-5-145492 Japanese Patent Laid-Open No. 7-202913 JP-A-8-316523 JP-A-11-112438

  Each of Patent Documents 2 to 4 includes a light receiving element for monitoring the light quantity and a light quantity automatic adjustment circuit that adjusts the light quantity based on the detection result of the light receiving element. However, such a device has a problem in that the circuit configuration becomes large, which complicates the mounting process and increases the cost.

  The present invention has been proposed in order to solve such a problem. In an optical transmission system that performs optical transmission between a master and a slave, the characteristics of a light emitting element or a light receiving element are suppressed while suppressing cost and circuit scale. An object of the present invention is to provide a master optical transmission apparatus and an optical transmission system capable of detecting a change and performing stable optical transmission.

  A master optical transmission apparatus according to the present invention is a master optical transmission apparatus that transmits and receives optical signals to and from a slave optical transmission apparatus, and has a predetermined error occurrence rate that is different in phase from the slave optical transmission apparatus. Phase range determination means for receiving a test data having a corresponding number of data and determining a captureable phase range capable of capturing an optical signal transmitted from the slave optical transmission device based on the presence or absence of an error; and the phase range Phase setting means for setting the slave optical transmission device so as to transmit an optical signal in a phase within the captureable phase range determined by the determination means, and the slave optical transmission device based on the captureable phase range And a light amount change detecting means for detecting a change in the light amount of the data transmission light emitting element.

  The master optical transmission device and the slave optical transmission device first adjust the phase of the optical signal. At this time, the master optical transmission device receives test patterns having different phases from the slave optical transmission device, collates test pattern data having different phases with a predetermined correct pattern, and determines the slave optical transmission device based on the collation result. The captureable phase range capable of capturing the optical signal transmitted from is determined, and the slave optical transmission device is set to transmit the optical signal at a phase within the determined captureable phase range.

  Incidentally, the captureable phase range is related to the light emission amount of the slave optical transmission device. For example, if the light emission amount of the slave optical transmission device is reduced, the captureable phase range is reduced, and if the light emission amount is increased, the captureable phase range is also increased. Therefore, the light quantity change detecting means detects the light quantity change of the data transmission light emitting element of the slave optical transmission device based on the captureable phase range.

  As described above, the master optical transmission device can detect a change in the amount of light of the data transmission light-emitting element of the slave optical transmission device based on the captureable phase range.

  A master optical transmission apparatus according to the present invention is a master optical transmission apparatus that transmits and receives optical signals to and from a slave optical transmission apparatus, and has a predetermined error occurrence rate that is different in phase from the slave optical transmission apparatus. Phase range determination means for receiving a test data having a corresponding number of data and determining a captureable phase range capable of capturing an optical signal transmitted from the slave optical transmission device based on the presence or absence of an error; and the phase range A phase setting means for setting the slave optical transmission device so as to transmit an optical signal in a phase within the captureable phase range determined by the determination means; and after the phase setting by the phase setting means, the captureable phase range Light that detects a change in the amount of light of the light transmitting element for data transmission of the slave optical transmission device based on the presence or absence of the error at the phase of at least one end of It includes a change detecting means.

  Incidentally, the captureable phase range is related to the light emission amount of the slave optical transmission device. For example, if the amount of light emitted from the slave optical transmission device decreases, it becomes impossible to capture an optical signal at the end of the captureable phase range. Further, if the light emission amount of the slave optical transmission device is increased again, an optical signal can be captured at the end of the captureable phase range.

  Therefore, the light quantity change detecting means is configured to determine whether or not there is an error in the phase of at least one end of the fetchable phase range after the phase setting by the phase setting means. Change in the amount of light is detected.

  As described above, the master optical transmission device transmits the data of the slave optical transmission device based on the presence / absence of the error in the phase of at least one end of the captureable phase range after the phase setting by the phase setting means. It is possible to detect a change in the light amount of the trusted light emitting element.

  An optical transmission system according to the present invention is an optical transmission system that transmits and receives an optical signal between a master optical transmission device and a plurality of slave optical transmission devices, and transmits a plurality of test pattern optical signals having different phases. A slave optical transmission device and the master optical transmission device according to claim 1 or 4 are provided.

  Thereby, the said optical transmission system can detect the light quantity change of the light emitting element in each slave optical transmission apparatus.

  The master optical transmission device and the optical transmission system according to the present invention can detect and adjust a change in the light emission amount of the slave optical transmission device due to an environmental change or a change over time, while suppressing cost and circuit scale.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an optical transmission system according to an embodiment of the present invention. The optical transmission system includes one master node 10 and a plurality of slave nodes 30 and performs one-to-many optical transmission. The master node 10 and the slave node 30 are connected by an optical fiber via the optical sheet bus 20.

  The master node 10 generates a parallel / serial conversion circuit 11, an optical transmitter 12 having a light emitting element, an optical receiver 13 having a light receiving element (for example, a photodiode), a serial / parallel conversion circuit 14, and a reference clock. A clock generator 15, a PLL circuit 16, 17 for generating a master internal clock, a memory 18 for storing a correct pattern and transmitted / received data, a control circuit 19 for controlling the entire master node 10, It has.

  The parallel / serial conversion circuit 11 performs parallel / serial conversion on data input from the outside in synchronization with the in-master clock supplied from the PLL circuit 16, and sends the serial data and the in-master clock to the optical transmitter 12. Supply.

  The optical transmitter 12 includes, for example, a surface emitting semiconductor laser array (VCSEL) as a light emitting element, and can output a plurality of optical signals simultaneously via the optical sheet bus 20. The optical transmitter 12 converts the serial data supplied from the parallel / serial conversion circuit 11 and the in-master clock into optical signals, and transmits these optical signals to each slave node 30. Therefore, data and an optical signal of the master clock are transmitted from the master node 10 to the slave node 30, respectively.

  On the other hand, the optical receiver 13 receives the optical signal transmitted from the slave node 30, converts it into serial data, and supplies it to the serial / parallel conversion circuit 14. The serial / parallel conversion circuit 14 performs serial / parallel conversion on the serial data supplied from the serial / parallel conversion circuit 14 in synchronization with the in-master clock supplied from the PLL circuit 17 and outputs the parallel data to the outside. . The PLL circuit 16 and the PLL circuit 17 generate the above-described master clock based on the reference clock generated by the clock generator 15. Therefore, data transmitted from the slave node 30 to the master node 10 is latched by the master clock.

  The memory 18 can read or write data between the parallel / serial conversion circuit 11 and the serial / parallel conversion circuit 14. The memory 18 stores a correct pattern corresponding to the test pattern used when the phase adjustment sequence is executed, and the presence / absence of an error in each phase during the phase adjustment sequence.

  The control circuit 19 controls each circuit in the master node 10 and executes a phase adjustment sequence. For example, the control circuit 19 reads the correct pattern from the memory 18 and collates it with the received test pattern, or sets the phase adjustment amount for the slave node 30 based on the collation result.

  The slave node 30 includes an optical receiver 31 having a light receiving element, a PLL circuit 32 that generates a clock in synchronization with the received master clock, a serial / parallel conversion circuit 33, and a timing adjustment circuit that determines a phase shift amount. 34, a delay circuit 35 that performs delay processing on the clock, a PLL circuit 36 that generates a clock in synchronization with the delayed clock, a parallel / serial conversion circuit 37, an optical transmitter 38 having a light emitting element, A memory 39 for storing test patterns and the like, and a control circuit 40 for controlling the entire slave node 30 are provided.

  The optical receiver 31 receives the optical signals of the data and the master clock transmitted from the master node 10, and generates serial data and the master clock. The PLL circuit 32 generates a predetermined clock in synchronization with the in-master clock generated by the optical receiver 31. The serial / parallel conversion circuit 33 performs serial / parallel conversion on the serial data generated by the optical receiver 31 in synchronization with the clock generated by the PLL circuit 32, and outputs the data and the clock to the outside.

  The timing adjustment circuit 34 determines, for example, the phase adjustment amount of data transmitted by the slave node 30. When the phase adjustment sequence is executed, the phase is shifted by, for example, 200 [psec] steps. The timing adjustment circuit 34 is controlled by the control circuit 40 in accordance with an instruction from the master node 10.

  The delay circuit 35 delays the clock output from the serial / parallel conversion circuit 33 according to the timing (phase shift amount) set by the timing adjustment circuit 34. The PLL circuit 36 generates a predetermined clock in synchronization with the clock delayed by the delay circuit 35. The parallel / serial conversion circuit 37 performs parallel / serial conversion on data input from the outside in synchronization with the clock generated by the PLL circuit 36 and supplies the serial data to the optical transmitter 38. The optical transmitter 38 converts the serial data into an optical signal and transmits the optical signal to the master node 10. Therefore, only the optical signal of data is transmitted from the slave node 30 to the master node 10.

  The memory 39 can read and write data between the serial / parallel conversion circuit 33 and the parallel / serial conversion circuit 37. For example, the memory 39 stores a test pattern used when the phase adjustment sequence is executed.

  The control circuit 40 controls each circuit in the slave node 30 and executes a phase adjustment sequence. For example, the control circuit 40 executes predetermined processing based on the optical signal received by the optical receiver 31, reads a test pattern from the memory 39, and transmits the optical signal of the test pattern to the optical transmitter 38. To control.

2A is a clock in the master, FIG. 2B is a timing specification of the slave node 30, and FIG. 2C is a diagram showing serial data transmitted from the slave node 30 to the master node 10. here,
Sampling Window: Minimum time that the master node 10 can receive data
RSKM: Jitter margin that the master node 10 allows for data
System SW: Setup hold time for data that can be created by an optical transmission system
System RSKM: Jitter generated in an optical transmission system.

  As shown in the figure, the minimum time during which the master node 10 can receive data out of the jitter margin allowed for the data by the master node 10 as a receiving device is determined. For this reason, it is necessary to adjust so that the phase of data transmitted from the slave node 30 to the master node 10 becomes an optimum phase.

  Therefore, the following phase sequence is executed.

(Operation of master node 10 in phase adjustment sequence)
FIG. 3 is a flowchart showing the operation of the master node 10 in the phase adjustment sequence. The control circuit 19 of the master node 10 executes the processing from step S1 to step S16 shown in FIG.

The control circuit 19 causes the optical transmitter 12 to transmit an ID signal for identifying the slave node 30 that is a phase adjustment target (step S1), and continues to transmit the ID signal to the optical transmitter 12 until the set time elapses. (Step S2). When the set time elapses, the control circuit 19 receives a test pattern from the slave node 30 via the optical receiver 13 (step S3). The test pattern is received M times (for example, 10 ¹¹ ) times of data corresponding to a predetermined error occurrence rate to be realized in the system for the same phase.

  The control circuit 19 collates the correct pattern stored in the memory 18 with the test pattern received by the optical receiver 13 (step S4), and displays a collation result indicating “success” or “failure”. Store in the memory 18 (step S5). Note that “success” is when M matches all times, and “failure” is when there is no match even once.

  The control circuit 19 determines whether the slave node 30 has transmitted test patterns for all phases and all timing tests have been completed (step S6). The timing change instruction signal is transmitted to the slave node 30 (step S7), and the timing change instruction signal is continuously transmitted to the slave node 30 until the set time elapses (step S8). Then, when the set time elapses, the control circuit 19 executes the processes after step S3 again.

As a result, the control circuit 19 receives test patterns with different phases one after another and collates them with correct patterns, and stores the collation results (success “◯” or failure “x”) at various phases in the memory 18. Among the collation results stored in the memory 18, the phase within the range of success “◯” is a phase satisfying the bit error rate (BER) < ¹⁰⁻¹¹ .

  Therefore, in the present embodiment, the phase range in which the collation result is successful “◯” is referred to as “capable phase range”.

  On the other hand, when all the timing tests are completed in step S6, the control circuit 19 reads the collation results of all the test patterns from the memory 18 (step S9), selects the optimum timing (step S10), and selects it. The result is transmitted to the slave node 30 (step S11). Thereby, the phase adjustment sequence between the master node 10 and one slave node 30 is completed.

  Next, the control circuit 19 determines whether or not the phase adjustment has been completed for all the IDs, that is, all the slave nodes 30 (step S12). If not, the ID of the slave node 30 to be adjusted is updated. To do. Specifically, the ID number is incremented (ID ← ID + 1) (step S13), and the processing after step S1 is executed again.

  On the other hand, when phase adjustment is completed for all IDs in step S12, the control circuit 19 controls the optical transmitter 12 to transmit an end notification signal to the slave node 30, and the optical transmitter until the set time elapses. 12 continues to transmit the end notification (step S15). When the set time elapses, the control circuit 19 outputs the final result and the status.

(Operation of slave node 30 in phase adjustment sequence)
FIG. 4 is a flowchart showing the operation of the slave node 30 in the phase adjustment sequence. The control circuit 40 of the slave node 30 executes the processing from step S21 to step S31 shown in FIG.

  The control circuit 40 first initializes the transmission timing (step S21), and then determines whether the optical receiver 31 has received the ID signal or the end notification signal from the master node 10 (step S21). S22). When no signal is received, the control circuit 40 waits until the signal is received. When the control circuit 40 receives the ID signal, the control circuit 40 compares the ID signal with its own ID and holds the verification result in the memory 39 ( Step S23).

  The control circuit 40 determines whether it is designated, that is, whether the ID signal and its own ID match (step S24). If it is not designated, all 0 is set to the master node 10. After controlling the optical transmitter 38 to transmit (step S25), the processing from step S24 is performed again. As a result, the slave node 30 declares to the master node 10 that it is not the designated slave node.

  On the other hand, when it is determined in step S24 that it is designated, the control circuit 40 controls the optical transmitter 38 so as to transmit the test pattern to the master node 10 (step S26).

  Next, the control circuit 40 determines whether a selection result signal or a timing change instruction signal is received from the master node 10, and when a signal other than these signals is received, the processing after step S24 is executed again. When receiving the timing change instruction signal, the control circuit 40 controls the timing adjustment circuit 34 to change the transmission timing of the test pattern by one step (step S28).

  When receiving the selection result signal, the control circuit 40 stores the transmission result in the memory 39 (step S29), sets the transmission timing (step S34), and stops the transmission of the test pattern (step S31). Thereafter, the processing from step S22 is executed again. If the control circuit 40 determines in step S22 that an end notification signal has been received, the control circuit 40 ends the phase adjustment sequence.

  The optical transmission system adjusts the amount of phase shift between the clock in the master and the data received by the master node 10 by executing the phase adjustment sequence as described above at regular time intervals. Can respond. This phase shift amount is referred to as “phase adjustment amount”.

In the present embodiment, the number of times the test pattern is transmitted in the phase adjustment sequence is set to a number smaller than (system target BER) ⁻¹ [times].

For example, when aiming at BER = 10 ⁻¹¹ at 500 Mbps, if it is attempted to test whether BER is satisfied for all phases, the number of phase adjustment steps × 200 seconds is also required. That is, in order to confirm whether BER = 10 ⁻¹¹ is satisfied, it is necessary to transmit the test pattern 10 ¹¹ times, which requires 200 seconds at 500 Mbps. For this reason, such a test is not realistic for an optical transmission system.

Therefore, even if the test pattern is transmitted a small number of times (for example, 10 ³ ) in the initial state so that the number of test pattern transmissions can be reduced, the light emission is performed so that the target BER is satisfied by setting the phase as the center. The light quantity of the element is set in advance. Thereby, the time required for the phase adjustment can be reduced (here, the number of phase adjustment steps × 2 μsec).

  Incidentally, the bit error rate has the following relationship with the light emission amount of the light emitting element of the slave node 30.

  FIG. 5 is a diagram showing the relationship between the bit error rate and the phase when the light emission amount is changed. In the drawing, the phase range indicated by the circles is “capable phase range”, the circles indicate “success”, and the crosses indicate “failure”. According to the figure, the bit error rate increases as the amount of light decreases. Thus, it can be seen that the bit error rate can be used as a guide for the change in the light emission amount.

  By the way, when there is a change in the light amount due to a change with time / environmental change, there is a possibility that the BER does not satisfy a certain condition even if the phase adjustment sequence is performed and the phase is set as the center. As a result, the system becomes unstable, causing a problem that data transmission cannot be performed.

  Accordingly, it is periodically checked whether or not the BER satisfies a predetermined condition. If the BER does not satisfy the condition, it is considered that the light amount has decreased. Therefore, it is necessary to return the light amount to the initial state.

  Specifically, in the present invention, the master node 10 detects the presence or absence of a decrease in light amount of the slave node 30 due to a change with time / environmental change or the like by using the following first to third light amount change detection methods. To do.

(Detection of first light intensity change: Transmission test at the center phase of the captureable phase range)
FIG. 6 is a diagram for explaining the detection of the first light quantity change based on the relationship between the bit error rate and the phase. In the detection of the first light quantity change, the master node 10 performs a transmission test N (BER ⁻¹ aimed by the system) [times] in the center phase of the captureable phase range to detect the presence or absence of the light quantity change. .

  First, the master node 10 sends a command to the slave node 30, so that the slave node 30 sets the phase adjustment amount to the center phase of the possible phase range, and sends a predetermined strike pattern N times. To do.

  The master node 10 compares the received test pattern and the correct answer pattern stored in the memory 18, and “success” is obtained when all N times coincides, and “one” or more when no coincidence occurs. It is determined as “failure”. Then, the master node 10 determines that the light emission amount of the slave node 30 has not decreased when “successful”, and determines that the light emission amount of the slave node 30 has decreased when “failure”.

In this way, the master node 10 performs a transmission test by increasing the number of test pattern transmissions in the center phase determined by the phase adjustment sequence (BER ^-1 times aimed by the system). It is determined that the amount of light received by the master node 10 has changed due to a decrease in the amount of light emitted from the light emitting element of the slave node 30.

In the phase adjustment sequence described with reference to FIGS. 3 and 4, the number of test pattern transmissions is, for example, M = 10 ³ , whereas N = 10 ¹¹ here. N is BER ^-1 aimed at in the system.

(Detection of second light quantity change: Transmission test at the end of the captureable phase range)
FIG. 7 is a diagram for explaining the detection of the second light quantity change based on the relationship between the bit error rate and the phase. In the detection of the second light quantity change, the master node 10 executes a transmission test M (<N = BER ⁻¹ targeted by the system) [times] at one end (or both ends) of the captureable phase range. The presence or absence of a change in light amount is detected.

  Assume that the phase adjustment amount in the phase adjustment sequence described with reference to FIGS. 3 and 4 is F, and the possible phase range in the initial state (immediately after execution of the phase adjustment sequence) is a <F <b. The phase at the end (outermost side) of the captureable phase range is a or b.

  First, the master node 10 transmits a command to the slave node 30, so that the slave node 30 sets the phase adjustment amount to the value a (or b) at the end of the captureable phase range in the initial state, A predetermined test pattern is transmitted M times.

  The master node 10 compares the received test pattern with the correct pattern stored in the memory 18, and “success” is obtained when all M times match, and “one” or more when no match occurs. It is determined as “failure”.

  In this way, the master node 10 performs M transmission tests at the end a of the captureable phase range determined by the phase adjustment sequence. If the result is a failure, the light emission of the light emitting element of the slave node 30 is performed. It is determined that the amount of light received by the master node 10 has changed because the amount has decreased.

Note that M is, for example, 10 ³ [times], and is a sufficiently small number with respect to BER ⁻¹ (for example, 10 ¹¹ ) aimed by the system. As a result, the number of transmission tests can be reduced as compared with the case of detecting the first light quantity change. Further, in the initial state, even if M is a small number as described above, if the phase adjustment amount is set at the center of the phase range that can be taken in, the BER (for example, 10 ⁻¹¹ ) aimed by the system is satisfied. The light quantity of the light emitting element of the slave node 30 can be adjusted.

(Detection of third light quantity change: transmission test in phase adjustment sequence)
In the detection of the third light quantity change, the master node 10 detects the presence or absence of the light quantity change using the captureable phase range obtained when the above-described phase adjustment sequence is executed.

  First, the master node 10 transmits a command to the slave node 30 to execute the phase adjustment sequence. In the phase adjustment sequence, first, the slave node 30 sets the phase adjustment amount to S degrees, and transmits the current phase adjustment amount and a predetermined test pattern to the master node 10 M times.

  The master node 10 compares the received test pattern with the correct pattern stored in the memory 18, and “success” is obtained when all M times match, and “one” or more when no match occurs. It is determined as “failure”. Then, the master node 10 stores the comparison result (“success” or “failure”) and the phase adjustment amount received from the slave node 30 in the memory 18. Then, by transmitting the command to the slave node 30, the slave node 30 sets the phase adjustment amount so that the phase is further shifted by S degrees, and transmits a predetermined test pattern M times. Then, the master node 10 transmits the above-mentioned command, compares the test pattern with the correct pattern, stores the comparison result and the phase adjustment amount, and the phase until the phase adjustment amount of the slave node 30 reaches (K × S) degrees. Change the adjustment amount repeatedly.

  When all the transmission tests in each phase are completed, the master 10 obtains the center phase of the phase range in which the transmission test was successful, and sends a command to the slave node 30 to set the phase adjustment amount to that value.

  When used as a detection of a change in the amount of light, at this time, the master node 10 stores the number L of phases when the test pattern and the correct pattern coincide with each other in the memory 18 as a possible phase range length L. Then, the captureable phase range length L is compared with the captureable phase range J obtained when the phase adjustment sequence is first executed. The reason for comparison with the captureable phase range J is as follows. That is, the captureable phase range J is a value obtained when the light emission amount of the slave node 30 is sufficient, and is therefore optimal as a threshold for detecting a decrease in the light emission amount.

  Then, when L becomes a value other than J (for example, when L <J), the master node 10 detects that the light amount of the slave node 30 has decreased.

M is a value such as 10 ³ , which is smaller than (target BER in the system) ⁻¹ (for example, 10 ¹¹ ). Further, in the initial state, even if M is a small number (for example, 10 ³ ), if the phase adjustment amount is set to the center phase of the possible phase range, the target BER (for example, 10 ⁻¹¹ ) is satisfied. Further, the light amount of the light emitting element of the slave node 30 is adjusted.

  As described above, the optical transmission system of the present invention obtains the captureable phase range length L during the phase adjustment sequence, and the light emission amount of the slave node 30 changes when L becomes a value other than the captureable phase range J. Can be detected. Thereby, the change of the light quantity can be detected together with the phase adjustment.

[Light intensity adjustment]
When the master node 10 detects that the light amount of the slave node 30 has changed by the above method, the master node 10 changes the value of a register that determines the light emission amount of the light emitting element of the slave node 30 (hereinafter referred to as “light emission amount determination register”). Thus, the amount of light can be changed. In the present embodiment, the following two light quantity adjustment methods will be described. As a light quantity detection method, the third light quantity change detection method is still used.

(First light amount adjustment: a method of changing the light amount by a certain amount)
When u is the minimum unit of light emission adjustment amount,
P = k × u
Q = 1 × u
And Note that k and l (el) are integers larger than 1.

  The master node 10 first obtains the above-described captureable phase range length L. Next, the master node 10 compares the captureable phase range length L with the captureable phase range J. If L <J, the master node 10 sets the value of the light emission amount determination register of the slave node 30 to “current value + P”. Set to. If L> J, the value of the light emission amount determination register of the slave node 30 is set to “current value−Q”. Then, the master node 10 obtains the above-described captureable phase range length L until L = J or the value of the light emission amount determination register reaches the maximum value or the minimum value, and the captureable phase range J Are repeatedly performed and the value of the light emission amount determination register is set.

  Note that the master node 10 transmits an error to a host device (not shown) when L = J is not satisfied even when the value of the light emission amount determination register of the slave node 30 reaches the maximum value or the minimum value.

  In addition, when the master node 10 does not satisfy L = J even if the number of repetitions of the comparison between the captureable phase range length L and the captureable phase range J and the resetting of the phase adjustment register value exceeds T times. Since the step unit of the light amount change is too large, k = k−1 and l = 1−1 are set. Thereafter, the comparison of the captureable phase range length L with the captureable phase range J and the resetting of the phase adjustment register value are repeated until L = J. If k = 1 or l = 1 but L = J is not satisfied, the master node 10 transmits an error to the host device.

  When L = J, the master node 10 checks the comparison between the captureable phase range length L and the captureable phase range J and the number of repetitions of resetting the phase adjustment register value, It is determined whether the number of steps is too small. If the number of steps is equal to or greater than a certain number, k = k + 1 and l = 1 + 1. Thereby, the master node 10 can return the light quantity of the slave node 30 to the initial value.

(Second light amount adjustment: a method of narrowing down while changing the light amount up and down)
Here, it is assumed that the maximum setting value of the light emission amount of the light emitting element of the slave node 30 is represented by 2 ^m .

Step S41: The master node 10 stores the current light intensity setting value (represented as an initial value here) in the memory 18, sets the light emission amount of the light emitting element of the slave node 30 to 2 ^m, and can capture the value. The phase range length L is obtained. Next, the master node 10 compares the captureable phase range length L with the captureable phase range J. If L = J, the master node 10 ends the light amount adjustment, and if L <J, an error is given to the host device. The transmitted light amount is returned to the initial value, and if L> J, n = 1 is set, and the process proceeds to step S42.

Step S42: The master node 10 sets the light emission amount of the slave node 30 to 2 ^m / 2 ⁿ (n = 1) and obtains the captureable phase range length L.

Step S43: If L = J, the master node 10 ends the light amount adjustment. If L> J, the master node 10 sets the light emission amount of the slave node 30 to “(currently set value) − (2 ^m / 2 ⁿ )”. If L <J, the light emission amount of the slave node 30 is set to “(currently set value) + (2 ^m / 2 ⁿ )”. Then, the captureable phase range length L is obtained, and n = n + 1 is set.

  Step S44: The master node 10 repeatedly executes Step S43, ends the light amount adjustment when L = J, and sends an error to the host device when L = J is not reached even when n = m, Return the light intensity to the initial value. Thereby, the master node 10 can return the light quantity of the slave node 30 to the initial value.

  Note that the master node 10 stores a history of the light quantity detection results of each slave node 30, and whether or not a change in the light quantity (change in the captureable phase range length) occurs only in the specific slave node 30. It is determined whether the same occurs also in the slave node 30, and based on the determination result, the light emitting element of the slave node 30 is deteriorated, the light receiving element of the master node 10 is deteriorated, or whether a specific part is broken. Identify.

  FIG. 8A shows that (A) is a slave whose number of OK (success in transmission test) is decreased by 3 or more, and (B) slave whose number of OK (success in transmission test) is decreased by 3 or more. It is a figure which shows when the number of nodes is N. Here, the number of slave nodes 30 is assumed to be three (Slave-1, Slave-2, and Slave-3).

  In FIG. 5A, the light emitting element of each slave node 30 has deteriorated, or there is some problem between the optical sheet bus 20 and Slave-1 (or the optical sheet bus 20 and Slave-2). I understand. In the case of FIG. 5B, it can be seen that the light emitting element of the master node 10 has deteriorated or that there is some problem between the optical sheet bus 20 and the master node 10.

  As described above in detail, the optical transmission system according to the embodiment of the present invention can detect the light amount of the light emitting element and readjust the light amount with a relatively small-scale and inexpensive circuit configuration. Thereby, it is possible to prevent a decrease in transmission quality due to a change in the amount of light emission caused by an environmental change or a change with time, and as a result, communication reliability can be improved.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can also be applied to a design modified within the scope described in the claims.

It is a figure which shows the structure of the optical transmission system which concerns on embodiment of this invention. (A) is a master internal clock, (B) is a timing specification of the slave node 30, and (C) is a diagram showing serial data transmitted from the slave node 30 to the master node 10. 4 is a flowchart showing a phase adjustment sequence of the master node 10. 4 is a flowchart showing a phase adjustment sequence by a slave node 30. It is a figure which shows the relationship between a bit error rate when changing the light emission amount, and a phase. It is a figure for demonstrating the detection of the 1st light quantity change by the relationship between a bit error rate and a phase. It is a figure for demonstrating the detection of the 2nd light quantity change by the relationship between a bit error rate and a phase. (A) shows that when the number of slave nodes whose OK number (the number of successful transmission tests) has decreased by 3 or more is less than N, (B) the number of slave nodes whose OK number (the number of successful transmission tests) has decreased by 3 or more It is a figure which shows the time of N.

Explanation of symbols

10 Master node 11, 37 Parallel / serial conversion circuit 12, 38 Optical transmitter 13, 31 Optical receiver 14, 33 Serial / parallel conversion circuit 15 Clock generator 16, 17, 32, 36 PLL circuit 18, 39 Memory 19, 40 Control circuit 20 Optical sheet bus 30 Slave node 34 Timing adjustment circuit 35 Delay circuit

Claims (8)

A master optical transmission device that transmits and receives optical signals to and from a slave optical transmission device,
Receiving test data of the number of data corresponding to a predetermined error occurrence rate to be realized with different phases from the slave optical transmission device, and capturing an optical signal transmitted from the slave optical transmission device based on the presence or absence of an error Phase range determining means for determining a possible captureable phase range;
Phase setting means for setting the slave optical transmission device so as to transmit an optical signal at a phase within the captureable phase range determined by the phase range determination means;
A light amount change detection means for detecting a change in the light amount of the data transmission light-emitting element of the slave optical transmission device based on the captureable phase range;
A master optical transmission device. When a light amount change is detected by the light amount change detecting unit, the light amount of the data transmitting light emitting element of the slave optical transmission device is adjusted until the captureable phase range determined by the phase range determining unit reaches a predetermined value. The master light transmission apparatus according to claim 1, further comprising an adjusting unit that adjusts the light amount while changing the light intensity or adjusts the sensitivity of the light receiving element. The master optical transmission apparatus according to claim 2, further comprising an error notification unit that notifies an error to a higher-level device when the captureable phase range determined by the phase range determination unit does not reach a predetermined value. A master optical transmission device that transmits and receives optical signals to and from a slave optical transmission device,
Receiving test data of the number of data corresponding to a predetermined error occurrence rate to be realized with different phases from the slave optical transmission device, and capturing an optical signal transmitted from the slave optical transmission device based on the presence or absence of an error Phase range determining means for determining a possible captureable phase range;
Phase setting means for setting the slave optical transmission device so as to transmit an optical signal at a phase within the captureable phase range determined by the phase range determination means;
A light amount for detecting a change in the light amount of the data transmission light-emitting element of the slave optical transmission device based on the presence or absence of the error in the phase of at least one end of the captureable phase range after the phase setting by the phase setting means Change detection means;
A master optical transmission device. When the light quantity change is detected by the light quantity change detection means, adjust the light quantity while changing the light quantity of the data transmission light emitting element of the slave optical transmission device until there is no error in the phase of the one end, or The master optical transmission apparatus according to claim 4, further comprising an adjusting unit that adjusts the sensitivity of the light receiving element. The master optical transmission apparatus according to claim 5, further comprising an error notification unit that notifies an error to a higher-level device when the captureable phase range determined by the phase range determination unit does not reach a predetermined value. An optical transmission system that transmits and receives optical signals between a master optical transmission device and a plurality of slave optical transmission devices,
A plurality of slave optical transmission devices that transmit test pattern optical signals having different phases, and
The master optical transmission device according to claim 1 or 4,
Optical transmission system equipped with. The master optical transmission device further includes failure cause determination means for determining a failure cause based on a change in a phase range in which an optical signal transmitted from each slave optical transmission device can be captured. Optical transmission system.

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