Optical communication device, optical communication method, and optical communication program

Abstract

To provide an optical communication device, an optical communication method, and an optical communication program with which it is possible to set an optimum FM demodulation parameter irrespective of differences between optical communication devices.SOLUTION: An optical communication device (10) comprises: an optical / electrical conversion unit (11) for converting an inputted optical signal into an electrical signal; an FM demodulation unit (14) for FM demodulating the electrical signal using an FM demodulation parameter; a signal amplification unit (15) for amplifying the FM-modulated electrical signal to a prescribed level; a signal performance estimation unit (23) for estimating the performance of the output signal outputted from the signal amplification unit (15); a determination unit (25) for determining the performance of the output signal estimated by the signal performance estimation unit (23) and extracting the FM demodulation parameter used in FM demodulation pertaining to the output signal whose performance is determined as optimum; and a FM demodulation parameter control unit (26) for controlling the FM demodulation unit (14) so that FM demodulation is carried out using the FM demodulation parameter extracted by the determination unit (25).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an optical communication device, an optical communication method, and an optical communication program.

Background Art

[0002] As an optical communication system, a PON (Passive Optical Network) system is known. The PON system is composed of an OLT (Optical Line Terminal) which is a master station device installed on the communication carrier side, and a plurality of ONUs (Optical Network Unit) which are slave station devices installed on the subscriber side.

[0003] In the PON system, there is a case where a frequency-division multiplexed multi-channel video signal such as a TV signal is optically transmitted to a subscriber's home by using the RoF (Radio on Fiber) technology of loading an RF (Radio Frequency) signal on an optical signal. As one of the RoF technologies for the above applications, an FM batch conversion method in which a video signal is modulated into an FM (Frequency Modulation) signal in a batch and optically transmitted over a long distance has been widely put into practical use.

[0004] In the FM batch conversion method, a video signal that has been batch-modulated into an FM signal on the transmission side is batch-demodulated by an optical communication device that is a slave station device on the reception side. Delay detection is sometimes adopted as a demodulation method. In this demodulation method, a pulse density modulation signal corresponding to the frequency of the input FM signal is generated, and the signal performance after demodulation varies depending on FM demodulation parameters such as the voltage threshold for pulse signal generation or the pulse height (pulse amplitude) of the generated pulse signal. In addition, since the signal performance also varies due to fluctuations in component performance caused by fluctuations in environmental conditions such as temperature, the optimal FM demodulation parameters vary depending on the environmental conditions.

[0005] As one of the methods for achieving the above solution, Patent Document 1 discloses an optical communication device that employs the FM batch conversion method. Based on a setting table showing the correspondence between "environmental conditions such as temperature" and "FM demodulation parameters to be set", the optical communication device sets FM demodulation parameters according to the environmental conditions to improve the performance of the output signal after FM demodulation.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in an actual optical communication device, even if the environmental conditions do not change, due to individual differences in the optical communication device, variations in performance occur in component noise characteristics, linearity, amplification factor, group delay characteristics, and offset characteristics. Therefore, the optimal FM demodulation parameters during FM demodulation are different for each individual. Consequently, in the setting of feed - forward type demodulation parameters using a setting table as in the optical communication device described in Patent Document 1, the FM demodulation parameters cannot be optimized for each individual. As a result, during production inspection, there are many individuals whose output signal performance does not meet the standards, and there is a problem that component replacement is required to improve the performance.

[0008] An object of the present disclosure is to provide an optical communication device, an optical communication method, and an optical communication program capable of setting optimal FM demodulation parameters regardless of individual differences in the optical communication device.

Means for Solving the Problems

[0009] The optical communication device of the present disclosure includes an optical / electrical conversion unit that converts an input optical signal into an electrical signal, an FM demodulation unit that FM demodulates the electrical signal using an FM demodulation parameter, a signal amplification unit that amplifies the FM demodulated electrical signal to a predetermined level, a signal performance estimation unit that estimates the performance of the output signal output from the signal amplification unit, a determination unit that determines the performance of the output signal estimated by the signal performance estimation unit and extracts the FM demodulation parameter used for FM demodulation related to the output signal with the optimally determined performance in the determination, and an FM demodulation parameter control unit that controls the FM demodulation unit to perform FM demodulation using the FM demodulation parameter extracted by the determination unit.

[0010] The optical communication method of the present disclosure is an optical communication method executed by a computer, and includes a step of converting an input optical signal into an electrical signal, a step of FM demodulating the electrical signal using an FM demodulation parameter, a step of amplifying the FM demodulated electrical signal to a predetermined level, a step of estimating the performance of the amplified output signal, a step of determining the performance of the estimated output signal and extracting the FM demodulation parameter used for FM demodulation related to the output signal with the optimally determined performance in the determination, and a step of performing FM demodulation using the extracted FM demodulation parameter.

[0011] The optical communication program of the present disclosure causes a computer to execute a step of converting an input optical signal into an electrical signal, a step of FM demodulating the electrical signal using an FM demodulation parameter, a step of amplifying the FM demodulated electrical signal to a predetermined level, a step of estimating the performance of the amplified output signal, a step of determining the performance of the estimated output signal and extracting the FM demodulation parameter used for FM demodulation related to the output signal with the optimally determined performance in the determination, and a step of performing FM demodulation using the extracted FM demodulation parameter.

Advantages of the Invention

[0012] According to the present disclosure, it is possible to provide an optical communication device, an optical communication method, and an optical communication program capable of setting an optimal FM demodulation parameter regardless of individual differences in optical communication devices.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0014] Hereinafter, optical communication devices according to Embodiments 1, 2, and 3 will be described with reference to the drawings. The following embodiments are merely examples, and it is possible to appropriately combine the embodiments and appropriately change each embodiment.

[0015] 《Embodiment 1》 FIG. 1 is a block diagram showing an example of the configuration of an optical communication device 10 according to Embodiment 1. In FIG. 1, solid arrows indicate the flow of the main signal, and dotted arrows indicate the flow of the control signal. As shown in FIG. 1, the optical communication device 10 includes an optical / electrical conversion unit 11, a group delay compensation unit 12, a limiting amplifier unit 13, an FM demodulation unit 14, a signal amplification unit 15, an optical signal monitor unit 21, an output signal monitor unit 22, a signal performance estimation unit 23, a storage unit 24, a determination unit 25, and an FM demodulation parameter control unit 26.

[0016] The optical / electrical conversion unit 11 converts an optical signal input to the optical communication device 10 from the transmission side into an electrical signal. When converting the optical signal into an electrical signal, a group delay corresponding to the electrical length in the optical / electrical conversion unit 11 occurs, which is the time for the electrical signal to travel. Therefore, the group delay compensation unit 12 compensates for the group delay characteristic of the signal output from the optical / electrical conversion unit 11. When the optical / electrical conversion unit 11 has a linear transfer response where the delay of the phase of the electrical signal when the electrical signal is transferred is proportional to the frequency of the electrical signal, the group delay takes a constant value. Thus, the group delay compensation unit 12 corrects the electrical signal with a predetermined group delay compensation amount stored in advance in the storage unit 24 or the like.

[0017] The limiting amplifier unit 13 amplifies the signal output from the group delay compensation unit 12 to a certain amplitude in order to perform FM demodulation. The FM demodulation unit 14 performs FM demodulation on the signal output from the limiting amplifier unit 13 based on the FM demodulation parameter controlled by the FM demodulation parameter control unit 26. However, when the optical communication device 10 operates for the first time, the FM demodulation unit 14 performs FM demodulation using the initial value of the FM demodulation parameter stored in advance in the storage unit 24 or the like. The signal amplification unit 15 amplifies the FM demodulated electrical signal output from the FM demodulation unit 14 to a predetermined level that can be reproduced by a video device such as a television and outputs it to the video device such as a television.

[0018] The optical signal monitor unit 21 detects the optical signal input to the optical / electrical conversion unit 11 and outputs the detection result to the output signal monitor unit 22. When the output signal monitor unit 22 receives a notification that an optical signal input has been detected from the optical signal monitor unit 21, it starts monitoring the output signal output from the signal amplification unit 15. As an example, the output signal monitor unit 22 monitors the output signal output from the signal amplification unit 15 by converting the output signal into a digital signal with an ADC (Analog Digital Converter) and performing FFT (Fast Fourier Transform) for confirmation in the frequency domain.

[0019] The signal performance estimation unit 23 estimates the performance of the output signal monitored by the output signal monitor unit 22. For example, as the signal characteristics to be estimated, the signal performance estimation unit 23 estimates the performance of the output signal by CL (Carieer Level) indicating the performance of the carrier level of the output signal, CNR (Carieer to Noise Ratio) indicating the performance of the noise level with respect to the carrier level, or CSO (Composite Second Order) indicating the performance of the distortion level with respect to the carrier level at a specific frequency channel.

[0020] The storage unit 24 stores the combination of the performance of the output signal estimated by the signal performance estimation unit 23 and the FM demodulation parameters used for FM demodulation related to the output signal. The FM demodulation parameters in the first embodiment are, for example, the voltage threshold for pulse signal generation or the pulse height (pulse amplitude) of the generated pulse signal. The determination unit 25 determines the performance of the output signal based on the combination of the performance of the output signal stored in the storage unit 24 and the FM demodulation parameters related to the output signal, and extracts the FM demodulation parameters that optimize the performance of the output signal in this determination. The determination unit 25 selects, for example, the best-performing one among the performance of the output signals in the vicinity of the performance of the current output signal as the vicinity solution for the optimal performance. If the vicinity solution is better than the performance of the current output signal, the determination unit 25 selects the performance of the current output signal by using a hill climbing method or the like to replace it with the vicinity solution. Then, the determination unit 25 determines that the FM demodulation parameters paired with the performance selected as optimal are the FM demodulation parameters that optimize the performance of the output signal. The FM demodulation parameters determined by the determination unit 25 to be optimal for the performance of the output signal are stored in the storage unit 24.

[0021] The FM demodulation parameter control unit 26 sets the FM demodulation parameters when performing FM demodulation in the FM demodulation unit 14 according to the FM demodulation parameters determined by the determination unit 25 to be optimal for the performance of the output signal.

[0022] FIG. 2 is a hardware configuration diagram showing an optical communication device 10 according to Embodiment 1. The optical communication device 10 is a kind of computer, and each of a CPU (Central Processing Unit) 210, a main memory 220, an input / output interface (I / O interface) 230, and a storage unit 240 is connected to each other via a system bus 250. The optical communication device 10 may be composed of a plurality of computers.

[0023] The CPU 210 is an IC (Integrated Circuit) that performs arithmetic processing. In addition to the CPU 210, arithmetic elements such as a DSP (Digital Signal Processor) or a GPU (Graphics Processing Unit) may be used. By executing an optical communication program, the CPU 210 functions as the above-described optical / electrical conversion unit 11, group delay compensation unit 12, limiting amplifier unit 13, FM demodulation unit 14, signal amplification unit 15, optical signal monitor unit 21, output signal monitor unit 22, signal performance estimation unit 23, storage unit 24, determination unit 25, and FM demodulation parameter control unit 26. Further, the optical communication program is provided, for example, by a recording medium on which these are recorded.

[0024] The main memory 220 is composed of a volatile storage device such as a RAM (Random Access Memory) or a non-volatile storage device such as a ROM (Read Only Memory). The storage unit 240 is composed of a non-volatile storage device such as an HDD (Hard Disk Drive) or a flash memory. The I / O interface 230 is a port to which a transmitting-side device and a video device such as a television are connected.

[0025] Next, a method for setting FM demodulation parameters in Embodiment 1 will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the setting operation of FM demodulation parameters according to Embodiment 1. In step S1, at the timing when an optical signal is input from the transmitting side to the optical / electrical conversion unit 11 of the optical communication device 10, the optical signal monitor unit 21 detects the optical signal input.

[0026] In step S2, when the output signal monitor unit 22 receives a notification that the optical signal monitor unit 21 has detected an optical signal input, the output signal monitor unit 22 starts monitoring the output signal output from the signal amplification unit 15 of the optical communication device 10. As described above, the output signal monitor unit 22 monitors the output signal by converting the output signal into a digital signal with an ADC and checking the output signal in the frequency domain using FFT.

[0027] In step S3, the signal performance estimation unit 23 estimates the performance of the output signal based on the information of the output signal monitored by the output signal monitor unit 22. As described above, the signal characteristics to be estimated are, at a specific frequency channel, CL indicating the performance of the carrier level of the output signal, CNR indicating the performance of the noise level with respect to the carrier level, or CSO indicating the performance of the distortion level with respect to the carrier level, etc.

[0028] In step S4, for use in subsequent optimal FM demodulation parameter search and determination, the combination of the performance of the output signal estimated by the signal performance estimation unit 23 and the FM demodulation parameters used for FM demodulation related to the output signal is stored in the storage unit 24.

[0029] In step S5, the determination unit 25 searches for the performance of the output signal based on the combination of the performance of the output signal and the FM demodulation parameters stored in the storage unit 24, and determines whether there is a combination that optimizes the performance, that is, whether there are FM demodulation parameters that optimize the performance. For the search for the optimal performance, a method such as the hill climbing method described above, in which a certain signal performance that reaches an extreme value is determined to be optimal, is used.

[0030] In step S6, the determination unit 25 outputs the determination result as to whether there are FM demodulation parameters that can be determined to optimize the performance of the output signal in step S5. If, in step S6, a determination result is output that there are no FM demodulation parameters that optimize the output performance signal, the procedure proceeds to step S7. If a determination result is output that there are FM demodulation parameters that optimize the output performance signal, the procedure proceeds to step S9.

[0031] In step S7, the determination unit 25 notifies the FM demodulation parameter control unit 26 of the change in the FM demodulation parameter. As described above, the FM demodulation parameter to be changed is the voltage threshold for pulse signal generation, the pulse height (pulse amplitude) of the generated pulse signal, or the like.

[0032] In step S8, the FM demodulation parameter control unit 26 changes the FM demodulation parameter used in the FM demodulation unit 14 in accordance with the notification from the determination unit 25. The amount of change in the FM demodulation parameter in step S8 may be one unit by which the FM demodulation parameter can be changed, or may be an amount of change calculated based on the obtained signal performance.

[0033] After changing the FM demodulation parameter in step S8, the procedure proceeds to step S2, and the output signal monitor unit 22 monitors the output signal again.

[0034] In step S3, the signal performance estimation unit 23 estimates the performance of the output signal, and in step S4, the estimated performance is stored in the storage unit 24 together with the FM demodulation parameter related to the performance.

[0035] In step S5, the determination unit 25 determines whether there is an FM demodulation parameter that optimizes the performance of the output signal in the combination of the performance of the output signal and the FM demodulation parameter related to the output signal stored in the storage unit 24, and outputs the determination result in step S6. If it cannot be determined in a subsequent determination that there is an FM demodulation parameter that optimizes the performance, the procedures of steps S2 to S8 are repeated in steps S5 and S6 until it is determined that there is an FM demodulation parameter that optimizes the performance of the output signal.

[0036] If it is determined in steps S5 and S6 that there is an FM demodulation parameter that optimizes the performance of the output signal, in step S9, the FM demodulation parameter control unit 26 sets the FM demodulation parameter that optimizes the performance of the output signal, and ends the setting of the demodulation parameter.

[0037] As described above, according to the first embodiment, in the optical communication device 10 adopting the FM batch conversion method, when an optical signal is input and detected, the output signal is monitored, the performance of the monitored output signal is estimated, and the FM demodulation parameter at the time of FM demodulation is controlled according to the estimated signal performance. By controlling such FM demodulation parameters, it becomes possible to set the optimal FM demodulation parameters in a feedback type so that the performance of the output signal is improved while checking the output signal. As a result, regardless of the individual differences of the optical communication device 10, it is possible to set the optimal FM demodulation parameters, and it is possible to improve the performance of the output signal after FM demodulation according to the individual differences of the optical communication device 10. It is possible to provide an optical communication device, an optical communication method, and an optical communication program capable of setting optimal FM demodulation parameters regardless of the individual differences of the optical communication device 10. In addition, since component replacement for performance improvement is not required after the inspection of the optical communication device 10, the yield during the production of the optical communication device 10 can be improved, and it is possible to produce the optical communication device 10 in consideration of the environment.

[0038] 《Second Embodiment》 Next, the second embodiment will be described. FIG. 4 is a block diagram showing an example of the configuration of the optical communication device 20 according to the second embodiment. The optical communication device 20 according to the second embodiment is different from the optical communication device 10 according to the first embodiment in that it has a temperature monitor unit 27 that monitors the temperature inside the optical communication device 20 and notifies the output signal monitor unit 22 when a temperature change inside the optical communication device 20 is detected. However, since the other configurations are the same as those in the first embodiment, the same configurations as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof are omitted.

[0039] Next, a method for setting the FM demodulation parameter in the second embodiment will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the setting operation of the FM demodulation parameter according to the second embodiment. In step S11, when a temperature change occurs inside the optical communication device 20, the temperature monitor unit 27 detects the temperature change.

[0040] In step S12, when the output signal monitor unit 22 receives a notification that the temperature monitor unit 27 has detected temperature fluctuations, the output signal monitor unit 22 starts monitoring the output signal output from the signal amplification unit 15 of the optical communication device 20. However, if no optical signal input is detected by the optical signal monitor unit 21, the output signal monitor unit 22 does not perform the monitoring of the output signal.

[0041] In step S13, similar to the first embodiment, the signal performance estimation unit 23 estimates the performance of the output signal based on the information of the output signal monitored by the output signal monitor unit 22.

[0042] In step S14, similar to the first embodiment, the combination of the performance of the output signal estimated by the signal performance estimation unit 23 and the FM demodulation parameter used for FM demodulation related to the output signal is stored in the storage unit 24 for use in subsequent optimal FM demodulation parameter search and determination.

[0043] In step S15, similar to the first embodiment, the determination unit 25 determines the FM demodulation parameter that optimizes the performance of the output signal based on the combination of the performance of the output signal and the FM demodulation parameter related to the output signal stored in the storage unit 24.

[0044] In step S16, the determination unit 25 outputs the determination result as to whether there is an FM demodulation parameter that can be determined to be optimal for the performance of the output signal in step S15. If the determination result that there is no FM demodulation parameter that optimizes the output performance signal is output in step S16, the procedure proceeds to step S17. If the determination result that there is an FM demodulation parameter that optimizes the output performance signal is output, the procedure proceeds to step S19.

[0045] In step S17, the determination unit 25 notifies the FM demodulation parameter control unit 26 of the change in the FM demodulation parameter. The FM demodulation parameter to be changed may be, in addition to the voltage threshold for pulse signal generation or the pulse height (pulse amplitude) of the generated pulse signal listed in the first embodiment, a change amount calculated based on the changed temperature amount.

[0046] In step S18, similar to the first embodiment, the FM demodulation parameter control unit 26 changes the FM demodulation parameters used in the FM demodulation unit 14 in accordance with the notification from the determination unit 25.

[0047] After changing the FM demodulation parameters in step S18, the procedure proceeds to step S12, and the output signal monitor unit 22 monitors the output signal again.

[0048] In step S13, the signal performance estimation unit 23 estimates the performance of the output signal, and in step S14, the estimated performance is stored in the storage unit 24 together with the FM demodulation parameters related to the performance.

[0049] In step S15, it is determined whether there are FM demodulation parameters that optimize the performance of the output signal, and the determination result is output in step S16. If it cannot be determined in the re - determination that there are FM demodulation parameters that optimize the performance of the output signal, in steps S15 and S16, the procedures of steps S12 to S18 are repeated until it is determined that there are FM demodulation parameters that optimize the performance of the output signal.

[0050] In steps S15 and S16, if it is determined that there are FM demodulation parameters that optimize the performance of the output signal, in step S19, the FM demodulation parameter control unit 26 sets the FM demodulation parameters that optimize the performance of the searched output signal, and ends the setting of the demodulation parameters.

[0051] As described above, according to the second embodiment, in the optical communication device 20 adopting the FM batch conversion method, when detecting temperature fluctuations together with the input detection of the optical signal, the output signal is monitored, the performance of the monitored output signal is estimated, and the FM demodulation parameter at the time of FM demodulation is controlled according to the estimated signal performance. By controlling such FM demodulation parameters, it becomes possible to set the optimal demodulation parameters in a feedback type so that the performance of the output signal is improved while checking the output signal during temperature fluctuations. As a result, even during temperature fluctuations, regardless of the individual differences of the optical communication device 20, it is possible to set the optimal FM demodulation parameters, and it is possible to improve the performance of the output signal after FM demodulation according to the individual differences of the optical communication device 20. Thus, it is possible to provide an optical communication device, an optical communication method, and an optical communication program capable of setting optimal FM demodulation parameters regardless of the individual differences of the optical communication device 20. In addition, since component replacement for performance improvement is not required after the inspection of the optical communication device 20, the yield during the production of the optical communication device 20 can be improved, and it becomes possible to produce the optical communication device 20 with consideration for the environment.

[0052] 《Third Embodiment》 Subsequently, the third embodiment will be described. In the first and second embodiments, a configuration for controlling the FM demodulation parameter at the time of FM demodulation according to the individual differences or temperature of the optical communication devices 10 and 20 was shown. However, when the performance of the FM signal input to the optical communication devices 10 and 20 is poor, or when the performance of the optical / electrical conversion unit 11 is poor due to component variations, etc., and thus the performance of the FM signal input to the FM demodulation unit 14 is poor, there is a problem that the performance of the output signal cannot be sufficiently improved only by changing the parameter setting of FM demodulation. In the third embodiment, a group delay compensation control unit 28 for controlling the group delay compensation amount of the group delay compensation unit 12 is additionally provided in the second embodiment, which is different from the second embodiment in terms of improving the performance of the FM signal input to the FM demodulation unit 14. However, since the other configurations are the same as those in the second embodiment, the same components as those in the second embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0053] FIG. 6 is a block diagram showing an example of the configuration of the optical communication device 30 according to Embodiment 3. As shown in FIG. 6, the optical communication device 30 according to Embodiment 3 has a group delay compensation control unit 28 in addition to the configuration of the optical communication device 20 according to Embodiment 2. The group delay compensation control unit 28 changes the group delay compensation amount of the group delay compensation unit 12 in accordance with an instruction from the determination unit 25. In Embodiment 3, when the optical communication device 30 starts operating for the first time, the group delay compensation unit 12 performs FM demodulation using the initial value of the group delay compensation amount stored in advance in the storage unit 24 or the like. In subsequent operations, the group delay compensation control unit 28 changes the group delay compensation amount so that the performance of the output signal becomes optimal. The initial value of the group delay compensation amount is, for example, a fixed value that can be taken when the optical / electrical conversion unit 11 has a linear transfer response.

[0054] Next, a method for setting the FM demodulation parameters in Embodiment 3 will be described with reference to FIG. 7. FIG. 7 is a flowchart showing the setting operations of the FM demodulation parameters and the group delay compensation amount according to Embodiment 3. In step S21, similarly to Embodiment 1, when an optical signal is input from the transmission side to the optical / electrical conversion unit 11 of the optical communication device 30, the optical signal monitor unit 21 detects the optical signal input.

[0055] In step S22, similarly to Embodiment 1, when the output signal monitor unit 22 receives a notification that the optical signal monitor unit 21 has detected an optical signal input, the output signal monitor unit 22 starts monitoring the output signal output from the signal amplification unit 15 of the optical communication device 30. Alternatively, similarly to Embodiment 2, when detecting temperature fluctuations together with the detection of the optical signal input, the monitoring of the output signal may be started.

[0056] In step S23, similarly to Embodiment 1, the signal performance estimation unit 23 estimates the performance of the output signal based on the information of the output signal monitored by the output signal monitor unit 22.

[0057] In step S24, the combination of the performance of the output signal estimated by the signal performance estimation unit 23, the group delay compensation amount related to the output signal, and the FM demodulation parameters used for FM demodulation related to the output signal is stored in the storage unit 24 for use in subsequent optimal group delay compensation amount, FM demodulation parameter search, and determination.

[0058] In step S25, the determination unit 25 searches for the performance of the output signal based on the combination of the performance of the output signal, the group delay compensation amount related to the output signal, and the FM demodulation parameters stored in the storage unit 24, and determines whether there is a combination that optimizes the performance, that is, whether there are a group delay compensation amount and FM demodulation parameters that optimize the performance. For the search for the optimal performance of the output signal, as in the first embodiment, a method such as the hill climbing method, which determines that a certain signal performance is an extreme value as optimal, is used.

[0059] In step S26, the determination unit 25 outputs the determination result as to whether there are a group delay compensation amount and FM demodulation parameters that were determined to optimize the performance of the output signal in step S25. If, in step S26, a determination result is output that there are no group delay compensation amount and FM demodulation parameters that optimize the output performance signal, the procedure proceeds to step S27. If a determination result is output that there are a group delay compensation amount and FM demodulation parameters that optimize the output performance signal, the procedure proceeds to step S30.

[0060] In step S27, the determination unit 25 notifies the FM demodulation parameter control unit 26 of changes to the group delay compensation amount and the FM demodulation parameters. In FIG. 7, an example in which changes to the group delay compensation amount and the FM demodulation parameters are simultaneously implemented is shown, but only the group delay compensation amount may be changed, or only the FM demodulation parameters may be changed. For example, in the case of first finding the optimal group delay compensation amount and then finding the optimal FM demodulation parameters, first only the group delay compensation amount is changed, and after finding the optimal group delay compensation amount, only the FM demodulation parameters are changed. As a result, it becomes possible to improve the performance of the output signal by changing the group delay compensation amount and then further improve the performance of the output signal by changing the FM demodulation parameters.

[0061] In step S28, the group delay compensation control unit 28 changes the group delay compensation amount used in the group delay compensation unit 12 in accordance with the notification from the determination unit 25. As a method of changing the group delay compensation amount, when the group delay compensation unit 12 is composed of an analog filter such as a resistor, a capacitor, or an inductor, a variable resistor, a capacitor with a variable capacitance such as a varicap, or a variable inductor using a core whose magnetic permeability is changed by an external magnetic field can be considered for control. Also, a method of configuring the group delay compensation unit 12 with a digital filter to make it easier to vary the group delay compensation amount is also conceivable.

[0062] In step S29, after changing the group delay compensation amount, similar to Embodiment 1, the FM demodulation parameter control unit 26 changes the FM demodulation parameters used in the FM demodulation unit 14 in accordance with the notification from the determination unit 25.

[0063] After changing the FM demodulation parameters in step S29, the procedure proceeds to step S22, and the output signal monitor unit 22 monitors the output signal again.

[0064] In step S23, the signal performance estimation unit 23 estimates the performance of the output signal, and in step S4, the estimated performance is stored in the storage unit 24 together with the group delay compensation amount and the FM demodulation parameters related to the performance.

[0065] In step S25, it is determined whether there are a group delay compensation amount and FM demodulation parameters that optimize the performance of the output signal in the combination of the performance of the output signal, the group delay compensation amount related to the output signal, and the FM demodulation parameters related to the output signal stored in the storage unit 24, and the determination result is output in step S26. If it cannot be determined in a re - determination that there are FM demodulation parameters that optimize the performance of the output signal, the procedures of steps S22 to S29 are repeated in steps S25 and S26 until it is determined that there are a group delay compensation amount and FM demodulation parameters that optimize the performance of the output signal.

[0066] In steps S25 and S26, when it is determined that there exist a group delay compensation amount and an FM demodulation parameter at which the performance of the output signal is optimal, in step S30, the group delay compensation control unit 28 sets the group delay compensation amount at which the performance of the searched output signal is optimal, and in step S31, the FM demodulation parameter control unit 26 sets the FM demodulation parameter at which the performance of the searched output signal is optimal, and the setting of the demodulation parameter and the group delay compensation amount is completed.

[0067] In the above description, as in Embodiment 1, it has been described that the group delay compensation amount is set together with the FM demodulation parameter at the time of optical input detection. However, as in Embodiment 2, the group delay compensation amount may be set together with the FM demodulation parameter at the time of temperature fluctuation detection.

[0068] As described above, according to Embodiment 3, in an optical communication device adopting the FM batch conversion method, the output signal is monitored at the time of optical input detection, the performance of the monitored output signal is estimated, and the FM demodulation parameter of the FM demodulation unit is controlled according to the signal performance, and the group delay compensation amount of the group delay compensation unit is also controlled. By controlling such FM demodulation parameters and group delay compensation amounts, it is possible to set the group delay compensation amount and FM demodulation parameters in a feedback manner so that the performance of the output signal is improved while checking the output signal. Therefore, even when the performance of the signal input to the FM demodulation unit 14 may deteriorate, the group delay compensation amount can be optimized according to the individual differences of the optical communication devices 30, and the performance of the signal input to the FM demodulation unit 14 can be improved. As a result, optimal FM demodulation can be realized, and it is possible to improve the performance of the output signal after FM demodulation. An optical communication device, an optical communication method, and an optical communication program capable of setting optimal FM demodulation parameters regardless of the individual differences of the optical communication device 30 can be provided. Further, in the inspection of the optical communication device 30, component replacement for performance improvement is not required, so the yield during the production of the optical communication device 30 can be improved, and the production of the optical communication device 30 considering the environment becomes possible.

Description of Reference Numerals

[0069] 10 Optical communication device, 11 Optical / electrical conversion unit, 12 Group delay compensation unit, 13 Limiting amplifier unit, 14 FM demodulation unit, 15 Signal amplification unit, 20 Optical communication device, 21 Optical signal monitor unit, 22 Output signal monitor unit, 23 Signal performance estimation unit, 24 Memory unit, 25 Judgment unit, 26 FM demodulation parameter control unit, 27 Temperature monitor unit, 28 Group delay compensation control unit, 30 Optical communication device, 210 CPU, 220 Main memory, 230 I / O interface, 240 Memory unit

Claims

1. An optical / electrical conversion unit that converts an input optical signal into an electrical signal; An FM demodulation unit that FM demodulates the electrical signal using FM demodulation parameters; A signal amplification unit that amplifies the FM demodulated electrical signal to a predetermined level; A signal performance estimation unit that estimates the performance of an output signal output from the signal amplification unit; A determination unit that determines the performance of the output signal estimated by the signal performance estimation unit, and extracts the FM demodulation parameters used for FM demodulation related to the output signal with the optimally determined performance; An FM demodulation parameter control unit that controls the FM demodulation unit to perform FM demodulation using the FM demodulation parameters extracted by the determination unit; An optical communication device comprising the above.

2. A group delay compensation unit that compensates for the group delay characteristic of the electrical signal output from the optical / electrical conversion unit; A limiting amplifier unit that amplifies the electrical signal with compensated group delay characteristics to a constant amplitude for FM demodulation; An optical signal monitor unit that detects the input of the optical signal to the optical / electrical conversion unit; An output signal monitor unit that monitors the output signal output from the signal amplification unit when the optical signal monitor unit detects the input of the optical signal; A storage unit that stores a combination of the estimated performance of the output signal and the FM demodulation parameters used for FM demodulation related to the output signal for which the performance was estimated; Further comprising the above, The FM demodulation unit FM demodulates the electrical signal amplified by the limiting amplifier unit; The signal performance estimation unit estimates the performance of the output signal monitored by the output signal monitor unit; The determination unit extracts the FM demodulation parameters that optimize the performance based on the combination of the performance of the output signal stored in the storage unit and the FM demodulation parameters. The optical communication device according to claim 1, characterized in that.

3. The determination unit, When there is no combination that optimizes the performance in the combination of the performance of the output signal stored in the storage unit and the FM demodulation parameters, it instructs the FM demodulation parameter control unit to change the FM demodulation parameters, and until the performance estimated by the signal performance estimation unit for the output signal obtained by FM demodulation using the FM demodulation parameters changed by the FM demodulation parameter control unit is determined to be optimal, it instructs the change of the FM demodulation parameters. The optical communication device according to claim 2.

4. Further comprising a temperature monitor unit that detects fluctuations in the temperature of the optical communication device. When the optical signal monitor unit detects an input of an optical signal and the temperature monitor unit detects a change in the temperature of the optical communication device, the output signal monitor unit monitors the output signal output from the signal amplification unit. The optical communication device according to claim 2 or claim 3, characterized in that.

5. Further comprising a group delay compensation control unit that controls the group delay compensation unit to compensate for the group delay characteristic of the electrical signal with a group delay compensation amount based on an instruction from the determination unit, The storage unit stores a combination of the estimated performance of the output signal, the FM demodulation parameter used for FM demodulation related to the output signal for which the performance was estimated, and the group delay compensation amount related to the output signal for which the performance was estimated, Based on the combination of the performance of the output signal, the FM demodulation parameter, and the group delay compensation amount stored in the storage unit, the determination unit extracts the group delay compensation amount and the FM demodulation parameter at which the performance is optimal, The group delay compensation control unit controls the group delay compensation unit to compensate for the group delay characteristic of the electrical signal using the group delay compensation amount extracted by the determination unit. The optical communication device according to claim 2, characterized in that.

6. The determination unit, When there is no combination in the combination of the performance of the output signal, the FM demodulation parameter, and the group delay compensation amount stored in the storage unit at which the performance is optimal, the determination unit instructs the group delay compensation control unit to change the group delay compensation amount and instructs the FM demodulation parameter control unit to change the FM demodulation parameter, and the group delay characteristic is compensated using the group delay compensation changed by the group delay compensation control unit, and the performance estimated by the signal performance estimation unit for the output signal obtained by FM demodulation using the FM demodulation parameter changed by the FM demodulation parameter control unit is optimal Until it is determined that, the change in the group delay compensation amount and the change in the FM demodulation parameter are instructed. The optical communication device according to claim 5, characterized in that.

7. An optical communication method executed by a computer, comprising: Converting an input optical signal into an electrical signal; FM demodulating the electrical signal using an FM demodulation parameter; Amplifying the FM demodulated electrical signal to a predetermined level; Estimating the performance of the amplified output signal; A step of determining the performance of the estimated output signal and extracting FM demodulation parameters used for FM demodulation related to the output signal with the optimum performance determined by the determination; A step of performing FM demodulation using the extracted FM demodulation parameters; An optical communication method having the above.

8. A step of converting an input optical signal into an electrical signal; A step of FM demodulating the electrical signal using FM demodulation parameters; A step of amplifying the FM demodulated electrical signal to a predetermined level; A step of estimating the performance of the amplified output signal; A step of determining the performance of the estimated output signal and extracting FM demodulation parameters used for FM demodulation related to the output signal with the optimum performance determined by the determination; A step of performing FM demodulation using the extracted FM demodulation parameters; An optical communication program for causing a computer to execute the above.

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