WO2005112332A1 - 光信号品質監視装置 - Google Patents
光信号品質監視装置 Download PDFInfo
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- WO2005112332A1 WO2005112332A1 PCT/JP2004/006809 JP2004006809W WO2005112332A1 WO 2005112332 A1 WO2005112332 A1 WO 2005112332A1 JP 2004006809 W JP2004006809 W JP 2004006809W WO 2005112332 A1 WO2005112332 A1 WO 2005112332A1
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- optical signal
- signal
- quality monitoring
- monitoring device
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07953—Monitoring or measuring OSNR, BER or Q
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/67—Optical arrangements in the receiver
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/20—Arrangements for detecting or preventing errors in the information received using signal quality detector
- H04L1/205—Arrangements for detecting or preventing errors in the information received using signal quality detector jitter monitoring
Definitions
- the present invention relates to an optical signal quality monitoring device that monitors the quality of an optical signal.
- quality monitoring by monitoring the number of errors in the FEC (Forward Error Collectio n) processing at the receiving end, and SDH (Synchronous Digitalhierarchy) Quality monitoring is performed by monitoring quality monitoring bits in a signal frame of a signal.
- FEC Forward Error Collectio n
- SDH Synchronous Digitalhierarchy
- Patent Document 1 the method of evaluating the optical signal quality by evaluating the histogram of the electric signal waveform in synchronization with the signal transmission speed (for example, Patent Document 1 and Non-Patent Document 1), and asynchronous sampling without depending on the signal transmission speed
- Patent Document 2 the method of estimating optical signal quality by performing histogram analysis at a frequency
- Patent Document 2
- Patent Document 1 and Non-Patent Document 1 described above have certain limitations on the signal transmission speed, and have the disadvantage that the configuration of the device becomes complicated.
- an object of the present invention is to provide an optical signal quality monitoring device capable of outputting accurate signal quality information with a simple configuration and independent of a signal transmission speed. Disclosure of the invention
- An optical signal quality monitoring device is an optical signal quality monitoring device for monitoring the signal quality of a predetermined optical signal transmitted through a communication line of an optical network system, wherein adjacent bits of the predetermined optical signal are adjacent to each other.
- An interferometer for outputting phase difference data between the first and second optical receivers; a first and a second optical receiver for converting an output optical signal output from the interferometer into an electrical signal; and the first and second optical receivers Calculating means for performing a predetermined operation on the electric signal converted by the above; a clock generating means for generating and outputting a peak signal having a predetermined frequency; and A discriminator for discriminating at the timing of the clock signal, a counter for calculating an integrated result within a predetermined time in which the discrimination output of the discriminator is counted for each logical level, and the predetermined light based on the integrated result of the power counter.
- a quality information calculation unit for outputting and outputting the identification information, wherein the classifier outputs an identification output identified for each of two or more different identification voltages, and the quality information calculation unit calculates for each of the amplitude identification voltages.
- the quality information is calculated based on the obtained integration result.
- identification outputs identified for each of two or more different amplitude identification voltages are integrated, and quality information is calculated based on the integration result calculated for each identification voltage.
- FIG. 1 is a block diagram illustrating a configuration of an optical signal quality monitoring device according to a first embodiment of the present invention.
- FIG. 2 is a diagram illustrating an example of a probability density distribution of an input optical signal. The figure shows the relationship between the electrical waveform of an NRZ (No Return Return Zero) OOK signal, the identification voltage when the NRZ- ⁇ ⁇ signal is input, and the error rate of the identification result.
- FIG. 4 is a diagram showing signal waveforms of main parts of the optical signal quality monitoring apparatus according to the first embodiment to which an optical DP SK signal is input, and FIG. 4B is a timing chart of each of them.
- FIG. 4C is a diagram showing a distribution of a mismatch rate (error rate) with respect to an identification voltage, and FIG.
- FIG. 5 is a diagram showing a configuration of an optical signal quality monitoring apparatus according to a second embodiment of the present invention.
- FIG. 6A is an optical signal product according to the second embodiment in which an optical DPSK signal is input.
- FIG. 6B is a diagram showing a signal waveform of a main part of the monitoring device,
- FIG. 6B is a diagram showing each timing chart, and
- FIG. 6C is a diagram showing a distribution of a mismatch rate (error rate) with respect to the identification voltage.
- FIG. 7 is a block diagram showing a configuration of an optical signal quality monitoring apparatus according to a third embodiment of the present invention.
- FIG. 8A is an embodiment in which an optical NRZ (NRZ-OOK) signal is input.
- FIG. 8B is a diagram showing a signal waveform of a main part of the optical signal quality monitoring device according to mode 3
- FIG. 8B is a diagram showing each timing chart
- FIG. 8C is a diagram showing a discrepancy rate (error)
- FIG. 9 is a block diagram showing a configuration of an optical signal quality monitoring device according to the fourth embodiment of the present invention
- FIG. 1 OA is a diagram showing an optical RZ-DP SK Optical signal according to the fourth embodiment in which a signal is input Main components of the quality monitoring device
- FIG. 10B is a diagram showing each timing chart
- FIG. 10C is a diagram showing a distribution of a mismatch rate (error rate) with respect to the identification voltage.
- FIG. 10B is a diagram showing a mismatch rate (error rate) with respect to the identification voltage.
- FIG. 11 is a block diagram showing a configuration of an optical signal quality monitoring device according to a fifth embodiment of the present invention.
- FIG. 12 is a block diagram showing an optical signal quality monitoring device according to a sixth embodiment of the present invention.
- FIG. 13 is a block diagram showing the configuration.
- FIG. 13 is a diagram showing the relationship between the match rate of the determination result and the error rate of the input signal.
- FIG. 17 is a block diagram showing a configuration of an optical signal quality monitoring device according to a seventh embodiment of the present invention.
- FIG. 1 is a block diagram showing a configuration of an optical signal quality monitoring device according to a first embodiment of the present invention.
- the optical signal quality monitoring device shown in FIG. 1 includes, for example, an interferometer 2 that outputs phase difference data between adjacent bits of an optical DPSK signal input from an optical fiber 1 and an optical signal that converts an optical signal into an electric signal.
- Optical receivers 3 and 4 as first and second light receivers, an adder 5 as an example of an arithmetic unit for performing a predetermined operation, a clock signal generator 6 for generating a clock signal, A discriminator 7 for discriminating the logic level (logic "1" or logic "0") of the input data based on a clock signal or a control signal; a counter 8 as counting means for counting the discrimination output of the discriminator 7; A quality information calculator 9 that calculates and outputs quality information necessary for monitoring the quality of an optical signal based on the output of the counter 8 and a controller 10 that controls predetermined components of the quality monitoring device are provided. .
- an optical DPSK (DifferentTialPhaseSeShiftKeyyng) signal is input to the interferometer 2.
- the interferometer 2 is provided with, for example, a 1-bit delay line (not shown), and generates an interference signal generated based on the optical signal that has passed through the 1-bit delay line and the optical signal that has not passed. Output is output.
- interferometer 2 has two output ports, and receives light according to the phase difference of the interference result. Output to one of optical devices 3 and 4. For example, when the phase difference of the interference result is "0", the signal is output to one optical receiver (for example, optical receiver 3). When the phase difference of the interference result is "1", the other optical receiver ( For example, it is output to the optical receiver 4).
- the optical receivers 3 and 4 convert the input optical signal into an electric signal.
- the electric signals converted by the optical receivers 3 and 4 are added by the adder 5 and output to the discriminator 7.
- the identification green 7 outputs, to the counter 8, the identification result (logic level determination result) identified at the timing of the clock (external clock) generated by the clock signal generation unit 6. Output.
- the counter 8 counts the identification result for each logic level (logic “1” or logic “0”), and outputs the integration result within a predetermined time to the quality information calculation unit 9.
- the quality information calculation unit 9 generates and outputs predetermined quality information based on information such as the count value of the identification result and the identification voltage.
- the control unit 10 controls a predetermined component of the optical signal quality monitoring device. For example, the interferometer 2 is stably controlled with respect to the optical signal wavelength.
- the control of the identification voltage of the classifier 7 and the output control of the quality information calculation unit 9 are also performed based on the control of the control unit 10.
- FIG. 2 is a diagram illustrating an example of a probability density distribution of an input optical signal.
- waveform 1 is a probability density distribution (noise distribution) corresponding to logic "1”
- waveform 2 is a probability density distribution (noise distribution) corresponding to logic "0”.
- ⁇ indicates the standard deviation in the probability density distribution corresponding to the logic “1”
- ⁇ Indicates the standard deviation in the probability density distribution corresponding to logic "0".
- FIG. 3 shows the relationship between the electrical waveform of the NRZ (No Return Return Zero) OK signal, the identification voltage when the NRZ-OOK signal is input, and the error rate of the identification result.
- FIG. Returning to FIG. 2, consider the case where the distribution of the logic "1" and the logic "0" is as shown in FIG. At this time, the data in the area A1 indicated by the horizontal line is determined to be logical "1". Therefore, the area A1 The probability that data of logic "0" will be judged as logic "1".
- the identification voltage is V 2 (Vi> V 2 ).
- the data of both areas obtained by adding the area A1 indicated by the oblique lines to the area A1 indicated by the horizontal lines is determined to be logic "1". Therefore, the area Al, A2 has a probability that data of logic "0" is determined to be logic "1".
- the probability that data of logic "0" is determined to be logic "1” at a predetermined identification voltage or the probability that data of logic "1" is determined to be logic "0” is determined by the identification voltage. Is defined as the "mismatch rate.”
- the inconsistency rate defined in this way means the ratio between the logic level of the transmission data when the identification voltage is varied and the determined logic level do not match. It can be equated with the error rate of the transmission data. Therefore, by using this mismatch rate, it can be used for monitoring the optical signal quality.
- the portion indicated by the broken lines K3 and K4 in FIG. 3 is a plot of this mismatch rate.
- the portion indicated by the broken line K4 in both cases is that the counter 8 counts the number that the discriminator 7 has discriminated as logic "1" when the discrimination voltage is changed to the logic "0" side.
- This is a plot of the mismatch rate calculated by the quality information calculation unit 9 based on the count number.
- the identification voltage V the mismatch factor when the Pi
- P 2 if put identification voltage V 2 Kino Noto mismatch index and P 2
- P i as is clear from the content of the above ⁇ P 2 (provided that V ,> V 2 ). Therefore, the portion of the broken line K 4 becomes a curve (histogram) falling downward.
- the identification voltage is set on the distribution side of the logic "1"
- the result shown by the broken line 3 is obtained.
- the slope of the curve representing the mismatch rate is a curve (histogram) that rises to the right and is symmetric to the curve shown by the broken line 4.
- FIG. 4 is a diagram showing a signal waveform of a main part of the optical signal quality monitoring apparatus according to the first embodiment to which the optical DPSK signal is input
- FIG. 4B is a diagram showing respective timing charts.
- Yes, Fig. 4C shows the distribution of the mismatch rate (error rate) with respect to the identification voltage.
- the optical DP SK signal waveform (A) input to the interferometer 2 has a constant intensity and has binary phase difference information (0, ⁇ ).
- the waveforms ( ⁇ ) and (C) obtained by photoelectrically converting the outputs of the interferometer 2 by the optical receivers 3 and 4 become NRZ signals of opposite polarities (different polarities). Therefore, the added signal obtained by adding these two signals is a signal obtained by adding both of FIGS. 4 (I) and 4 (C), and is a logical "1" as shown in FIG. 4 (D). Is obtained.
- the discriminator 7 to which such an addition signal has been input outputs the discrimination result, which is discriminated at the timing of the external clock, to the counter 8 based on the discrimination voltage output from the control unit 10.
- the counter 8 counts the identification result and outputs the result to the quality information calculation unit 9.
- the quality information calculation unit 9 estimates the average value of the probability density distribution and the standard deviation ⁇ based on the histogram obtained in the above processing, and generates optical signal quality information based on the equation (1). Output.
- the discrimination voltage is applied to the logic "0" level side as described above. Need not be changed. That is, although only the upper half distribution (histogram) as shown in Fig. 4C is obtained, it is assumed that the probability density distributions of logic "1" and logic "0" follow a Gaussian distribution. The distribution in the lower half can be treated as symmetric to the distribution in the upper half.
- Equation (1) the Q value of the optical signal quality monitoring device according to the present embodiment is calculated using equation (1).
- ⁇ i ⁇ .
- Two ⁇ . Toke can be simplified as follows.
- the optical signal quality monitoring apparatus of the present embodiment two or more different amplitude discrimination voltages are applied to the DPSK modulation optical signal.
- the identification output identified for each identification voltage is integrated, and the quality information is calculated based on the integration result calculated for each identification voltage, so that the quality of the optical signal can be easily estimated and evaluated independent of the transmission speed be able to.
- the DPSK signal input to the interferometer 2 is an NRZ-DPSK signal.
- the present invention is not limited to the NRZ-DPSK signal. It does not matter.
- the average value ⁇ i of the probability density distribution and the standard deviation ⁇ ⁇ only need to calculate a mismatch rate based on at least two or more different identification voltages. Because if we have at least 2 points of data, we can estimate the mean ⁇ of Gaussian distribution and standard deviation ⁇ .
- FIG. 5 is a block diagram showing a configuration of an optical signal quality monitoring device according to a second embodiment of the present invention.
- the optical signal quality monitoring device shown in the figure is the same as the optical signal quality monitoring device shown in FIG. 1, except that the polarities of the optical receivers 4 are inverted, and the photoelectrically converted signals at each optical receiver are subtracted. Input to 1 and 2 to generate a difference signal.
- the other configuration is the same as or equivalent to that of the first embodiment, and these components are denoted by the same reference numerals.
- FIG. 6 is a diagram showing the signal waveform of the main part of the optical signal quality monitoring device according to the second embodiment to which the optical DPSK signal is input, and FIG. 6B is a timing chart for each.
- FIG. 6C is a diagram showing the distribution of the mismatch rate (error rate) with respect to the identification voltage.
- the optical DPSK signal waveform input to interferometer 2 (A) has constant intensity and binary phase difference information (0, ⁇ ).
- the waveforms (C) and ( ⁇ ) obtained by photoelectrically converting the outputs of the interferometer 2 by the optical receivers 3 and 4 have the same logic, and the waveform ( ⁇ ) is the same as the negative potential NRZ signal.
- the output of the optical receiver 4 shown in FIG. 6 is inverted as compared with the output in FIG. 4A. Therefore, the signals obtained by subtracting the two signals (B) and (C) by the subtraction circuit 12 are all signals having a logic “1” as shown in FIG. 6B (D).
- the subsequent processing is the same as the processing of the first embodiment, and a description thereof will be omitted.
- the discriminator 7 and counter 8 in Fig. 5 are replaced with a soft decision discriminator having M (M ⁇ 2) discriminators and a D / A converter, so that As in the first embodiment, the number of bits can be detected in parallel, and the quality of the optical signal can be estimated and evaluated with high accuracy in real time.
- the interferometer 2 has a small effect on the transmission speed difference due to the error correction redundancy, and when the transmission speed is N times (N 2), the interferometer 2 is an N-bit interferometer. Since it can be operated, an optical signal quality monitoring device independent of the signal transmission speed can be provided by using an interferometer corresponding to the minimum transmission speed existing on the optical network.
- the identification output identified for each of the two or more different amplitude identification voltages is integrated with the optical signal of the DP SK modulation method, Since the quality information is calculated based on the integration result calculated for each identification voltage, the quality of the optical signal can be easily estimated and evaluated without depending on the transmission speed.
- FIG. 7 is a block diagram illustrating a configuration of an optical signal quality monitoring device according to a third embodiment of the present invention.
- the optical signal quality monitoring device shown in the figure is configured so that the interferometer 2 is replaced with an optical splitter 28 in the optical signal quality monitoring device shown in FIG. are doing.
- Other configurations are the same as in the second embodiment. They are the same or equivalent, and these portions are denoted by the same reference numerals.
- FIG. 8A is a diagram showing a signal waveform of a main part of the optical signal quality monitoring device according to the third embodiment to which an optical NRZ (NRZ-OOK) signal is input
- FIG. 8C is a diagram showing a timing chart
- FIG. 8C is a diagram showing a distribution of a mismatch rate (error rate) with respect to the identification voltage.
- the optical NRZ signal waveform input to the optical splitter 28 has binary intensity information.
- the waveforms (c) and (b) obtained by photoelectrically converting the outputs of the optical splitter 28 by the optical receivers 3 and 4 are of the same polarity, and the waveform (B) is a negative potential NRZ signal. It becomes. Accordingly, a signal obtained by subtracting the two signals (B) and (C) in the subtraction circuit 12 is a signal having all logic "1" as shown in FIG. 8B (D).
- the optical signal processed in this embodiment is an OOK signal
- the probability density distributions of logic "1" and logic "0" are different, so that the signal of In the probability density distribution, the probability density distribution of the logic "1" of the original optical OOK signal is dominant, ⁇ 10 ⁇ , ⁇ ⁇ . Is established.
- the average value of the logic "1” and the logic "0” are different, the average value of the signal obtained by adding both is the sum of the average values of the logic "1” and the logic "0" of the original optical OOK signal. Therefore ⁇ . / ⁇ +. Is established.
- the Q value of the present embodiment obtained from the histogram shown in FIG. 8C can be simplified as in the following equation.
- the subsequent processing is the same as in the second embodiment, and a description thereof will not be repeated.
- the identification output identified for each of the two or more different amplitude identification voltages is added to the optical signal of the OOK modulation method, and Since the quality information is calculated based on the integration result calculated in (1), the quality of the optical signal can be easily estimated and evaluated without depending on the transmission speed.
- FIG. 9 is a block diagram showing a configuration of an optical signal quality monitoring device according to Embodiment 4 of the present invention.
- the optical signal quality monitoring device shown in the figure is the same as the optical signal quality monitoring device shown in FIG. 1, except that the clock signal (electric signal) applied to the discriminator 7 is transmitted by the transmitted optical RZ-DP SK signal ( And a delay adjuster 15 that adjusts the phase (timing) of the clock signal applied to the discriminator 7.
- Other configurations are the same as or equivalent to those in Embodiment 1, and these portions are denoted by the same reference numerals.
- FIG. 1A is a diagram showing signal waveforms of main parts of the optical signal quality monitoring apparatus according to the fourth embodiment to which an optical RZ-DP SK signal is input
- FIG. 10C is a diagram illustrating an timing chart
- FIG. 10C is a diagram illustrating a distribution of a mismatch rate (error rate) with respect to the identification voltage.
- the optical RZ-DP SK signal waveform (A) input to interferometer 2 is an optical pulse train whose repetition frequency is the bit rate frequency. It consists of phase difference information (0, ⁇ ).
- the waveforms ( ⁇ ) and (C) obtained by photoelectrically converting the outputs of the interferometer 2 with the optical receivers 3 and 4 are the opposite polar RZ signals. By adding these two signals, an RZ signal showing logic "1" can be obtained.
- the subsequent processes are the same as those of the first and second embodiments except that the logic level is determined based on the identification voltage that is changed based on the clock signal separately reproduced in the identifier 7. Therefore, the description is omitted.
- the repetition frequency of the input optical RZ-DP SK signal is a pulse train of the bit rate frequency, and no special port extraction circuit is required.
- the structure of the extraction circuit itself does not depend on the transmission speed.
- interferometer 2 has a small effect on the transmission rate difference due to the error correction redundancy, and when the transmission rate is N times (N 2), N bit Since it can be operated as an interferometer, an optical signal quality monitoring device that does not depend on the signal transmission speed can be realized by using an interferometer corresponding to the minimum transmission speed existing on the optical network.
- the optical signal quality monitoring device of the present embodiment since the clock signal is generated based on the electric signal converted by the optical receiver, it does not depend on the transmission speed. It is possible to easily estimate and evaluate the quality of an optical signal.
- Embodiment 5 since the clock signal is generated based on the electric signal converted by the optical receiver, it does not depend on the transmission speed. It is possible to easily estimate and evaluate the quality of an optical signal. Embodiment 5.
- FIG. 11 is a block diagram showing a configuration of an optical signal quality monitoring device according to a fifth embodiment of the present invention.
- the optical signal quality monitoring device shown in the figure is the same as the optical signal quality monitoring device of the fourth embodiment shown in FIG. 9 except that the clock signal (electric signal) applied to the discriminator 7 is converted into the branch output ( (Electrical signal).
- the other configurations are the same as or similar to those of the fourth embodiment, and these components are denoted by the same reference numerals.
- the operation of the optical signal quality monitoring device shown in FIG. 11 will be described.
- the output signal (electric signal) of the adder 5 itself is a mouth signal whose repetition frequency is a bit rate frequency.
- this signal can be branched and used as a clock signal to be applied to the discriminator 7.
- optical signal quality monitoring device configured as shown in FIG. 11 can have the same or equivalent functions as in the fourth embodiment.
- the clock signal is generated based on the sum output of the respective electric signals converted by the optical receiver, so that the transmission It is possible to easily estimate and evaluate the quality of optical signals regardless of speed.
- FIG. 12 is a block diagram showing a configuration of an optical signal quality monitoring apparatus according to Embodiment 6 of the present invention.
- the optical signal quality monitoring device shown in the figure is composed of an optical variable attenuator 16 that adjusts the optical signal power of the optical NRZ-DPSK signal or the RZ-DPSK signal input from the optical fiber 1, and the optical signal attenuator adjacent to the input optical signal.
- An interferometer 2 that outputs phase difference data between bits, optical receivers 3 and 4 that are first and second optical receivers that convert optical signals into electrical signals, and optical receivers 3 and 4 respectively.
- Clock extractors 17 and 18 for generating respective clock signals based on the outputs; discriminators 19 and 20 for discriminating the logic level of each input data based on the clock signals;
- An exclusive OR circuit 21 for performing an exclusive OR operation on each of the outputs 9 and 20;
- a counter 8 as a counting means for counting the output of the exclusive OR circuit 21;
- an output of the counter 8 Product that calculates and outputs quality information required for optical signal quality monitoring based on An information calculation unit 9, and a control unit 1 0 for controlling the predetermined configuration of the quality monitoring apparatus.
- an optical NRZ-DPSK signal or The RZ-DP SK signal is input, and the optical signals at the two output ports of the interferometer are photoelectrically converted by the optical receivers 3 and 4, respectively.
- the optical signal input to the interferometer 2 is adjusted to a desired value by the optical variable attenuator 16.
- Each of the electrical signals photoelectrically converted by the optical receivers 3 and 4 shows a different logic level (logic “1” or logic “0") with respect to the logic level of the input optical signal.
- Each electric signal is branched independently and input to the classifiers 19 and 20 and the clock extractors 17 and 18.
- Each of the clock signals extracted independently by the clock extractors 17 and 18 is input to the classifiers 19 and 20 after performing phase adjustment.
- the discrimination voltage applied to the two discriminators 19 and 20 is given a constant value that minimizes the number of errors.
- the discrimination results determined by the discriminators 17 and 18 are input to the exclusive OR circuit 21, respectively, and a match or mismatch between the two discrimination results is determined.
- the result of the integration within the time is output to the calculation unit 9.
- the quality information calculating unit 9 generates and outputs predetermined quality information based on information such as a force value of the identification result.
- the control unit 10 controls predetermined components of the optical signal quality monitoring device. For example, the variable attenuator 16 is controlled so that the level of the input optical signal is optimized, and the interferometer 2 is stably controlled according to the optical signal wavelength.
- the output control of the quality information calculating unit 9 is also performed based on the control of the control unit 10.
- the optical signals output from the two output ports of the interferometer 2 are obtained from different components on the optical frequency axis, their probability density distributions have no correlation with each other. Therefore, when the discriminators 19 and 20 have each discrimination voltage set on each distribution of the input signal, the discrimination results discriminated by the discriminators 19 and 20 are erroneous at almost the same rate. On the other hand, there is no correlation between them.
- FIG. 13 is a diagram showing the relationship between the match rate of the determination result and the error rate of the input signal.
- the rate at which the two discrimination results determined by the discriminators 19 and 20 match is regarded as being proportional to the error rate of the input signal. be able to. In this way, by calculating the ratio of the coincidence of the discrimination results, the quality of the input optical signal can be estimated and evaluated.
- the discrimination voltage of each discriminator is set to a fixed value in advance, it is not necessary to change (search) the discrimination voltage, and the quality of an optical signal excellent in real time can be monitored. Can be.
- FIG. 14 is a block diagram showing a configuration of an optical signal quality monitoring apparatus according to Embodiment 7 of the present invention.
- the embodiment 7 shown in the figure shows an example in which the optical signal quality monitoring apparatus shown in the above-described Embodiments 1 to 5 is arranged on a transmission line on which an optical wavelength multiplexed signal is transmitted. .
- an optical wavelength multiplexed signal transmitted on an optical transmission line 22 is connected to an optical cross-connect 24 via a branching power 23.
- the output of the branching power splitter for monitoring the optical signal quality is output to the optical signal quality monitoring device 26 while extracting the desired optical signal in the variable optical filter 25.
- the optical signal quality monitoring device 26 outputs predetermined quality information relating to the optical signals described in the first to fifth embodiments to the control unit 27.
- the extracted signal extracted by the variable optical filter 25 and the quality information of the extracted signal output by the optical signal quality monitoring device 26 are notified to the optical cross-connect 24 via the control unit 27.
- the optical signal quality monitoring device 26 does not depend on the transmission speed for the optical signals of the DPSK modulation method and the OOK modulation method, and furthermore, Since it is a device that can easily perform quality evaluation, for example, an optical signal transmitted through the transmission path 22 is an optical signal in which optical signals with different transmission speeds are multiplexed. Even if it is a wavelength multiplexed signal, it has the ability to support optical signals of any transmission speed, so it can be applied uniformly to any optical signal, and the signal quality of each optical signal can be easily reduced. Can be estimated and evaluated.
- the quality of an optical signal transmitted through an optical network system can be controlled independently of the transmission speed by using the optical signal quality monitoring device shown in the first to fifth embodiments. It can be easily estimated and evaluated. Industrial applicability
- the optical signal quality monitoring apparatus is useful for evaluating the signal quality of an optical signal, and is particularly useful when evaluating the quality of an optical signal in a networked optical communication line. It is suitable.
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EP1686709A1 (en) * | 2005-01-31 | 2006-08-02 | Lucent Technologies Inc. | Optical receiver apparatus and corresponding method |
JP2006270909A (ja) * | 2005-02-28 | 2006-10-05 | Fujitsu Ltd | 光信号受信装置 |
JP2008011304A (ja) * | 2006-06-30 | 2008-01-17 | Fujitsu Ltd | 光受信装置 |
JP2008118416A (ja) * | 2006-11-06 | 2008-05-22 | Nippon Telegr & Teleph Corp <Ntt> | デジタル受信器 |
JP2008252460A (ja) * | 2007-03-30 | 2008-10-16 | Kddi Corp | 光信号品質モニタ装置及び方法 |
JP2009094743A (ja) * | 2007-10-05 | 2009-04-30 | Nippon Telegr & Teleph Corp <Ntt> | 干渉計制御装置及び方法 |
JP2009141854A (ja) * | 2007-12-10 | 2009-06-25 | Kddi Corp | 光信号品質監視装置 |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1686709A1 (en) * | 2005-01-31 | 2006-08-02 | Lucent Technologies Inc. | Optical receiver apparatus and corresponding method |
JP2006217605A (ja) * | 2005-01-31 | 2006-08-17 | Lucent Technol Inc | 光受信装置および方法 |
JP2006270909A (ja) * | 2005-02-28 | 2006-10-05 | Fujitsu Ltd | 光信号受信装置 |
JP4589836B2 (ja) * | 2005-02-28 | 2010-12-01 | 富士通株式会社 | 光信号受信装置 |
JP2008011304A (ja) * | 2006-06-30 | 2008-01-17 | Fujitsu Ltd | 光受信装置 |
JP4684180B2 (ja) * | 2006-06-30 | 2011-05-18 | 富士通株式会社 | 光受信装置 |
JP2008118416A (ja) * | 2006-11-06 | 2008-05-22 | Nippon Telegr & Teleph Corp <Ntt> | デジタル受信器 |
JP2008252460A (ja) * | 2007-03-30 | 2008-10-16 | Kddi Corp | 光信号品質モニタ装置及び方法 |
JP2009094743A (ja) * | 2007-10-05 | 2009-04-30 | Nippon Telegr & Teleph Corp <Ntt> | 干渉計制御装置及び方法 |
JP2009141854A (ja) * | 2007-12-10 | 2009-06-25 | Kddi Corp | 光信号品質監視装置 |
Also Published As
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JPWO2005112332A1 (ja) | 2008-03-27 |
JP4523588B2 (ja) | 2010-08-11 |
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