JP2003110632A - Error rate acquisition method, its program and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an error rate acquisition method capable of obtaining an error rate of a pulse signal in a short time. SOLUTION: This method includes; a prescribed level frequency distribution measurement value acquisition step S1 of acquiring a measured value of a prescribed level timing versus frequency graph for representing a frequency distribution as to number of prescribed pulse periods in timings when the pulse takes a prescribed level within one pulse period started from a prescribed timing of joints of optical pulse signals, a frequency distribution decision procedure S2 of deciding the measured value from the prescribed level timing versus frequency graph subjected to frequency error correction as a timing versus frequency graph, an estimate step S3 of estimating a distribution fluctuation width of the timing versus frequency graph when the prescribed pulse period number is increased, an eye width derivation procedure S4 of using the distribution fluctuation width and the distribution width of the timing versus frequency graph to obtain an eye width after fluctuation, and an error rate introduction step S5 of obtaining the error rate from the eye width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error rate acquisition method for obtaining an error rate included in a signal when transmitting and receiving a signal, a program therefor, and a recording medium.

[0002]

2. Description of the Related Art For obtaining an error rate (BER) which is a ratio of errors contained in a pulse signal when transmitting and receiving a pulse signal in a transmitting and receiving system such as transmitting and receiving an optical signal through an optical fiber cable, it has been a conventional practice. Measured the error rate directly. This error rate acquisition method is
This is measured by transmitting n bits of appropriate data and counting the number of erroneously transmitted bits. As the number of erroneously transmitted bits, there is a method of first measuring an eye pattern of a signal and adopting the number of bits included in a certain area in the eye pattern.

[0003]

[Problems to be Solved by the Invention] However, IEEE
As the error rate of 10 ^-12 or less is specified in the E1394 communication system standard, the error rate must be extremely small. Therefore, if the error rate is directly measured as described above, the number of measured bits is However, there is a problem in that it takes a lot of time and takes a lot of time. Therefore, this method requires a huge amount of time and cost, especially when the transmission / reception system is mass-produced.

The present invention has been made in view of the above conventional problems, and an object thereof is an error rate acquisition method capable of obtaining an error rate of a pulse signal in a short time,
And its program and recording medium.

[0005]

In order to solve the above-mentioned problems, the error rate acquisition method of the present invention transmits / receives a pulse signal in which one-pulse information is represented by either a High level or a Low level. In an error rate acquisition method for obtaining an error rate of the pulse signal of the system, the pulse signal has a predetermined level near an eye width definition level within one pulse period starting from a predetermined timing with respect to a pulse joint of the received pulse signal. A predetermined level frequency distribution measurement value acquisition procedure for acquiring a measurement value of a predetermined level timing vs. frequency graph indicating how often the timing of taking a sample value is distributed in a predetermined number of pulse periods, and the predetermined level frequency Measurement of the above specified level timing vs. frequency graph acquired in the distribution measurement value acquisition procedure , Or those subjected to error correction of the frequency of the measurement value of the predetermined level timing versus frequency graph, one pulse period in the above pulse signal starting from said predetermined timing of the timing of taking the predetermined level,
From the timing vs. frequency graph determined in the frequency distribution determination procedure and the frequency vs. frequency graph determining the frequency vs. frequency graph representing an appropriate frequency distribution for the predetermined pulse period number, the predetermined pulse period number is made larger. The predetermined pulse using the estimation procedure for estimating the distribution variation width of the timing vs. frequency graph when the number is increased, and the distribution variation width and the distribution width of the timing vs. frequency graph estimated by the estimation procedure. From the eye width derivation procedure for obtaining the eye width when the number of periods is increased to the larger number above, and the predetermined pulse period number from the eye width obtained in the eye width derivation procedure to the larger number above. And an error rate derivation procedure for obtaining the error rate when the error rate is increased.

According to the above invention, the measurement value of the predetermined level timing versus frequency graph is acquired by the predetermined level frequency distribution measurement value acquisition procedure. This predetermined level timing vs. frequency graph shows that the timing at which the pulse signal takes a predetermined level near the eye width definition level as a sample value within one pulse period starting from the predetermined timing with respect to the pulse joint of the received pulse signal, It shows how often the distribution is performed when the number of predetermined pulse periods is viewed. Then, by the frequency distribution determination procedure, the measurement value of the predetermined level timing vs. frequency graph acquired in the predetermined level frequency distribution measurement value acquisition procedure or the measurement value of the predetermined level timing vs. frequency graph is subjected to frequency error correction. , As a timing vs. frequency graph. This timing vs. frequency graph properly represents how often the timing at which the pulse signal takes a predetermined level within one pulse period starting from the predetermined timing is distributed in terms of the number of predetermined pulse periods. Is determined as

Since the timing vs. frequency graph determined by the frequency distribution determination procedure changes as the number of predetermined pulse periods increases, the estimation vs. frequency vs. frequency graph determined by the frequency distribution determination procedure The distribution fluctuation range of the timing vs. frequency graph when the number of predetermined pulse periods is increased to a larger number is estimated. Since the period during which the pulse signal does not take the predetermined level represents the eye width, the eye width deriving procedure is then used to determine the predetermined pulse duration using the distribution variation width estimated in the estimation procedure and the distribution width of the timing vs. frequency graph. Find the eye width when increasing the number to a larger number. Then, by the error rate derivation procedure,
An error rate when the number of predetermined pulse periods is increased to a larger number from the eye width obtained in the eye width deriving procedure is obtained.

As described above, the measured value for the predetermined number of pulse periods is used to obtain the eye width when the predetermined number of pulse periods is increased to a larger number, and the corresponding error rate is obtained. Assuming that the number required to directly measure and obtain the error rate, an accurate error rate can be obtained from the measured values for a small number of predetermined pulse periods. Therefore, the error rate of the pulse signal can be obtained in a short time.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned subject, it is characterized by including a predetermined level decision procedure which makes the median between the High level and the Low level of the received pulse signal the above-mentioned predetermined level.

According to the above invention, the high level and the L level of the received pulse signal are determined by the predetermined level determining procedure.
Since the median value between the low level and the low level is set as the predetermined level, the predetermined level can be determined as an accurate level close to the eye width defining level which is the median value between the High level and the Low level in the ideal state. .

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, a level vs. frequency graph showing how often the level of the received pulse signal taken at a specific timing within one pulse period is distributed as a sample value in the number of specific pulse periods. Specific timing frequency distribution measurement value acquisition procedure for acquiring measurement values, and peaks near the maximum and minimum sample values of the measurement values of the level vs. frequency graph acquired by the above specific timing frequency distribution measurement value acquisition procedure , The sample value taking the peak value near the maximum sample value is set to the High level, and the sample value taking the peak value near the minimum sample value is set to the Low level. It is characterized by being.

According to the above invention, the level taken by the pulse signal at a specific timing within one pulse period is distributed as a sample value by the specific timing frequency distribution measurement value acquisition procedure at what frequency in a specific pulse period number. Acquires the measurement value of the level vs. frequency graph indicating whether or not there is. Then, according to the level range determination procedure, from the peak position appearing in the measured value of the level vs. frequency graph to the high level of the pulse signal.
Determine level and low level. That is, when peaks appear near the maximum sample value and near the minimum sample value of the level vs. frequency graph, the peak value near the maximum sample value is taken as the high level, and the peak value near the minimum sample value is taken. The sample value is set to the Low level. The sample value of the above peak is H
Since the high level and the low level are well reflected, the high level and the low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problems, it is possible to determine how often the level of the received pulse signal taken at a specific timing excluding the vicinity of the pulse joint in one pulse period is distributed as a sample value in a specific pulse period number. Represents the measured value of the level vs. frequency graph other than the joint The specific timing frequency distribution measured value acquisition procedure other than the joint and the specified timing frequency distribution measured value acquisition procedure other than the joint Measured value of the level versus frequency graph other than the joint Find the first level, which is the sample value that takes the maximum frequency of
A multiplication distribution is created by multiplying the level-frequency graph other than the joint with a function that is the smallest at the first level and increases as the distance from the first level approaches a constant value, and takes the maximum value of the multiplication distribution. A second range which is a sample value is obtained, and a level range determining procedure in which the larger one of the first level and the second level is the High level and the smaller one is the Low level is included. It has a feature.

According to the above invention, the level taken by the pulse signal at the specific timing within one pulse period is used as the sample value by the specific timing frequency distribution measurement value acquisition procedure other than the joint, and at what frequency in the specific pulse period number. Acquires the measured value of the level vs. frequency graph other than the joint where the distribution is shown. Then, according to the level range determination procedure, the measured values of the level vs. frequency graph other than the joints are processed to change the High level and the Low level of the pulse signal.
Determine the level. That is, the first level, which is the sample value that takes the maximum frequency of the level versus frequency graph other than the joint, is obtained, and the function that is the smallest at the first level and increases as it moves away from the first level and approaches a constant value is compared with the level other than the joint. Create a multiplication distribution that is multiplied by the frequency graph and take the maximum value of the multiplication distribution.
The level is obtained, and the larger one of the first level and the second level is set as the high level, and the smaller one is set as the low level.

The first level and the second level are sample values having a peak value near the maximum sample value or sample values having a peak value near the minimum sample value included in the level vs. frequency graph other than the joint, and are high levels. And the Low level is well reflected. Therefore, the High level and the Low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, an all-level-versus-frequency graph showing how often the level of the received pulse signal taken through all the timings within one pulse period is distributed as a sample value at a specific number of pulse periods. Of the total timing frequency distribution measurement value acquisition procedure for acquiring the measurement value of, and the maximum sample value of the measurement values of the all level vs. frequency graph acquired in the above all timing frequency distribution measurement value acquisition procedure, or near the maximum sample value. A level range determining procedure in which a sample value having a peak value is set to the High level, and a minimum sample value of the all level vs. frequency graph or a sample value having a peak value near the minimum sample value is set to the Low level. It is characterized by being out.

According to the above invention, the level of the pulse signal at all the timings within one pulse period is distributed as the sample value by the all timing frequency distribution measurement value acquisition procedure at any frequency in the specific pulse period number. Acquires the measurement value of the all level vs. frequency graph that indicates whether or not And
By the level range determination procedure, the High level and the Low level of the pulse signal are determined from the measured values of the all level vs. frequency graph. That is, the maximum sample value of the all level vs. frequency graph, or the sample value having the peak value near the maximum sample value is set to the high level, and the minimum sample value or the sample value having the peak value near the minimum sample value is set to the Low level. Level. The maximum sample value or the sample value having a peak value near the maximum sample value reflects the High level, and the sample value having the minimum sample value or the peak value near the minimum sample value reflects the Low level, The High level and the Low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, an all-level-versus-frequency graph showing how often the level of the received pulse signal taken through all the timings within one pulse period is distributed as a sample value at a specific number of pulse periods. All timing frequency distribution measurement value acquisition procedure for acquiring measurement values of all timings, and sample value that takes the maximum frequency of measurement values of all level vs. frequency graphs acquired by all timing frequency distribution measurement value acquisition procedure A level is calculated, a function that is the smallest at all the first levels and increases as it moves away from the first level and approaches a constant value is created as a total multiplication distribution by multiplying the all level vs. frequency graph, and An all second level which is a sample value taking the maximum value of the multiplication distribution is obtained, and the larger one of the all first levels and the all second levels is the High level. And Bell, the smaller the Low
It is characterized by including a level range determination procedure for a level.

According to the above invention, the level of the pulse signal at all the timings within one pulse period is distributed as the sample value by the all timing frequency distribution measurement value acquisition procedure at any frequency in the specific pulse period number. Acquires the measurement value of the all level vs. frequency graph that indicates whether or not And
By the level range determination procedure, all the first levels, which are the sample values that take the maximum frequency of the measured values of the all levels vs. frequency graph, are obtained, and are the smallest at all the first levels, and increase as the distance from the all first levels increases to a constant value. Create a total multiplication distribution by multiplying the function approaching to the all levels vs. frequency graph, find all the second levels that are the sample values that take the maximum value of all the multiplication distributions, and calculate all the first levels and all the second levels. The larger one is set to the high level, and the smaller one is set to the low level.

All the first levels and all the second levels are sample values having a peak value near the maximum sample value or sample values having a peak value near the minimum sample value included in the all-level vs. frequency graph, and are high. The level and the Low level are well reflected. Therefore, the High level and the Low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, an all-level-versus-frequency graph showing how often the level of the received pulse signal taken through all the timings within one pulse period is distributed as a sample value at a specific number of pulse periods. All timing frequency distribution measurement value acquisition procedure for acquiring the measurement value of, and an average sample value of the measurement values of all level vs. frequency graph acquired in the above all timing frequency distribution measurement value acquisition procedure is set to the predetermined level. It is characterized by including a level determination procedure.

According to the above invention, the level of the pulse signal at all the timings within one pulse period is distributed as the sample value by the total timing frequency distribution measurement value acquisition procedure at any frequency in the specific pulse period number. Acquires the measurement value of the all level vs. frequency graph that indicates whether or not And
According to the predetermined level determination procedure, the average sample value of the measured values of all levels vs. frequency graph is set as the predetermined level. Therefore, the predetermined level is set to the High level and the Low
It can be determined as an accurate level close to the eye width definition level that is the median between the levels.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problems, the timing at which the received pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is used as a sample value, and what is the number of the predetermined pulse periods. In another frequency level distribution graph showing the other level timing vs. frequency graph indicating whether or not the distribution is performed by frequency, the other level frequency distribution measurement value acquisition step of acquiring the measurement value for each one or more specific levels, Measurement values of the predetermined level timing vs. frequency graph acquired in the predetermined level frequency distribution measurement value acquisition procedure and measurement values of the other level timing vs. frequency graph acquired in the arbitrary other level frequency distribution measurement value acquisition procedure The above-mentioned error correction is performed by synthesizing the It is characterized in.

According to the above invention, the timing of taking a specific level other than the predetermined level within one pulse period starting from the predetermined timing is set as the sample value by the predetermined number of pulse periods by the arbitrary other level frequency distribution measurement value acquisition procedure. A measurement value is acquired for each of one or more specific levels of another level timing vs. frequency graph showing how often the distribution is made. Then, in the frequency distribution determination procedure, by combining the measurement value of the predetermined level timing vs. frequency graph and each measurement value of the other level timing vs. frequency graph, the frequency error is added to the measurement value of the predetermined level timing vs. frequency graph. It is corrected and determined as a timing vs. frequency graph.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, in the frequency distribution determination procedure, with respect to the measurement value of the predetermined level timing vs. frequency graph acquired in the predetermined level frequency distribution measurement value acquisition procedure, while centering the sample value, Create a normal distribution probability density function that assigns probability densities to sample values within a predetermined range from the central sample value, and for each of the above probability density functions, multiply the frequency of the sample values by the probability density. It is characterized in that the error correction is performed by setting the total sum as a new frequency of the sample value at the center of the probability density function, and the timing-frequency graph is determined.

According to the above-mentioned invention, in the frequency distribution determination procedure, the normal distribution in which the probability density is assigned to the sample values in the predetermined range from the sample value as the center with respect to the measured value of the predetermined level timing vs. frequency graph. A probability density function is created for each sample value, and the sum of the values obtained by multiplying the frequency of the sample value by the probability density is set as the new frequency of the sample value at the center of the probability density function. The measured value of the level timing vs. frequency graph is subjected to frequency error correction to determine the above timing vs. frequency graph.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error.

Furthermore, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, the timing at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is used as a sample value and distributed at any frequency in the predetermined pulse period number. In the frequency distribution determination procedure, the predetermined level is included in another frequency distribution measurement value acquisition procedure for acquiring another measurement value for one or more specific levels of the other level timing vs. frequency graph indicating whether The measured value of the predetermined level timing vs. frequency graph acquired in the frequency distribution measured value acquisition procedure and the respective measured value of the other level timing vs. frequency graph acquired in the arbitrary other level frequency distribution measured value acquisition procedure With respect to the graph created by combining, the sample value is centered and a predetermined range is set from the center sample value. Create a probability density function that is normally distributed by assigning a probability density to the sample value for each sample value, and for each probability density function, add the sum of the values obtained by multiplying the frequency of the sample value by the probability density of the above probability density function. The above-described error correction is performed by setting a new frequency of the central sample value, and the timing-frequency graph is determined.

According to the above invention, the timing for taking a specific level other than the predetermined level within one pulse period starting from the predetermined timing is set as the sample value by the predetermined number of pulse periods by the arbitrary other level frequency distribution measurement value acquisition procedure. A measurement value is acquired for each of one or more specific levels of another level timing vs. frequency graph showing how often the distribution is made. Then, in the frequency distribution determination procedure, a graph created by synthesizing the measured value of the predetermined level timing vs. frequency graph and each measured value of the other level timing vs. frequency graph is centered around the sample value Create a probability distribution function that is normally distributed by assigning a probability density to the sample values in the range for each sample value, and calculate the sum of the values obtained by multiplying the frequency of the sample values by the probability density for each probability density function at the center of the probability density function. By setting a new frequency of the sample value of, the measured value of the predetermined level timing versus frequency graph is subjected to error correction of the frequency, and is determined as the above timing versus frequency graph.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, in the estimation procedure, a first approximation curve that approximates a first region that is a region near the minimum sample value of the timing vs. frequency graph and a neighborhood of the maximum sample value of the timing vs. frequency graph A second approximation curve approximating a second area, which is an area, is obtained, and the vicinity of the minimum sample value of the timing vs. frequency graph when the predetermined pulse period number is increased from the first approximation curve to the larger number. The third that approximates the third region, which is the region of
Fourth approximation of a fourth region, which is a region near the maximum sample value of the timing vs. frequency graph when the approximation curve is obtained and the predetermined pulse period number is increased from the second approximation curve to the larger number. An approximate curve is obtained, a first sample value variation from the minimum sample value of the first area to the minimum sample value of the third area is obtained based on the third approximate curve, and based on the fourth approximate curve. The second sample value variation from the maximum sample value of the second area to the maximum sample value of the fourth area is calculated, and the sum of the first sample value variation and the second sample value variation is calculated. It is characterized in that it has the above-mentioned distribution variation width.

According to the above invention, in the estimation procedure, the first approximation curve that approximates the first region, which is the region near the minimum sample value of the timing-frequency graph, and the region near the maximum sample value of the timing-frequency graph. Is the second
And a second approximation curve that approximates the region. Then the first
A third approximation curve that approximates a third region, which is a region near the minimum sample value of the timing vs. frequency graph when the number of predetermined pulse periods is increased from the approximation curve, is obtained.
A fourth approximation curve that approximates the fourth region, which is a region near the maximum sample value of the timing vs. frequency graph when the number of predetermined pulse periods is increased to a larger number from the second approximation curve, is obtained. That is, how the first region and the second region change when the number of predetermined pulse periods is increased to a larger number is obtained.

Then, the first sample value fluctuation amount from the minimum sample value of the first region to the minimum sample value of the third region is obtained based on the third approximation curve, and based on the fourth approximation curve, The second sample value fluctuation amount from the maximum sample value to the maximum sample value of the fourth region is obtained, and the sum of the first sample value fluctuation amount and the second sample value fluctuation amount is set to be larger than the predetermined pulse period number. The distribution fluctuation range of the timing vs. frequency graph when the number is increased.

Therefore, it is possible to easily and accurately estimate the distribution variation width of the timing vs. frequency graph when the number of predetermined pulse periods is increased to a larger number.

Further, the error rate acquisition method of the present invention is
In order to solve the above problems, in the estimation procedure, on the timing vs. frequency graph, from the minimum sample value of the timing vs. frequency graph, the smallest sample when the timing vs. frequency graph is separated into a predetermined number of peaks. Up to the sample value that takes the value of the peak on the value side, or up to the sample value that takes the value of the peak that appears immediately after the first area where the frequency increases monotonically for a time corresponding to a certain increase in the sample value. , The first region.

According to the above invention, in the estimation procedure, the first area which is an area near the minimum sample value of the timing vs. frequency graph is determined by one of the following methods. 1
The second is from the minimum sample value of the timing vs. frequency graph on the timing vs. frequency graph to the sample value taking the value of the peak on the side of the minimum sample value when the timing vs. frequency graph is separated into a specified number of peaks. Is the first area. The second is a peak that appears immediately after the first region where the frequency monotonically increases continuously for the time corresponding to a certain increase in the sample value from the minimum sample value of the timing vs. frequency graph. This is a method in which the first area extends to the sample value that takes the value of.

By adopting either of the above two methods, the first region can be determined as a region that can be easily approximated by the first approximation curve.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, in the estimation procedure, on the timing vs. frequency graph, a sample value that takes the value of the peak at the maximum sample value side when the timing vs. frequency graph is separated into a predetermined number of peaks From
Or from the sample value that takes the value of the peak that appears immediately before the last region where the frequency continuously decreases monotonically for a time corresponding to a certain increase in the sample value to the maximum sample value of the above timing vs. frequency graph, It is characterized in that it is the second region.

According to the above invention, in the estimation procedure, the second area which is an area near the maximum sample value of the timing vs. frequency graph is determined by one of the following methods. 1
The second is from the sample value that takes the peak value on the maximum sample value side when the timing vs. frequency graph is separated into a predetermined number of peaks on the timing vs. frequency graph to the maximum sample value of the timing vs. frequency graph. This is a method of setting the second area. Second, on the timing vs. frequency graph, the timing vs. frequency is calculated from the sample value that takes the value of the peak that appears immediately before the last area where the frequency monotonically decreases continuously for the time corresponding to a certain increase in the sample value. In this method, the maximum sample value of the graph is set as the second area.

By adopting either of the above two methods, the second region can be determined as a region that can be easily approximated by the second approximation curve.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, in the estimation procedure, when the timing vs. frequency graph is separated into the predetermined number of peaks, the sample value having the maximum frequency in the timing vs. frequency graph is set to the first timing and the first timing. The first multiplication distribution obtained by multiplying the above timing vs. frequency graph by the first function, which is the smallest at the timing and increases toward the first constant and approaches the first constant value, is the maximum of the first multiplication distribution. A value obtained by multiplying the first multiplication distribution by a second function that takes the smallest sampled value at the second timing, the second timing, increases as it moves away from the second timing, and approaches a second constant value. Is the second multiplication distribution, and k is a natural number of 3 or more, the smallest at the (k-1) th timing and the (k-1) th Those obtained by multiplying the function of the (k-1) which increases with distance from the timing approaches a constant value of the (k-1) in the (k-2) multiplication distribution the (k
-1) Multiplying distribution, the sample value that takes the maximum value of the (k-1) th multiplying distribution is defined as the kth timing, and the predetermined number is a natural number N of 2 or more, and is sequentially from the first timing to the Nth timing. It is characterized in that each of the obtained first timing to the Nth timing thus obtained is a sample value that takes the value of a peak to be separated.

According to the above invention, when the timing vs. frequency graph is separated into a predetermined number of peaks in the estimation procedure, it is determined from the first timing to the Nth timing (N ≧ 2) that the above definition has been made. Then, each of the obtained first timing to Nth timing is set as a sample value that takes the value of the peak to be separated.

Therefore, the timing vs. frequency graph can be easily and accurately separated into a predetermined number of peaks, including the case where no clear peak exists.

Furthermore, the error rate acquisition method of the present invention is
In order to solve the above problem, in the above estimation procedure, a normal distribution function in which the standard deviation is a first constant multiple of the standard deviation of the timing vs. frequency graph with the first timing as the center is used. The standard deviation of the standard deviation of the (k-2) th multiplication distribution is defined as the function obtained by subtracting from the first constant value, and the standard deviation of the (k-1) th function is centered at the (k-1) th timing. It is characterized in that it is a function obtained by subtracting a normal distribution function that is a constant multiple of the (k-1) th constant from the constant value of the (k-1) th constant.

According to the above invention, in the estimation procedure, the first function used for separating the timing vs. frequency graph into the predetermined number of peaks is the standard deviation of the timing vs. frequency graph with the standard deviation centered around the first timing. First deviation
The normal distribution function that is a constant multiple of is subtracted from the first constant value, and the (k-1) th function is multiplied by the standard deviation (k-2) th centering on the (k-1) th timing. A normal distribution function that is a (k-1) th constant multiple of the standard deviation of the distribution is a function obtained by subtracting the (k-1) th constant value.

Therefore, the next peak can be obtained by excluding the already obtained peak as much as possible, and the timing vs. frequency graph can be easily separated into a predetermined number of peaks.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, the timing at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is used as a sample value and distributed at any frequency in the predetermined pulse period number. Other level timing that indicates whether or not the other level frequency distribution measurement value acquisition procedure for acquiring the measurement value of the frequency graph is included, and the other level timing acquired in the other level frequency distribution measurement value acquisition procedure in the above estimation procedure The number of peaks included in the other level timing versus frequency graph is obtained based on the measured value of the versus frequency graph, and the number of peaks is set to N.

According to the above-mentioned invention, 1 is started from a predetermined timing by the other level frequency distribution measurement value acquisition procedure.
A measurement value of another level timing vs. frequency graph showing how often the timing of taking a specific level other than the predetermined level within the pulse period is distributed as the sample value in the predetermined number of pulse periods. Then, in the estimation procedure, the number of peaks included in the other level timing vs. frequency graph is obtained based on the measured value of the other level timing vs. frequency graph, and this peak number is set as the predetermined number of peaks separated in the timing vs. frequency graph. . The peaks included in the other level timing vs. frequency graph clearly appear, and this number of peaks is the same as the number of peaks included in the timing vs. frequency graph.

Therefore, the predetermined number of peaks to be separated can be accurately determined from the timing vs. frequency graph.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, in the above estimation procedure, a first probability density function that normally distributes the first approximation curve is obtained as a function by multiplying a first coefficient, and a second distribution that normally distributes the second approximation curve is obtained. It is characterized in that the probability density function of is obtained as a function obtained by multiplying by a second coefficient.

According to the above invention, in the estimation procedure, the first approximated curve is obtained as a function obtained by multiplying the first probability density function which is normally distributed by the first coefficient, and the second approximated curve is normally distributed. The probability density function is obtained as a function obtained by multiplying the probability density function by the second coefficient. Since the first area approximated by the first approximate curve and the second area approximated by the second approximate curve originally have a normal distribution, a function obtained by multiplying the first probability density function by the first coefficient, and The function obtained by multiplying the probability density function of 2 by the second coefficient is appropriate as the first approximation curve and the second approximation curve.

Therefore, the first approximate curve and the second approximate curve can be easily and accurately obtained.

Further, the error rate acquisition method of the present invention is
In order to solve the above problems, in the estimation procedure, δq / δt is defined from the frequency change δq with respect to each sample value change step δt of the timing vs. frequency graph, and a differential function of the timing vs. frequency graph is obtained. The sample value that takes the value of the upward peak of the differential function in the area corresponding to one area is t ₁ , and the sample value t is
_{When the} frequency of the timing vs. frequency graph at ₁ is F ₁ and the value of the differential function at the sample value t ₁ is G ₁ , the standard deviation σ ₁ of the first probability density function is F ₁ / G ₁ , The center μ ₁ of the first probability density function is t ₁ + σ ₁ , and the first coefficient l ₁ is (2πe) ^0.5 × F ₁ ² / G ₁ .

According to the above invention, the estimation procedure
By the above definition, the differential function of the timing vs. frequency graph is
Number, and the standard deviation σ of the first probability density function₁To F₁/
G₁, The center of the first probability density function μ₁T₁+ Σ₁, First
Coefficient l of 1₁(2πe)^{0. Five}× F₁ ²/ G₁And

Therefore, the first for obtaining the first approximation curve
The probability density function of and the first coefficient can be accurately obtained.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, in the estimation procedure, when each sample value change step δt of the timing vs. frequency graph is equal, δq / δt is defined from the frequency change δq with respect to the sample value change step δt to define the timing pair. The differential function of the frequency graph is calculated, and the first
The sample value t _{m of the} region is t (minimum) + δt ×, where the minimum sample value of the timing vs. frequency graph is t (minimum).
m (m is an integer of 0 or more), the sample value t frequency of f (t _m) of the timing versus frequency graph of _m, the value of the differential function of the sample values _{t m g (t m),} j (t
_{m) = g (t m)} / f (t m), σ m 2 = δt / {j
(T _{m + 1} ) −j (t _m )}, the standard deviation σ ₁ of the first probability density function is the average of σ _m , and μ _m = t _{m
^{+ Σ 1 2 × g (t}} m) / f when the (t _m), the center mu ₁ of the first probability density function and the mean of mu _m, the coefficient l ₁ of the first in the sample values t _m f (t _m) /
(Value at the sample value t _m of the first probability density function).

According to the above invention, the estimation procedure
By the above definition, the differential function of the timing vs. frequency graph is
Number, and the standard deviation σ of the first probability density function₁Σ_mof
Mean, center of the first probability density function μ₁Μ_mThe mean of the
Coefficient l of 1₁The sample value t _mAt f (t_m) /
(Sample value t of the first probability density function_mIn
Value).

Therefore, the first for obtaining the first approximation curve
The probability density function of and the first coefficient can be accurately obtained.

Furthermore, the error rate acquisition method of the present invention is
In order to solve the above problems
The sample value change scan of the above timing vs. frequency graph.
Define δq / δt from frequency change δq with respect to step δt
The differential function of the above timing vs. frequency graph,
The downward direction of the differential function in the area corresponding to the second area
The sample value that takes the peak value is t₂, The sample value t
₂The frequency of the above timing vs. frequency graph in₂,the above
Sample value t₂The value of the above differential function at₂As above
The standard deviation σ of the second probability density function₂To -F₂/ G₂,
Center of the second probability density function μ₂T₂−σ₂,the above
Second coefficient l₂Is-(2πe)^0.5× F₂ ²/ G₂Tosu
It is characterized by that.

According to the above invention, the estimation procedure
By the above definition, the differential function of the timing vs. frequency graph is
The standard deviation σ of the second probability density function₂To -F₂
/ G ₂, The center of the second probability density function μ₂T₂−σ₂,
Second coefficient l₂Is-(2πe)^0.5× F₂ ²/ G₂Tosu
It

Therefore, the second for obtaining the second approximated curve
The probability density function and the second coefficient of can be accurately obtained.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, in the estimation procedure, when each sample value change step δt of the timing vs. frequency graph is equal, δq / δt is defined from the frequency change δq with respect to the sample value change step δt to define the timing pair. The differential function of the frequency graph is calculated, and the second
The sample value t _{n of the} area is t (maximum) + δt ×, where t (maximum) is the maximum sample value of the timing vs. frequency graph.
n (n is an integer of 0 or less), the frequency of the timing vs. frequency graph at the sample value t _n is f (t _n ), and the value of the differential function at the sample value t _m is g (t _n ), j (t
_n ) = g (t _n ) / f (t _n ), σ _n ² = δt / {j
(T _{n + 1} ) −j (t _n )}, the standard deviation σ ₂ of the second probability density function is the average of σ _n , and μ _n = t _n
+ Σ ₂ ² × g (t _n ) / f (t _n ), the center μ ₂ of the second probability density function is the average of μ _n , and the second coefficient l ₂ is the sample value t _n . f (t _n ) /
(Value at the sample value t _n of the second probability density function).

According to the above invention, the estimation procedure
By the above definition, the differential function of the timing vs. frequency graph is
The standard deviation σ of the second probability density function₂Σ_nof
Mean, center of the second probability density function μ₂Μ_nThe mean of the
Coefficient of 2₂The sample value t _nAt f (t_n) /
(Sample value t of the second probability density function_nIn
Value).

Therefore, the second for obtaining the second approximated curve
The probability density function and the second coefficient of can be accurately obtained.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, in the estimation procedure, the third approximated curve is obtained by multiplying the first approximated curve by the ratio of the scaling factor corresponding to the larger number to the predetermined pulse period number, The fourth approximation curve is obtained by multiplying the second approximation curve by the ratio.

According to the above invention, in the estimation procedure, the third approximation curve is multiplied by the ratio of the scaling coefficient corresponding to a larger number to the predetermined pulse period number to obtain the third approximation curve.
An approximated curve is obtained, and the fourth approximated curve is obtained by multiplying the second approximated curve by the ratio. Therefore, the third approximate curve and the fourth approximate curve can be easily and accurately obtained.

Further, the error rate acquisition method of the present invention is
In order to solve the above problem, 1 / (error rate to be achieved) is set as the scaling coefficient in the estimation procedure.

According to the above invention, since 1 / (error rate to be achieved) is used as the scaling factor in the estimation procedure, the third approximation curve and the fourth approximation curve for obtaining the error rate can be obtained. , It is possible to set an accurate scaling coefficient.

Furthermore, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, in the above-mentioned estimation procedure, Hi among the pulse joints of the above-mentioned predetermined pulse period is Hi.
R _{m is} the ratio of the number of changes from the gh level to the Low level or from the Low level to the High level, and R _{m is} the High level to Low level or the Low level to High level among the pulse joints of all the transmitted and received pulses.
Let R _{d be} the ratio of the number that changes to the level, R _d / {R
It is characterized in that _m × (error rate to be achieved)} is used as the scaling coefficient.

According to the above invention, since R _d / {R _m × (error rate to be achieved)} is used as the scaling factor in the estimation procedure assuming that the above definition is made, the first method for obtaining the error rate is An accurate scaling factor can be set for obtaining the third approximation curve and the fourth approximation curve.

Furthermore, the error rate acquisition method of the present invention is
In order to solve the above problems
Of the pulse joints of the predetermined pulse period
From gh level to Low level, or Low level
From the high level to the R level_m, Send and receive
High level of the pulse joints of all the pulses
To Low level, or from Low level to High
R is the ratio of the number that changes to a level_d, The above ratio R_dThought of
R is the largest value determined_worstAs R_{wors t}/
{R_m× (error rate to be achieved)} is the scaling factor
It is characterized by

According to the above invention, the estimation procedure
Then, assuming the above definition, R_{wors t}/ {R_m× (achieved
Error rate)} is the scaling factor, so the error
Third approximation curve and fourth approximation curve for obtaining the rate
An accurate scaling factor can be set to obtain
It

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, in the above-mentioned estimation procedure, Hi among the pulse joints of the above-mentioned predetermined pulse period is Hi.
Let R _{m be} the ratio of the number that changes from the gh level to the Low level or from the Low level to the High level,
It is characterized in that 1 / {R _m × (error rate to be achieved)} is used as the scaling coefficient.

According to the above invention, in the estimation procedure, 1 / {R _m × (error rate to be achieved)} is used as the scaling factor, assuming that the above definition has been performed. Therefore, the third method for obtaining the error rate is used. For obtaining the approximated curve and the fourth approximated curve, it is possible to set an appropriate scaling coefficient including a margin.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, the timing at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is used as a sample value and distributed at any frequency in the predetermined pulse period number. Other level timing that indicates whether or not the other level frequency distribution measurement value acquisition procedure for acquiring the measurement value of the frequency graph is included, and the other level timing acquired in the other level frequency distribution measurement value acquisition procedure in the above estimation procedure The number of peaks appearing in the other level timing vs. frequency graph based on the measured value of the vs. frequency graph is _Pn , from the High level to the Low level or from the Low level to the High level among the pulse joints of the predetermined number of pulse periods. the ratio of the number that varies as _{R m, P n / {2} × R m × ( to be achieved Erare The)} it is characterized in that the above scaling factor.

According to the above-mentioned invention, 1 is started from a predetermined timing by the other level frequency distribution measurement value acquisition procedure.
A measurement value of another level timing vs. frequency graph showing how often the pulse signal takes a specific level other than a predetermined level within the pulse period is distributed as a sample value in a predetermined number of pulse periods. And
In the estimation procedure, _Pn /
Since {2 × R _m × (error rate to be achieved)} is used as the scaling factor, an accurate scaling factor is used to determine the third approximation curve and the fourth approximation curve for determining the error rate.
The margin can be set in consideration of the reception amount of the reflected signal on the transmission path used for transmitting and receiving the pulse signal.

Further, the error rate acquisition method of the present invention is
In order to solve the above-mentioned problem, in the above estimation procedure, the minimum sample value among the sample values of the third approximate curve having a frequency of 1 or more is set as the minimum sample value of the third region, and the frequency of the fourth approximate curve is set. The maximum sample value of the sample values of 1 or more is set as the maximum sample value of the fourth area, and the difference between the minimum sample value of the first area and the maximum sample value of the second area in the eye width deriving procedure. Is the distribution width of the timing vs. frequency graph, and the value obtained by subtracting the sum of the distribution width and the distribution fluctuation width from one pulse period is the eye width.

According to the above invention, in the estimation procedure, the minimum sample value of the sample values having the frequency of the third approximation curve of 1 or more is set as the minimum sample value of the third region, and the frequency of the fourth approximation curve is 1 or more. The maximum sample value of the sample values that becomes is the maximum sample value of the fourth region. In the eye width deriving procedure, the difference between the minimum sample value of the first area and the maximum sample value of the second area is set as the distribution width of the timing vs. frequency graph, and the sum of the distribution width and the distribution fluctuation width is 1 pulse. The value subtracted from the period is the eye width.

Frequency 1 of the third approximation curve and the fourth approximation curve
Since the distribution variation width is obtained using the above sample values, it is possible to obtain an accurate eye width when the number of predetermined pulse periods is increased to the larger number.

Further, the error rate acquisition method of the present invention is
To solve the above problems, in the error rate deriving procedure, the eye width obtained in the eye width deriving procedure, and the relationship between the eye width and the error rate obtained in advance, the predetermined pulse period It is characterized in that the error rate is obtained when the number is increased to the larger number.

According to the above invention, in the error rate deriving procedure, the predetermined pulse period number is increased to a larger number based on the eye width obtained and the relationship between the eye width and the error rate obtained in advance. Since the error rate at that time is obtained, the error rate can be easily obtained.

The program of the present invention is a program for causing a computer to execute each procedure of the error rate acquisition method described in any of the above.

According to the above invention, the computer can be made to execute the above-mentioned error rate acquisition method.

The recording medium of the present invention is a recording medium in which the program described above is recorded in a computer-readable manner.

According to the above invention, since the above program can be executed by various computers, the above-mentioned error rate acquisition method becomes highly versatile.

[0087]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an error rate acquisition method, a program therefor, and a recording medium according to the present invention will be described below with reference to FIGS. 1 to 18.

FIG. 18 shows the configuration of the error rate measurement system 1 for executing the error rate acquisition method according to this embodiment. The error rate measurement system 1 includes a transmitter 2,
The measuring instrument 3, the optical fiber cable 4, and the electric signal cable 5 are provided. The transmitter 2 includes transmitters 2a and 2b, and the transmitter 2a is an optical signal (pulse signal) 101.
Is transmitted to the measuring device 3 via the optical fiber cable 4, and the transmitter 2b transmits the clock signal 102, which is an electric signal, to the measuring device 3 via the electric signal cable 5. Optical signal 10
1 represents the information of one pulse at one of the High level and the Low level, and the High level or the Low level
Each level periodic pulse is transmitted continuously. The clock signal 102 is transmitted in synchronization with the optical signal 101, the period is equal to one pulse period of the optical signal 101, and the rising timing or the falling timing is synchronized with the pulse joint of the optical signal 101.

At least the transmitter 2a of the transmitter 2 constitutes a part of the transmission / reception system for transmitting / receiving the optical signal 101, and the measuring device 3 receives the optical signal 101 transmitted by the transmitter 2a and outputs the clock signal. A bit error rate (error rate, hereinafter BE
R), that is, the BER at the receiving side of the transmitting / receiving system. The measuring instrument 3 has a built-in computer and executes a program that realizes each procedure of the error rate acquisition method according to the present embodiment. The above computer may be provided as an external device connected to the measuring device 3.

FIG. 1 shows a flowchart for explaining each procedure of the error rate acquisition method realized by the above program. In S1, a predetermined level frequency distribution measurement value acquisition procedure, S
2 is the frequency distribution determination procedure, S3 is the estimation procedure, S4
Then, the eye width deriving procedure is executed, and the error rate deriving procedure is executed in S5.

The predetermined level frequency distribution measurement value acquisition procedure of S1 is a procedure for acquiring the measurement value of the predetermined level timing versus frequency graph. This predetermined level timing vs. frequency graph shows that the optical signal 101 takes a predetermined level near the eye width definition level within one pulse period starting from the predetermined timing with respect to the pulse joint of the optical signal 101 received by the measuring instrument 3. It shows how often the timing is distributed in the case of the predetermined number of pulse periods. The vicinity of the pulse joint of the optical signal 101 will be described later with reference to FIG.
In this state, the predetermined level timing versus frequency graph becomes, for example, a graph 121 shown in FIG. 3 described later.

The frequency distribution determining procedure in S2 is performed by using the measured value of the predetermined level timing vs. frequency graph obtained in S1 or the measured value of the predetermined level timing vs. frequency graph subjected to the frequency error correction to obtain the timing vs. frequency. This is a procedure for determining a graph. This timing vs. frequency graph properly shows how often the timings at which the optical signal 101 takes the above-mentioned predetermined level within one pulse period starting from the above-mentioned predetermined timing are distributed in the case of the predetermined number of pulse periods. It is decided to represent. For example, a graph 121 of FIG. 3 described later is one in which the measured value of the predetermined level timing vs. frequency graph is determined as the timing vs. frequency graph, and a graph 313 of FIG. The graph 322 of FIG. 7 described later is a graph of the timing vs. frequency graph in which the measured value of the predetermined level timing vs. frequency graph is subjected to frequency error correction.

Since the timing vs. frequency graph determined in S2 changes as the number of the predetermined pulse periods is increased, the estimation procedure in S3 changes the predetermined number of pulse periods from the timing vs. frequency graph determined in S2. This is a procedure for estimating the distribution fluctuation range of the timing vs. frequency graph when the number is increased to a large number. For example, the graph 501 in FIG.
Is a graph 121 of FIG. 3, which is a timing vs. frequency graph.
It is estimated that the sample value 507 at the left end of the graph 501 changes to the sample value 506 at the left end of the graph 504 in FIG. 12 when the predetermined pulse period number is increased to a larger number. This is graph 12
The same applies to the right end of 1 to estimate the distribution fluctuation width as the sum of the fluctuations.

The procedure for deriving the eye width in S4 is performed by using the distribution variation width estimated in S3 and the distribution width of the timing vs. frequency graph to increase the number of the predetermined pulse periods to the larger number. This is a procedure for obtaining the width. For example, in FIG.
In FIG. 6, the difference between the width 133 and the width 132 is the distribution fluctuation width, and the sum of this distribution fluctuation width and the distribution width of the timing vs. frequency graph is the width 135. The difference between the width 134 and the width 135 which is one pulse period. Is obtained as the width 132 which is the eye width.

The error rate deriving procedure in S5 is a procedure for obtaining the BER when the number of the predetermined pulse periods is increased from the eye width obtained in S4 to the larger number.
For example, the relationship between the eye width and the BER as shown in FIG. 17 is obtained in advance, and the BER corresponding to the eye width is obtained using this relationship.

The above-mentioned larger number is a number determined according to the BER to be obtained as described later.

As described above, the measured value for the predetermined number of pulse periods is used to obtain the eye width when the predetermined number of pulse periods is increased to a larger number, and the corresponding BER is obtained. If the number is necessary to directly measure and obtain the BER, the accurate BER can be obtained from the measured values for a small number of predetermined pulse periods. Therefore, the BER of the pulse signal can be obtained in a short time.

Next, details of each step of the flowchart of FIG. 1 will be described. In the following explanation,
Since the graph showing the pair frequency is a graph showing the distribution of how many samples having the value exist for each value, all the values on the horizontal axis are called sample values. 1. S1 Predetermined Level Frequency Distribution Measured Value Acquisition Procedure (1) Measured Values of Predetermined Level Timing vs. Frequency Graph FIG. 2 shows pulse joints of the optical signal 101 received by the measuring instrument 3 using the timing of the clock signal 102. On the other hand, an example of the result of measuring the level of the optical signal 101 within one pulse period starting from a predetermined timing is shown.
The optical signal 101 is around the pulse joint and falls from the High level 114 to the Low level 115 for a certain period of time, or it falls from the Low level 115 to the High level 1
There are four ways of rising to 14, requiring a certain time, maintaining the high level 114, or maintaining the low level 115.

In FIG. 3, the optical signal 101 corresponds to the level 11 of FIG.
Graph 1 showing how often the timing of taking 3 is distributed when viewed for a predetermined number of pulse periods
21 is shown. The level 113 in FIG. 2 is a predetermined level near the eye width definition level, and the graph 121 in FIG. 3 is a measured value of the predetermined level timing vs. frequency graph. The program may be configured to cause the measuring instrument 3 to measure the graph 121, or the measuring instrument 3 may separately measure the graph 121, and the program may capture the measured value. It may be. In the measurement, as shown in FIG. 2, the high level 114 and the low level 114 are set at each step (sample value change step) δt which is a time sufficiently shorter than one pulse period of the optical signal 101.
Level interval δp sufficiently smaller than the difference from level 115
Then, the level of the optical signal 101 is measured, and the number of times that can be regarded as the level 113 is counted. (2) Predetermined Level Determination Method 1 As the prescribed level determination method 1 for determining the prescribed level, the prescribed level frequency distribution measurement value acquisition procedure in S1 is performed by the optical signal 101 received by the measuring device 3 at the prescribed level. H
It includes a predetermined level determination procedure for setting a median value between the high level 114 and the low level 115.
3 can be determined thereby. This predetermined level determination procedure may be independent of S1. According to the predetermined level determination procedure, the above predetermined level is set to the optical signal 1 in an ideal state.
It can be determined as an appropriate level close to the eye width definition level which is the median between the High level and the Low level of 01.

However, High level 114 and Lo
The w level 115 is the High level of the optical signal 101 in the ideal state.
Since it may deviate from the level and the Low level, a method of determining the High level 114 and the Low level 115 which is effective in such a case will be described below.

High Level 114 and Low Level 115 Determination Method 1 As High Level 114 and Low Level 115 determination method 1, a specific timing frequency distribution measurement value acquisition procedure and a level range determination procedure are included in the predetermined level determination procedure. The specific timing frequency distribution measurement value acquisition procedure and the level range determination procedure may be independent of the predetermined level determination procedure and S1.

In the specific timing frequency distribution measurement value acquisition procedure, how often the level of the optical signal 101 received by the measuring instrument 3 at a specific timing within one pulse period is distributed in the number of specific pulse periods. Gets the measurement value of the level vs. frequency graph representing. FIG. 4 shows the time 116 of FIG.
The graph 141 which is the measured value of the level vs. frequency graph when the above is the specific timing is shown.

In the level range determination procedure, the optical signal 10 is calculated from the peak position appearing in the measured value of the level vs. frequency graph.
The High level 114 and the Low level 115 of 1 are determined. That is, when peaks appear near the maximum sample value and near the minimum sample value in the level vs. frequency graph, the sample value that takes the peak value near the maximum sample value is set to High level 114, and the peak value near the minimum sample value is set. Take the sample value at Low level 11
Set to 5. In the graph 141 of FIG. 4, a peak 143 appears near the maximum sample value and a peak 142 appears near the minimum sample value. Therefore, the sample value taking the value of the peak 143 is set to the high level 114, and the peak 142
The sample value taking the value of is set to the Low level 115.

The sample value of such a peak is High
Since the level 114 and the low level 115 are well reflected, the high level 114 and the low level 115 of the optical signal 101 can be easily and accurately determined. It should be noted that, as the above-mentioned specific timing, in the vicinity of the pulse joint of the optical signal 101 in FIG.
Two distinct peaks corresponding to the gh level 114 and the Low level 115 are likely to appear, which is desirable.

Method 2 for Determining High Level 114 and Low Level 115 In the above-mentioned graph 141 of FIG. 4, the low level of the optical signal 101 is shown.
A peak 144 also appears near level 115. However, the peak 144 is the peak 142 due to the performance of the transmitter 2a.
Is the peak that appeared after splitting. Since the peak value of the graph 141 increases in the order of the peak 142, the peak 144, and the peak 143, the peaks 143 and 142 are peaks corresponding to the High level 114 and the Low level 115.
In selecting, it is preferable that there is a clear guideline for selection based on the peak size.

Therefore, High level 114 and Lo
As the determination method 2 of the w level 115, the predetermined level determination procedure includes a specific timing frequency distribution measurement value acquisition procedure other than the joint and a level range determination procedure. The specific timing frequency distribution measurement value acquisition procedure and the level range determination procedure other than the joint may be independent of the predetermined level determination procedure and S1.

In the specific timing frequency distribution measurement value acquisition procedure other than the joint, the level of the optical signal 101 received by the measuring instrument 3 at the particular timing except for the vicinity of the pulse joint within one pulse period is determined by the number of the particular pulse periods. Acquires the measured value of the level vs. frequency graph other than the joint where the distribution is shown at various frequencies. The graph 141 of FIG.
Since the time 116 is a specific timing excluding the vicinity of the pulse joint, it is the measured value of the level versus frequency graph other than the joint. As a result, first, a large peak is suppressed from appearing in the graph 141 at the intermediate level position between the high level 114 and the low level 115.

In the level range determination procedure, the High level 114 and the Low level 115 of the optical signal 101 are determined by processing the measured values of the level versus frequency graph other than the joints. That is, the first level, which is the sample value that takes the maximum frequency in the level-versus-frequency graph other than the joint, is obtained, and the function that is the smallest at the first level and increases toward the first level and approaches a constant value is used as the level pair other than the joint. A multiplication distribution that is multiplied by the frequency graph is created, a second level that is a sample value that takes the maximum value of the multiplication distribution is obtained, the larger one of the first level and the second level is set as the High level, and the smaller one is set as the Low level. Level.

For example, in the graph 141, the first level is a sample value having the peak 142. Next, graph 14
A standard deviation of 1 is obtained, and a Gaussian function that is a probability density function having a normal distribution centered on the first level is obtained with this standard deviation. Then, the function 145 obtained by subtracting the Gaussian function from the function that is constant at the peak value of the Gaussian function is the function that is the smallest at the first level and increases as the distance from the first level increases and approaches a constant value. The function 145 becomes 0 at the first level, and the value becomes closer to a positive constant value as it gets away from the first level. Graph 141 Function 1
A graph 146 obtained by multiplying by 45 is a multiplication distribution. The graph 146 is the property of the graph 141 and the function 14
Because it has the property of multiplying with the property of 5,
The level becomes 0, and the property of the graph 141 is reflected as the distance from the first level increases. Therefore, the position of the peak 143 is naturally found by finding the peak position of the graph 146, so the peak position of the graph 146 is set to the second level. Since the first level has a smaller sample value than the second level, the first level is the Low level 11
5, the second level is determined to be the High level 114.

The first level and the second level are graph 1
The sample value having a peak value near the maximum sample value included in 41 or the sample value having a peak value near the minimum sample value becomes High level 114 and Lo.
It reflects w level 115 well. Also, graph 14
1 to High level 114 or Low level 115
Even if the peak corresponding to
The level and the second level can be determined. Therefore, High level 114 and Low of the optical signal 101
The level 115 can be easily and accurately determined.

High Level 114 and Low Level 115 Determining Method 3 As the High level 114 and Low level 115 determining method 3, the predetermined level determining procedure includes the all timing frequency distribution measurement value acquisition procedure and the level range determining procedure. The total timing frequency distribution measurement value acquisition procedure and the level range determination procedure may be independent of the predetermined level determination procedure and S1.

In the total timing frequency distribution measurement value acquisition procedure, how often the levels taken by the optical signal 101 received by the measuring device 3 at all timings within one pulse period are distributed in a specific number of pulse periods. Gets the measurement value of the all level versus frequency graph that represents. The graph 151 in FIG.
The number of levels taken at each time in the pulse period is measured, and the number of times is added up for the number of specific pulse periods, and the horizontal axis represents the level and the vertical axis represents the frequency. It is the measured value of the graph.

In the level range determination procedure, the High level and the Low level of the pulse signal are determined from the measured values of the all level vs. frequency graph. That is, the maximum sample value of all level vs. frequency graph is set to High level, and the minimum sample value is set to Low level. In the graph 151, the maximum sample value 152 is set to the High level 114, and the minimum sample value 153 is set to the Low level 115.

The maximum sample value 152 of the graph 151 is H
High level 114, the minimum sample value 153 is Low
Since the level 115 is reflected well, the High level 114 and the Low level 115 of the optical signal 101 can be easily and accurately determined.

Method 4 for determining High level 114 and Low level 115 As method 4 for determining High level 114 and Low level 115, a predetermined level determining procedure includes a total timing frequency distribution measurement value acquisition procedure and a level range determining procedure. The total timing frequency distribution measurement value acquisition procedure and the level range determination procedure may be independent of the predetermined level determination procedure and S1.

In the all-timing frequency distribution measurement value acquisition procedure, how often the levels taken by the optical signal 101 received by the measuring instrument 3 at all timings within one pulse period are distributed in a specific number of pulse periods. Gets the measurement value of the all level versus frequency graph that represents. The graph 151 of FIG. 5 is the measured value of the all level vs. frequency graph.

In the level range determining procedure, the sample value taking the peak value near the maximum sample value of the measured values of the all level vs. frequency graph is set to the High level, and the sample value taking the peak value near the minimum sample value is set to the Low level. . In the graph 151, the sample value of the peak 154 appearing near the maximum sample value 152 is set to the High level 114, and the peak 15 appearing near the minimum sample value 153 is shown.
The sample value of 5 is set to the Low level 115.

Since the sample value having the peak value near the maximum sample value 152 well reflects the High level 114 and the sample value having the peak value near the minimum sample value 153 well reflects the Low level 115, the Hi level of the optical signal 101 is high.
The gh level 114 and the Low level 115 can be easily and accurately determined.

It should be noted that the determination method 3 and the determination method 4 are combined to set the maximum sample value 152 to High.
h level 114 and minimum sample value 153
The sample value taking the peak value in the vicinity is Low level 115
Or the sample value taking the peak value near the maximum sample value 152 is set to the High level 114 and the minimum sample value 153 is set to the Low level 115, the High level 114 and the Low level of the optical signal 101 are similarly set. 115 can be determined easily and accurately.

Method 5 for determining High level 114 and Low level 115 As method 5 for determining High level 114 and Low level 115, a predetermined level determining procedure includes a total timing frequency distribution measurement value acquisition procedure and a level range determining procedure. The total timing frequency distribution measurement value acquisition procedure and the level range determination procedure may be independent of the predetermined level determination procedure and S1.

In the all-timing frequency distribution measurement value acquisition procedure, how often the levels taken by the optical signal 101 received by the measuring instrument 3 at all timings within one pulse period are distributed in a specific number of pulse periods. Gets the measurement value of the all level versus frequency graph that represents. The graph 151 of FIG. 5 is the measured value of the all level vs. frequency graph.

In the level range determination procedure, all the first levels, which are the sample values taking the maximum frequency of the measured values of the all level vs. frequency graph, are obtained, and are the smallest at all the first levels and increase as the distance from the first level increases. , A function that approaches a constant value is multiplied by the all-level vs. frequency graph to create an all-multiply distribution, and the all-second level, which is the sample value that takes the maximum value of all-multiply distribution, is obtained. Of the two levels, the larger one is the High level and the smaller one is the Lo level.
Set to w level.

Since the optical signal 101 stays at the high level 114 or the low level 115 for a long time,
In the graph 151, a large peak is unlikely to appear at a level intermediate between the High level 114 and the Low level 115. Therefore, the total first level and the total second level obtained by creating the total multiplication distribution from the graph 151 are
High level and Low level are well represented. In the graph 151, the sample values taking the peak 155 are all the first levels, and the sample values taking the peak 154 are the all second levels. Since all first levels are lower than all second levels, all first levels are Low level 115 and all second levels are High level 114.

As described above, all the first levels and all the second levels have the maximum sample value 152 included in the graph 151.
A sample value taking a peak value in the vicinity or a sample value taking a peak value in the vicinity of the minimum sample value 153 becomes H
The high level 114 and the low level 115 are well reflected. In addition, the graph 151 shows High level 11
Even if the peak corresponding to 4 or Low level 115 does not clearly appear, all the first levels and all the second levels can be determined. Therefore, the High level 114 and the Low level 115 of the optical signal 101 can be easily and accurately determined. (3) Predetermined level determination method 2 In the predetermined level frequency distribution measurement value acquisition procedure of S1, the predetermined level may be determined by a method different from the above (2), and the level 113 is determined accordingly. You can The predetermined level determining method 2 will be described below.

The predetermined level determination method 2 includes a total timing frequency distribution measurement value acquisition procedure and a predetermined level determination procedure. The total timing frequency distribution measurement value acquisition procedure and the predetermined level determination procedure may be independent of S1, or one of them may be included in the other.

In the all-timing frequency distribution measurement value acquisition procedure, the level of the pulse signal of the optical signal 101 received by the measuring instrument 3 at all timings within one pulse period is distributed at a certain number of pulse periods. Acquire the measurement value of the all level vs. frequency graph showing whether or not. The graph 151 of FIG. 5 is a measured value of the all level vs. frequency graph. In the predetermined level determination procedure, the measured values of all levels vs. frequency graph,
That is, the average sample value of the graph 151 is set to a predetermined level.

As a result, the predetermined level is set to H in the ideal state.
It can be determined as an accurate level close to the eye width definition level which is the median between the high level and the Low level. 2. Regarding the frequency distribution determination procedure in S2, in S2, the measured value of the predetermined level timing vs. frequency graph obtained in S1 or the measured value of the predetermined level timing vs. frequency graph subjected to frequency error correction is used as a timing vs. frequency graph. The method of error correction will be described below. (1) Error Correction Method 1 In error correction method 1, an arbitrary other level frequency distribution measurement value acquisition procedure is provided, and error correction is performed using the result of this arbitrary other level frequency distribution measurement value acquisition procedure. . The arbitrary other level frequency distribution measurement value acquisition procedure may be independent of S1 and S2, or may be included in S1 and S2.

In the arbitrary other level frequency distribution measurement value acquisition procedure, the timing at which the optical signal 101 received by the measuring device 3 takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is the predetermined pulse period. A measurement value is acquired for each of one or more specific levels of another level timing vs. frequency graph representing how often the frequencies are distributed. Graph 311 indicated by the solid line in FIG.
6 is the measured value of the predetermined level timing vs. frequency graph for level 113, which is the predetermined level in FIG.
A graph 312 indicated by a broken line is a measured value of another level timing vs. frequency graph when the level 118, which is larger than the level 113 by δp in FIG.
If δp is sufficiently small and measurement noise or the like is not included, the graph 311 and the graph 312 have substantially the same shape.

In the frequency distribution determining procedure, the measured value of the predetermined level timing vs. frequency graph acquired in S1 and each measured value of the other level timing vs. frequency graph are combined to obtain the predetermined level timing vs. frequency graph. A frequency error correction is applied to the measured value, and it is determined as a timing vs. frequency graph. In FIG. 6, a graph 313 is created by adding the graph 311 and the graph 312 together, and the graph 313 is synthesized by halving it in the vertical axis direction. As a result, the graph 311 is erroneously corrected in frequency, and the error-corrected graph is determined as the timing vs. frequency graph.

Since both the graph 311 and the graph 312 do not have smooth shapes due to a small number of samples or a large amount of noise mixed in the measurement, the graph 31
1 / graph 313, which is the sum of 1 and graph 312,
By doubling, the estimation in the estimation procedure of S3 can be performed more accurately than using the timing vs. frequency graph determined only from the graph 311. In this way, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error.

The added graph 313 may be used as a timing vs. frequency graph, but in this case it may be assumed that the number of predetermined pulse periods is doubled in S1. Furthermore, as a specific level other than the level 113, the level 113
Although the level 118 larger by δp is adopted, the level 118 is not limited to this, and a level smaller by δp than the level 113 may be adopted. Further, the number of specific levels may be two or more instead of one, and the specific level may be a level having a difference larger than the level 113 and δp. In addition, the ratio of adding the graphs is level 1
It can be said that it is more realistic if the specific level far from 13 is reduced. As this ratio, for example, level 11
A Gaussian function having a peak at 3 can be adopted. (2) Method 2 of error correction Method 2 of error correction is S1 in the frequency distribution determination procedure.
For the measured value of the predetermined level timing vs. frequency graph acquired in step 1, create a probability density function for each sample value that is normally distributed and assigns the probability density to the sample value in the predetermined range centered on the sample value. , The error of the frequency in the measurement value of the predetermined level timing vs. frequency graph is set by setting the sum of the values obtained by multiplying the frequency of the sample value by the probability density for each probability density function as the new frequency of the sample value at the center of the probability density function. It is corrected and determined as a timing vs. frequency graph.

The graph 321 in FIG. 7 is the predetermined level in FIG.
Predetermined level timing pair for level 113 which is
It is a measurement value of a frequency graph, and there are few samples
Or the shape may slip due to a large amount of noise in the measurement.
Not ridiculous. Graph 3
21 q = f_n(t), the corrected graph 322 is q = f
As (t),     f (t) = Σf_n(t + m ・ δt) × G (m) (1) Ask in. However, in equation (1), Σ is a constant a
F from m = -a to a _nTotal of (t + m ・ δt) × G (m)
It shows that the sum is sought. Also, G (m) is each sump
With a standard deviation σ centered on the
In other words, the probability density is
Is a normally distributed probability density function. This and
So that G (a) and G (-a) are close enough to 0.
And σ are determined.

The sum of f _n (t + mδt) × G (m) is set as the new frequency of the sample value at the center of each probability density function. Q = f (t) thus obtained is q = f _n (t)
Since the graph becomes a smoothed graph by performing the error correction of the frequency of, the graph 322 is higher than the graph 321 at the level 113.
Reflects well.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error. (3) Error Correction Method 3 In the error correction method 3, an arbitrary other level frequency distribution measurement value acquisition procedure is provided, and error correction is performed using the result of this arbitrary other level frequency distribution measurement value acquisition procedure. . An arbitrary other level frequency distribution measurement value acquisition procedure is the same as the method (1) of the error correction (1). Further, the procedure for acquiring the arbitrary other level frequency distribution measurement value may be independent of S1 and S2, or may be included in S1 and S2.

In the frequency distribution determination procedure, first, the measured values of the predetermined level timing vs. frequency graph acquired in S1,
An arbitrary other level frequency distribution measurement value acquisition procedure is combined with each of the measured values of the arbitrary other level timing versus frequency graph acquired in the acquisition procedure. The synthesis method is described in (1) above.
This is the same as the error correction method 1. Then, as in the method (2) of error correction (2) described above, a normally distributed probability density function in which probability density is assigned to sample values in a predetermined range from the sample value Created for each probability density function and measuring the sum of values obtained by multiplying the frequency of sample values by the probability density as the new frequency of the sample value at the center of the probability density function A frequency error correction is applied to the value to determine the timing vs. frequency graph.

Therefore, even if some error such as measurement noise is included in the measured value of the predetermined level timing vs. frequency graph, the timing vs. frequency graph can be obtained by accurately correcting the error. 3. About the estimation procedure of S3 In the estimation procedure of S3, more specifically, the first approximation curve that approximates the first region, which is the region near the minimum sample value of the timing vs. frequency graph, and the maximum sample value of the timing vs. frequency graph. A second approximation curve that approximates the second area, which is a nearby area, is obtained. Next, a third approximation curve that approximates a third region, which is a region near the minimum sample value of the timing vs. frequency graph when the number of predetermined pulse periods is increased from the first approximation curve, is obtained, and the second approximation is performed. A fourth approximation curve that approximates the fourth region, which is a region near the maximum sample value of the timing vs. frequency graph when the number of predetermined pulse periods is increased from the curve, is obtained. That is, how the first region and the second region change when the number of predetermined pulse periods is increased to a larger number is obtained.

Then, the first sample value fluctuation amount from the minimum sample value of the first region to the minimum sample value of the third region is obtained based on the third approximation curve, and based on the fourth approximation curve, The second sample value fluctuation amount from the maximum sample value to the maximum sample value of the fourth region is obtained, and the sum of the first sample value fluctuation amount and the second sample value fluctuation amount is set to be larger than the predetermined pulse period number. The distribution fluctuation range of the timing vs. frequency graph when the number is increased.

Therefore, it is possible to easily and accurately estimate the distribution variation width of the timing vs. frequency graph when the number of predetermined pulse periods is increased to a larger number.

Next, a method of determining the above-mentioned first area and second area will be described. (1) First Area / Second Area Determination Method 1 In S3, a first area that is an area near the minimum sample value and a second area that is an area near the maximum sample value in the timing vs. frequency graph determined in S2 The following method is used as the first area / second area determination method 1 for determining

In the first area, the value of the peak on the side of the smallest sample value when the timing vs. frequency graph is separated into a predetermined number of peaks from the minimum sample value of the timing vs. frequency graph on the timing vs. frequency graph. Up to the sample value taken. The second region is the maximum sample of the timing vs. frequency graph from the sample value taking the peak value on the maximum sample value side when the timing vs. frequency graph is separated into a predetermined number of peaks on the timing vs. frequency graph. Up to the value.

For example, in FIG. 3, as a result of separating the graph 121 into a predetermined number of peaks, the graph 121 in the range 122 from the minimum sample value of the graph 121 to the sample value taking the value of the peak on the minimum sample value side. The upper area is the first area. The minimum sample value is the left edge of the first area. The first approximation curve that approximates the first region in this case is the graph 124. In addition, from the sample value taking the peak value on the maximum sample value side, the graph 12
The area on the graph 121 in the range 123 up to the maximum sample value of 1 is the second area. The maximum sample value is the right edge of the second area. The second approximation curve that approximates the second region in this case is the graph 125. Thereby, the first region can be determined as a region that can be easily approximated by the first approximate curve, and the second region can be determined as a region that can be easily approximated by the second approximate curve.

Method of Separating into a Predetermined Number of Peaks Next, a method of separating the timing versus frequency graph into a predetermined number of peaks will be described.

In S3, when the timing vs. frequency graph determined in S2 is separated into a predetermined number of peaks, as a method 1 of separating into a predetermined number of peaks, the sample value taking the maximum frequency of the timing vs. frequency graph is 1st timing, which is the smallest at 1st timing, increases as it moves away from the 1st timing, and approaches the 1st constant value, is multiplied by the timing vs. frequency graph to obtain the 1st multiplication distribution, the 1st multiplication described above. The sample value taking the maximum value of the distribution is multiplied by the second function, which is the smallest at the second timing, the second timing, increases as it moves away from the second timing, and approaches the second constant value. The combined one is the second multiplication distribution, and when k is a natural number of 3 or more, it is the smallest at the (k−1) th timing and is the above (k−1) th. The (k-1) th multiplication distribution is obtained by multiplying the (k-1) th function by increasing with increasing distance from the timing and approaching the (k-1) th constant value. The sample value taking the maximum value of the (k-1) th multiplication distribution is defined as the kth timing.

Then, the predetermined number is set to a natural number N of 2 or more, and is sequentially obtained from the first timing to the Nth timing.
Each of the obtained first timing to Nth timing is set as a sample value of the peak value to be separated.

For example, the graph 171 of FIG. 8 is a timing vs. frequency graph determined in S2, but it has four peaks of different sizes, and the second largest peak is likely to overlap the maximum peak. , It has a shape that is hard to distinguish. Therefore, first, the sample value 172 having the highest frequency in this graph 171 is set as the first timing. Next, the first function 173 is created, and the graph 174 obtained by multiplying the graph 171 by the first function 173 is created as the first multiplication distribution. Then, the sample value 175 having the maximum value in the graph 174 is set as the second timing.

To separate the third or more peaks, the second
A sample value 1 that takes a maximum value of the second multiplication distribution by creating a second function (not shown) from the timing and multiplying it by the graph 174
In order to separate the k-th peak such that 76 is the third timing, the (k-1) -th multiplication distribution used in separating the (k-1) -th peak is used for the (k-1) -th distribution. ) Function to create a (k-1) th multiplication distribution. This makes it possible to easily and accurately separate the timing vs. frequency graph into a predetermined number of peaks, including the case where there is no clear peak.

Method for Determining First Function and (k-1) th Function Next, in separating the predetermined number of peaks by the above method, the first function and the (k-1) th function are A method of determining will be described.

In S3, the first function used to separate the timing vs. frequency graph into a predetermined number of peaks is such that the standard deviation around the first timing is the first constant multiple of the standard deviation of the timing vs. frequency graph. The normal distribution function is a function obtained by subtracting from the first constant value, and the standard deviation of the (k-1) th function is the standard deviation of the (k-2) th multiplication distribution with the standard deviation centered at the (k-1) th timing. The normal distribution function that is the (k-1) th constant multiple of is a function obtained by subtracting from the (k-1) th constant value.

For example, in FIG. 8, in determining the graph 173 which is the first function, the standard deviation of the graph 171 is multiplied by 1 as the first constant, centered on the sample value 172 which is the first timing. The normal distribution function 177 is calculated as the standard deviation, and the normal distribution function 177 is subtracted from the first constant value equal to the peak value of the normal distribution function 177. Although not shown, the determination of the (k−1) th function is as described above, and the concept is the same as that of determining the first function.

The first function and the (k-1) th function obtained as described above very well reflect the shapes of the timing vs. frequency graph and the (k-2) th multiplication distribution, respectively. Therefore, it is possible to deal with the shape of a graph having some peaks. In the above example, 1 is adopted as the first constant multiple, but by using the first constant multiple different from 1 according to the tendency of the data at the time of measurement,
It is possible to expect accurate peak position identification. Further, when the peak value of the normal distribution function 177 is used as the first constant value as in the above example, the graph 173 becomes 0 at the sample value 172 which is the first timing of the graph 171, so that the second timing candidate If it is known that the peak is far from the peak at the first timing,
This is very useful because it facilitates peak separation.

According to the above method, the peak already obtained can be excluded as much as possible to obtain the next peak, and the timing vs. frequency graph can be easily separated into a predetermined number of peaks.

Method for Determining Predetermined Number of Peaks to be Separated Next, a method for determining a predetermined number in separating into a predetermined number of peaks by the above method will be described.

In this method, another level frequency distribution measurement value acquisition procedure is provided, and the predetermined number is determined according to the result of this procedure.

In the other level frequency distribution measurement value acquisition procedure, the timing when the optical signal 101 received by the measuring instrument 3 takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is the predetermined pulse period number. Then, the measurement value of the other level timing vs. frequency graph that represents the frequency distribution is acquired. The graph 401 of FIG. 9 exists in the area between the high level 114 and the low level 115 of FIG.
It is a measured value of another level timing vs. frequency graph when 7 is set to the above-mentioned specific level. At this position, the splitting of the peak is generally detected more clearly than the predetermined level timing vs. frequency graph and the timing vs. frequency graph for the level 113, but it is temporally connected to the rising edge and the falling edge of one pulse. , The number of peaks is essentially the same as the number of peaks detected in the timing vs. frequency graph.

Therefore, in S3, the number of peaks included in the other level timing vs. frequency graph is obtained based on the measured value of the other level timing vs. frequency graph, and this peak number is separated by the predetermined number of peaks in the timing vs. frequency graph. (N above). It can be seen that the graph 401 has four peaks. Therefore, from the above concept, there are four peaks in the predetermined level timing vs. frequency graph and the timing vs. frequency graph (for example, the graph 121 in FIG. 3). Therefore, it can be seen that it is sufficient to separate the four peaks in the timing vs. frequency graph by the above method. And
Of the peaks separated in the timing vs. frequency graph, the first region is obtained using the peak on the side of the smallest sample value,
The second region is obtained using the peak on the maximum sample value side.

With the above method, the predetermined number of peaks to be separated can be accurately determined on the timing vs. frequency graph. In the above example, the specific level is level 11
I chose level 117, which is lower than 3, but level 11
You may choose a level higher than 3. (2) First Area / Second Area Determination Method 2 In S3, the first area that is an area near the minimum sample value and the second area that is an area near the maximum sample value in the timing vs. frequency graph determined in S2 The following method is adopted as the first area / second area determination method 2 for determining

The first region is immediately after the first region where the frequency monotonically increases on the timing vs. frequency graph from the minimum sample value of the timing vs. frequency graph continuously for a time corresponding to a certain increase in sample value. Up to the sample value that takes the value of the peak appearing in. In the second area, the timing vs. frequency graph is taken from the sample value taking the peak value that appears immediately before the last area where the frequency monotonously decreases continuously for a time corresponding to a certain increase in the sample value. Up to the maximum sample value of the frequency graph.

The graph 411 of FIG. 10 is a timing vs. frequency graph, and is an example where the peak is not clear. In such a case, it is easier to determine the first area / second area by the method 1 for determining the first area / second area than the method 1 for determining the first area / second area in (1) above. Is. Graph 411
Then, the peak appearing immediately after the first region in which the frequency monotonously increases continuously for a time corresponding to a certain increase in the sample value is a peak 412, and the peak 412 continues for the time corresponding to a certain increase in the sample value. The peak that appears immediately before the last region where the frequency decreases monotonically is peak 413. The time corresponding to a certain increase in the sample value may be different between the first area and the second area. By adjusting this time, a small peak near the minimum sample value that is considered to be caused by noise can be obtained. 414 and small peaks 415 near the maximum sample value may not be considered as peaks to be separated.

By the above method, the first region can be determined as a region that can be easily approximated by the first approximation curve, and the second region can be determined as a region that can be easily approximated by the second approximation curve.

The method 1 and 2 for determining the first area and the second area have been described above. However, the first area and the second area may be determined by only the method 1 or 2 for determination, or the method 1 or 2 for determination may be used. One region may be determined and the second region may be determined by the determination method 2, or the second region may be determined by the determination method 1 and the determination method 2
The first area may be determined by. (3) Method of determining first approximate curve and second approximate curve Next, a method of determining the first approximate curve and the second approximate curve will be described.

In S3, the first approximate curve is obtained as a function obtained by multiplying the first probability density function having a normal distribution by the first coefficient, and the second approximate curve is obtained as a second probability density function having a normal distribution. It is calculated as a function that is multiplied by the coefficient of. Since the first area approximated by the first approximate curve and the second area approximated by the second approximate curve originally have a normal distribution, a function obtained by multiplying the first probability density function by the first coefficient, and The function obtained by multiplying the probability density function of 2 by the second coefficient is appropriate as the first approximation curve and the second approximation curve.

A graph 124 in FIG. 3 is a first approximation curve that approximates the first region determined by the range 122. The first probability density function that is normally distributed and approximated from the curve of the first region is the first coefficient l ₁ It is a doubled curve. Also, graph 12 in the figure
Reference numeral 5 is a second approximation curve that approximates the second region determined by the range 123, and is a curve obtained by multiplying the second probability density function, which is normally distributed and approximated from the curve of the second region, by the second coefficient l ₂ . Here, it is a feature that the graphs 124 and 125 approximate the curves of the first region and the second region to a part of the probability density function that is normally distributed.

Therefore, the first approximation curve and the second approximation curve can be easily and accurately obtained.

The first and second probability density functions, the first and second
And method 1 for determining the second coefficient Each sample value of the timing vs. frequency graph in S3
From the frequency change δq for the change step δt, δq / δt
To obtain the differential function of the timing vs. frequency graph,
Upward peak of the differential function in the region corresponding to the first region
A sample value that takes the value of₁, Sample value t₁In Thailand
The frequency of the ming vs. frequency graph is F₁, Sample value t₁In
The value of the differential function is G₁As the standard of the first probability density function
Deviation σ₁To F₁/ G₁, The center of the first probability density function μ₁
T₁+ Σ₁, The first coefficient l ₁(2πe)^0.5×
F₁ ²/ G₁And

Further, in S3, δq / δt is defined from the frequency change δq for each sample value change step δt of the timing vs frequency graph, the differential function of the timing vs frequency graph is obtained, and the differential function in the region corresponding to the second region is obtained. The sample value taking the value of the downward peak of the differential function is t ₂ , the frequency of the timing vs. frequency graph at the sample value t ₂ is F ₂ ,
Let G _{2 be} the value of the differential function at the sample value t ₂ , the standard deviation σ ₂ of the second probability density function is −F ₂ / G ₂ , and the center μ ₂ of the second probability density function is t ₂ −σ _2. , And the second coefficient l ₂ is − (2πe) ^0.5 × F ₂ ² / G ₂ .

Therefore, the first and second probability density functions and the first and second coefficients for obtaining the first and second approximate curves can be accurately obtained.

The above method will be described with a specific example. A graph 163 of FIG. 11 is a differential function g (t) of the graph 121 (referred to as f (t)) of FIG.
The part 123 is defined as the ranges 161 and 162 in FIG. Probability density function l ₁ e in which the first region in FIG. 3 is normally distributed
It can be approximated to a function (t, μ ₁ , σ ₁ ). e (t, μ ₁ , σ ₁ ) is the first probability density function, and e (t, μ ₁ , σ ₁ ) = exp {− (t−μ ₁ ) ² /
(2σ ₁ ² )} / (2πσ ₁ ² ) ^0.5 is satisfied. The function obtained by differentiating e (t, μ ₁ , σ ₁ ) by t is e ′ (t, μ ₁ , σ ₁ ) = − exp {− (t−
μ ₁ ) ² / (2σ ₁ ² )} × (t−μ ₁ ) / (2πσ ₁
⁶ ) ^{Meets 0.5} .

E '(t, μ ₁ , σ ₁ ) is t = μ ₁ −σ ₁
Has a convex peak at the time of, and has a convex peak at the time of t = μ ₁ + σ ₁ . When t = μ ₁ −σ ₁ , e (μ ₁ −σ ₁ , μ ₁ , σ ₁ ) = (2πeσ ₁ ² ) ^−0.5 e ′ (μ ₁ −σ ₁ , μ ₁ , σ ₁ ) = (2πeσ ₁ ⁴ )
^-0.5 e (μ ₁ −σ ₁ , μ ₁ , σ ₁ ) / e ′ (μ ₁ −σ ₁ , μ
₁ , σ ₁ ) = σ ₁ where t ₁ is the sample value having an upward convex peak in the range 161, and μ ₁ is the same as the sample value having an upward convex peak in g (t). = T ₁ + σ ₁ f (t ₁ ) / g (t ₁ ) = σ ₁ (where f (t ₁ ) = F ₁ and g (t ₁ ) = G ₁ ) l ₁ = (2πe) ^0.5 × f ( The relationship of t ₁ ) ² / g (t ₁ ) is established. From this relationship, the graph 124 of FIG. 3, which is the first approximation curve, is obtained. By performing the same calculation for the second region of FIG. 3, the graph 125 of FIG. 3, which is the second approximate curve, can be obtained. In this case, range 1 in FIG. 11
It is derived from the relationship of t ₂ = μ ₂ + σ ₂ where t ₂ is a sample value having a downward convex peak at 62.

First and second probability density functions, first and second
And a method 2S3 for determining the second coefficient,
The sampling value change step δt of the graph
If the sample value change step δt
Δq / δt is defined from
F differential function is obtained, and the sample value t of the first region_mIn thailand
The minimum sample value of the ming vs. frequency graph is t (minimum)
T (minimum) + δt × m (m is an integer of 0 or more), sump
Value t_mThe frequency of the above timing vs. frequency graph in
f (t_m), Sample value t_mThe value of the differential function at
(T_m), J (t_m) = G (t_m) / F (t_m), Σ_m
²= Δt / {j (t_{m + 1}) -J (t _m)}
Standard deviation σ of the first probability density function₁Σ_mAnd the average of
μ_m= T_m+ Σ₁ ²× g (t_m) / F (t_m)
The center μ of the first probability density function₁Μ_mAnd the average of
First coefficient l₁The sample value t_mAt f (t_m) /
(Sample value t of the first probability density function_mIn
Value).

Further, in S3, timing vs. frequency
If the rough sample value change step δt is equal,
Δ from the frequency change δq for the sample value change step δt
Differential function of timing vs. frequency graph by defining q / δt
And sample value t of the second region_nTiming vs frequency
The maximum sample value of the graph is t (maximum), and t (maximum)
+ Δt × n (n is an integer of 0 or less), sample value t_nTo
The frequency of the timing vs. frequency graph is f (t_n), Sun
Pull value t_mThe value of the differential function at g (t_n), J (t
_n) = G (t_n) / F (t_n), Σ_n ²= Δt / {j
(T_{n + 1}) -J (t_n)}, The second probability density
Standard deviation of the function σ₂Σ_nThe average of _n= T_n+ Σ
₂ ²× g (t_n) / F (t_n), The second probability
Center of density function μ₂Μ_nAnd the second coefficient l₂
The sample value t_nAt f (t_n) / (The second confirmation above)
Sample value t of the rate density function_nValue).

Therefore, the first for obtaining the first approximation curve
The probability density function of and the first coefficient can be accurately obtained.

The above method will be described with a specific example. A graph 163 of FIG. 11 is a differential function g (t) of the graph 121 (referred to as f (t)) of FIG.
The part 123 is defined as the ranges 161 and 162 in FIG. Probability density function l ₁ e in which the first region in FIG. 3 is normally distributed
It can be approximated to a function (t, μ ₁ , σ ₁ ). e (t, μ ₁ , σ ₁ ) is the first probability density function as above. In addition, δt is set to the minimum width of equal intervals that can be measured by the measuring device 3, and the range 122 in FIG.
T _m = t each sample values t _m the minimum sample value as t (min) in (Min) + .DELTA.t × m (m is 0
It is represented by the above integer).

Here, j (t_m) As j (t_m) = E ′ (t_m, Μ₁, Σ₁) / E (t_m, Μ
₁, Σ₁) =-(T_m-Μ₁) / Σ₁ ² Is defined. Then, j (t_{m + 1}) -J (t_m) =-(T_m−δt) / σ₁ ²
+ T_m/ Σ₁ ²= Δt / σ₁ ² Meet the relationship of σ₁ ²= Δt / {j (t_{m + 1}) -J (t_m)} Is established. And K (t_m) = Δt / {g (t_{m + 1}) / F (t_{m + 1}) -G
(T_m) / F (t_m)} For each t_mAbout K (t_m) Mean square root also
Is K (t_m), The average of the square roots of₁, Σ₁)
Standard deviation of₁Calculate as At this time, e (t, μ
₁, Σ₁) Center μ₁The value of μ (t_m) = T_m+ Σ₁ ²× g (t_m) / F (t_m) For each t_mFor μ (t_m) Average value
It l₁For f (t _m) / E (t, μ₁, Σ₁)
Take the average of. For the second area, use the same method.
Ku.

Although the methods 1 and 2 for determining the first and second probability density functions and the first and second coefficients have been described above, since the method 1 is determined only by the peak position of the differential function, Method 2 is more effective when the transmitter 2a has a characteristic that the position of the peak is not clear.
On the other hand, in Method 2, the value to be obtained is greatly influenced by the method of selecting the ranges 122 and 123. Therefore, when it is difficult to select the ranges 122 and 123 because many peaks appear in the timing vs. frequency graph, Is more effective. (4) Method of Determining Third Approximation Curve and Fourth Approximation Curve Next, a method of determining the third approximation curve and the fourth approximation curve will be described.

At S3, the third approximation curve is obtained by multiplying the first approximation curve by the ratio of the scaling coefficient D corresponding to a larger number to the predetermined number of pulse periods, and the second approximation curve is multiplied by the above ratio. The fourth approximated curve is obtained by

For example, the graph 501 of FIG. 12 is an enlarged display of the rising portion of the first region of the graph 121 of FIG. 3, and the graph 502 is the rising portion of the graph 124 of FIG. 3 which is the first approximation curve. It is an enlarged display of the corresponding part. Further, a graph 504 in FIG. 12 is a third approximated curve obtained by multiplying the graph 502 by the above ratio, and a graph 503 is a graph obtained by multiplying the graph 501 by the above ratio.

The value obtained by dividing the value on the vertical axis in FIGS. 3 and 12 by the amount of data transmitted from the transmitter 2a is the appearance probability. Therefore, 1 can be sent in 10 hours when 10 ¹² data are transmitted.
When counted only, the appearance probability at that time is 10
^It becomes ^-12 , and the appearance probability for the transmitted data is calculated by knowing the part having the frequency of 1 or more. vice versa,
The eye width is the time when no data is detected.

If there is not a sufficient amount of data (number of samples) as the number of predetermined pulse periods, the boundary between the portion having a frequency of 1 (frequency 505) and the time zone in which no data is detected is the sample value 507 in FIG. Therefore, when the number of predetermined pulse periods is set to be a sufficiently large number, it is considered that the boundary fluctuates toward the sample value side smaller than the sample value 507. However, even if the graph 501 is obtained by multiplying the graph 501 by the ratio, the boundary does not change from the sample value 507. Further, if the error correction is performed by the methods (1) to (3) of 2 above, there is a possibility that the boundary will be at a position different from the measured value of the predetermined level timing vs. frequency graph, but it can be said to be sufficiently accurate. Absent.

On the other hand, in the graph 504 obtained by multiplying the graph 502 by the above ratio, the boundary between the portion having the frequency of 1 or more and the time zone in which the data is not detected is the portion of the graph 121 in FIG. Sample value 5 while reflecting accurately
Move to sample value 506 less than 07. The difference between the sample value 506 and the sample value 507 is the first sample value variation, and the sum of the width of the first region and the first sample value variation is the width of the third region. The same applies to the second sample value variation and the fourth region.
Then, the first sample value variation and the second
The sum of the sample value fluctuation amount of the above is taken as the distribution fluctuation width of the timing vs. frequency graph when the number of predetermined pulse periods is increased to a larger number.

As described above, the first approximation curve and the second approximation curve are multiplied by the ratio of the scaling coefficient D corresponding to a larger number to the predetermined number of pulse periods to obtain the third approximation curve and the fourth approximation curve. Can be obtained easily and accurately.

Next, a method of determining the scaling coefficient D will be described.

Method 1 for determining the scaling coefficient D For example, as specified in IEEE1394, 10
Assuming that a BER of ^-12 is achieved, the distribution variation width of the timing vs. frequency graph may be estimated assuming a data amount of at least 10 ¹² . Therefore, in S3, 1 / (BER to be achieved) is set as the scaling coefficient D. This makes it possible to set an appropriate scaling coefficient D for obtaining the third approximate curve (graph 504) and the fourth approximate curve for obtaining the BER.

Method 2 for Determining Magnification Factor D The pattern of the optical signal 101 at the time of measurement and the pattern of the optical signal at the time of actual use in the transmission / reception system may be different. In preparation for such a case, in S3, from the High level 114 to the L level among the pulse joints of the predetermined pulse period number.
To low level 115 or from low level 115 to H
The ratio of the number that changes to the high level 114 is R _m , and the ratio of the number that changes from the high level 114 to the low level 115, or the ratio that changes from the low level 115 to the high level 114 among the pulse joints of all the transmitted and received pulses is R _m . _{As d} , R _d / {R _m × (BE to be achieved
Let R)} be the scaling factor D. This makes it possible to set an appropriate scaling coefficient D for obtaining the third approximate curve (graph 504) and the fourth approximate curve for obtaining the BER.

Further, when the transmission / reception system is actually used, the ratio R _d may change greatly with each use. In preparation for such a case, in S3, the assumed _maximum value of the ratio R _d is set as R _worst , and R _worst / {R
_The scaling factor D may be _m × (BER to be achieved)}. This makes it possible to set a more accurate scaling coefficient D for obtaining the third approximate curve (graph 504) and the fourth approximate curve for obtaining the BER.

By setting the numerator of the scaling factor D to be R _d or R _worst as in the above two examples, the eye width described later is calculated as a value closer to the ideal value, and the BER becomes a value closer to the ideal value. . That is, the scaling coefficient D is a value including a margin for more accurately obtaining the BER.

Furthermore, it is most likely that an error will occur in transmission / reception of the optical signal 101 when the pulse level changes from the High level 114 to the Low level 115 or from the Low level 115 to the High level 114. . Therefore, 1 / {R _m × (BER to be achieved)} may be used as the scaling coefficient D. According to this, since the numerator of the scaling factor D is 1, the numerator is R _d or R
_The scaling coefficient D becomes larger than that in the _worst case, and the scaling coefficient D is easier to determine. Therefore, the third approximation curve (graph 504) and the fourth approximation curve for obtaining the BER are calculated so as to narrow the eye width described later, as compared with the case where the numerator of the scaling coefficient D is R _d or R _worst. Can
It is practical that a clear standard is set in a state including a margin in order to perform defect selection on the BER at the time of mass production of the transmission / reception system. In this way, the scaling factor D is set to 1 / {R _m
By setting x (BER to be achieved)}, an appropriate scaling coefficient D can be set including a margin.

Method of Determining Magnification Coefficient D 3 A method of deciding a magnification coefficient D useful for a transmission / reception system using an optical fiber cable will be described. FIG. 13 shows the configuration of an optical transmission / reception system (transmission / reception system) 511 that performs full-duplex communication using an optical fiber cable. The optical transceiver system 511 includes optical transceivers 512 and 514 and a single-core optical fiber cable 513. Further, the optical transceiver 512 includes an optical transmitter 512a and an optical receiver 512.
b, the optical transceiver 514 includes an optical transmitter 514a and an optical receiver 514b.

In performing full duplex communication using a single-core optical fiber cable, the largest cause of error is
This is to reflect the optical signal output by itself by the incident side end face or the output side end face of the optical fiber cable and the optical transceiver on the other side. FIG. 13 shows that when the optical transmission / reception system 511 adopts the full-duplex communication method, the optical transmission / reception device 512 receives the optical signal of the optical transmission / reception device 514 on the other side.
The optical signal 515 reflected before the optical signal transmitted by the transmitter 512a enters the optical fiber cable 513 and the optical signal transmitted by the transmitter 512a are the optical fiber cable 513.
Through the other side module and the optical fiber cable 5
The optical signal 516 reflected by the tip surface of 13 is also received at the same time.

If the optical fiber cable 513 has a certain length, the reflected optical signal 516 will not be received at the same time as the optical signal 515 because there is a time difference when reciprocating in the optical fiber cable 513. Therefore, in the above example, the levels of the optical signals received by the receiver 512b at a certain moment are, as shown in FIG. 14A, the optical signal u from the transmitter 514a of the transceiver 514 and the optical signal 515. The level of the optical signal w is obtained by adding the optical signals v having four levels v1 to v4 depending on the presence or absence of each of 516. The level v1 is the optical signal 515.
Level v2 when both 516 do not exist
Is the level when only the optical signal 515 is present, level v3 is the level when only the optical signal 516 is present, and level v4 is the level when both the optical signals 515 and 516 are present.

When the optical signal u changes from the high level to the low level, it changes gently over a certain period of time as shown in FIG.
Even if a transmits the optical signal u at the same level, the transmitter 512
When a shines randomly, the light intensity of the optical signal w from the high level to the low level is also divided into four.
If the measuring device 3 in FIG. 18 is equipped with the same optical transceiver as the other party as in the optical transceiver 512 in FIG. 13 and performs full duplex communication, the level 113 in FIG. When the graph is measured to obtain the timing vs. frequency graph, four peaks appear in the timing vs. frequency graph. Since there is a pattern in which the optical signal u changes from the Low level to the High level, when considering this situation, as shown in FIG. 14B, the timing vs. frequency graph has a maximum of eight peaks in total. Expected to appear. In practice, the optical signal 515 and the optical signal 516 may be the same or one of them may be extremely low, so the number of peaks is likely to decrease. Further, how many bits the High level state continues to become the Low level and how many bits the Low level state continues to become the High level are factors that increase the peak.

At this time, when looking at the margin for the BER to be achieved as in the method 2 for determining the scaling coefficient D, one peak that is the factor that narrows the eye width the most among the split peaks. In order to consider, it is ideal to consider the amount of data as many as the number of split peaks.
In the above example, the case where the peaks are separated into four as shown in FIG. 15A has been described. However, in reality, the reflection of the optical signal 516 is very small, or the distance of the optical fiber cable 513 is short, which appears. There are cases where the number of peaks is less than four, and there is a possibility that the transmitted optical signal is reflected back and forth and five or more peaks appear, and it is impossible to calculate only by calculation. For example, FIG. 15 (b) shows four peaks represented by dotted lines in FIG. 15 (a) overlapping each other and observed as two peaks represented by solid lines. The scattered peaks such as 10 are caused by the combination of a certain optical transceiver with the peak 41 of FIG.
It is a figure corresponding to the state concentrated on the position of 2 · 413.

As described above, since the optical transceivers to be combined cannot be predicted, in consideration of the worst situation as shown in FIG. 15 (b) in which clear peak separation does not occur, a predetermined level 117 shown in FIG. Unlike the level 113, which is a level, it is appropriate to count and acquire the number of peaks by measuring and acquiring a graph of timing versus frequency at a specific level where peak separation is remarkable. When the number of peaks is counted using the above specific level,
For example, as shown by the solid line in FIG. 15A, the peaks when a predetermined level is used are clearly separated as the dotted line, so that they are easy to count. Further, since the total number of peaks counted at the above-mentioned specific level includes the state of changing from the High level to the Low level and the state of changing from the Low level to the High level at the same time, the number of peaks to be separated is the It is half the total number of peaks.

Therefore, the measuring device 3 is provided with a transceiver similar to the full-duplex communication system so that even in the case of full-duplex communication, even if there is signal reflection on the transmission line, It indicates how often the timings at which the optical signal 101 received by the measuring device 3 takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is distributed in a predetermined number of pulse periods. Other level frequency distribution measurement value acquisition procedure for acquiring measurement values of level timing vs. frequency graph is provided. Then, in S3, the number of peaks appearing in the other level timing vs. frequency graph based on the measurement value of the other level timing vs. frequency graph acquired in the other level frequency distribution measurement value acquisition procedure is _Pn , and the pulse of the predetermined pulse period number Let R _{m be} the ratio of the number of transitions from the High level to the Low level or from the Low level to the High level among the joints, and _let P _n / {2 × R _m × (BER to be achieved)} the scaling factor D. To do.

As a result, in order to obtain the third approximate curve and the fourth approximate curve for obtaining the BER, an accurate scaling factor is mixed with the optical signal 101 and the reflection signal on the transmission line, and the eye width is increased accordingly. The margin can be set in consideration of the narrowing and the increase in BER. This has a larger margin than the scaling coefficient D of 1 / {R _m × (BER to be achieved)}, and the scaling coefficient D is P _n × R _d / {2 × R _m. × (BE to achieve
R)} (or R _worst instead of R _d ), a clear criterion is set in a state including a margin for practically selecting a BER defect in mass production of a transmission / reception system, which is more practical. is there. 4. Regarding the eye width derivation procedure of S4, FIG. 16 shows the pattern of the optical signal 101 of FIG. 2 observed in a time range longer than one pulse period.
The distribution of the rising and falling patterns of 1 is shown twice. The width 132 is the maximum sample value of the fourth region obtained in S3 for the distribution of the rising and falling patterns of the left optical signal 101 (hereinafter referred to as the left distribution) and the rising and falling of the right optical signal 101. It is the length between the pattern distribution (hereinafter referred to as the right distribution) and the minimum sample value of the third region obtained in S3, and is the eye width corresponding to the larger number. The width 133 is the maximum sample value of the second region obtained in S3 for the left distribution and S3 for the right distribution.
It is the length between the minimum sample value of the first region obtained in step 1, and is the eye width directly measured from the distribution for the number of predetermined pulse periods. That is, the eye width is usually measured directly from the measured data, but with this method,
If the measured data is small, the eye width becomes large like the width 133, and as the measured data becomes large, the eye width becomes small like the width 132.

Here, if the left distribution and the right distribution are the same, the distribution fluctuation width estimated in S3 is equal to the difference between the width 133 and the width 132. In addition, the width 134 is the optical signal 10
1 pulse period. The width 135 is the sum of the distribution fluctuation width estimated in S3 and the distribution width of the timing vs. frequency graph obtained in S2.

Therefore, in S4, the difference between the minimum sample value of the first area and the maximum sample value of the second area is set as the distribution width of the timing vs. frequency graph, and the sum of the distribution width and the distribution fluctuation width is 1 pulse. The value subtracted from the period is the eye width. S
3, the distribution variation width is obtained using the sample values of the third approximation curve and the fourth approximation curve having a frequency of 1 or more. Therefore, the number of predetermined pulse periods is increased to a larger number by the above eye width deriving method. It is possible to obtain an accurate eye width when it is made. 5. Regarding the error rate deriving procedure of S5 FIG. 17 is an example of a graph showing the relationship between the eye width and the BER of the optical signal 101 transmitted from the transmitter 2a. The horizontal axis represents the value obtained by dividing the eye width by one pulse period of the optical signal 101, and the vertical axis represents the BER in that eye width. With the same transmitter, the eye width and error rate are always the same, but if there are variations in production due to mass production,
Even transmitters of the same design have different eye widths, and the BER also changes according to the eye width. However, since the relationship is a straight line with a semi-logarithm as shown in FIG. 17, the eye width and BER as shown in FIG.
If the relationship with
You can know the ER. Therefore, the measurement can be performed only for the predetermined number of pulse periods, and the BER when the eye width corresponding to the larger number obtained in S4 is increased to a larger number can be obtained without directly measuring the BER.
This makes it possible to easily obtain the BER when the number of predetermined pulse periods is increased to a larger number.

The procedures from S1 to S5 have been described above in detail. Although the pulse signal is the optical signal 101 in the above description, it may be an electric signal transmitted / received via an electric transmission path. The clock signal 102 may be an electric signal or an optical signal. Furthermore, the above-mentioned 3-
The method (4)-can also be applied to the case of using an electric transmission line in which reflection of an electric signal poses a problem.

Further, as described above, the error rate acquisition method according to the present embodiment is realized by the program for causing the computer to execute each procedure of the error rate acquisition method described above. It can be easily executed by a computer.
Further, this program is stored in a computer-readable recording medium. With such a recording medium, the program of the error rate acquisition method can be supplied to various computers, and the error rate acquisition method becomes highly versatile. This recording medium is, for example, RO
M, a mask ROM used as a non-volatile memory, E
A medium such as a semiconductor memory such as a PROM, an EEPROM, a flash ROM, and a hard disk, which is provided in a computer and carries a fixed program, a tape system such as a magnetic tape or a cassette tape, and a floppy disk. Magnetic disks such as removable hard disks and CD-ROM / MO / MD /
It is a medium that is driven by an external medium drive device such as a disc system of an optical disc such as a DVD or a card system such as an IC card (including a memory card) / optical card and is separable from the device.

In any case, the stored program may be executed by the access of the CPU, or the read program is downloaded to the program storage area such as RAM and the It may be configured to be executed. It is assumed that this download program is stored in advance in the computer main body.

If the computer has a network interface and can be connected to a communication network including the Internet, the medium may be a medium that carries the program fluidly so as to download the program from the communication network. When the program is downloaded from the communication network in this way, the download program may be stored in advance in the computer main body or installed from another recording medium.

The contents stored in the recording medium are not limited to the program, and may include data as shown in FIG.

[0202]

As described above, according to the error rate acquisition method of the present invention, the pulse signal is near the eye width definition level within one pulse period starting from a predetermined timing with respect to the pulse joint of the received pulse signal. A predetermined level frequency distribution measurement value acquisition procedure for acquiring a measurement value of a predetermined level timing vs. frequency graph showing how often the timing of taking a predetermined level of is distributed as a sample value in a predetermined number of pulse periods; Starting from the above-mentioned predetermined timing, the measured value of the above-mentioned predetermined level timing vs. frequency graph acquired by the predetermined level frequency distribution measurement value acquisition procedure or the measured value of the above described predetermined level timing vs. frequency graph is subjected to frequency error correction. Of the timing at which the pulse signal takes the predetermined level within one pulse period
From the timing vs. frequency graph determined in the frequency distribution determination procedure and the frequency vs. frequency graph determining the frequency vs. frequency graph representing an appropriate frequency distribution for the predetermined pulse period number, the predetermined pulse period number is made larger. The predetermined pulse using the estimation procedure for estimating the distribution variation width of the timing vs. frequency graph when the number is increased, and the distribution variation width and the distribution width of the timing vs. frequency graph estimated by the estimation procedure. From the eye width derivation procedure for obtaining the eye width when the number of periods is increased to the larger number above, and the predetermined pulse period number from the eye width obtained in the eye width derivation procedure to the larger number above. And an error rate derivation procedure for obtaining the error rate when the error rate is increased.

Therefore, the measured value for the predetermined number of pulse periods is used to find the eye width when the predetermined number of pulse periods is increased to a larger number, and the corresponding error rate is obtained. If the error rate is set to the number necessary for direct measurement, the accurate error rate can be obtained from the measured values for a small number of predetermined pulse periods. Therefore, it is possible to obtain the error rate of the pulse signal in a short time.

Further, the error rate acquisition method of the present invention is
As described above, the High level of the received pulse signal is
This is a configuration including a predetermined level determination procedure for setting the median between the h level and the low level as the predetermined level.

Therefore, the predetermined level is set to Hi in the ideal state.
The effect is that it can be determined as an accurate level close to the eye width definition level that is the median between the gh level and the Low level.

Further, the error rate acquisition method of the present invention is
As described above, the measured value of the level vs. frequency graph showing how often the level of the received pulse signal taken at a specific timing within one pulse period is distributed as a sample value in the number of specific pulse periods. When peaks appear near the maximum sample value and near the minimum sample value of the measured values of the specific timing frequency distribution measurement value acquisition procedure and the level vs. frequency graph acquired by the specific timing frequency distribution measurement value acquisition procedure. The sample value that takes a peak value near the maximum sample value above
and a level range determining procedure in which a sample value having a peak value in the vicinity of the minimum sample value is set to the Low level.

Therefore, the high level and the low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
As described above, except for the joint where the level of the received pulse signal at a specific timing excluding the vicinity of the pulse joint in one pulse period is distributed as a sample value in the number of specific pulse periods The maximum frequency of the measured values of the level vs. frequency graph other than the joint, which is acquired by the procedure for acquiring the specific timing frequency distribution measurement value other than the joint, which acquires the measured value of the level vs. frequency graph, and the procedure for acquiring the specific timing frequency distribution measured value other than the joint. The first level, which is a sample value, is obtained, and a function that is the smallest at the first level and increases as it moves away from the first level and approaches a constant value is multiplied by the level-frequency graph other than the joints. To obtain the second level which is a sample value that takes the maximum value of the above multiplication distribution, The larger of the level and the second level and the High level, the smaller the Lo
and a level range determination procedure for setting the w level.

Therefore, the high level and the low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
As described above, the measured value of the total level vs. frequency graph indicating how often the level of the received pulse signal taken through all the timings in one pulse period is distributed as the sample value in the specific pulse period number. To obtain the all-timing frequency distribution measurement value acquisition procedure, and the maximum sample value of the measurement values of the all-level vs. frequency graph obtained in the all-timing frequency distribution measurement value acquisition procedure, or the peak value near the maximum sample value. The sample value to be taken is the above High
And a level range determining procedure for setting the minimum sample value of the all level vs. frequency graph or a sample value having a peak value near the minimum sample value as the low level.

Therefore, the High level and the Low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
As described above, the measured value of the total level vs. frequency graph indicating how often the level of the received pulse signal taken through all the timings in one pulse period is distributed as the sample value in the specific pulse period number. To obtain the all-timing frequency distribution measurement value acquisition procedure and the all-first level which is the sample value taking the maximum frequency of the measurement values of the all-level vs. frequency graph obtained in the all-timing frequency distribution measurement value acquisition procedure. , A total multiplication distribution is created by multiplying the above-mentioned all-level vs. frequency graph with a function that is the smallest at all the first levels and increases as the distance from the all first levels approaches a constant value. All the second levels, which are the sample values that take the maximum value, are obtained and
The higher of the level and the above-mentioned second level is the above-mentioned Hi.
gh level, and a level range determining procedure for setting the smaller one to the Low level.

Therefore, the High level and the Low level of the pulse signal can be easily and accurately determined.

Further, the error rate acquisition method of the present invention is
As described above, the measured value of the total level vs. frequency graph indicating how often the level of the received pulse signal taken through all the timings in one pulse period is distributed as the sample value in the specific pulse period number. To obtain the total timing frequency distribution measurement value acquisition procedure, and a predetermined level determination procedure in which the average sample value of the measurement values of the all level vs. frequency graph obtained in the above all timing frequency distribution measurement value acquisition procedure is the predetermined level It is a configuration including and.

Therefore, the predetermined level is set to Hi in the ideal state.
The effect is that it can be determined as an accurate level close to the eye width definition level that is the median between the gh level and the Low level.

Further, the error rate acquisition method of the present invention is
As described above, the timing at which the received pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is used as a sample value and distributed at any frequency in the predetermined pulse period number. In the frequency distribution determination procedure, the predetermined level is included in another frequency distribution measurement value acquisition procedure for acquiring another measurement value for one or more specific levels of the other level timing vs. frequency graph indicating whether The measured value of the predetermined level timing vs. frequency graph acquired in the frequency distribution measured value acquisition procedure and the respective measured value of the other level timing vs. frequency graph acquired in the arbitrary other level frequency distribution measured value acquisition procedure The above-mentioned error correction is performed by synthesizing, and the timing-frequency graph is determined.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error.

Further, the error rate acquisition method of the present invention is
As described above, in the frequency distribution determination procedure, with respect to the measurement value of the predetermined level timing vs. frequency graph acquired in the predetermined level frequency distribution measurement value acquisition procedure, the sample value is centered and the center sample Create a probability distribution function that is normally distributed by assigning a probability density to sample values within a predetermined range from each value, and for each of the above probability density functions, calculate the sum of the values obtained by multiplying the frequency of the sample values by the probability density. The error correction is performed by setting a new frequency of the sample value at the center of the probability density function, and the timing-frequency graph is determined.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately performing the error correction.

Further, the error rate acquisition method of the present invention is
As described above, how often the timing at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is distributed as the sample value in the predetermined pulse period number. In the frequency distribution determination procedure, the predetermined level frequency distribution measurement is performed in the frequency distribution determination procedure, including an arbitrary other level frequency distribution measurement value acquisition procedure for acquiring a measurement value for each of one or more specific levels of the other level timing vs. frequency graph. The measured value of the predetermined level timing vs. frequency graph acquired in the value acquisition procedure and each measured value of the other level timing vs. frequency graph acquired in the arbitrary other level frequency distribution measured value acquisition procedure are combined. For the created graph, the sample value is centered and the sample value within the predetermined range from the center sample value Create a probability density function with a normal distribution that assigns probability density to each sample value, and for each of the above probability density functions, add the sum of the values obtained by multiplying the frequency of the sample values by the probability density to the center of the above probability density function. The error correction is performed by setting a new frequency of the sample value, and the timing-frequency graph is determined.

Therefore, even if the measured value of the predetermined level timing vs. frequency graph includes some error such as measurement noise, the timing vs. frequency graph can be obtained by accurately correcting the error.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, the first approximation curve that approximates the first region, which is the region near the minimum sample value of the timing vs. frequency graph, and the region near the maximum sample value of the timing vs. frequency graph. A second approximation curve that approximates the second region is obtained, and in a region near the minimum sample value of the timing versus frequency graph when the predetermined pulse period number is increased from the first approximation curve to the larger number. In a region near the maximum sample value of the timing vs. frequency graph when the third approximate curve approximating a certain third region is obtained and the predetermined pulse period number is increased from the second approximate curve to the larger number. A fourth approximated curve approximating a certain fourth area is obtained, and based on the third approximated curve, from the minimum sample value of the first area to the minimum sample value of the third area. The sample value fluctuation amount of 1 is obtained, and the second sample value fluctuation amount from the maximum sample value of the second region to the maximum sample value of the fourth region is calculated based on the fourth approximation curve, The sum of the sample value variation and the second sample value variation is set as the distribution variation width.

Therefore, it is possible to easily and accurately estimate the distribution variation width of the timing vs. frequency graph when the number of predetermined pulse periods is increased to a larger number.

Furthermore, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, on the timing vs. frequency graph, from the minimum sample value of the timing vs. frequency graph to the most minimum sample value side when the timing vs. frequency graph is separated into a predetermined number of peaks. Up to a sample value that takes a peak value or a sample value that takes a peak value that appears immediately after the first region in which the frequency increases monotonically for a time corresponding to a certain increase in sample value, This is a structure having one area.

Therefore, by adopting either of the above two methods, it is possible to determine the first region as a region that can be easily approximated by the first approximation curve.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, on the timing vs. frequency graph, from the sample value taking the value of the peak on the maximum sample value side when the timing vs. frequency graph is separated into a predetermined number of peaks, or From the sample value that takes the value of the peak that appears immediately before the last region where the frequency monotonically decreases continuously for a time corresponding to a certain increase in the sample value to the maximum sample value in the timing vs. frequency graph, This is a structure having two regions.

Therefore, by adopting either of the above two methods, it is possible to determine the second region as a region that can be easily approximated by the second approximation curve.

Furthermore, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, when the timing vs. frequency graph is separated into the predetermined number of peaks, the sample value taking the maximum frequency in the timing vs. frequency graph is the first timing or the first timing. A first multiplication distribution obtained by multiplying the timing vs. frequency graph by a first function that is small and increases as it moves away from the first timing and approaches a first constant value takes the maximum value of the first multiplication distribution. A second value is obtained by multiplying the first multiplication distribution by a second function, which has the smallest sample value at the second timing and the second timing, increases as it moves away from the second timing, and approaches the second constant value. The multiplication distribution, which is the smallest at the (k-1) th timing when k is a natural number of 3 or more,
1) It increases as it goes away from the timing and becomes the (k−
The (k-1) th function approaching the constant value of
2) The product obtained by multiplying the multiplication distribution is defined as the (k-1) th distribution, and the sample value taking the maximum value of the (k-1) th distribution is defined as the kth timing, and the predetermined number is 2 or more. A natural number N is sequentially obtained from the first timing to the Nth timing, and the obtained first timing to the Nth timing are obtained.
The configuration is such that each of the values up to the timing is a sample value that takes the value of the peak to be separated.

Therefore, it is possible to easily and accurately separate the timing-versus-frequency graph into a predetermined number of peaks, including the case where no clear peak exists.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, the first normal function is the normal distribution function whose standard deviation is the first constant times the standard deviation of the timing vs. frequency graph with the first timing as the center. Of the standard deviation of the (k-2) th multiplication distribution with the standard deviation centered at the (k-1) th timing. In this configuration, a normal distribution function that is a constant multiple of -1) is subtracted from the (k-1) th constant value.

Therefore, it is possible to eliminate the already-obtained peak as much as possible and obtain the next peak, and it is possible to easily separate the timing vs. frequency graph into a predetermined number of peaks.

Further, the error rate acquisition method of the present invention is
As described above, how often the timing at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is distributed as the sample value in the predetermined pulse period number. Including the other level frequency distribution measurement value acquisition procedure for acquiring the measurement value of the other level timing vs. frequency graph, the other level timing vs frequency graph acquired in the other level frequency distribution measurement value acquisition procedure in the estimation procedure The number of peaks included in the other level timing vs. frequency graph is obtained based on the measured value of 1 and the number of peaks is set to N.

Therefore, there is an effect that the predetermined number of peaks to be separated can be accurately determined on the timing vs. frequency graph.

Further, the error rate acquisition method of the present invention is
As described above, in the above estimation procedure, the first probability density function that normally distributes the first approximate curve is obtained as a function that is multiplied by the first coefficient, and the second probability density that normally distributes the second approximate curve is obtained. The configuration is such that a function is obtained by multiplying the function by a second coefficient.

Therefore, the first approximate curve and the second approximate curve can be easily and accurately obtained.

Further, the error rate acquisition method of the present invention is
As described above, in the above estimation procedure,
For each sample value change step δt
The frequency change δq is defined as δq / δt.
The differential function of the frequency vs.
The value of the upward peak of the above differential function in the corresponding region
Sample value₁, The sample value t₁Above in Thailand
The frequency of the ming vs. frequency graph is F₁, The sample value t₁
The value of the above differential function at₁As the first probability density
Standard deviation σ of the degree function₁To F₁/ G₁, The first probability density above
Degree function center μ ₁T₁+ Σ₁, The first coefficient l₁To
(2πe)^0.5× F₁ ²/ G₁The configuration is

Therefore, there is an effect that the first probability density function and the first coefficient for obtaining the first approximate curve can be accurately obtained.

Further, the error rate acquisition method of the present invention is
As described above, in the above estimation procedure, when each sample value change step δt of the timing vs. frequency graph is equal, δq / δt is defined from the frequency change δq with respect to the sample value change step δt to define the timing vs frequency graph. A differential function is obtained, and the sample value t _m of the first region is t (minimum) + δt × m (m is an integer of 0 or more), where the minimum sample value of the timing-frequency graph is t (minimum), and the sample value t _m the above timing versus the frequency of frequency graph f (t _m) in the value of the differential function of the sample values _{t m g (t m),} j (t m) = g
_{(T m) / f (t} m), σ m 2 = δt / {j (t m + 1)
-J (t _m )}, the standard deviation σ ₁ of the first probability density function is the average of σ _m , and μ _m = t _m + σ ₁ ² ×
g (t _m) / f when the (t _m), the center mu ₁ of the first probability density function and the mean of mu _m, the first coefficient l
₁ sample values t _m in f (t _m) / is configured to (the value of the sample values t _m of the first probability density function).

Therefore, there is an effect that the first probability density function and the first coefficient for obtaining the first approximated curve can be accurately obtained.

Further, the error rate acquisition method of the present invention is
As described above, in the above estimation procedure, δq / δt is defined from the frequency change δq with respect to each sample value change step δt of the timing vs. frequency graph, the differential function of the timing vs. frequency graph is obtained, and the second area is set. corresponding sample values t ₂ to take a downward peak values of the differential function of the area, frequently a F ₂ of the timing versus frequency graph of the above sample values t _2, the sample value t ₂
The differential value of the function as G _2, the -F ₂ / G ₂ standard deviation sigma ₂ of the second probability density function, centered mu ₂ to t ₂ - [sigma] ₂ of the second probability density function, the The second coefficient l ₂
Is-(2πe) ^0.5 × F ₂ ² / G ₂ .

Therefore, there is an effect that the second probability density function and the second coefficient for obtaining the second approximate curve can be accurately obtained.

Furthermore, the error rate acquisition method of the present invention is
As described above, in the above estimation procedure, when each sample value change step δt of the timing vs. frequency graph is equal, δq / δt is defined from the frequency change δq with respect to the sample value change step δt to define the timing vs frequency graph. A differential function is obtained, and the sample value t _n of the second region is t (maximum) + δt × n (n is an integer of 0 or less), where t is the maximum sample value of the timing vs. frequency graph, and sample value t _n f (t _n) the frequency of the timing versus frequency graph of the value of the differential function of the sample values _{t m g (t n),} j (t n) = g
(T _n ) / f (t _n ), σ _n ² = δt / {j (t _{n + 1} ).
-J (t _n )}, the standard deviation σ ₂ of the second probability density function is the average of σ _n , and μ _n = t _n + σ ₂ ² ×
When g (t _n ) / f (t _n ), the center μ ₂ of the second probability density function is the average of μ _n , and the second coefficient l is
₂ is set to f (t _n ) / (value at the sample value t _n of the second probability density function) at the sample value t _n .

Therefore, there is an effect that the second probability density function and the second coefficient for obtaining the second approximate curve can be accurately obtained.

Furthermore, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, the third approximation curve is obtained by multiplying the first approximation curve by the ratio of the scaling factor corresponding to the larger number to the predetermined pulse period number, and the second approximation curve is obtained. The fourth approximation curve is obtained by multiplying the approximation curve by the ratio.

Therefore, there is an effect that the third approximate curve and the fourth approximate curve can be easily and accurately obtained.

Further, the error rate acquisition method of the present invention is
As described above, in the above estimation procedure, 1 / (error rate to be achieved) is used as the scaling coefficient.

Therefore, in obtaining the third approximation curve and the fourth approximation curve for obtaining the error rate, it is possible to set an appropriate scaling factor.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure,
From the high level of the pulse joint of the number of loose periods
High level to or from Low level
R is the ratio of the number that changes to _m, All pulses transmitted and received
From the high level of the pulse joint of
Change from low level to high level
The ratio of the number_dAs R_d/ {R_m× (Achieve all
Error rate)} as the scaling factor.

Therefore, it is possible to set an appropriate scaling factor for obtaining the third approximation curve and the fourth approximation curve for obtaining the error rate.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure,
From the high level of the pulse joint of the number of loose periods
High level to or from Low level
R is the ratio of the number that changes to _m, All pulses transmitted and received
From the high level of the pulse joint of
Change from low level to high level
The ratio of the number_d, The above ratio R_dThe largest expected of
R is a good value_worstAs R_worst/ {R_m× (achieve
Power error rate)} as the scaling coefficient.
It

Therefore, it is possible to set an appropriate scaling factor for obtaining the third approximation curve and the fourth approximation curve for obtaining the error rate.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure,
From the high level of the pulse joint of the number of loose periods
High level to or from Low level
R is the ratio of the number that changes to _mAs 1 / {R_m×
(Error rate to be achieved)} as the scaling coefficient
It is a success.

Therefore, in obtaining the third approximation curve and the fourth approximation curve for obtaining the error rate, it is possible to set an appropriate scaling coefficient including a margin.

Furthermore, the error rate acquisition method of the present invention is
As described above, how often the timing at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is distributed as the sample value in the predetermined pulse period number. Including the other level frequency distribution measurement value acquisition procedure for acquiring the measurement value of the other level timing vs. frequency graph, the other level timing vs frequency graph acquired in the other level frequency distribution measurement value acquisition procedure in the estimation procedure The number of peaks appearing in the other level timing vs. frequency graph based on the measured value of P _n , and the number of changes from the High level to the Low level or from the Low level to the High level among the pulse joints of the above-described predetermined pulse period. the proportion of the R _m, the the _{P n / {2 × R m} × ( error rate to be achieved)} A configuration in which the multiplication factor.

Therefore, in order to obtain the third approximation curve and the fourth approximation curve for obtaining the error rate, an accurate scaling factor is used, and the reception component of the reflection signal on the transmission line used for transmitting and receiving the pulse signal is calculated. It is possible to set the margin including the margin.

Further, the error rate acquisition method of the present invention is
As described above, in the estimation procedure, the minimum sample value of the sample values having the frequency of the third approximate curve of 1 or more is set as the minimum sample value of the third region, and the fourth sample
The maximum sample value of the sample values having the frequency of the approximate curve of 1 or more is set as the maximum sample value of the fourth region, and in the eye width derivation procedure, the minimum sample value of the first region and the maximum sample of the second region. The difference from the value is the distribution width of the timing vs. frequency graph, and the value obtained by subtracting the sum of the distribution width and the distribution fluctuation width from one pulse period is the eye width.

Therefore, it is possible to obtain an accurate eye width when the number of the predetermined pulse periods is increased to the larger number.

Furthermore, the error rate acquisition method of the present invention is
As described above, in the error rate deriving procedure, from the relationship between the eye width obtained in the eye width deriving procedure and the eye width obtained in advance and the error rate,
The error rate is obtained when the number of the predetermined pulse periods is increased to the larger number.

Therefore, it is possible to obtain the error rate easily.

Further, the program of the present invention is a program for causing a computer to execute each procedure of the error rate acquisition method described in any of the above.

Therefore, it is possible to cause the computer to execute the above-mentioned error rate acquisition method.

Further, the recording medium of the present invention is a recording medium in which the program described above is recorded so that it can be read by a computer.

Therefore, since the above program can be executed by various computers, the above-mentioned error rate acquisition method becomes highly versatile.

[Brief description of drawings]

FIG. 1 is a flowchart showing each procedure of an error rate acquisition method according to an embodiment of the present invention.

FIG. 2 is a first waveform diagram showing the relationship between time and level of an optical signal.

FIG. 3 is a first graph showing a relationship between time and frequency of an optical signal.

FIG. 4 is a first graph showing a relationship between a level of an optical signal and a frequency.

FIG. 5 is a second graph showing the relationship between the level of an optical signal and the frequency.

FIG. 6 is a second graph showing the relationship between time and frequency of an optical signal at a certain light level.

FIG. 7 is a third graph showing the relationship between time and frequency of an optical signal at a certain light level.

FIG. 8 is a fourth graph showing a relationship between time and frequency of an optical signal at a certain light level.

FIG. 9 is a fifth graph showing the relationship between time and frequency of an optical signal at a certain light level.

FIG. 10 is a sixth graph showing a relationship between time and frequency of an optical signal at a certain light level.

FIG. 11 is a graph showing a relationship between time and frequency differential value of an optical signal at a certain optical level.

FIG. 12 is a seventh graph showing the relationship between time and frequency of an optical signal at a certain light level.

FIG. 13 is an explanatory diagram illustrating an optical signal reception state in the optical transmission / reception system.

14 (a) and 14 (b) are explanatory diagrams for explaining an optical signal reception state affected by the presence of a reflected signal in the optical transmission / reception system of FIG.

15 (a) and (b) are received in the presence of a reflected signal in the optical transmission / reception system of FIG.
It is a graph which shows the relationship between the time and frequency of the optical signal in a certain optical level.

FIG. 16 is a second waveform chart showing the relationship between time and level of an optical signal.

FIG. 17 is a graph showing the relationship between eye width and error rate.

FIG. 18 is a block diagram showing a configuration of an error rate measurement system that executes an error rate acquisition method according to an embodiment of the present invention.

[Explanation of symbols]

101 optical signal (pulse signal) 113 level (predetermined level) 114 High level 115 Low level 121 graph (predetermined level timing vs. frequency graph measurement value, timing vs. frequency graph) 124 graph (first approximate curve) 125 graph (second) Approximate curve) 132 width (eye width) 134 width (1 pulse period) 141 graph (measured value of level vs. frequency graph, measured value of level vs. frequency graph other than joint) 146 multiplication distribution 151 graph (measurement of all level vs. frequency graph) Value) 163 graph (differential function) 171 graph (predetermined level timing vs. frequency graph measurement value, timing vs. frequency graph) 172 sample value (first timing) 173 first function 174 first multiplication distribution 175 sample value (second value) Timing) 176 sample value (3rd tie 177 Normal distribution function 311 Graph (measured value of predetermined level timing vs. frequency graph) 312 Graph (measured value of other level timing vs. frequency graph) 321 Graph (measured value of predetermined level timing vs. frequency graph) 322 Graph (timing vs. Frequency graph) 401 graph (measured value of other level timing vs. frequency graph) 411 graph (measured value of predetermined level timing vs. frequency graph, timing vs. frequency graph) 504 graph (third approximate curve) 511 Optical transmission / reception system (transmission / reception system) δt step (sample value change step)

Claims (31)

[Claims] 1. Information of one pulse is high level and L
In an error rate acquisition method for obtaining an error rate of the pulse signal of a transmission / reception system that transmits / receives a pulse signal represented by any one of the ow levels, the method starts from a predetermined timing with respect to a pulse joint of the received pulse signal. As a sample value, the timing at which the pulse signal takes a predetermined level near the eye width definition level within the pulse period, and the measured value of the predetermined level timing vs. frequency graph showing how often the pulse signal is distributed in the predetermined pulse period number. The predetermined level frequency distribution measurement value acquisition procedure to be acquired, and the measurement value of the predetermined level timing vs. frequency graph acquired in the predetermined level frequency distribution measurement value acquisition procedure or the measurement value of the predetermined level timing vs. frequency graph The error-corrected one is started from the above specified timing. Of the timing at which the pulse signal takes the predetermined level within the pulse period, the frequency distribution determination procedure for determining a timing vs. frequency graph showing an appropriate frequency distribution for the predetermined pulse period number, and the frequency distribution determination procedure. From the timing vs. frequency graph, an estimation procedure for estimating the distribution variation width of the timing vs. frequency graph when the predetermined pulse period number is increased to a larger number, and the distribution variation width estimated by the estimation procedure. And the distribution width of the timing vs. frequency graph, the eye width derivation procedure for obtaining the eye width when the predetermined pulse period number is increased to the larger number, and the eye width derivation procedure. An error rate guide for obtaining the error rate when the predetermined pulse period number is increased from the eye width to the larger number. A method of acquiring an error rate, which comprises: 2. The High of the pulse signal received.
The error rate acquisition method according to claim 1, further comprising a predetermined level determination procedure that sets the median between the level and the Low level to the predetermined level. 3. A measured value of a level vs. frequency graph showing how often the level of the received pulse signal at a specific timing within one pulse period is distributed as a sample value in the number of specific pulse periods. When peaks appear near the maximum sample value and the minimum sample value of the measured values of the level vs. frequency graph acquired by the specific timing frequency distribution measurement value acquisition procedure and the specific timing frequency distribution measurement value acquisition procedure And a level range determining procedure for setting a sample value having a peak value near the maximum sample value to the High level and a sample value having a peak value near the minimum sample value to the Low level. The error rate acquisition method according to claim 2, characterized in that 4. A level other than a seam indicating a level at which the level of the received pulse signal at a specific timing excluding the vicinity of the pulse seam within one pulse period is distributed as a sample value in a specific pulse period number. The maximum frequency of the measured value of the level vs. frequency graph other than the joint obtained by the procedure for acquiring the measured value of the specific timing frequency distribution other than the joint and the step of acquiring the measured value of the specific timing frequency distribution other than the joint that acquires the measured value of the level versus frequency graph The first level, which is a sample value, is obtained, and a function that is the smallest at the first level and increases as it moves away from the first level and approaches a constant value is multiplied by the level-frequency graph other than the joints. To obtain the second level, which is the sample value that takes the maximum value of the above-mentioned multiplication distribution, The higher one of the level and the second level is set to the High level,
3. The error rate acquisition method according to claim 2, further comprising a level range determination procedure in which the smaller one is the Low level. 5. A measured value of a total level vs. frequency graph showing how often the level of the received pulse signal taken through all the timings within one pulse period is distributed as a sample value at a specific number of pulse periods. To obtain the total timing frequency distribution measurement value acquisition procedure, and the maximum sample value of the measurement values of the above all level vs. frequency graph obtained in the above all timing frequency distribution measurement value acquisition procedure,
Alternatively, a sample value having a peak value near the maximum sample value is set to the High level, and a minimum sample value of the all level vs. frequency graph or a sample value having a peak value near the minimum sample value is set to the Low level. The error rate acquisition method according to claim 2, further comprising a range determination procedure. 6. A measured value of a total level vs. frequency graph showing how often the level of the received pulse signal taken throughout all the timings within one pulse period is distributed as a sample value at a specific number of pulse periods. To obtain the all-timing frequency distribution measurement value acquisition procedure, and to obtain all the first levels that are the sample values that take the maximum frequency of the measurement values of the all-level vs. frequency graph obtained in the all-timing frequency distribution measurement value acquisition procedure. , A total multiplication distribution is created by multiplying the above-mentioned all-level vs. frequency graph with a function that is the smallest at all the first levels and increases as the distance from the all first levels approaches a constant value. All the second levels, which are the sample values that take the maximum value, are obtained, and the larger one of the above all the first levels and the above all the second levels is set as the above High level, and Sai is the above Lo
The error rate acquisition method according to claim 2, further comprising: a level range determining procedure for setting the w level. 7. A measured value of a total level vs. frequency graph showing how often the level of the received pulse signal taken through all the timings within one pulse period is distributed as a sample value at a specific number of pulse periods. To obtain the total timing frequency distribution measurement value acquisition procedure, and a predetermined level determination procedure in which the average sample value of the measurement values of the all level vs. frequency graph obtained in the above all timing frequency distribution measurement value acquisition procedure is the predetermined level The error rate acquisition method according to claim 1, further comprising: 8. The timing at which the received pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is a sample value,
An arbitrary other level frequency distribution measurement value acquisition procedure for acquiring a measurement value for one or more respective specific levels in the other level timing vs. frequency graph showing how often the distribution is performed in the predetermined pulse period number. Including, in the frequency distribution determination procedure, the measurement value of the predetermined level timing versus frequency graph acquired in the predetermined level frequency distribution measurement value acquisition procedure, and the others acquired in the arbitrary other level frequency distribution measurement value acquisition procedure The error rate acquisition according to any one of claims 1 to 7, wherein the error correction is performed by synthesizing each measurement value of the level timing vs. frequency graph to determine the timing vs. frequency graph. Method. 9. In the frequency distribution determining procedure, the measured value of the predetermined level timing vs. frequency graph acquired in the predetermined level frequency distribution measured value acquisition procedure is centered on a sample value and at the center sample. Create a probability distribution function that is normally distributed by assigning a probability density to sample values within a predetermined range from each value, and for each of the above probability density functions, calculate the sum of the values obtained by multiplying the frequency of the sample values by the probability density. The error rate acquisition according to any one of claims 1 to 7, wherein the error correction is performed by setting a new frequency of the sample value at the center of the probability density function to determine the timing vs. frequency graph. Method. 10. The frequency at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is distributed as a sample value in the predetermined number of pulse periods. Including other arbitrary level frequency distribution measurement value acquisition procedure for acquiring measurement values for one or more specific levels of the other level timing vs. frequency graph, wherein in the frequency distribution determination procedure, the predetermined level frequency distribution measurement is performed. The measured value of the predetermined level timing vs. frequency graph acquired in the value acquisition procedure and each measured value of the other level timing vs. frequency graph acquired in the arbitrary other level frequency distribution measured value acquisition procedure are combined. For the created graph, the sample value is centered and the sample value within the predetermined range from the center sample value Create a probability distribution function that is normally distributed by assigning probability density to the pull value for each sample value, and add the sum of the values obtained by multiplying the frequency of the sample value by the probability density for each of the above probability density functions to the center of the above probability density function. The error rate acquisition method according to any one of claims 1 to 7, wherein the error correction is performed by setting a new frequency of the sample value to determine the timing-frequency graph. 11. A first approximation curve that approximates a first region, which is a region near the minimum sample value of the timing vs. frequency graph in the estimation procedure, and a region near the maximum sample value of the timing vs. frequency graph. A second approximation curve that approximates the second region is obtained, and in a region near the minimum sample value of the timing versus frequency graph when the predetermined pulse period number is increased from the first approximation curve to the larger number. In a region near the maximum sample value of the timing vs. frequency graph when the third approximate curve approximating a certain third region is obtained and the predetermined pulse period number is increased from the second approximate curve to the larger number. A fourth approximated curve approximating a certain fourth area is obtained, and based on the third approximated curve, from the minimum sample value of the first area to the minimum sample value of the third area. The sample value fluctuation amount of 1 is obtained, and the second sample value fluctuation amount from the maximum sample value of the second region to the maximum sample value of the fourth region is calculated based on the fourth approximation curve, and the first sample value fluctuation amount is calculated. 11. The error rate acquisition method according to claim 1, wherein the sum of the sample value variation and the second sample value variation is used as the distribution variation width. 12. In the estimation procedure, on the timing vs. frequency graph, from the minimum sample value of the timing vs. frequency graph to the side of the smallest sample value when the timing vs. frequency graph is separated into a predetermined number of peaks. Up to a sample value that takes a peak value or a sample value that takes a peak value that appears immediately after the first region in which the frequency increases monotonically for a time corresponding to a certain increase in sample value, 12. The error rate acquisition method according to claim 11, wherein the error rate is set to one area. 13. In the estimation procedure, from the sample value taking the value of the peak on the maximum sample value side when the timing vs. frequency graph is separated into a predetermined number of peaks on the timing vs. frequency graph, or From the sample value that takes the value of the peak that appears immediately before the last region where the frequency monotonically decreases continuously for a time corresponding to a certain increase in the sample value to the maximum sample value in the timing vs. frequency graph, The error rate acquisition method according to claim 11 or 12, wherein the error rate is set to two areas. 14. In the estimation procedure, when the timing vs. frequency graph is separated into the predetermined number of peaks, the sample value having the maximum frequency in the timing vs. frequency graph is the first timing or the first timing. A first multiplication distribution obtained by multiplying the timing vs. frequency graph by a first function that is small and increases as the distance from the first timing approaches the first constant value, and takes the maximum value of the first multiplication distribution. A second value is obtained by multiplying the first multiplication distribution by a second function, which has the smallest sample value at the second timing and the second timing, increases as it moves away from the second timing, and approaches the second constant value. The multiplication distribution, which is the smallest at the (k-1) th timing when k is a natural number of 3 or more,
1) It increases as it goes away from the timing and becomes the (k−
The (k-1) th function approaching the constant value of
2) The product obtained by multiplying the multiplication distribution is defined as the (k-1) th distribution, and the sample value taking the maximum value of the (k-1) th distribution is defined as the kth timing, and the predetermined number is 2 or more. A natural number N is sequentially obtained from the first timing to the Nth timing, and the obtained first timing to the Nth timing are obtained.
The error rate acquisition method according to claim 12, wherein each of the timings up to the timing is a sample value that takes a value of a peak to be separated. 15. In the above estimation procedure, a normal distribution function whose standard deviation is a first constant times the standard deviation of the timing vs. frequency graph centered on the first timing is used as the first distribution function. Of the standard deviation of the (k-2) th multiplication distribution with the standard deviation centered at the (k-1) th timing. The error rate acquisition method according to claim 14, wherein a normal distribution function that is a constant multiple of -1) is a function obtained by subtracting from the (k-1) th constant value. 16. The frequency at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing is distributed as a sample value in the predetermined pulse period number. Including the other level frequency distribution measurement value acquisition procedure for acquiring the measurement value of the other level timing vs. frequency graph, the other level timing vs frequency graph acquired in the other level frequency distribution measurement value acquisition procedure in the estimation procedure 16. The error rate acquisition method according to claim 14, wherein the number of peaks included in the other level timing vs. frequency graph is obtained based on the measurement value of, and the number of peaks is set to N. 17. In the above estimation procedure, a first probability density function that normally distributes the first approximation curve is obtained as a function that is a first coefficient multiple, and a second probability density that normally distributes the second approximation curve. 17. The error rate acquisition method according to claim 11, wherein the function is obtained as a function obtained by multiplying the function by a second coefficient. 18. In the above estimation procedure, δq / δt is defined from the frequency change δq for each sample value change step δt of the timing vs. frequency graph, and the differential function of the timing vs. frequency graph is obtained, and the differential function is obtained in the first region. t ₁ the sample value takes a value upward peak of the differential function in the corresponding area, the frequency of F ₁ of said timing versus frequency graph of the above sample values t _1, the sample values t ₁
As G ₁ a value of the derivative function, the standard deviation sigma ₁ F ₁ / G ₁ of the first probability density function, t ₁ + sigma ₁ centered mu ₁ of the first probability density function, said first The error rate acquisition method according to claim 17, wherein the coefficient l ₁ of ₁ is (2πe) ^0.5 × F ₁ ² / G ₁ . 19. In the estimation procedure, the timing
The sampling value change step δt of the graph
If the sample value change step δt is
The above timing pair is defined by defining δq / δt from the degree change δq.
Obtain the differential function of the frequency graph and sample the first region
Value t_mThe minimum sample value of the above timing vs. frequency graph
Is t (minimum), t (minimum) + δt × m (m is 0 or more)
Integer), sample value t _mAbove timing vs.
The frequency of the degree graph is f (t_m), Sample value t_mIn
The value of the differential function is g (t_m), J (t_m) = G
(T_m) / F (t_m), Σ_m ²= Δt / {j (t_{m + 1})
-J (t_m)}, The first probability density function
Standard deviation σ₁Σ_mThe average of_m= T_m+ Σ₁ ²×
g (t_m) / F (t_m), The first probability density
Degree function center μ₁Μ_mOf the first coefficient l
₁The sample value t_mAt f (t_m) / (First above
Sample value t of the probability density function_mValue)
An error rate acquisition method according to claim 17, wherein
Law. 20. In the estimation procedure, the timing
For each sample value change step δt
The frequency change δq is defined as δq / δt.
And the differential function of the graph
The value of the downward peak of the above differential function in the corresponding region
Sample value₂, The sample value t₂Above in Thailand
The frequency of the ming vs. frequency graph is F₂, The sample value t₂
The value of the above differential function at₂As the second probability density
Standard deviation σ of the degree function₂To -F₂/ G₂, The second probability above
Center of density function μ₂T₂−σ₂, The second coefficient l₂
Is-(2πe)^{0. Five}× F₂ ²/ G₂It is characterized by
20. The error message according to any one of claims 17 to 19.
How to get a ticket. 21. In the estimation procedure, the timing
The sampling value change step δt of the graph
If the sample value change step δt is
The above timing pair is defined by defining δq / δt from the degree change δq.
Obtain the differential function of the frequency graph and sample the second region
Value t_nThe maximum sample value of the above timing vs. frequency graph
Is t (maximum) and t (maximum) + δt × n (n is 0 or less)
Integer), sample value t _nAbove timing vs.
The frequency of the degree graph is f (t_n), Sample value t_mIn
The value of the differential function is g (t_n), J (t_n) = G
(T_n) / F (t_n), Σ_n ²= Δt / {j (t_{n + 1})
-J (t_n)}, The second probability density function
Standard deviation σ₂Σ_nThe average of_n= T_n+ Σ₂ ²×
g (t_n) / F (t_n), The second probability density
Degree function center μ₂Μ_nOf the second coefficient l
₂The sample value t_nAt f (t_n) / (Second above
Sample value t of the probability density function_nValue)
20. The method according to claim 17, wherein
Error rate acquisition method. 22. In the estimation procedure, the third approximation curve is obtained by multiplying the first approximation curve by a ratio of a scaling coefficient corresponding to the larger number to the predetermined pulse period number, and the second approximation curve is obtained. 22. The error rate acquisition method according to claim 11, wherein the fourth approximated curve is obtained by multiplying the approximated curve by the ratio. 23. The error rate acquisition method according to claim 22, wherein 1 / (error rate to be achieved) is used as the scaling factor in the estimation procedure. 24. In the estimation procedure, R _{m is} a ratio of the number of changes from a high level to a low level or a low level to a high level among the pulse joints having the predetermined number of pulse periods, and R _m is the total number of transmitted and received pulses. from the High level of the pulse joint to the Low level or the Low level ratio of the number of changes to High level as _{R d, R d / {R} m × ( error rate to be achieved)} and the scaling factor 23. The error rate acquisition method according to claim 22, wherein: 25. In the estimation procedure, R _{m is} the ratio of the number of changes from a high level to a low level or from a low level to a high level in the pulse connection of the predetermined number of pulse periods, R _m , of all transmitted and received pulses. R _worst / {R _m , where R _{d is} the ratio of the number of changes from the High level to the Low level or from the Low level to the High level among the pulse joints, and R _worst is the assumed _maximum value of the ratio R _d. The error rate acquisition method according to claim 22, wherein x (error rate to be achieved)} is used as the scaling coefficient. 26. In the estimation procedure, 1 / {R _m , where R _m is the ratio of the number of changes from High level to Low level or from Low level to High level among the pulse joints of the predetermined number of pulse periods. ×
23. The error rate acquisition method according to claim 22, wherein (error rate to be achieved)} is used as the scaling coefficient. 27. What frequency is distributed in the predetermined number of pulse periods as a sample value at which the pulse signal takes a specific level other than the predetermined level within one pulse period starting from the predetermined timing. Including the other level frequency distribution measurement value acquisition procedure for acquiring the measurement value of the other level timing vs. frequency graph representing the other level timing vs. frequency graph acquired in the other level frequency distribution measurement value acquisition procedure in the estimation procedure The number of peaks appearing in the other level timing vs. frequency graph based on the measured value of P _n , and the number of changes from the High level to the Low level or from the Low level to the High level among the pulse joints of the above-described predetermined pulse period. the proportion of the R _m, the the _{P n / {2 × R m} × ( error rate to be achieved)} Error rate acquisition method according to claim 22, characterized in that the multiplication factor. 28. In the above estimation procedure, the minimum sample value among the sample values of the third approximate curve having a frequency of 1 or more is set as the minimum sample value of the third region, and the fourth sample value is set.
The maximum sample value of the sample values having the frequency of the approximate curve of 1 or more is set as the maximum sample value of the fourth region, and in the eye width derivation procedure, the minimum sample value of the first region and the maximum sample of the second region. 28. The eye width is defined as a distribution width of the timing vs. frequency graph, and a value obtained by subtracting a sum of the distribution width and the distribution fluctuation width from one pulse period is defined as an eye width. The error rate acquisition method described in any of the above. 29. In the error rate deriving procedure, based on the eye width obtained in the eye width deriving procedure and the relationship between the eye width and the error rate obtained in advance,
The error rate acquisition method according to any one of claims 1 to 28, wherein the error rate is obtained when the number of the predetermined pulse periods is increased to the larger number. 30. A program for causing a computer to execute each procedure of the error rate acquisition method according to any one of claims 1 to 29. 31. A recording medium on which the program according to claim 30 is recorded so that it can be read by a computer.