JP3395880B2 - Jitter analyzer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jitter analyzer for measuring pulse width jitter of periodic signals, pulse signals, etc., and more particularly to a jitter analyzer capable of measuring jitter regardless of the type of input signal.

[0002]

2. Description of the Related Art A jitter meter has been used for jitter analysis of an optical disk drive such as a CD or a CD-ROM. A conventional jitter meter has a pulse width modulated EF.
It is to extract and measure a specific pulse width of an M (Eight-to-Fourteen Modulation) signal and display the jitter.

FIG. 14 is a block diagram showing an example of such a conventional jitter meter. In FIG. 14, 1 is an amplifier, 2 and 11 are low-pass filter circuits (hereinafter simply referred to as filter circuits), 3 is a window circuit, 4 is a comparator, 5, 6 and 7 are standard speed, double speed and 4 respectively.
Time-voltage converter for double speed input signal, 8 A / D converter, 9 data acquisition circuit, 10 D / A converter, 12 jitter conversion circuit, 13 display circuit, 100 EFM signal, etc. Input signal of.

The input signal 100 is input to the amplifier 1, and the output of the amplifier 1 is connected to the filter circuit 2 and the window circuit 3. The output of the filter circuit 2 is connected to the comparator 4, and the output of the comparator 4 is connected to the time-voltage converters 5, 6 and 7, respectively.

The outputs of the time-voltage converters 5, 6 and 7 are A /
It is connected to the D converter 8, and the output of the A / D converter 8 is connected to the data fetch circuit 9. The output of the window circuit 3 is connected to the control terminal of the data acquisition circuit 9.

The output of the data acquisition circuit 9 is the D / A converter 1
0, and the output of the D / A converter 10 is connected to the filter circuit 11.

The output of the filter circuit 11 is connected to the jitter conversion circuit 12, and the output of the jitter conversion circuit 12 is connected to the display circuit 13.

Here, the operation of the conventional example shown in FIG. 14 is shown in FIG.
This will be described using 5. FIG. 15 is a timing chart showing an example of the input signal 100, which is an example of the EFM signal from the CD-ROM drive.

In FIG. 15, "a", "b", "
“H”, “D”, “H”, “H”, “TO” and “H” are sampling clocks “T” of “3” and “T”, respectively.
The pulse signals are 5 "," 11 "," 4 "," 8 "," 3 "," 6 ", and" 4 "double widths.

As described above, the input signal 100 is such that pulse signals having a width of 3 to 11 times (hereinafter, abbreviated as 3T to 11T) are randomly distributed. Of these, the jitter of the 3T pulse signal is the largest, so the jitter of the 3T pulse signal is measured in the evaluation of the CD-ROM drive.

The input signal 100 is appropriately amplified by the amplifier 1, the high frequency component is removed by the filter circuit 2, and the comparator 4
Entered in. The comparator 4 binarizes the input signal and inputs it to the time-voltage converters 5, 6 and 7.

One of the time-voltage converters 5, 6 and 7 is selected based on the transfer rate of the input signal 100. For example, if the transfer rate is double speed, the time-voltage converter 6 is selected.

The time-voltage converter 6 converts the input pulse signal into a voltage value and inputs the voltage value into the A / D converter 8. The A / D converter 8 converts the voltage value into a digital signal.

The data fetch circuit 9 fetches the output of the A / D converter 8 based on the window width determined by the window circuit 3 and outputs it to the D / A converter 10.

The output of the D / A converter 10 is the filter circuit 1
1 is input to the jitter conversion circuit 12 and the output of the jitter conversion circuit 12 is displayed on the display circuit 13.

As a result, the jitter of the input signal 100 having the double transfer rate can be measured. Further, by properly selecting the time-voltage conversion circuits 5 and 7, it becomes possible to measure the jitter of the input signal having the transfer rate of the standard speed or the quadruple speed.

[0017]

However, in the conventional jitter meter, the above-mentioned time-voltage conversion circuit must be selected in accordance with the transfer rates such as standard speed, double speed and quadruple speed, in other words, the range must be changed. There was a problem that the measurement was troublesome.

At present, there are CD-ROM drives having transfer rates such as 10x speed and 12x speed, and in order to measure these, a time-voltage conversion circuit suitable for the transfer rate is added. It is necessary to modify the jitter meter.

In addition, in the future, 24x speed and DVD (Di
Gital Versatile Disc) is being developed, and there is a problem that it is difficult to use the conventional jitter meter in the future.

On the other hand, the current CD-ROM drive rotation system control method is the CLV control method (Constant Line Velocit).
y, constant linear velocity. ), Even if the pulse signal is taken out at an arbitrary point of the CD-ROM, the same double width, for example, 3T
Has a constant pulse width.

However, the Z-CLV control system (Zone
Constant Line Velocity, constant linear velocity for each zone. )
The CAV control method (Constant Angle Velocity, constant angular velocity) has been developed, and even if a pulse signal of the same width is taken out at any point of the CD-ROM, it will be scattered depending on the taking-out position, and in the conventional jitter meter. There is a problem that it is difficult to measure. Therefore, the problem to be solved by the present invention is to realize a jitter analyzer capable of measuring jitter irrespective of the transfer rate and the rotary system control method without the need for remodeling or range change of the device.

[0022]

In order to achieve such a object, according to a first aspect of the present invention, in a jitter analyzer for measuring jitter by measuring a time width of a pulse width modulated input signal, and time measurement circuit for measuring a time width of an input signal, and the acquisition memory for storing the output of the time measuring circuit as a histogram distribution, Pas
Probability distribution memory that stores the probability distribution for each pulse width, and the data obtained by scanning the contents of the acquisition memory.
The transfer rate is specified from the position of the
If it is within the range of the rate distribution, specify the pulse width,
Or, the probability distribution of the data and the probability distribution are the same
In this case, a control means for specifying the pulse width and calculating the jitter based on the data and displaying the jitter on the display means is provided.

In order to achieve such a subject, in the second aspect of the present invention, in the first aspect of the present invention, a scanning position memory storing scanning positions corresponding to a plurality of transfer rates is provided,
The contents of the acquisition memory are scanned based on the scanning position.

In order to achieve such a subject, in the third aspect of the present invention, the reference distribution storing the reference distribution data which is the pulse width set by the reference distribution setting means in the first and second aspects of the present invention. A memory is provided, and the contents of the acquisition memory are scanned based on the reference distribution data.

In order to achieve such a subject, in the fourth aspect of the present invention, the histogram distribution display means for displaying the histogram distribution scanned from the acquisition memory is provided in the first to third aspects of the present invention. It is characterized by.

In order to achieve such a subject, in the fifth aspect of the present invention, in the first to third aspects of the present invention, a reference distribution display means for displaying the reference distribution data stored in the reference distribution memory is provided. It is characterized by that.

In order to achieve such a subject, a sixth aspect of the present invention is characterized in that, in the first to third aspects of the present invention, a transfer rate display means for displaying the transfer rate is provided. is there.

In order to achieve such a subject, the seventh aspect of the present invention is characterized in that, in the first to third aspects of the present invention, the display means displays the jitter as a percentage regardless of the type of the input signal. To do.

In order to achieve such a subject, the eighth aspect of the present invention is characterized in that, in the first aspect of the present invention, the acquisition memory and the probability distribution memory are configured by one storage circuit. Is.

In order to achieve such a subject, in the ninth aspect of the present invention, in the second aspect of the present invention, the acquisition memory, the probability distribution memory and the scanning position memory are configured by one storage circuit. It is a feature.

In order to achieve such a subject, in the tenth aspect of the present invention, in the third aspect of the present invention, the acquisition memory, the probability distribution memory and the reference distribution memory are configured by one storage circuit. It is a feature.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the jitter analyzer according to the present invention.

In FIG. 1, 100 is assigned the same reference numeral as in FIG. 14, 14 is a time measuring circuit, 15 is an acquisition memory, 16 is a probability distribution memory, 17 is a data reading means, 18 is a read data memory, and 19 is a read data memory. Jitter calculation means,
Reference numeral 20 is a display means, 21 is a scanning position memory, 22 is a reference distribution memory, and 23 is an input means. Further, 17 to 19 form a control means 50.

The input signal 100 is input to the time measuring circuit 14, and the output of the time measuring circuit 14 is connected to the acquisition memory 15.

Input and output of the acquisition memory 15, the probability distribution memory 16, the read data memory 18, the scanning position memory 21 and the reference distribution memory 22 are connected to the data reading means 17.

The output of the read data memory 18 is connected to the jitter calculating means 19, and the output of the jitter calculating means 19 is connected to the display means 20. The output of the input means 23 is connected to the reference distribution memory 22.

The operation of the embodiment shown in FIG. 1 will now be described with reference to FIGS.
This will be described with reference to FIG. 2 to 4 are explanatory views showing a distribution state of data in the acquisition memory 15.

The time measuring circuit 14 uses the rising or falling edge of the input signal 100 as a trigger to measure the pulse width and the time difference between the two signals.

The measured data are sequentially stored in the acquisition memory 15. However, acquisition memory 1
In 5, the measurement data itself is not stored, but the histogram distribution shape of the measurement data is stored.

That is, the time measuring circuit 14 stores data as a frequency in the address or the like of the acquisition memory 15 corresponding to the measured data value.

For example, if the measured pulse width is "694n"
In the case of "s", "694 in the acquisition memory 15"
The frequency of the memory area corresponding to "ns" is incremented by "+1".

As a result, the histogram distributions as shown in FIGS. 2 to 4, for example, are stored in the acquisition memory 15.

FIGS. 2, 3 and 4 show histogram distributions stored in the acquisition memory 15 when the EFM signals of the standard speed, 2 × speed and 6 × speed CD-ROM drives are measured. Represents the frequency and the horizontal axis represents the measured pulse width.

Further, in FIG. 2, "a" to "li" are respectively "
The distribution state of the pulse signals of 3T "to" 11T "is shown. Here," T "indicates the sampling clock inside the CD-ROM drive, and this sampling clock is proportional to the data transfer rate.

The data reading means 17 reads the data from the probability distribution memory 16, the scanning position memory 21 and the reference distribution memory 22, and the data reading means 17 reads the data from the acquisition memory 15 on the basis of these data and the like to read the data. It is stored in the memory 18.

Then, the jitter calculating means 19 calculates the jitter based on the data stored in the read data memory 18 and displays it on the display means 20.

The jitter (standard deviation) "σ" is "n" for the number of histogram bins in the read data memory 18, "Pi" for the i-th relative frequency, "Xi" for the i-th measured value, and "average" for the average value. In the case of Ave ″, σ = {Σ (Xi-Ave) ² × Pi / n} ^1/2 (1) is calculated. However, “Σ” means addition from “i = 1” to “n”.

Further, the operation of the embodiment will be more specifically shown in FIG.
~ It demonstrates using FIG. FIG. 5 is a plan view showing a specific example of the surface panel of the jitter analyzer, and FIGS. 6, 7, 8 and 9 show the contents of the probability distribution memory 16, scanning position memory 21, read data memory 18 and reference distribution memory 22. FIG. 10 is a flow chart for explaining the operation of the embodiment,
FIG. 11 is an explanatory diagram for explaining the data reading method.

In FIG. 5, 24 is a measurement function display means, 25 is a reference distribution display means, 26 is a transfer rate display means, 27 is a histogram distribution display means, 28 is a measurement function selection means, 29 is a reference distribution selection means, 3
Reference numeral 0 is a jitter display means, 31 and 32 are input terminals, and 33 is a CD-ROM drive to be measured.

The EFM signal and the sampling clock signal from the CD-ROM drive 33 are input to the input terminals 31 and 32 of the jitter analyzer.

As shown in FIG. 10A, the user first sets the reference distribution data by the reference distribution selecting means 29. Specifically, how many times wider than the sampling clock “T” the pulse signal is measured is selected.

By this selecting operation, the reference distribution data is stored in the reference distribution memory 22. For example, if a pulse signal having a triple width of the sampling clock is selected, "3T" is stored as shown in FIG.

At this time, as shown in FIG. 5, the reference distribution display means 25 displays the "3T" portion in reverse video. Specifically, every time the reference distribution selecting means 29 is operated, the inverted display portion of the reference distribution displaying means 25 shifts to the right or left.

As shown in FIG. 10B, the jitter analyzer starts measuring the input signal. For example, input signal 10
0 means that the transfer rate is "6x speed" and "100000"
It is assumed that the "point" is measured and the jitter of the "3T" pulse signal is measured.

As shown in FIG. 10C, the data reading means 17 reads the contents of the reference distribution memory 22 and the scanning position memory 21. Then, it is determined whether or not the scanning position remains in the acquisition memory 15.

If the scanning position remains, then FIG.
As shown in (d), the acquisition memory 15 is scanned based on the contents of the reference distribution memory 22 and the scanning position memory 21.

In this case, as described above, the reference distribution memory 22
Since "3T" is stored in, the data of the operation start point is read from the scanning position memory 21 based on "3T".

Data as shown in FIG. 7 is stored in the scanning position memory 21, and "3T" shown in "A" in FIG. 7 is stored.
Are sequentially scanned from "24x speed".

Specifically, "28.92 ns" and "shown in" B "in FIG. 7 corresponding to" 24 times speed "in the row of" 3T ".
Sampling clock at 24x speed "in Fig. 7"
“T = 9.641 ns” shown in “C” is read out, and the range of 28.92 ± 9.641 / 2 (ns) (2) is scanned from the acquisition memory 15.

Then, as shown in FIG. 10E, it is determined whether or not data exists in the scanning range.

If the data does not exist, FIG.
Return to (c) and FIG. 10 (d) to find data,
Alternatively, the scanning range is sequentially scanned until there is no scanning position in the acquisition memory 15.

In this case, since the transfer rate is "6x speed", "24x speed" in the row of "3T" shown in "a" in FIG.
Since there is no data in the position corresponding to, "3T"
The sequential scanning is repeated until the line becomes "6x speed",
Data is obtained by scanning within the scanning range of 115.7 ± 38.56 / 2 (ns) ”.

Then, as shown in FIGS. 10F and 10G, the scanned data is compared with the data in the probability distribution memory 16 to judge the validity of the scanned data.

The content of the probability distribution memory 16 is "a" in FIG.
As shown in, the probability distribution of "3T" is "31.46% ~
Since it is 38.46% ", it is judged whether or not" (total number of scanned data) / (total number of measurement points) "falls within the above range.

In this case, the total number of measurement points is "10000."
Since it is “0”, the total number of scanned data is “3146”.
It is judged to be appropriate if it is within the range of 0 to 38460 ", that is," 3 "of the transfer rate" 6x speed ".
This means that the histogram distribution of the pulse signal of T ″ is obtained.

Therefore, as shown in FIG. 10 (h), the data reading means 17 reads the scanned data into the read data memory 18
Write in.

Further, as shown in (i) and (j) of FIG. 10, the jitter calculating means 19 reads the data from the read data memory 18 to calculate the jitter, calculates the percentage of the jitter, and displays the jitter on the display means 20. indicate.

In this case, the transfer rate "6x speed"
Since the histogram distribution of the pulse signal of 3T "has been obtained," x6 "of the transfer rate display means 26 is reversely displayed to indicate that it is" 6x speed ".

The histogram distribution stored in the read data memory 18 is displayed by the histogram distribution display means 27 using a liquid crystal panel (hereinafter referred to as LCD panel) or the like.

Further, regardless of the type of the input signal 100, the jitter is displayed by the jitter display means 30 such as an analog meter. Specifically, the jitter display means 30 displays the percentage obtained by dividing the jitter by the sampling clock.

For example, if the jitter is "2.384 ns", the percentage "0.91%" divided by "38.56 ns" which is the sampling clock of the transfer rate "6 times speed" is displayed.

As a result, the acquisition memory 15 is scanned on the basis of the data from the scanning position memory 21 and the reference distribution memory 22, and the validity of the scanned data is judged using the probability distribution memory 16. Jitter can be measured regardless of transfer rate without changing the range.

However, when measuring a "3T" pulse signal with a transfer rate of "6x speed", the "3T" row of the scanning position memory 21 shown in "a" in FIG. If scanning is performed, data collision does not occur, but in the following cases, a data collision problem occurs.

That is, "8T" of transfer rate "12 times speed"
In the case of measuring the pulse signal of, the row of "8T" of the scanning position memory 21 shown in "F" in FIG. 7 is sequentially scanned from "24 times speed".

The scanning position in this case is "77.13 ns" shown in "T" in FIG. 7, which is the transfer rate "1".
This coincides with the scanning position of the pulse signal of "4T" of double speed.

Therefore, in FIG. 10 (e), the data is detected by the time it reaches the "12x speed" of the "8T" row of the scanning position memory 21.

In this case, as shown in FIG. 11, the data reading means 17 exceeds the normal scanning range "77.13 ± 9.641 / 2 (ns)" indicated by "a" in FIG. The data in the range shown by "B" and "C" in FIG. 11 are scanned until the PP point (both ends of the hem of the normal distribution) is found.

As described above, when all the histogram distributions are scanned, the probability distribution thereof coincides with the pulse signal of "4T". Therefore, in FIG. 10G, it is determined that the data is unsuitable, and the scanning of the next scanning range is performed. Will move.

As a result, the scanning range "77.1" is obtained.
Even if the probability distribution of the data of 3 ± 9.641 / 2 (ns) coincides with the probability distribution of the pulse signal of “8T”, it is erroneously recognized as the pulse signal of “8T” of the transfer rate “24 times speed”. Can be prevented.

FIG. 12 shows a histogram distribution when the time difference between the EFM signal of the double speed CD-ROM drive and the sampling clock is measured.

This measurement is "Data-to-Cloc".
This is called "k" measurement and all the jitter components of "3T" to "11T" are distributed around the time value proportional to the sampling clock. Due to the high speed and high density, it is not possible to measure the jitter of "3T" only. It is useful for measuring DVDs which are said to be sufficient.

Such a "Data-to-Cloc"
Also in the case of performing k "measurement, the time value of the sampling clock can be easily obtained by using the value of" T "of each transfer rate of the scanning position memory 21 shown by" LI "in FIG.

Therefore, by scanning the acquisition memory 15 with this time value as the scanning position, it becomes possible to recognize the transfer rate of the drive and measure the jitter.

FIG. 13 shows the CD-R of the CAV control method.
It is a histogram distribution for one track of the EFM signal of the OM drive.

In this case, the scanning position cannot be specified from the scanning position memory 21, but the probability distribution in the probability distribution memory 16 is the same for one track. Therefore, in FIG.
By comparing the probability distributions of the histogram distributions shown in “a”, “b”, “c”, etc. with the probability distributions in the probability distribution memory 16, it is possible to specify what T each histogram is and obtain the jitter. .

In this case, since the scanning position varies depending on the selected track position, it is sufficient to sequentially scan from the beginning of the acquisition memory 15. This gives, for example,
It is possible to determine whether the distribution indicated by "B" in FIG. 13 is a normal distribution or noise.

As a result, by comparing the probability distribution of the histogram distribution with the probability distribution in the probability distribution memory 16, the jitter can be measured regardless of the rotary system control method.

Although the contents of the scanning position memory 21 and the reference distribution memory 22 are used in the description of the embodiment, the histogram distribution obtained by scanning the acquisition memory 15 is validated based on the data in the probability distribution memory 16. Jitter can be measured by determining the property.

Further, even if the contents of the reference distribution memory 22 are not used, the acquisition memory 15 is scanned based on all the contents of the scanning position memory 21, and the obtained histogram distribution is validated based on the data in the probability distribution memory 16. It is also possible to measure the jitter by judging the property.

Further, although the scanning position memory 21 sequentially scans from the one having the highest transfer rate, it may scan from the one having the slowest transfer rate.

However, if scanning is performed from the slowest transfer rate, the initial scanning range is wide and it takes a long scanning time, or the above-mentioned data collision easily occurs and the processing time becomes long to judge its validity. I will end up.

Further, in the description of FIG. 1, the data reading means 17 and the jitter calculating means 19 are shown separately for simplification of description, but in reality, they are realized by an internal program of the control circuit 50. is there.

The read data memory 18 need not be separately provided if the storage circuit in the control means 50 is used.

Similarly, although the acquisition memory 15, the probability distribution memory 16, the scanning position memory 21, and the reference distribution memory 22 are shown separately, they may be configured by one storage circuit, or they may be combined appropriately and integrated. It doesn't matter.

Although the LCD panel is illustrated as the histogram distribution display means 27 in FIG. 5, the histogram distribution display means 27 is not limited to the LCD panel, but may be a CRT (Cathode Ray Tube) or an LED.
Any display means capable of displaying a histogram such as (Light Emitting Diode) may be used.

Further, in FIG. 5, the jitter value display means 30
Although an analog meter is exemplified as the above, the present invention is not limited to the analog meter, and any device capable of displaying a jitter value such as a CRT, LCD, or LED may be used.

In the description of the embodiments, the CD-ROM drive is exemplified, but DVD, MD (Magnetic Disk)
k), MO (Magnet-Optical Disc) and hard disk jitter can also be measured.

If the data in the scanning position memory 21 does not apply, the CAV control method may be used.

Since the transfer rate need not be recognized every time, it may be recognized only at the first measurement. further,
A switching unit that determines whether or not to automatically recognize the transfer rate may be provided.

[0100]

As is apparent from the above description,
The present invention has the following effects. The acquisition memory is scanned based on the data from the scanning position memory and the reference distribution memory, and the validity of the scanned data is judged using the probability distribution memory. A jitter analyzer capable of measuring jitter can be realized.

Further, by comparing the probability distribution of the histogram distribution with the probability distribution in the probability distribution memory, it is possible to realize a jitter analyzer capable of measuring jitter regardless of the rotary system control method.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a jitter analyzer according to the present invention.

FIG. 2 is an explanatory diagram showing a distribution state of data in an acquisition memory.

FIG. 3 is an explanatory diagram showing a distribution state of data in an acquisition memory.

FIG. 4 is an explanatory diagram showing a distribution state of data in an acquisition memory.

FIG. 5 is a plan view showing a specific example of a front panel of a jitter analyzer.

FIG. 6 is an explanatory diagram showing the contents of a probability distribution memory.

FIG. 7 is an explanatory diagram showing the contents of a scanning position memory.

FIG. 8 is an explanatory diagram showing the contents of a read data memory.

FIG. 9 is an explanatory diagram showing the contents of a reference distribution memory.

FIG. 10 is a flowchart illustrating the operation of the embodiment.

FIG. 11 is an explanatory diagram illustrating a data reading method.

FIG. 12 is a histogram distribution when the time difference between the EFM signal of the double speed CD-ROM drive and the sampling clock is measured.

FIG. 13E of a CD-ROM drive of CAV control method
It is a histogram distribution for one round of the FM signal.

FIG. 14 is a configuration block diagram showing an example of a conventional jitter meter.

FIG. 15 is a timing chart showing an example of an input signal.

[Explanation of symbols]

1 amplifier 2,11 Low-pass filter circuit 3 window circuit 4 comparator 5, 6, 7 hours voltage converter 8 A / D converter 9 Data acquisition circuit 10 D / A converter 12 Jitter conversion circuit 13 Display circuit 14 hour measuring circuit 15 acquisition memory 16 Probability distribution memory 17 Data reading means 18 Read data memory 19 Jitter calculation means 20 Display means 21 Scan position memory 22 Reference distribution memory 23 Input means 24 Measurement function display means 25 Reference distribution display means 26 Transfer rate display means 27 Histogram distribution display means 28 Measurement function selection means 29 Reference distribution selection means 30 Jitter display means 31, 32 input terminals 33 CD-ROM drive 50 control means 100 input signal

Claims (10)

(57) [Claims] 1. A jitter analyzer for measuring jitter by measuring the time width of a pulse width modulated input signal, comprising: a time measuring circuit for measuring the time width of the input signal; and a histogram of the output of the time measuring circuit. An acquisition memory that stores the distribution, a probability distribution memory that stores a probability distribution for each pulse width , and a data obtained by scanning the contents of the acquisition memory.
The transfer rate is specified from the position of the data
If the pulse width is specified when it is within the range of the probability distribution,
Or the probability distribution of the data and the probability distribution
In the same case, a jitter analyzer is provided, which has a control means for specifying a pulse width and calculating a jitter on the basis of the data to display on a display means. 2. A scan position memory storing scan positions corresponding to a plurality of transfer rates, wherein the contents of the acquisition memory are scanned based on the scan position. Jitter analyzer. 3. A pulse set by the reference distribution setting means.
The jitter analyzer according to claim 1 or 2, further comprising: a reference distribution memory that stores reference distribution data that is a width, and the content of the acquisition memory is scanned based on the reference distribution data. 4. The jitter analyzer according to claim 1, further comprising a histogram distribution display means for displaying a histogram distribution scanned from the acquisition memory. 5. The jitter analyzer according to claim 1, further comprising reference distribution display means for displaying reference distribution data stored in the reference distribution memory. 6. The method according to claim 1, further comprising transfer rate display means for displaying the transfer rate.
To the jitter analyzer according to claim 3. 7. The jitter analyzer according to claim 1, wherein the display means displays the jitter as a percentage regardless of the type of the input signal. 8. The jitter analyzer according to claim 1, wherein the acquisition memory and the probability distribution memory are configured by a single storage circuit. 9. The jitter analyzer according to claim 2, wherein the acquisition memory, the probability distribution memory, and the scanning position memory are constituted by one storage circuit. 10. The jitter analyzer according to claim 3, wherein the acquisition memory, the probability distribution memory, and the reference distribution memory are configured by one storage circuit.