JP2000295298A - Automatic eye numerical aperture measuring method and its instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically measure the numerical aperture of an eye pattern by obtaining a maximum value and a minimum value from whole waveform data amplitude level values, obtaining whole times when the amplitude level value becomes the same as a desired comparison level value within the range from the maximum value to the min. value, obtaining the minimum value and the maximum value from the whole times and obtaining an eye numerical aperture. SOLUTION: The maximum value and the minimum value are obtained from the whole waveform data amplitude level values stored in a storage device 30. The desired comparison level value within the range from the maximum one to the min. one is made to be Y1 and a comparison level Y1 is obtained by Y1=(a+b)/2 as the average value of the maximum value (a) and the minimum value (b). The whole waveform data amplitude level values stored in the storage device 30 are retrieved and whole time data are obtained, when the amplitude level value becomes the same as the comparison level value Y1. The min. value T1 and the minimum value T4 are obtained from the whole time data, a comparison time T is obtained within the range and, then, the eye numerical aperture is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for automatically measuring an eye opening ratio of an eye pattern, which is one of the methods for evaluating waveform quality of a digital signal waveform.

[0002]

2. Description of the Related Art There has not been a method and an apparatus for automatically measuring an eye opening ratio of an eye pattern, which is one of the methods for evaluating the waveform quality of a digital signal waveform. Therefore, an example of measurement by eye measurement in the related art will be described with reference to FIG.

First, an eye opening ratio of an eye pattern will be described. Synchronizing the digital signal waveform and displaying the eye pattern with the X axis as time and the Y axis as amplitude,
It can be observed as eye distortion. And the eye opening ratio is
It can be expressed by an eye opening ratio (amplitude) and an eye opening ratio (time).

The eye opening ratio (amplitude) is expressed by the following equation (1), where A is the maximum amplitude and B is the minimum amplitude. Eye opening ratio (amplitude) = 2B / (A + B) (1)

The eye opening ratio (time) is expressed by the following equation (2), where C is the maximum spread of the zero-crossing time width and D is the minimum. Here, the zero cross refers to a cross between the time axis (X axis) and the waveform in the average amplitude of the observed waveform. Eye opening ratio (time) = 2D / (C + D) (2)

Next, a conventional method for visually measuring the eye opening ratio of an eye pattern will be described. Conventionally, using an oscilloscope or the like, an eye pattern as shown in FIG. 3 is observed by synchronizing a digital signal waveform with time on the X axis and amplitude on the Y axis. And A of the maximum amplitude, B of the minimum amplitude
And the maximum C and the minimum D of the spread of the zero-crossing time width are visually determined. Furthermore, aperture ratio (amplitude)
Is given by the above equation (1), and the aperture ratio (time) is given by the above equation (2)
, Respectively, to calculate and obtain.

[0007]

As described above, the conventional method of measuring the eye opening ratio of an eye pattern is performed visually and obtained by calculation.
Measurement results tend to vary from person to person. The present invention has been made in view of such a problem, and an object of the present invention is to provide a method and an apparatus for automatically measuring an eye opening ratio of an eye pattern.

[0008]

That is, a first aspect of the present invention, which has been made to achieve the above object, is to provide a method for automatically measuring an eye opening ratio of an eye pattern. Find a value a and a minimum value b,
Within the range between the maximum value a and the minimum value b, the desired comparison level value is set to Y1, the amplitude level values of all the waveform data are searched, and the time when the amplitude level value becomes the same as the comparison level value Y1 All data are obtained, a minimum value T1 and a maximum value T4 are obtained from the total time data, and a desired comparison time within a range between the minimum value T1 and the maximum value T4 is defined as T. The maximum time smaller than the comparison time T is T2.
And the minimum time longer than the comparison time T is T3, and the eye opening ratio (time) is obtained from the following equation. Eye opening ratio (time) = 2 × (T3-T2) / ((T4-T
1) + (T3-T2)) From all the waveform data, an amplitude level value is searched in a time range larger than T2 and smaller than T3, the maximum value of the amplitude level value is set to L4, the minimum value is set to L1, and the maximum value is set to L1. Within the range between the value L4 and the minimum value L1, the desired comparison level value is set to Y2, and T
In a desired time range smaller than 3, the amplitude level value is searched, and the maximum level value smaller than the comparison level value Y2 and the maximum level value is set as L2, the amplitude level value larger than the comparison level value Y2 and the minimum is set as L3, The ratio (amplitude) is obtained from the following equation, and the eye opening ratio (amplitude) = 2 × (L3−L2) / ((L4−L
1) + (L3-L2)) The eye opening ratio automatic measuring method for obtaining the eye opening ratio by the above method is the gist.

A second aspect of the present invention, which has been made to achieve the above object, is to receive a trigger signal synchronized with an input signal and start outputting a sample clock, and a timing generator using the sample clock. An AD converter that converts an input signal waveform into a digital signal, a storage device that stores the amplitude level value of the digitalized input signal waveform and the time of the level value, and calculates the waveform data stored in the storage device And a processing unit for performing the processing, and the gist of the automatic eye opening ratio measuring apparatus for automatically measuring the eye opening ratio.

Further, a third aspect of the present invention, which has been made to achieve the above object, is a gist of an automatic eye opening ratio measuring apparatus according to the second aspect of the present invention, which performs measurement by the method according to the first aspect of the present invention.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in the following examples.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. First, the configuration and operation of the automatic eye opening ratio measuring apparatus of the present invention will be described. As shown in FIG. 1, the automatic eye opening ratio measuring apparatus of the present invention
It comprises a generator 10, an AD converter 20, a storage device 30, and a processing unit 40. The storage device 3
0 and the processing unit 40 may be integrally configured as the CPU 50.

The timing generator 10 receives a trigger signal synchronized with an input signal and
Start output of sample clock.

The AD converter 20 converts an input signal waveform into a digital signal using a sample clock of the timing generator 10. Also, the AD converter 20
Uses a high-speed AD converter that can sufficiently sample the input signal waveform.

The storage device 30 stores a start time (T0) as a plurality of waveform data of a digitally converted input waveform.
And the amplitude level value for that sample time. Further, the storage device 30 needs a memory capacity capable of storing at least a plurality of waveform data capable of forming an eye pattern.

The processing section 40 performs arithmetic processing on a plurality of waveform data stored in the storage device 30.

Next, a method of automatically measuring the eye opening ratio from a plurality of waveform data that can form a stored eye pattern will be described below with reference to FIG. First, the comparison time T of the eye pattern is obtained in steps (1) to (3).

(1) A maximum value a and a minimum value b are obtained from the amplitude level values of all the waveform data stored in the storage device 30. Within the range between the maximum value a and the minimum value b, a desired comparison level value is set to Y1. For example, the comparison level value Y1
Is determined from the following equation as the average value of the maximum value a and the minimum value b (the center point of the amplitude of the eye pattern). Y1 = (a + b) / 2

(2) The amplitude level values of all the waveform data stored in the storage device 30 are searched, and the time data (t1, t2, t3,...) When the amplitude level value becomes the same as Y1 is obtained.
・ ・) All time data (t1, t2,
t3,...), a minimum value T1 and a maximum value T4 are obtained.

(3) Let T be a desired comparison time within the range between the minimum value T1 and the maximum value T4. For example, the comparison time T
Is obtained from the following equation as an average value of the minimum value T1 and the maximum value T4 (the time center point of the eye pattern). T = (T1 + T4) / 2

(4) All time data (t1, t2, t3,
..), T2 is the time that is shorter and longer than the comparison time T, and T3 is the time that is longer and shorter than the comparison time T.

(5) The eye opening ratio (time) is obtained from the following equation. Eye opening ratio (time) = 2 × (T3-T2) / ((T4-T
1) + (T3-T2))

(6) From all the waveform data stored in the storage device 30, an amplitude level value is searched in a desired time range larger than T2 and smaller than T3, the maximum value of the amplitude level value is set to L4, and the minimum value is set to L4. Let the value be L1. Within the range between the maximum value L4 and the minimum value L1, a desired comparison level value is set to Y2. For example, the comparison level value Y2 is obtained from the following equation as an average value (the center point of the amplitude of the eye pattern). Y2 = (L1 + L4) / 2

(7) From all the waveform data stored in the storage device 30, an amplitude level value is searched in a time range larger than T2 and smaller than T3, and the comparison level value Y is searched.
The maximum level value smaller than 2 is L2, and the amplitude level value larger than the comparison level value Y2 and minimum is L3.

(8) The eye opening ratio (amplitude) is obtained from the following equation. Eye opening ratio (amplitude) = 2 × (L3-L2) / ((L4-L
1) + (L3-L2))

By automatically performing the above calculations, the eye opening ratio (time) and the eye opening ratio (amplitude) can be automatically measured.

[0027]

The present invention is embodied in the form described above and has the following effects. That is,
Since the eye opening ratio of the eye pattern can be automatically measured, the quality of the signal waveform can be inspected in a short time, and the data can be easily displayed, processed, and stored.

[Brief description of the drawings]

FIG. 1 is a block diagram of an automatic eye opening ratio measuring device of the present invention.

FIG. 2 is a waveform diagram illustrating a method of automatic eye opening ratio measurement according to the present invention.

FIG. 3 is an explanatory diagram of an eye opening ratio.

[Explanation of symbols]

 Reference Signs List 10 timing generator 20 AD converter 30 storage device 40 processing unit 50 CPU

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G036 AA28 BA13 CA01 5K004 AA01 BB04 5K029 KK25

Claims (3)

[Claims] In a method for automatically measuring an eye opening ratio of an eye pattern, a maximum value a and a minimum value b are obtained from amplitude level values of all waveform data, and a range between the maximum value a and the minimum value b is determined. Then, the desired comparison level value is set to Y1, the amplitude level values of all the waveform data are searched, and all the time data when the amplitude level value becomes the same as the comparison level value Y1 are obtained. , A desired comparison time within the range between the minimum value T1 and the maximum value T4 is defined as T, and a time smaller than the comparison time T and the maximum time is defined as T2 in the entire time data. And the minimum time longer than the comparison time T is T3, and the eye opening ratio (time) is obtained from the following equation. Eye opening ratio (time) = 2 × (T3-T2) / ((T4-T
1) + (T3-T2)) From all the waveform data, an amplitude level value is searched in a time range larger than T2 and smaller than T3, the maximum value of the amplitude level value is set to L4, the minimum value is set to L1, and the maximum value is set to L1. Within a range between the value L4 and the minimum value L1, a desired comparison level value is set to Y2. From all the waveform data, an amplitude level value is searched in a desired time range larger than T2 and smaller than T3.
The maximum and lower level value than the comparison level value Y2 is L2
, And the minimum amplitude level value larger than the comparison level value Y2 is L3, and the eye opening ratio (amplitude) is obtained from the following equation. Eye opening ratio (amplitude) = 2 × (L3−L2) / ((L4−L
1) + (L3-L2)) An automatic eye opening ratio measuring method for obtaining the eye opening ratio by the above method. 2. A timing generator for starting output of a sample clock in response to a trigger signal synchronized with an input signal, an AD converter for converting an input signal waveform into a digital signal by the sample clock, and a digital signal The amplitude level value of the converted input signal waveform,
An automatic eye-opening-ratio measuring device for automatically measuring an eye opening ratio, comprising: a storage device for storing the time of the level value; and a processing unit for performing arithmetic processing on the waveform data stored in the storage device. 3. The automatic eye opening ratio measuring apparatus according to claim 2, wherein the measurement is performed by the method according to claim 1.