JP3047267B2 - Waveform measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform measuring apparatus, and more particularly, to an improvement in the frequency display of a plurality of waveform data strings.

[0002]

2. Description of the Related Art When measuring a waveform with jitter,
It is desirable to display the appearance frequency of a plurality of waveform data strings including a jitter component.

Conventionally, two methods of color frequency display and histogram display have been put to practical use as such frequency display methods of a plurality of waveform data strings.

First, the color grade display is a method in which a plurality of waveform data strings are developed and displayed on a display, and displayed in different colors in order of appearance frequency. On the other hand, the histogram display is a method of displaying the distribution of the appearance frequency as a bar graph.

[0005]

However, the color grade display requires a color display, which increases the cost. On the other hand, although histogram display can be performed with an inexpensive single-tone display, an area for displaying a bar graph is required in addition to an area for displaying a waveform data string, and the form of the display screen is complicated. .

The present invention has been made in view of these problems, and has as its object to reduce the frequency of occurrence of a plurality of waveform data strings on a simple display screen using a single-tone display. An object of the present invention is to realize a waveform measuring device capable of performing display.

[0007]

SUMMARY OF THE INVENTION The present invention for solving such a problem is based on an A / D converter for sampling an input signal and converting it into a digital signal, and a digital signal converted by the A / D converter. a data memory for storing a data string, and a random number generator, the dots of randomly determining the position of a dot to be interpolated on the basis of the inter-adjacent data stored in the data memory to the random number applied from the random number generator <br /> The interpolating circuit and the complex interpolated at random dot positions
It is characterized by comprising a display device for displaying dots by superimposing a number of data strings , and a microprocessor for controlling these units.

[0008]

[Function] Random dot interpolation between adjacent data is performed.
The dot-interpolated display data is displayed on the display so as to be overwritten.

As a result, the appearance frequency distribution of the data string is displayed in the form of shades of dots.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes an A / D converter, which samples an input signal and converts it into a digital signal. The A / D
The digital signal converted by the converter 1 is stored in the data memory 2 as a data string. A random number generator 3 outputs a random number to the dot interpolation circuit 4. Reference numeral 5 denotes a display, which adds the appearance frequency distribution of the data string to the data string and displays it. 6
Is a microprocessor for controlling these components.

FIG. 2 is a flowchart showing the flow of the operation of FIG. First, the display 5 is initialized (step), and the process enters a first loop. Then, in the first loop, the input signal is A / D converted (step), and the conversion result is stored in the data memory 2 (step). Here, assuming that the number of data is n, d ₀ is stored in the data memory 2.
So that to d _n of the data is stored. Then the second
Enters a loop, dots interpolated by the data _{d i + 1} and the difference between the _{d i (d i + 1 -d} i) the random number (step). After the interpolation processing, the data string after the interpolation is transferred to the display 5 via the pool and displayed (step). The display 5 is overwritten each time. After that, the processing shifts to another processing via the pool.

The step processing will be further described.
Consider a data string as shown in FIG. In FIG. 3, “○ d
n "represents the data converted A / D," ● In "De
It shows dot-interpolated data at random positions between data.

In the data interpolation , the number of points to be complemented between d3 to d4 or d4 to d5 is determined according to the difference between the data (for example, d4 to d3 or d5 to d4). For example, when performing two-point interpolation between d3 and d4, d
Interpolation data I1 and I2 are generated based on random numbers so that 3 <I1 <I2 <d4.

Further, for example, _d 4 similarly when interpolating three points in between _{~d 5, d 4 <I 3} <I 4 <I 5 < interpolation to be _{d 5} data _{I 3,} I 4, _{I 5} Generate.

Here, the number of interpolated data according to the difference (dif) between the data is defined as follows, for example. dif ≦ 10: no interpolation 10 <dif ≦ 50: two-point interpolation 50 <dif ≦ 100: four-point interpolation 100 <dif: six-point interpolation These definitions can be determined as appropriate according to the characteristics of the data sequence, the performance of the system, and the like. I just need.

Next, how the appearance frequency distribution of waveform data can be expressed by such dot interpolation will be described. As a specific example, the sampled data sequence has a rising waveform, and there is no data in the rising portion.
FIGS. 4 to 8 show display examples in which a waveform having jitter is overwritten 1000 times.

FIG. 4 shows a display example when no interpolation is performed.
If linear interpolation is performed on such a display waveform, the display screen becomes filled as shown in FIG. However,
When the random dot interpolation according to the present invention is performed, it can be clearly seen that the appearance frequency is distributed at the center of the screen as shown in FIGS. FIG. 6 shows a case in which five points of random dot interpolation are performed when there is 200 dots between L level and H level data, and FIG. 7 shows 15 points of random dot interpolation when there are 200 dots between L level and H level data. FIG. 8 shows a case where random dot interpolation is performed, and FIG. 8 shows a case where 40 dot random dot interpolation is performed when the data between the L level and the H level is 200 dots.

In such a configuration, the display does not necessarily have to be a color display, and a display of a single gradation can be used, and it is not necessary to secure a special area for displaying the frequency. Therefore, it can be constructed relatively inexpensively, and the display form is simplified, so that it is easy to see.

The display may be color display or monochrome display, and there is no limitation as long as it displays dots such as CRT and EL.

[0020]

As described above in detail, according to the present invention, it is possible to realize a waveform measuring apparatus capable of visually expressing the distribution of the appearance frequency of a waveform together with the original waveform by randomly interpolating dots. This is effective for the measurement of various signals including.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of the operation of FIG.

FIG. 3 is a data string diagram for explaining the operation of the present invention.

FIG. 4 is a display example diagram without dot interpolation.

FIG. 5 is a display example when linear interpolation is performed.

FIG. 6 is a display example when five points are randomly interpolated between 200 dots.

FIG. 7 is a display example diagram when 15 points are randomly interpolated between 200 dots.

FIG. 8 is a display example in a case where 40 points are randomly interpolated between 200 dots.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 A / D converter 2 Data memory 3 Random number generator 4 Dot interpolation circuit 5 Display 6 Microprocessor

Claims (1)

(57) [Claims] An A / D converter for sampling an input signal and converting the digital signal into a digital signal; a data memory for storing the digital signal converted by the A / D converter as a data string; a random number generator; dots for interpolating based between adjacent data stored in the data memory to the random number applied from the <br/> random number generator
A dot interpolation circuit that randomly determines the position of the dot, and multiple data strings interpolated at random dot positions
A waveform measuring apparatus comprising: a display for displaying dots in a superimposed manner ; and a microprocessor for controlling each of these units.