JP3084729B2 - Digital oscilloscope - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital oscilloscope, and more particularly, to increasing the density of waveform display information.

<Conventional technology> There has been a digital oscilloscope. In this digital oscilloscope, an analog input signal is sampled under the control of a sampling clock and converted into a digital signal, and the digital output is stored and stored in a waveform memory as a continuous series of waveform information. The contents of the waveform memory are read out and processed in synchronization, and are displayed as one waveform on a display screen in which the horizontal axis is the time axis and the vertical axis is the waveform size.

<Problems to be solved by the invention> By the way, in such a conventional digital oscilloscope, when data converted into digital data by an analog / digital converter (hereinafter referred to as an AD converter) is displayed on a screen, the number of data points is It was limited to 500 or 2000 points. Therefore, when the length (capacity) of the waveform memory for storing the waveform data is longer, for example, when one continuous waveform data is stored in a memory having a capacity of 100 kilowords, a waveform having a length of 100 kilowords is displayed on the display. In order to display the data, it is necessary to perform a thinning process, so that the Nyquist frequency is reduced by the thinning, and there is a problem in that the waveform data originally stored in the waveform memory is displayed as a partially missing waveform.

On the other hand, in the case of an analog oscilloscope, such a problem does not occur. This is because, even on the same time axis as above, it is possible to display a waveform of information of almost the entire band including information that is detailed in a change in luminance.

The object of the present invention has been made in view of such a point, and when the number of data points of the waveform data is larger than the number of display data points, all information can be displayed on a limited number of display screens. It is to provide a digital oscilloscope.

<Means for Solving the Problems> In order to achieve the above object, the present invention converts an analog signal waveform into a digital signal using an AD converter, stores the digital signal in a waveform memory, and then displays the contents of the waveform memory on a screen using a waveform processor. In a digital oscilloscope, which is converted into an image and displayed on a display screen of a display device, a plurality of memories for storing data converted into a screen image, wherein each memory has a one-to-one dot on a display screen. A plurality of display memories corresponding to each other and weighted with luminance for each memory, wherein the waveform processor includes a plurality of display memories each having a larger number of waveform data points than the number of display data points on the display screen. Are divided into groups, and the data value and the number of waveform occurrence frequencies are calculated for each group. The display device is configured to have a function of sorting and storing the data in the display memory, and the display device is configured to be capable of gradation display. It is characterized in that it can be simultaneously displayed on a display screen.

<Operation> In the present invention, the display memory is composed of a plurality of memories, each of which corresponds to a dot (pixel) on the display screen in a one-to-one manner and is weighted with luminance.

In addition, when the number of data points of the waveform data is larger than the number of display pixels, the waveform processor divides the waveform data into a predetermined number and divides the waveform data into groups. Is converted to display image data in such a form that the frequency of occurrence corresponds to the luminance, and stored in the display memory.

The display device combines the data of the display memory together with the weighting of the luminance and displays the gradation on the display screen.

Thus, all information of the data stored in the waveform memory can be displayed on the display screen having a limited number of points (the number of pixels of the display screen).

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of a digital oscilloscope according to the present invention.

In the figure, 1 is an AD converter for converting an analog input signal into a digital signal based on a predetermined sample clock, and 2 is an AD converter.
A waveform memory 3 for storing output data of the converter 1 is a waveform processor, and a microprocessor or the like is used.

Reference numeral 4 denotes a display memory, which includes a plurality of memories of the same configuration having addresses corresponding to pixels (dots) of the display screen on a one-to-one basis, and stores only waveform data (dot data) in the memory. This is a memory that cannot store dot data and luminance information together. The luminance information is associated with the display memory. Therefore, a plurality of display memories are respectively weighted with luminance.

The waveform processor 3 divides the data of the waveform memory into groups, and expresses the frequency of occurrence of the waveform of each group by luminance (details will be described later). When storing the dot data in the display memory, a display memory corresponding to the obtained luminance is selected, and the dot data is stored in the display memory.

Reference numeral 5 denotes a display device capable of displaying gradation data for displaying data in the display memory 4, and a CRT is usually used as the display device.

The operation in such a configuration will now be described. An analog signal is converted into a digital signal by the AD converter 1 and stored in the waveform memory 2. A case where the number of waveform data points is four times the number of pixel points on the display screen will be described. In this case, the display gradation is also set to four gradations. The data sequence of the waveform memory 2 is divided into four data units as shown in FIG. 2, and each group (4 data) is displayed in one pixel column as shown in FIG. The waveform processor 3 expresses the occurrence frequency information of the waveform of each group by luminance, out of the four data, data having four identical values is the brightest luminance, and data having three identical values is the second brightest. Data having two luminance values are converted so that the data having the same value is the third brightest luminance, and data having only one same value is the darkest luminance, and are stored in the display memory 4.

The display device 5 combines the data from the plurality of memories of the display memory 4 together with the weighted luminance and displays the data on the display screen.
FIG. 3 shows the relationship between the waveform data in the waveform memory and the display dots on the display device. FIG. 7A shows waveform data of each group, and FIG. 7B shows a display example. Regarding the four waveform data of the group (1), the two waveform data at both ends are stored as the darkest luminance in the display memory corresponding to the darkest luminance, and the two central waveform data correspond to the third brightest luminance. Stored in the display memory. For group (2), the left three waveform data are stored in the display memory corresponding to the second brightest luminance, and the rightmost waveform data is stored in the display memory corresponding to the darkest luminance. As for group (3), there are four identical values, so that they are stored in the display memory corresponding to the brightest luminance. The group (4) is stored in the display memory according to the group (1).

When the data stored in each display memory is displayed simultaneously with gradations, a display as shown in FIG. 3B is obtained. In the figure, the brightest gradation is represented by a black circle, the second brightest gradation is represented by a circle with a diagonal cross, and the third brightest gradation is represented by a hatched circle.

By dividing the data into groups as described above and forming a gradation display including the waveform generation frequency information for each group, even if the waveform data has more than the number of display pixel points, all the waveform information can be displayed without being truncated. Can be.

Note that the present invention is not limited to the embodiments, and various modifications can be made without departing from the object of the present invention.

For example, in the embodiment, the waveform data is divided into four data units and displayed on the screen in four gradations. However, other division numbers and gradation numbers may be used.

Further, when the relationship between the number of data in the waveform memory and the number of pixels on the horizontal axis of the display is different from the gradation value, the same can be coped with by changing the number of the same value data for changing the gradation. For example, when displaying 100 data in 16 gradations, the relationship is as shown in Table 1.

Further, the weighting of the luminance can be made variable. In this case, the weighting can be changed on the waveform processor 3 side or the display device 4 side. When the data is stored in the display memory 4, when the data is stored in the display memory 4, the storage destination is changed, and when the data is changed in the display device 4, the data is combined by changing the luminance weighting. .

It is also possible to enlarge and display a specific portion on the time axis after capturing the waveform.

<Effects of the Invention> As described in detail above, the present invention has the following effects.

When the number of data in the waveform memory is larger than the number of pixels on the time axis of display, displaying all data and its waveform generation frequency at the same time increases the amount of information to be displayed, and enables detailed portions to be specified.

Aliasing occurs due to thinning in the conventional digital oscilloscope, but such aliasing does not occur in the present invention.

When a specific portion is enlarged and displayed on the time axis after capturing the waveform, the waveform image does not change before and after the enlargement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a digital oscilloscope according to the present invention, FIG. 2 is a diagram for explaining grouping of waveform data, and FIG. 3 is an explanatory diagram for explaining a relationship between data contents and display. It is. 1 ... AD converter, 2 ... waveform memory, 3 ... waveform processor, 4 ... display memory, 5 ... display device.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 13/00-13/42 G09G 5/36

Claims (1)

(57) [Claims] An analog signal waveform is digitally converted by an AD converter, stored in a waveform memory, and then the contents of the waveform memory are converted into a screen image by a waveform processor and displayed on a display screen of a display device. In a digital oscilloscope, a plurality of memories for storing data converted into a screen image, wherein each memory corresponds to a dot on a display screen on a one-to-one basis, and a plurality of displays are weighted for each memory. When the number of data points of the waveform in the waveform memory is larger than the number of display data points on the display screen, the waveform processor divides the waveform data into groups, and for each group, the data value and the number of waveform occurrences. And has a function of distributing and storing them in the display memory so that the number of waveform occurrence frequencies corresponds to the luminance. The display device is configured to be capable of gradation display, wherein the contents of the entire display memory are simultaneously displayed so that all information on the data of the waveform memory can be simultaneously displayed on a display screen. And a digital oscilloscope.